4 treatments x 4 sites effect of two seasons of cover crop ... stewcrop7-gaudin poster.pdf ·...
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Effect of two seasons of cover crop on soil health in almond orchards along a precipitation-gradient
Cynthia Crézé1, Amanda Hodson2, Mohammad Yaghmour3, Danielle Lightle3, David Doll3, Cameron Zuber3, Jeffrey Mitchell4, William Horwath1 & Amélie Gaudin4
1Department of Land, Air & Water Resources, UC Davis2Department of Entomology and Nematology, UC Davis
3University of California Agriculture and Natural Resources - Cooperative Extension4Department of Plant Sciences, UC Davis
We thank Project APIS and Kamprath Seeds for providing the seeds for this study. Financial support for this research is
provided by the Almond Board of California, the Western Sustainable Agriculture Research and Education graduate
fellowship (WSARE), the CDFA Healthy Soils program and Annie’s Sustainable Agriculture scholarship. The authors would
also like to acknowledge the help of UCCE Centers (Glenn, Merced and Kern counties). We also acknowledge the help of
the Gaudin, Horwath and Hodson labs for the support in conducting field work and sample analyses.***Site K 2019 pollinator was just 6 feet wide.
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RV PM SM
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Site T - 2019 Cover biomass
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B RV PM SM
Site M - 2019 Cover biomass
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Site K - 2019 Cover biomass
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Ryegrass
Vetch
Clover
Radish
Mustard
Canola
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Site K - 2018 Cover biomass
RV
Ryegrass
Vetch
Clover
Radish
Mustard
Canola
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B RV PM SM
Site M - 2018 Cover biomass
Acknowledgements - Project ID: STEWCROP7
Cover vegetation biomass (g/m2) x 3 sites – 2018-2019
00.20.40.60.8
11.21.41.61.8
Nov Feb May
Site K- SOC
SM PM B
00.2
0.40.6
0.81
1.21.4
1.61.8
Nov Feb May
Site M- SOC
SM PM RV B
0200
400600800
100012001400
16001800
Nov Feb May
Site M-TN
SM PM RV B
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0.60.8
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Nov Feb May
Soi
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bon
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Site T- SOC
SM PM RV
0200400600800
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Nov Feb May
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)
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Site K-TN
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Soil health shifts – 2 seasons of cover crop
Conclusions
Methodology
Introduction
Research Questions
• Design: Randomized Complete Block Design (RCBD) with four
replicates
• Field trials were established in conventional, commercial
orchards in Tehama county (site T), Merced county (site M) and
Kern county (site K).
• Cover crops (CC) were seeded with either soil mix (SM) (density
56 kg/ha) or a pollinator mix (PM) (density 9 kg/ha). The 2 cover
crop mixes were compared to resident vegetation and/or bare
soil (B) as controls.
• Covers were seeded from Oct 30-Nov 6 in 2017 and
from Nov 1-Dec 21 in 2018.
• Covers were terminated from March 30-April 10 in
2017 and from April 5-12 in 2018 (latest termination).
• Soil samples were collected at baseline, post cover
crop termination in Nov 2018, during the cover
establishment in Feb 2019, and post termination in
May 2019.
• Soil carbon (SOC) and nitrogen (TN) measurements are
reported on a per-weight basis.
• Despite similar seeding rates and
identical seed mixes, cover biomass
production and species composition
were site and season-dependent.
• Biomass production in the seeded
CC compared to RV varied with up
to 2 x more biomass in the CC in
2018, whereas there were little
differences observed in 2019.
• CC provided better groundcover (%)
in 2018 whereas RV provided better
cover in 2019.
• In 2019, the SM and PM contributed
7.8 and 8.1 g N/m2 to the system,
respectively.
0
0.5
1
1.5
2
2.5
3
3.5
Nov Feb May
Site M - SAR
SM PM RV B
0
0.5
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1.5
2
2.5
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3.5
Nov Feb May
Sod
ium
Ads
orpt
ion
Rat
io
Site T - SAR
SM PM RV
0
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1.5
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3.5
Nov Feb May
Site K - SAR
SM PM B
B>SB>RV*
• Results of SAR measurements from the
2018-19 winter cover crop season
indicated a decrease in sodicity under
vegetative covers (RV, PM and SM) with
significant differences (P<0.05) with
B>SM and B> RV at site M.
• Similarly, we observed season-dependent
trends of increased TN and SOC (P>0.05)
in the top 15-cm of the soil with up to
14% increases in both TN and SOC during
the cover crop.
• However, these factors (SAR, TN and SOC)
returned to near identical conditions
across treatments following termination
of the vegetative cover.
• Biological indicators showed significant
(P<0.05) and site-dependent effects of
the seeded cover: higher enzyme activity
of C processors (BG and CB) was
observed in the PM at site M and higher
food web enrichment index was
measured in the SM at sites T and M (not
pictured).
Figure 1. Cover vegetation biomass (g/m2) per site and per season
Figure 2. Sodium Adsorption ratio (SAR), soil organic carbon (SOC) and total soil nitrogen (TN) per site
1. Significant soil improvements were found in all vegetative covers (resident
vegetation and cover crop mixes), despite considerable differences in biomass
production.
2. Cover cropping can significantly enhance soil enzyme activity, thereby
supporting soil nutrient cycling functions.
3. Most soil quality improvements from cover cropping (i.e. SAR) occurred during
the cover establishment.
4. Further continuation of the practice (>2 seasons) is necessary to observe
substantial soil health enhancements.
1) To what extent does the selection and use of cover crops enhance the provision of multiple ecosystem
services such as soil health and C and N cycling in conventional almond orchards?
2) Does location along a precipitation gradient affect cover crop services?
Healthy soils provide critical ecosystem services for agriculture: biological processes for nutrient cycling, retention of
mineralized nutrients as well as water conductivity and storage. Cover cropping has been demonstrated to have a large impact
on soil health in arid, irrigated agricultural systems of the Central Valley (Mitchell et al., 2017). Cover crop species mixes and
functional trait selection have gained increasing attention, as a way to capture specific plant-to-soil effects and associated soil
health improvements (Cortois et al., 2016). Although short-term studies in the 1990s showed that cover cropping is compatible
with almond production, this practice was never widely implemented due to remaining concerns over resource competition
and operational challenges. This project addresses the increasing demand for soil-building resources and the adaptability of
this practice for almond orchards in California.
Coefficient gradient
Final stage: Overall performance
Ecosystem services
• Per cover crop combinations
• Based on coefficient gradients of ecosystem services
Developing Cover Crop Systems for Almond OrchardsCynthia M. Crézé1, Jeffrey Mitchell1, Andreas Westphal2, Danielle Lightle3, David Doll3, Mohammad Yaghmour3, Neal Williams4,
Amanda Hodson4, Brad Hanson1, Houston Wilson5, Steven Haring1 and Amélie C. M. Gaudin11 Department of Plant Sciences, University of California – Davis
2Department of Nematology, University of California – Riverside3 University of California Agriculture and Natural Resources – Cooperative Extension
4 Department of Entomology and Nematology, University of California – Davis 5 Department of Entomology, University fo California – Riverside
Develop feasible and practical winter cover crop systems for almond growers, which maximize agronomic
benefits and reduce operational concerns.Objective
Introduction
Experimental Sites
Experimental Design
2) Pollinator Mix (5 species/1 family) at 8 lbs./acre
ü 15% Bracco White Mustard (Brassica hirtum)
ü 20% Daikon Radish (Raphanus sativus)
ü 15% Nemfix Yellow Mustard
(Brassica juncea)ü 15% Common Yellow
Mustard (Brassica hirtum)ü 35% Canola
(Brassica napus)
AcknowledgementsFinancial support for this research is provided by The Almond Board of California(Modesto, CA) and graduate student fellowships from Western SARE (Project ID:GW18-142) and Annie’s Homegrown. The authors would like to thank SteveGruenwald, Jeff Bergeron and Greg Wegis for providing the sites to conduct thisresearch. The authors would also like to acknowledge Kimiora Ward, Cindy Montes,Cameron Zuber, Sequoia Williams, Janina Milkereit and members of the different labsinvolved for their help with orchard operations, sampling and analysis. Thank you!
Results 2018, First seasonNovember – April (~"month cover)
California - Almond Cover Crop surveyWe want to hear from growers! This survey will bring valuable insight into region-
specific needs as well as operational challenges. Results will be used to develop regionalbest management practices, as well as guide further research and extension activities.
www.almondcovercrop.faculty.ucdavis.edu
Almond production is faced with multiple challenges, many of which arerelated to soil degradation. Despite the need for soil health improvementstrategies, there is currently no scientific assessment of the impact of differentsoil management practices on soil health of almond orchards. Short-term studiesconducted in the 1990s showed that cover cropping is compatible with theseproduction systems. However, this practice was never widely implemented dueto remaining concerns regarding possible tradeoffs, particularly relating to waterusage. To address these uncertainties, our multi-disciplinary research team isevaluating multiple potential benefits and tradeoffs of cover cropping onecosystem services (soil health and food web support, weed management,pollination, parasitic nematode and NOW suppression and water balance). Thiswill provide growers with a comprehensive opportunity cost assessment andsupport the adoption of sustainable soil management practices.
BR
AS
SI
CA
1) Soil Mix (5 species/3 families) at 50 lbs./acre
ü 10% Bracco White Mustard (Brassica hirtum)
ü 10% Daikon Radish (Raphanus sativus)
ü 30% Merced Ryegrass (Secale cereale)
ü 20% Berseem Clover (Trifolium alexandrinum)
ü 30% Common Vetch (Vicia sativa)
GR
ASS
LEG
UM
E4 treatments x 4 sites
RCBD, replicated
BR
ASS
ICA
ü Strong cover crops effectively suppress weeds by outcompeting weeds for water, light, and other resources.
In greenhouse susceptibility assay,Root lesion nematodeü All cover crops suppressed root
lesion nematodes.ü Most suppressive cover crops:
Sunnhemp, Balansa Clover, andMedic.
ü Least suppressive cover crop:Lupine.
Ring nematodeü Crops that suppress root lesion do
not necessarily suppress ringnematodes.
ü Large variability in the suppressionpotential of different clover typeswas observed.
ü Sunnhemp was less suppressivecompared to many Clovers.
Both Root lesion & Ringü Rose clover suppressed both
nematode populations.
Cover crop impact on plant-parasitic nematodes from greenhouse susceptibility assay
(A) Root lesion nematode, (B) Ring nematodes
ü Cover cropping did not affect visitation to the orchard nor nut set of the trees.
For more info: Poster #23
ü Topsoil temperatures were cooler in the cover croppedtreatments than in the resident vegetation, whichindicate that the cover crops act as a barrier to heatflow and storage in the soil. However, temperatures at5 ft. during the critical frost periods were nearlyidentical between treatments.
Two Termination Dates:1) Early : February-March, at bloom2) Late: end of April
Water Usage
Almond Harvest
ü There was no observable cover crop present at Harvest.
ü Cover crop termination was successful.
ü Higher yields were observed in cover cropped (CC) plots compared to bare plots and resident vegetation plots (RV).
2nd leaf
16th leaf 16th leaf
Frost Risks
Weed pressure
For more info: Poster #113/114
Pollination
For more info: Poster #98
Navel Orangeworm (NOW)
Parasitic Nematode Suppression Soil Health
Cover Crop Functional Traits
ü Biomass production was proportional to precipitationamounts by vegetative cover type.
ü The seeded cover crop produced more biomass than thelocal resident vegetation at all three sites.
ü It is important to note that the species composition of thecover crop mixes varied widely amongst regions.
ü Due to differences in species composition by region, theC:N ratio of the cover crop also varied amongst sites.
ü Soil structure improved with higher macro and microaggregates in cover cropped plots.
ü Water infiltration improved both in the irrigated wetting zone and in the un-irrigated orchard middles.
ü Higher labile carbon was measured in cover cropped plots compared to the control.
ü There was no visible effect on tree stem water potential in this first season.
ü We are monitoring soil moisture through neutron probe readings taken to 9-feet depths.
ü Cover cropping does not interfere with and can even facilitate NOW sanitation by improving trafficability for shaking and mowing.
INSIGHTFUL AND CATCHY TITLE
Author list 1Department of Plant Sciences, University of California – Davis
Introduction
Methods
Acknowledgements
Conclusions and Future Research
References
Results Results
Text : minimum Arial 28
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 2. Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 3. Pollinator mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Cover Crop Survey To gain a better understanding of current barriers and motivators of cover cropping, we are conducting a California-wide almond growers’ survey. This will bring valuable insight into region-specific needs as well as operational challenges. Results will be used to develop regional best management practices, as well as guide further research and extension activities.
Frost risk (Tehama County). The goal was to monitor the microclimate above the cover crop compared to rows containing only resident vegetation to understand how orchard temperatures fluctuate and whether cover crops heighten frost risks. The most critical time period for frost damage was February 19-28, 2018. During this time period, average biomass was 63% greater in cover cropped plots, though normalized difference vegetation index (NDVI, a measure of presence of vegetation) values showed roughly 25% greater ground coverage in resident vegetation plots, indicating that there was much more cover crop biomass that had grown up, but that native vegetative grew out to cover more soil area. In row middles, sheltered temperature loggers were placed at 2 in., 3 ft. and 5 ft. height, and soil temperatures were measured at 2.5 in. depth. Frost protection irrigation was not utilized during this period. Figure 3 shows an example of the temperature fluctuations in the resident vegetation vs cover cropped plots. Topsoil temperatures were cooler in the cover cropped treatments than in the resident vegetation, which indicate that the cover crops act as a barrier to heat flow and storage in the soil. However, temperatures at 5 ft. during the critical frost periods were nearly identical between treatments. We plan to directly measure bud temperature in 2019 to better understand whether conditions experienced by the buds are different in cover cropped or resident vegetation areas.
Figure 3. Average temperatures (degrees C) in the resident vegetation (left graph) and the cover cropped (right graph) treatments from the frost event occurring February 19, 2018. Temperatures were measured in the topsoil and at 2 inch, 3 feet, and 5 feet above ground (AB). Temperatures at 5 ft were nearly identical between cover cropped and resident vegetation treatments.
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2Pr
ecip
itatio
n (m
m)
Arvin Late Termination
Dry biom
ass (g/m2)
Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Bare (4 rep) CC (4 rep)
0.0000
0.0005
0.0010
0.0015
Treatment
Kfs
(cm
/s)
Infiltration
Bare (4 rep) CC (4 rep)
0.0000
0.0005
0.0010
0.0015
Treatment
Kfs
(cm
/s)
Infiltration
Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 2. Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 3. Pollinator mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Pollinator mix species composition by dry matter weight-proportion by site
Cumulative precipitation and biomass production by CC mix and by site
CC (6rep) RV (3rep) Bare(3rep)0
100
200
300
400
POXC
(mg
C/k
g so
il)
Labile Soil Carbon
283.41
212.57
271.78
0 20 40 60 80 100
CC (8 reps)
RV (4 reps)
Bare (4 reps)
Total Soil Weight %
Aggregate stability
Large macroaggregates
Small macroaggregates
Microaggregates
Silt and clayCC (24rep) RV (8rep) Bare (8rep)
0.0
0.5
1.0
1.5
2.0
BD
(g/c
m3 )
Bulk density
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
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Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
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Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
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CorningLate Termination
Nov. 6 - Ap. 2
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ecip
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Arvin Late Termination
Dry biom
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Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
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CorningLate Termination
Nov. 6 - Ap. 2
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Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
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0
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CorningLate Termination
Nov. 6 - Ap. 2
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Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
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Nov. 6 - Ap. 2
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Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Benefits TradeoffsBenefits Tradeoffs
Wegis & Young, Kern County
Bosque Verde, Glenn Country
Castle Farms Merced County
Kearney Experimental Station, Fresno County
Nematode Suppression StudyInfected orchard + Greenhouse study
4/20 4/27 5/4 5/11 5/21 5/22 6/1 6/8 6/12 6/22 6/26
-15
-10
-5
0
Bar
Stem Water Potential
CC (8 reps)
Bare (4 reps)
Recorded at Kern County site
Tehama Merced Kern
0
1000
2000
3000
4000
5000
lbs/
acre
Average kernel yields per treatment (lbs/acre)
CC (8 reps) Bare (4 reps) RV (4 reps)
Coefficient gradient
Final stage: Overall performance
Ecosystem services
• Per cover crop combinations
• Based on coefficient gradients of ecosystem services
Developing Cover Crop Systems for Almond OrchardsCynthia M. Crézé1, Jeffrey Mitchell1, Andreas Westphal2, Danielle Lightle3, David Doll3, Mohammad Yaghmour3, Neal Williams4,
Amanda Hodson4, Brad Hanson1, Houston Wilson5, Steven Haring1 and Amélie C. M. Gaudin11 Department of Plant Sciences, University of California – Davis
2Department of Nematology, University of California – Riverside3 University of California Agriculture and Natural Resources – Cooperative Extension
4 Department of Entomology and Nematology, University of California – Davis 5 Department of Entomology, University fo California – Riverside
Develop feasible and practical winter cover crop systems for almond growers, which maximize agronomic
benefits and reduce operational concerns.Objective
Introduction
Experimental Sites
Experimental Design
2) Pollinator Mix (5 species/1 family) at 8 lbs./acre
ü 15% Bracco White Mustard (Brassica hirtum)
ü 20% Daikon Radish (Raphanus sativus)
ü 15% Nemfix Yellow Mustard
(Brassica juncea)ü 15% Common Yellow
Mustard (Brassica hirtum)ü 35% Canola
(Brassica napus)
AcknowledgementsFinancial support for this research is provided by The Almond Board of California(Modesto, CA) and graduate student fellowships from Western SARE (Project ID:GW18-142) and Annie’s Homegrown. The authors would like to thank SteveGruenwald, Jeff Bergeron and Greg Wegis for providing the sites to conduct thisresearch. The authors would also like to acknowledge Kimiora Ward, Cindy Montes,Cameron Zuber, Sequoia Williams, Janina Milkereit and members of the different labsinvolved for their help with orchard operations, sampling and analysis. Thank you!
Results 2018, First seasonNovember – April (~"month cover)
California - Almond Cover Crop surveyWe want to hear from growers! This survey will bring valuable insight into region-
specific needs as well as operational challenges. Results will be used to develop regionalbest management practices, as well as guide further research and extension activities.
www.almondcovercrop.faculty.ucdavis.edu
Almond production is faced with multiple challenges, many of which arerelated to soil degradation. Despite the need for soil health improvementstrategies, there is currently no scientific assessment of the impact of differentsoil management practices on soil health of almond orchards. Short-term studiesconducted in the 1990s showed that cover cropping is compatible with theseproduction systems. However, this practice was never widely implemented dueto remaining concerns regarding possible tradeoffs, particularly relating to waterusage. To address these uncertainties, our multi-disciplinary research team isevaluating multiple potential benefits and tradeoffs of cover cropping onecosystem services (soil health and food web support, weed management,pollination, parasitic nematode and NOW suppression and water balance). Thiswill provide growers with a comprehensive opportunity cost assessment andsupport the adoption of sustainable soil management practices.
BR
AS
SI
CA
1) Soil Mix (5 species/3 families) at 50 lbs./acre
ü 10% Bracco White Mustard (Brassica hirtum)
ü 10% Daikon Radish (Raphanus sativus)
ü 30% Merced Ryegrass (Secale cereale)
ü 20% Berseem Clover (Trifolium alexandrinum)
ü 30% Common Vetch (Vicia sativa)
GR
ASS
LEG
UM
E
4 treatments x 4 sitesRCBD, replicated
BR
ASS
ICA
ü Strong cover crops effectively suppress weeds by outcompeting weeds for water, light, and other resources.
In greenhouse susceptibility assay,Root lesion nematodeü All cover crops suppressed root
lesion nematodes.ü Most suppressive cover crops:
Sunnhemp, Balansa Clover, andMedic.
ü Least suppressive cover crop:Lupine.
Ring nematodeü Crops that suppress root lesion do
not necessarily suppress ringnematodes.
ü Large variability in the suppressionpotential of different clover typeswas observed.
ü Sunnhemp was less suppressivecompared to many Clovers.
Both Root lesion & Ringü Rose clover suppressed both
nematode populations.
Cover crop impact on plant-parasitic nematodes from greenhouse susceptibility assay
(A) Root lesion nematode, (B) Ring nematodes
ü Cover cropping did not affect visitation to the orchard nor nut set of the trees.
For more info: Poster #23
ü Topsoil temperatures were cooler in the cover croppedtreatments than in the resident vegetation, whichindicate that the cover crops act as a barrier to heatflow and storage in the soil. However, temperatures at5 ft. during the critical frost periods were nearlyidentical between treatments.
Two Termination Dates:1) Early : February-March, at bloom2) Late: end of April
Water Usage
Almond Harvest
ü There was no observable cover crop present at Harvest.
ü Cover crop termination was successful.
ü Higher yields were observed in cover cropped (CC) plots compared to bare plots and resident vegetation plots (RV).
2nd leaf
16th leaf 16th leaf
Frost Risks
Weed pressure
For more info: Poster #113/114
Pollination
For more info: Poster #98
Navel Orangeworm (NOW)
Parasitic Nematode Suppression Soil Health
Cover Crop Functional Traits
ü Biomass production was proportional to precipitationamounts by vegetative cover type.
ü The seeded cover crop produced more biomass than thelocal resident vegetation at all three sites.
ü It is important to note that the species composition of thecover crop mixes varied widely amongst regions.
ü Due to differences in species composition by region, theC:N ratio of the cover crop also varied amongst sites.
ü Soil structure improved with higher macro and microaggregates in cover cropped plots.
ü Water infiltration improved both in the irrigated wetting zone and in the un-irrigated orchard middles.
ü Higher labile carbon was measured in cover cropped plots compared to the control.
ü There was no visible effect on tree stem water potential in this first season.
ü We are monitoring soil moisture through neutron probe readings taken to 9-feet depths.
ü Cover cropping does not interfere with and can even facilitate NOW sanitation by improving trafficability for shaking and mowing.
INSIGHTFUL AND CATCHY TITLE
Author list 1Department of Plant Sciences, University of California – Davis
Introduction
Methods
Acknowledgements
Conclusions and Future Research
References
Results Results
Text : minimum Arial 28
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 2. Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 3. Pollinator mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Cover Crop Survey To gain a better understanding of current barriers and motivators of cover cropping, we are conducting a California-wide almond growers’ survey. This will bring valuable insight into region-specific needs as well as operational challenges. Results will be used to develop regional best management practices, as well as guide further research and extension activities.
Frost risk (Tehama County). The goal was to monitor the microclimate above the cover crop compared to rows containing only resident vegetation to understand how orchard temperatures fluctuate and whether cover crops heighten frost risks. The most critical time period for frost damage was February 19-28, 2018. During this time period, average biomass was 63% greater in cover cropped plots, though normalized difference vegetation index (NDVI, a measure of presence of vegetation) values showed roughly 25% greater ground coverage in resident vegetation plots, indicating that there was much more cover crop biomass that had grown up, but that native vegetative grew out to cover more soil area. In row middles, sheltered temperature loggers were placed at 2 in., 3 ft. and 5 ft. height, and soil temperatures were measured at 2.5 in. depth. Frost protection irrigation was not utilized during this period. Figure 3 shows an example of the temperature fluctuations in the resident vegetation vs cover cropped plots. Topsoil temperatures were cooler in the cover cropped treatments than in the resident vegetation, which indicate that the cover crops act as a barrier to heat flow and storage in the soil. However, temperatures at 5 ft. during the critical frost periods were nearly identical between treatments. We plan to directly measure bud temperature in 2019 to better understand whether conditions experienced by the buds are different in cover cropped or resident vegetation areas.
Figure 3. Average temperatures (degrees C) in the resident vegetation (left graph) and the cover cropped (right graph) treatments from the frost event occurring February 19, 2018. Temperatures were measured in the topsoil and at 2 inch, 3 feet, and 5 feet above ground (AB). Temperatures at 5 ft were nearly identical between cover cropped and resident vegetation treatments.
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
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(mm
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Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
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300
0
200
400
600
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Oct. 30 - Mar. 6
Prec
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(mm
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Arvin Early Termination
Dry biom
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Precip.
SM PM RV0
100
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300
0
200
400
600
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Nov. 2 - Apr. 9
Prec
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(mm
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Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
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300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Bare (4 rep) CC (4 rep)
0.0000
0.0005
0.0010
0.0015
Treatment
Kfs
(cm
/s)
Infiltration
Bare (4 rep) CC (4 rep)
0.0000
0.0005
0.0010
0.0015
Treatment
Kfs
(cm
/s)
Infiltration
Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 2. Soil mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Figure 3. Pollinator mix species composition by dry matter weight-proportion by site
Almond Board of California - 12 - 2017.2018 Annual Research Report
Figure 11. Pollinator mix species composition by dry-matter weight proportion by site
Figure 12. C:N ratio by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)) and by site
Corning, Tehama County
60.32% White Mustard16.92% Radish19.08% Ryegrass2.41% Vetch0.10% Clover1.17% Other
Merced, Merced County
8.41% White Mustard4.15% Radish59.40% Ryegrass17.90% Vetch1.32% Clover8.81% Other
Arvin, Kern County
28.14% White Mustard11.04% Radish49.49% Ryegrass4.82% Vetch0.02% Clover6.49% Other
Merced, Merced County
13.15% White Mustard7.39% Radish7.19% Yellow Mustard1.44% Nemfix YM16.07% Canola54.76% Other
Arvin, Kern County
44.62% White Mustard7.49% Radish19.34% Yellow Mustard7.83% Nemfix YM19.06% Canola1.65% Other
Corning , Tehama County
27.63% White Mustard10.98% Radish23.36% Yellow Mustard9.70% Nemfix YM25.94% Canola2.38% Other
Pollinator mix species composition by dry matter weight-proportion by site
Cumulative precipitation and biomass production by CC mix and by site
CC (6rep) RV (3rep) Bare(3rep)0
100
200
300
400
POXC
(mg
C/k
g so
il)
Labile Soil Carbon
283.41
212.57
271.78
0 20 40 60 80 100
CC (8 reps)
RV (4 reps)
Bare (4 reps)
Total Soil Weight %
Aggregate stability
Large macroaggregates
Small macroaggregates
Microaggregates
Silt and clayCC (24rep) RV (8rep) Bare (8rep)
0.0
0.5
1.0
1.5
2.0
BD
(g/c
m3 )
Bulk density
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Almond Board of California - 11 - 2017.2018 Annual Research Report
Figure 9. Cumulative precipitation and biomass production by vegetative cover type (soil mix (SM), pollinator mix (PM) and resident vegetation (RV)), by site and by termination date
Figure 10. Soil mix species composition by dry-matter weight proportion by site
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
CorningLate Termination
Nov. 6 - Ap. 2
Prec
ipita
tion
(mm
) Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Nov. 2 - Mar. 12
Prec
ipita
tion
(mm
)
Merced Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM0
100
200
300
0
200
400
600
800
Oct. 30 - Mar. 6
Prec
ipita
tion
(mm
)
Arvin Early Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Nov. 2 - Apr. 9
Prec
ipita
tion
(mm
)
Merced Late Termination
Dry biom
ass (g/m2)
Precip.
SM PM RV0
100
200
300
0
200
400
600
800
Oct. 30 - Apr. 2
Prec
ipita
tion
(mm
)
Arvin Late Termination
Dry biom
ass (g/m2)
Figure 4. Cumulative precipitation and biomass production by cover crop mix and by site
Benefits TradeoffsBenefits Tradeoffs
Wegis & Young, Kern County
Bosque Verde, Glenn Country
Castle Farms Merced County
Kearney Experimental Station, Fresno County
Nematode Suppression StudyInfected orchard + Greenhouse study
4/20 4/27 5/4 5/11 5/21 5/22 6/1 6/8 6/12 6/22 6/26
-15
-10
-5
0
Bar
Stem Water Potential
CC (8 reps)
Bare (4 reps)
Recorded at Kern County site
Tehama Merced Kern
0
1000
2000
3000
4000
5000
lbs/
acre
Average kernel yields per treatment (lbs/acre)
CC (8 reps) Bare (4 reps) RV (4 reps)
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References:
Cortois, R. et al. 2016. Plant-soil feedbacks: role of plant functional group and plant traits. Journal of Ecology 104:1608-1617. https://doi.org/10.1111/1365-
2745.12643
Mitchell, J. et al. 2017. Cover cropping and no-tillage improve soil health in an arid irrigated cropping system in California’s San Joaquin Valley, USA. Soil and Tillage
Research 165:325-335. https://doi.org/10.1016/j.still.2016.09.001B = bare plots; RV = Resident vegetation; PM = Pollinator mix; SM = Soil mix
B = bare plots; RV = Resident vegetation; PM = Pollinator mix; SM = Soil mix