cover cropping for small farms
TRANSCRIPT
Arkansas-Oklahoma Horticulture
Industries Show 2017
Cover Cropping for Small Farms
Presenter Luke FreemanHorticulture Specialist
1. Introduction
2. Benefits
3. Species
4. Management
5. Economics
Outline
2
What are cover crops?
3
• Grown for the benefit of the soil
• Mowed, tilled, grazed, but not harvested
• Improving soil quality Aggregation
Benefits of cover crops
4
• Improving soil quality OM + soil food web
Benefits of cover crops
5
• Improving soil quality Water infiltration
Benefits of cover crops
6
So this doesn’t happen
Photos by Rex Dufour, NCAT
• Keeping soil in place preventing erosion
Benefits of cover crops
7
• Suppressing weeds Smother crops + allelopathy
Benefits of cover crops
8
• Controlling diseases and nematodes– Phytophthora blight
– Verticillium wilt
Benefits of cover crops
9
Bio-fumigant mustard cover crop in high tunnel.Photo by Elena Garcia, U of AMarigold can suppress root-knot, lesion,
and reniform nematodes.
Photo attributed to Steve Groff
• Contributing Nitrogen (legumes)
• Recycling, capturing N (non-legumes)
Benefits of cover crops
10
• Attracting pollinators & beneficials
Benefits of cover crops
11
Summer cover crops
Cover crop species for AR & OK
12
Winter cover crops
Grasses
Legumes
Non-legume broadleaves (Brassicas)
• Sorghum-Sudangrass (Sudex)
– Seeded at 35-50 lb/a
– Weed suppression
– N scavenger
– 6+ ft tall
– 8-10k lb/a DM
– Mowed when 3-4’
– Drought-resistant
– Winter kill
Summer cover crops - Grasses
13
• Pearl millet
– Seeded at 15-20 lb/a
– 4-6 ft tall
– 60-70 DTM
– Can be difficult to kill
– Also German foxtail, and Japanese millet
Summer cover crops - Grasses
14
• Cowpea (Southern pea)
– ‘Iron and Clay’
– Seeded at 40-75 lb/a
– 60-90 DTM
– Drought tolerant
– 3-4k lb/a DM
– Can fix 75 lb N/a
– Mix with Sudex or millet
15
• Sunn hemp
(Crotalaria juncea)
– Seeded at 30 lb/a
– Weed control
– 9’ in 60 days
– 100-140 lb N/a
– Drought-tolerant
– Woody after 60 days
16
Sunn hemp terminated by walk-behind roller-crimper.Photo by Carolina Farm Stewardship Association
• Buckwheat
– Seeded at 48-90 lb/a
– Fast-growing
– Flowers in 30-45 days
– 2.5’ tall
– Allelopathic
– Beneficial habitat
– Can become weedy
17
• Cereal rye (Secale cereal)
– Seeded at 100 lb/a
– Grows to 3-6’ tall
– Extensive root system
– Weed suppressive
– Catch crop
Winter cover crops - Grasses
18
• Oats
– Seeded at 100 lb/a
– Nurse crop
– Rapid ground cover
– Grows 2-5’ tall
– Will winter-kill
19
Photo by Bob Bugg, University of California
Photo from the Ohio State University
• Crimson clover
– Seeded at 15-20 lb/a
– Significant growth in spring
– Can fix 160 lbs N/a
– Can be overseededinto fall vegetable plots
Winter cover crops - Legumes
20
• Hairy vetch
– Seeded at 20-30 lb/a
– Will fix 150 lb N/acre
– Can become weedy
– Will climb tall grain crops
21
• Austrian winter pea
– Seeded at 60-90 lb/a
– Sown as late as Oct.
– Will fix 130 lb N/acre
– Mixes well with rye or wheat
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• Tillage/Daikon radish
– Seeded at 8-20 lbs/a
– Fast growing
– Suppresses weeds
– Bio-drilling
– Winter-kills
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• Mustard
– Seeded at 5-15 lbs/a
– Fast growing
– Catch crop
– Allelopathic
– Glucosinolates act as bio-fumigant
– Beneficial habitat
Winter cover crops - Brassicas
24
Multi-Species Mixes
25
• Diversity
• Grass/legume
• C/N ratio
• Height
• Rooting depth
Managing cover crops
26
Planting and establishment – Seed drill
27
Small-scale grain drill. Photo by Jordan Engineering, jordanatveng.com
Timing of planting is key
Planting and establishment –Broadcasting
28
Hand-crank seed broadcaster. Photo from smallfarmtools.com
Planting and establishment –Incorporating seed
29
Planting and establishment –Irrigation?
30
Cover crop care – Irrigation & mowing
31
Reproductive phase: After flowering / before hard seed
Termination – WHEN?
32
Soft dough
Termination - Mowing
33
Sickle bar
Flail mowerPhoto by Local Roots Farm
Bush hogPhoto by Becky Sideman, from MOFGA.org
EarthtoolsBCS.com
Termination – Small scale solutions
34
Weed eater
Scythe/sickle
Termination – Roller/crimper
35
Incorporation
36
Incorporating cover crop with disks. Photo by Canewater Farm
Plowing in cover crop. Photo by Mark Schonbeck, VABF
Tilling in cover crop. Photo by Butternut Valley Farm
• Surface mulch
Incorporation – or not?
37
• Small-scale application residue management
Incorporation – or not?
38
• Small-scale application surface mulch
Incorporation – or not?
39
• Planting too late
• Cover crop becoming a weed problem
• Not being able to terminate in time
• Planting delay (3 weeks after incorporation)
• C-rich biomass resulting in N tie-up
• Cold soils from cover crop mulch
Potential pitfalls
40
Assessing cover crop performance
41
Biomass production by height
• Rule of Thumb Estimate:
– For 100% groundcover
– 6 inches = 2,000 lb/acre DWT
– Additional in. = 150 lb/acre
• Example:
– Cover crop 5’10” = 70 in.
– (2,000 lb) + (64)(150 lb)
= 2,000 + 9,600
= 11,600 lb/acre DWT
Assessing cover crop performance
42
Biomass production by weight• Use quadrat
– 1x1 m or 3x3 ft
• Cut biomass
• Place in bag or sack– Tear weight of bag
• Dry biomass
• Weigh biomass
• Calculation
– 43560 sq ft = 1 acre
– For 3x3 ft sample:
___ lb x 4840 = ___ lb/acre dry matter
Assessing cover crop performance
43
Assessing performance – Benchmarks
44
Cover crop Dry matter (lbs/acre)
Sorghum-Sudangrass 8,000-10,000
Grain rye 3,000-10,000
Oats 2,000-10,000
Buckwheat 2,000-4,000
Mustard 3,000-9,000
Radish 4,000-7,000
Cowpea 2,500-4,500
Crimson clover 3,500-5,500
Austrian winter pea 4,000-5,000
Hairy vetch 2,300-5,000
• Legumes
• Nodulation
• Inoculation
• Timing of termination
Assessing performance N fixation
45
Calculating biomass N
• N% of cover crop biomass
– Legumes: 3-4% N
– Cereals: 1.5-2.5% N
– 50/50 mix: 2.5-3% N
• Biomass N (lb/a) = N% x Dry wt biomass (lb/a)
• 50-60% of N will be plant available (PAN)
Cowpea example: 4,000 lb/a DM and 3.5% N
Biomass N = 0.035 x 4,000 x 0.5 = 70 lb/a PAN
Assessing performance N fixation
46
Assessing performance N fixation
47
Legume N content (lbs/a)
Cowpea 75-150
Sunn hemp 100
Crimson clover 70-150
Austrain winter pea 90-150
Hairy vetch 60-120*
*Studies have shown hairy vetch to contribute as much as
100 lbs/a of plant-available N
• Fertilizer N reduction with legumes
– Expect fertilizer replacement of 50-100 lb N/a
– Oregon State University study demonstrated savings of $500/a using vetch cover crop instead of feather meal in organic broccoli (Garrett, 2009) https://www.uvm.edu/vtvegandberry/NMP/PANFromCoverCrops.pdf
• Cost of cover crop PAN estimated at $2-3/lb
• Cost of PAN from feather meal fertilizer $5/lb
Economics of cover cropping
48
• Fertilizer reduction
– Kansas study showed Austrian winter peas and hairy vetch could provide enough N for muskmelons in plasticulture system without additional fertilizer (Singogo, 1996)
• Yield compared to fertilizer rates of 63 to 90 lbs N/a
Economics of cover cropping
49
• Oregon State University study (Luna, 2009)
– Oat-legume cover crop led to net increase of $50/a in revenue for organic corn production
– Phacelia-vetch cover crop increased broccoli production by 1.3 tons/a compared to fallow
• $2,370 increase in economic value per acre
– Oat-vetch cover crop increased broccoli yield when fertilized at 90 lbs/acre
• $3,460 increase in economic value per acre
From SARE Project “Managing cover crop and conservation tillage systems to enhance vegetable crop yields, economic returns and environmental quality”
Economics of cover cropping
50
• Reduced cost of weed control
– Biological management
– Bio-extensive system “Weed the soil”
– Weed-suppressive killed mulch
Economics of cover cropping
51
Pumpkins planted into killed rye cover crop.Photo by Ajay Nair, Iowa State University
Cover crops allow the Nordells to run a 6 acre market garden with just 2 people and horses.Photo from uvm.edu
Innovative applications
52
Cover crop seed
53
greencoverseed.com/
www.deercreekseed.com/
www.johnnyseeds.com/farm-seed/
www.groworganic.com/
www.southernexposure.com/
Resources
54
• ATTRA• www.ncat.attra.org
• SARE Cover Crops Topic Room• http://www.sare.org/Learning-
Center/Topic-Rooms/Cover-Crops
• Managing Cover Crops Profitably• NCSU Growing Small Farms, Cover
Crops Portal• https://growingsmallfarms.ces.ncsu.ed
u/growingsmallfarms-covcropindex/
• UC Davis SAREP Cover Crop Database• http://asi.ucdavis.edu/programs/sarep
/research-initiatives/are/nutrient-mgmt/cover-crops-database1
https://www.uvm.edu/vtvegandberry/
NMP/PANFromCoverCrops.pdf
