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

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

Summary

Second year studies suggest that depending on the species winter cover crops improve soil organic matters and soil fertility for sweetpotato production. Yields were similar among cover crops and fertilized/non-fertilized treatments suggesting that legume cover crops may provide for the nitrogen requirement in sweetpotato. Insect damage was the same among treatments this year. Outreach activities include presentations at growers/farmers meetings in Mississippi and Arkansas. Results were also presented at regional and national professional meetings. In addition, participating farmers have gained knowledge and in Mississippi, two growers have adopted cover crops in their production system.

Objectives/Performance Targets

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

Second year incorporation of winter cover crops into sweetpotato production was evaluated in two on-farm trials and at the NMREC-Pontotoc research station (photos). An additional on-farm study was conducted, but an unexpected change in the farmer’s plan resulted in the field planted to soybean after the cover crop. In addition, a second year conservational tillage trial was conducted at the experiment station to evaluate the adaptability of sweetpotato to no till planting after winter cover crop (photo). Cover crop biomass production was higher in the conservational tillage and ranged from 1ton/ac for weedy fallow to 6ton/ac for crimson clover and wheat. In the conventional tillage, biomass of grasses was higher while rape and mustard were similar to weedy fallow. Radish biomass, however, was similar to legumes. The increase in soil organic matter was significant with legumes and wheat, especially in light sandier soils.

Similar to the first year, sweetpotato yield after cover crops was similar to the control fallow ranging between 350bu/ac and 500bu/ac total. In addition, sweetpotato yields in no-till management system were similar to conventional system. A heavy rain right after planting may have help with moisture requirement for plant establishment and storage root initiation. These results suggest that cover crops and conservational tillage may help in soil conservation and improvement, and in reducing production costs without scarifying yield. However, soil type and moisture at planting may play a role in the success of this system. In addition, legume cover crops may reduce the use of nitrogen fertilizer.

Insect damage at harvest was evaluated also and was not significantly impacted by cover crop as well as by tillage. There were no differences in the total insect incidence between no-till plots and conventional plots in sandy soil. However, storage roots grown in heavier soil had less damage. When comparing insect damage among fields, in contrast to last year, insect incidence in the organic field was similar to the adjacent 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 seed-roots (small storage roots with no commercial value) were hand planted in flat ground and hipped after they sprouted. Covering the short vines with soil promoted development of new storage roots in some varieties, but not in Beauregard. The excessively grown old storage roots have no commercial value in the fresh market. Marketable yield ranged between 300 and 500bu/ac among varieties. Since the main goal is to optimize US1 storage roots, careful selection of varieties is necessary when direct planting. These results suggest that the flat planting and hipping system is a promising technology with varieties prone to restricted growth of the mother root.

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

During this project, sustainable practices have been promoted through on-farm studies with cover crops, one to one discussion with participating growers, and at the NMREC-Pontotoc station field day, July 14, 2011. Participating farmers in Mississippi and Arkansas have gained knowledge on cover crops and sustainable production of sweetpotatoes. In Mississippi, two participating farmers have adopted cover crops for the first time in their fields (photos). These represent an 80 acre conventional field and a 100 organic field. These fields will continue to be monitored for further evaluations.
In addition, results of the cover crop trials were presented at the National Sweetpotato Collaborators Group meeting in conjunction with the National Sweetpotato Convention in Alabama and the Southern Region ASHS meeting in Hawaii. More than 300 sweetpotato growers from US and Canada meet at the Sweetpotato Convention annually.

• Cover crop Trial at Earp’s
• No-till planted sweetpotato
• Cover crop trial at the Pontotoc research station
• Cover crop trial at Clark’s

Accomplishments/Milestones

Mississippi accomplished
1. Two years of on-farm cover crops experiments with three conventional sweetpotato growers (S. Bailey, Norman Clark and Jamie Earp) and in an organically managed field (Penick Produce) for farmers to experience the benefits and to promote adoption.
2. Established an additional long term cover crop and conservational tillage experiment at the NMREC-Pontotoc to evaluate insect populations, effect on soil characteristics, swetpotato yield and quality, and insect damage.
3. Conducted field studies on direct planting seed roots to reduce planting costs in sweetpotato production. Developed a system to promote initiation of new storage roots by planting in flat ground and hipping after sprouting.
4. Replanted cover crops for the 2012 production season: three on-farm studies and at the research station. Based on results from the previous years, cover crop species were modified in some fields according to the farmer interest and needs.
5. Conducted a field day at the NMREC-Pontotoc station for sweetpotato growers to showcase the cover crop and conservational tillage experiments.
6. Presented first year results to farmers at the MS Sweet Potato Council Meeting, January 7, Pittsboro, MS and at the sweetpotato production meeting, March 18, 2011, Pittsboro, MS.
7. Presented results at the National Sweetpotato Collaborators Group meeting in Orange Beach, AL and at the ASHS annual meeting in Hawaii.

Mississippi up coming
1. Analyze data and present second year results to stakeholders and scientific community (sweetpotato production meeting, PAC meeting, Southern Sustainable Agriculture Working Group meeting, and National Sweetpotato Collaborators Group/SR-ASHS meeting).
2. Continue evaluating participating farmers that adopted cover crop.
3. Repeat and evaluate direct seed-root planting in flat ground and hipping system to promote initiation of new storage roots.
4. Compile all data for final report and write journal/extension articles.

Arkansas accomplished

March 2011
1. Soil samples were collected and analyzed for nematodes
2. Farmers and students participated in soil sample collection for analysis.
3. All four participating farmers, Ms. Edwards, Mr. Walker, Ms. Bradley and Mr. Cline planted their cover crops by April 5th. Ms. Edwards and Mr. Walker planted their cover crops in October 2010.
June 2011
1. Three of the four participating farmers planted their sweetpotatoes by June 10, 2011. Mr. Walker planted his sweetpotato slips by the end of June.
2. Ms. Edwards and Mr. Walker irrigated their sweetpotato plot as needed. Ms. Edward was very satisfied with her yields (about 350 bushels per acre). There was minimum insect damage. (see picture below).
3. Mr. Walker’s sweetpotatoes did not yield well due to late planting followed by a very hot summer.
4. Ms. Bradley’s sweetpotatoes performed relatively well (about 300 bushels per acre)
5. Mr. Cline did not irrigate his sweetpotatoes. His crop received very little rain throughout the growing season. His yields were very low (see picture below).

December 2011 – Workshops
1. December 12, 2011: Co-PI conducted a “Sustainable Vegetable Production” workshop at Marianna, AR. The workshop included participants from Lee, Phillips, Monroe, and St. Francis counties. The project’s (sweetpotato/cover crop rotation) objectives and progress were discussed. There were 51 participants, including 5 extension agents and Mr. Bradley who represented Ms. Bradley (one of the project’s contact farmer).
2. December 20, 2011: Co-PI conducted a “Sustainable Vegetable Production” workshop at the University of Arkansas at Pine Bluff, AR. The workshop included participants from Jefferson, Grant, and Lincoln counties. The project’s (sweetpotato/cover crop rotation) objectives and progress were discussed. There were 23 participants, including 4 extension agents and 3 project’s contact farmers (Mr. Cline, Ms. Edward, and Mr. Walker).

Arkansas challenges
1. A very hot and dry growing season. Mr. Cline, a transitioning Organic Farmer did not have irrigation for his sweetpotatoes and he experienced very low yields.
2. Lack of uniformity in participating farmer’s cultural practices.
3. Collecting reliable data.

• Harvest at Ms. Edward’s
• Mustard and turnip greens at Mr. Walker’s

Impacts and Contributions/Outcomes

This project has evaluated and generated information about the benefits of adopting sustainable practices adapted to the region that are cost efficient and environmentally friendly. The on-farm studies allowed farmers to experience and gain knowledge on cover crops and sustainable practices. Two participating farmers in Mississippi (Bailey and Penick) as well as in Arkansas have adopted winter/srping cover crops as part of their sweetpotato production system for the first time. The Mississippi growers are or have been members of the MS Sweetpotato Council and are well known among sweetpotato farmers who look up to them for innovative production practices. Therefore, it is expected that more farmers will learn and adopt sustainable production practices in Mississippi.

Conservational tillage and direct seed-root planting looks promising and may aid in reducing production costs and would impact directly on the energy requirements and the environment. However, more studies are needed before recommendation and careful selection of varieties adapted to these technologies is necessary. This is critical not only for farmers but also for the processing industry which has expanded significantly in the last two years. Increase in the demand for sweetpotato is attributed to its health attributes that makes it very desirable by consumers, but the high production cost is still acting as a barrier to further expansion.

• Bailey’s field to wheat and radish cover crop, MS
• Penick’s organic field with hairy vetch, MS

Collaborators: