Developing low-cost sustainable sweet potato production strategies to facilitate adoption in the mid-south

2010 Annual Report for LS09-215

Project Type: Research and Education
Funds awarded in 2009: $185,000.00
Projected End Date: 12/31/2013
Region: Southern
State: Mississippi
Principal Investigator:
Dr. Ramon Arancibia
University of Missouri Extension

Developing low-cost sustainable sweet potato production strategies to facilitate adoption in the mid-south

Summary

On-farm studies with the participation of sweetpotato growers and studies at the experiment station were conducted in Mississippi and Arkansas. Long term incorporation of winter cover crops (legumes, grasses and Brassicas) into the production system were evaluated in year 1. Cover crops sustained soil organic matter with a positive response in the conventional field. Yields were the same though. Legume cover crops had more wireworm damage, but insect damage was significantly lower in the organic field. Participating farmers in both states have gained knowledge about the benefits of cover crops and sustainable production systems, and will continue with the trials.

Objectives/Performance Targets

1. Evaluate sustainable ground management strategies to improve sweetpotato production in a sustainable production system.

First year incorporation of winter/spring cover crops into sweetpotato production was evaluated in two on-farm trials and at the NMREC-Pontotoc research station. In the on-farm trials, incorporation of Brassica cover crops (rape, radish and mustard) was compared to weedy fallow. At the research station, legume (crimson clover and hairy vetch), grasses (wheat and ryegrass) and Brassica (radish, rape and mustard) cover crops were compared to weedy fallow. In addition, conventional tillage prior to sweetpotato planting was compared to conservational tillage (no-till). Legume biomass were the highest followed by grasses, but Brassicas were inconsistent, either higher or the same as weedy fallow. Planting time may have influenced germination and growth. Cover crops sustained soil organic matter and in this first year a positive response was detected in the conventional field. Although sweetpotato yield differed among fields, first year incorporation of cover crops had no effect on yield compared to conventional fallow. Yield in no-till sweetpotato, however, was lower than conventional till except with hairy vetch which was the same.
Insect damage at harvest was evaluated also. Higher proportion of storage roots were free from insect damage in no-till fields compared to tilled fields. Part of this was due to marginally reduced wireworm damage. The type of cover crop planted had a marginal impact on the amount of wireworm damage observed. The legume cover crop treatments had significantly more wireworm damage than fallow or Brassica cover crop treatments. However, this difference did not result in any significant differences in the number of roots without any damage. When comparing insect damage among fields, however, significantly lower damage occurred in the organically managed field and the highest damage occurred in the conventional field.

2. Develop sweetpotato planting strategies including planting method and type of planting material to increase production efficiency and reduce costs.

Direct planting of sweetpotato seed roots was investigated in Mississippi to reduce planting costs. Pre-sprouted Beauregard seed roots (small storage roots) were hand planted in raised rows. Number of sprouts ranged from 3 to 11 per root. These vines initiated storage roots which were harvested and evaluated as new storage roots. Old seed roots, however, continued to enlarge and comprised 50% of the harvest. Storage roots of current fresh market sweetpotato varieties are prone to continue growing when replanted a year after harvested, however, there are varieties developed for industrial purposes that are less prone to overgrow when used as seed. Next season, direct planting trials will be focused on stimulating initiation of new storage roots.

3. Promote adoption of sustainable sweetpotato production systems through farmer participation in on-farm research and demonstrations trials, workshops and publications.

Initial steps to promote sustainable practices have been through on-farm studies with cover crops, one to one discussion with participating growers, informational workshop (August 9, 2010) in Pittsboro, MS, and the NMREC-Pontotoc station field day, August 17, 2010. Participating farmers in Mississippi and Arkansas have gained knowledge on use of cover crops and sustainable production of sweetpotatoes. Discussions with growers and presentation of first year results at production meetings are planned.

Accomplishments/Milestones

Mississippi accomplished

1. Established long term on-farm cover crops experiments with three sweetpotato growers including an organically managed field (S. Bailey, Penick Produce and N. Clark).
2. Established an additional long term cover crop and conservational tillage experiment at the NMREC-Pontotoc Experiment Station.
3. Conducted first year studies on the benefits of cover crops and no till on sweetpotato production. Evaluated biomass production, insect populations, effect on soil, swetpotato production, and insect damage.
4. Conducted field studies on direct planting seed roots to reduce planting costs in sweetpotato production. Evaluated sprouting, storage root initiation and production.
5. Replanted cover crops for the 2011 production season: three on-farm studies and at the research station. Based on results from the first year, cover crop species were modified in some fields according to the farmer interest and needs.
6. Offered a workshop to discuss sustainable practices in sweetpotato production
7. Conducted a field day for sweetpotato growers to showcase the cover crop and conservational tillage experiments.

Mississippi up coming

1. Analyze data and present first year results to stakeholders and scientific community.
2. Continue with on-farm research and demonstration trials on cover crops with participating farmers. A new field with high infestation of nematodes has been added to the project.
3. Continue with field studies with cover crops and conservational tillage in the station.
4. Repeat direct planting studies of seed roots to evaluate sprouting and storage root initiation
5. Conduct workshop/field day to showcase studies and discuss sustainable sweet potato production.

Arkansas accomplished

Co-PI visited and discussed with farmers individually during the growing season.
April 2010 – Soil analysis and cover crop planting
• Farmers participated in soil sample collection for analysis
• Soil samples were collected before the cover crop and analyzed for number of parasitic nematodes present.
• The four farmers, Ms. Edwards, Mr. Walker, Ms. Bradley and Mr. Cline planted their cover crops by April 15th. Delay in planting was caused by wet field conditions.
o Ms. Edwards broadcasted mixed brassica (collard, kale, mustard and turnip) seeds.
o Mr. Walker, Mr. Cline and Ms. Bradley planted the cover crops separately in rows (see pictures below).

June 2010 – Turning under cover crops
• Cover crops were ploughed under and sweetpotato slips planted one week after.
• Two soil samples were collected for nematode analysis, one before planting cover crops and the other just before sweetpotato harvesting.

June 2010 – Planting and harvesting sweet potatoes
• All four farmers were supplied with slips for planting whenever their fields were ready.
• Mr. Cline lost all his slips to drought. He did not have an irrigation system.
• The other three farmers irrigated their plots.

October 2010 – Harvesting sweet potatoes
• Soil samples were collected before harvesting and analyzed for number of parasitic nematodes present.
• Ms. Edwards and Ms. Bradley averaged 250 bushels per acre.
• Mr. Walker planted late and the potato roots did not size up. Most of potatoes were curls.

Overall, participating farmers now understand the cover crop sweet potato rotation system and are better prepared. We anticipate better data collection in the second year.

Arkansas challenges

• Delayed planting due to wet fields did not allow cover crops to get to flowering stage before they were incorporated into the soil as scheduled.
• Mr. Isiah Cline’s farm had no irrigation system and he lost his crop to drought.
• Mr. Walker planted his field late and the sweet potato roots did not size up. Most of his yields were curls.
• Collecting reliable data.

Arkansas up-coming

• Continued farm visits
• Planting of cover crops at Mr. Cline, Mr. Walker and Ms. Bradley’s farms.
• Conduct a first year’s sustainable production review meeting with collaborating farmers in April 2011.
• Continue with second year production activities.
• Conduct a workshop to discuss sustainable sweet potato production in May 2011. The workshop will include a review of the on-farm demonstration activities.
• May – June 2011, plant second year sweet potato crop following cover crops.

Impacts and Contributions/Outcomes

This project is evaluating and generating information about the benefits of adopting sustainable practices adapted to the region that are cost efficient and environmentally friendly. In addition, the on-farm studies are allowing farmers to experience and gain knowledge on cover crops and sustainable practices. The grower with the conventionally managed field became aware of the low OM content in his field and wants to include species that provide more biomass. The grower with the organically managed field has planted the whole field with hairy vetch this fall. The very low insect damage in the organically managed field support the benefits of sustainable/organic insect management practices in sweetpotato and offer the potential reduction in pesticide use if adopted in other fields. Evaluation of the entomofauna of these trials to determine the role of beneficial insects is warranted. With the opening of the sweetpotato processing plant in Delhi, LA, sweetpotato growers and the industry are looking for practices that can reduce production costs towards processing. Conservational tillage may aid in this goal and would impact directly on the energy requirements and the environment. Direct planting of root pieces/segments may also reduce planting costs, but they need further evaluation.

Collaborators:

Obadiah Njue

njueo@uapb.edu
Extension Horticulture Specialist
University of Arkansas at Pine Bluff
1200 N University Drive
Pine Bluff, AR 71601
Office Phone: 8705758152
Mark Shankle

shankle@ra.msstate.edu
Associate Research Professor
Mississippi State University
8320 Highway 15 South
Pontotoc, MS 38863
Office Phone: 6624894621
William Burdine

bburdine@ext.msstate.edu
Area Extension Agronomist
Mississippi State University
415 Lee Horn Dr., Suite 4
Houston, MS 38851
Office Phone: 6624564269
Fred Musser

fmusser@entomology.msstate.edu
Assistant Professor
Mississippi State University
Clay-Lyle Complex, Rm 127
Mississippi State, MS 39762
Office Phone: 6623252974