by john m womack - iowa state university

by John M Womack

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Background - Biography

Born and raised in Cumberland County, Virginia Grew up on a farm raising tobacco, beef cattle, and poultry Life goal was to farm

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Attended Ferrum College in Virginia Obtained a BS in Agriculture with majority of course work focused on animal production.

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Got married

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Farming was not paying the bills Was hired by the Peter Francisco Soil and Water Conservation District as a Conservation Specialist

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Wanted to learn more about soil and crop science, to assist the farmers I was working with Discovered the online Master of Science in Agronomy program at ISU

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After 5 years left the SWCD and started to work for USDA Natural Resources Conservation Service as Soil Conservationist After 5 years working in Virginia transferred to the field office in American Samoa

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American Samoa

Located in the South Pacific 14o South and 170o West Territory of United States Made up of five islands and two atolls Tutuila, Aunuu, Rose, Swains, Tau, Olosega, and Ofu

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American Samoa

Climate Tropical marine 119 inches average annual precipitation 81 degrees F average temperature

Average Precipitation (inches) Pago Pago 1971-2000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

14.36 12.14 11.15 11.16 10.43 6.10 5.76 6.43 7.36 10.03 11.16 13.38

119.47

Average Temperature (degrees F) Pago Pago 1971-2000 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

81.6 81.9 82.0 81.6 80.9 80.5 79.6 79.7 80.4 80.8 81.3 81.7 81.0

Average precipitation and temperatures recorded at the Pago Pago Airport NOAA weather station for years 1971 through 2000

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American Samoa

Local Agricultural Small subsistence farms Communal owned land system Major crops – taro, breadfruit, bananas, coconut, pineapple, and papaya Major livestock - swine

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American Samoa

Local Agriculture Mostly traditional crops grown in a agro-forestry setting Current trend to raise more vegetables in garden type systems.

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American Samoa

Soils 4 main orders found on Tutuila

Soils orders on Tutuila Island compiled from USDA-NRCS soil map

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American Samoa

Soils Mollisols – Basalt parent material with tropical forest vegetation Inceptisols – Volcanic ash and/or cinders on lava or tuff Entisols – Young organic soils on lava flows Histisols – Organic muck

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American Samoa

Limitations to Agriculture Steep Slopes Shallow soils Loss of land to homes Rapid loss of fertility

NPS photo by Tavita Togai

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American Samoa

Resource Concerns Loss of soil due to steep slopes and high precipitation

Collection of sediment on coral reefs, causing the loss of marine habitat

Loss of soil fertility due to organic matter depletion

Need for additional weed control, either by mechanical or chemical methods

Reduction in soil moisture, due to loss of soil structure and increased evaporation

Increase use of herbicide for weed control

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Sunn Hemp

Origin Crotalaria juncea L. India ‘Tropic Sun’ variety released by University of Hawaii and NRCS

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Sunn Hemp

Benefits Increase soil organic matter Nitrogen fixation Cover for soil erosion and moisture conservation Weed suppression

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Project Objectives

Elevation where sunn hemp will grow on American Samoa The weed suppression ability of sunn hemp The rate of growth and days to flower Feasibility of sunn hemp as a cover crop using traditional hand farming methods on American Samoa

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Materials and Methods

Site Locations

Village Annual Rainfall

Soil Type Elevation Percent Slope

of Field Site 1 Aasu 204 Oloava silty clay loam 1200 ft 10% Site 2 Iliili 150 Iliili extremely stoney mucky clay loam 200 ft 8% Site 3 Viatogi 122 Iliili extremely stoney mucky clay loam 90 ft 3%

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Material and Methods

Site layout

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Material and Methods Site preparation Site were measured and flagged Then prepared by hand with machetes and hand tools

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Site preparation

Clearing land with lako

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Site preparation

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Seed preparation Sunn hemp seed, ‘Tropic Sun’ was provided by NRCS PMC in Hawaii The seed was treated with Apron 25W to meet import requirements Was treated with N-Dure inoculant the day of planting

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Planting Plots were sown by hand at a rate of 60 lbs/acre

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Observation and Data Collection Measurements

Germination Count - 14 days after seeding

Growth Rate – taken every 7 days

Soil Test – Taken on day of seeding and cutting

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Observation and Data Collection

Site 3 at 3 days after planting

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Site 2 at 60 days after planting, cutting with machete

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Ground cover of sunn hemp after cutting

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Row layout at each site

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Row Crop Variety Plant Type Seed/Slip

Planting Method Row/

Hill Site 2 1 Tomato Roma Slip Hill

2 Tomato Roma Slip Hill 3 Cucumber Unknown Seed Hill 4 Cucumber Unknown Seed Hill 5 Bean Long Seed Row 6 Bean Long Seed Row

Site 3 1 Corn Hawaii Supersweet Seed Row 2 Corn Hawaii Supersweet Seed Row 3 Sweetpotato Unknown Slip Hill 4 Sweetpotato Unknown Slip Hill 5 Tomato Cherry Slip Hill 6 Tomato Cherry Slip Hill

Vegetables planted at each site

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Results

Germination

Sunn hemp and weed seedling counts in each sunn hemp plot, 14 days after seeding

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Results

Germination

!" !" #"

Germination rates at each elevation. Means followed by the same letter are not significantly different at P=0.05.

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Results

Germination – Site 1 issues

Canopy cover of sunn hemp 30 days after seeding at site 2

Canopy cover of sunn hemp 30 days after seeding at site 1.

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Results

Germination – Site 1 issues Higher rainfall Cooler temperatures Trial done in winter

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Results

Growth Rate

Average plant height measurements in inches for sunn hemp and understory weeds

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Results

Growth Rate

a !"#"

Average growth rate per day in inches for sunn hemp and weeds at the three locations. Means followed by the same letter are not significantly different at P=0.05

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Results

Growth Rate

Growth of sunn hemp and understory weeds at each location over 60-day period

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Results

Before and After Soil Test

Soil analysis of location 2 and 3, before seeding sunn hemp and after cut down. Analysis preformed by University of Hawaii Soil lab.

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Results


Percent total soil nitrogen, before seeding sunn hemp and after cut down

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Results


Sunn hemp ground cover at 14 days after cutting cover at site 1

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Results

Weed Growth

Fallow Sunn Hemp Weed growth 30 days after sunn hemp cut down

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Conclusion

Grows well at lower elevations Can be planted with traditional methods Easy to cut down at first bloom Forms mat on ground for weed suppression and nitrogen release.

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Conclusion

Additional Studies Maximum elevation of growth Pest concerns Winter vs. Summer growth Available N for next crop

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Thank You

Questions?

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by john m womack - iowa state university

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