Winter cover crops were evaluated for a third year in on-farm and station studies. Results suggest that sweetpotato yields after cover crops were comparable or better than fallow, and the same between conservational and conventional tillage. Insect damage was the same among treatments this year. The information generated was presented and discussed with farmers through outreach activities and presentations at grower’s meetings. Participating farmers in Arkansas and Mississippi have gained knowledge and at least two growers have adopted winter cover crops two consecutive years in their production systems. Results were also presented at the National Sweetpotato Collaborators Group meeting.
Third year of winter cover crops incorporated into sweetpotato production was evaluated in on-farm trials and at the NMREC-Pontotoc research station. In addition, a third year conservational tillage (no till) trial was conducted at the experiment station to evaluate the adaptability of sweetpotato to no till planting after winter cover crop. Similar to the previous year, cover crop biomass ranged from 0.7 ton/ac to 2.4 ton/ac for fallow and crimson clover, respectively. In the on-farm study, legume and radish cover crops were the best biomass producers, then the grasses and at the bottom were mustard and weedy fallow. Although soil organic matter was the same among treatments, soil nitrate-nitrogen increased with legume cover crops. Sweetpotato yield after grasses and radish cover crops were comparable of better than fallow, but the yields after legume cover crops were reduced. It is possible that an excess of nitrogen, considering the broadcast fertilization made by the farmer, may have reduced storage root initiation. At the station trial, yields were the same among cover crops and comparable to the control fallow. Similarly, conservational tillage appears to have no detrimental effect on yield and yield classification. Marketable yield ranged between 536 bu/ac and 767 bu/ac. Conservational tillage appeared to have no effect on soil organic matter, but allowed access to planting sooner than conventionally cultivated field, in particular after a heavy rain. Modifications were made to a mechanical sweetpotato transplanter to include a coulter and a sub-soiling shank to facilitate planting into the stale bed (photo). This resulted in better plant stand and growth. Our results suggest that cover crops and conservational tillage may help in soil conservation and improvement, and in reducing production costs without sacrificing yield. However, soil type and moisture at planting may play a role in the success of the conservational tillage system.
Insect populations were monitored in the cover crops and sweetpotato crop. Sweep net samples collected in the spring while the cover crops were growing had many significant differences in insect densities. Aphids and parasitoids were most abundant in the mustard and vetch treatments. Lady beetles were abundant in the mustard, but no other treatments varied significantly. Big-eyed bug was abundant in the clover+ryegrass treatments, while plant bugs were most abundant in the flowering mustard and radish treatments. Similar differences were observed in the on-farm study. Soil insect were also monitored with pitfall traps when sweetpotato growth had cover the ground at both locations. There were no significant differences among cover crops for any of the most numerous species captured. However, when comparing no-tilled plots to tilled plots, there were a few significant differences. Carabid beetles were fewer in the no-tilled plots while ants were more numerous in the no-till plots.
Insect damage on sweetpotatoes was relatively light at both locations in 2012, especially in the on-farm study. None of the cover crop treatments was significantly different from each other at Pontotoc, but there were fewer large holes in the no-till plots compared to the equivalent tilled plots. The overall proportion of storage roots free of damage was not impacted by tillage or cover crop at the Pontotoc station. In the on-farm study, there were more large holes where vetch was grown than any other cover crop. As a result, under very light insect pressure, there were fewer undamaged storage roots after vetch and ryegrass than in any other cover crop treatment.
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 at two depths in flat ground and hipped after they sprouted to inhibit growth of the old root and promote development of new storage roots. Similar to previous years, covering the short vines with soil promoted development of new storage roots. This was significant in feedstock varieties. In fresh market varieties, however, the old seed-root tended to grow more in detriment of newly developed storage roots. The excessively grown old storage roots have no commercial value in the fresh market. Since the main goal is to promote development of new storage roots, selection and development of suitable varieties is necessary for direct planting.
During this project, sustainable practices have been promoted in Mississippi and Arkansas through on-farm demonstration studies with cover crops, one to one discussion with participating growers and other interested parties. Participating farmers in Mississippi and Arkansas have gained knowledge on cover crops and sustainable production of sweetpotatoes. In Mississippi, two of the initial three participating farmers have continued planting cover crops in their fields. These represent an 80 acre conventional field and a 100 acre organic field. In addition, results of the cover crop trials were presented and discussed with farmers at the Sustainable Agriculture Working Group (SAWG) meeting in Little Rock, AR, the Mississippi Sweetpotato Production Meeting in Pittsboro, MS, at the Mississippi Sweetpotato Producer Advisory Council (PAC) meeting in Verona, MS, and at the MS Fruit & Vegetable Growers/Agritourism Conference & Trade Show in Jackson, MS. In addition, results were presented to peers at the National Sweetpotato Collaborators Group meeting in conjunction with the SR-ASHS in Birmingham, AL. In Arkansas, two vegetable production workshops to discuss sustainable production systems were conducted. Two of the project’s contact farmers participated and shared their sustainable production experiences.
1.	Third year of on-farm cover crops experiments with three sweetpotato growers (S. Bailey and Jamie Earp) and in an organically managed field (Penick Produce) for farmers to experience the benefits and to promote adoption of cover crops.
2.	Continued with the long term cover crop and conservational tillage experiments at the NMREC-Pontotoc to evaluate insect populations, effect on soil characteristics, swetpotato yield and quality, and insect damage.
3.	Modified a sweetpotato planter for stale beds (no-till planting) that improved stand.
4.	Conducted field studies on direct planting depth of 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.
5.	Presented second year results to farmers at the MS and at the sweetpotato production meeting in Pittsboro, MS, February 9, 2012, the MS Sweet Potato Producer Advisory Council meeting in Verona, MS, February 16, 2012, and the Mississippi Fruit and Vegetable Growers/Agritourism Conference & Trade Show in Jackson, MS.
6.	Presented results at the Southern Sustainable Agriculture Working Group in Little Rock, AR, January 19-21, 2012.
7.	Presented results at the National Sweetpotato Collaborators Group meeting in Birmingham, AL, February 4-5, 2012.
1.	All the four contact farmers participated in the 2012 production year. They collected soil samples for nutrient and nematode analysis, planted their cover crops by April 10th, incorporated the cover crops and planted sweetpotato slips by June 15th.
2.	The Co-PI met with the farmers individually throughout the growing season and discussed the progress of the project.
3.	The Co-PI conducted two vegetable production workshops in which sustainable methods of production were discussed. Two of the project’s contact farmers participated and shared their sustainable production experiences.
4.	The contact farmers were very satisfied with the yields and quality of the roots.
5.	No insect damage was observed on sweet roots. The brassica cover crop (collards, turnips, mustard and kale) combinations provided control of sweetpotato soil-borne insects pests (note, this was based on observation and no scientific analysis was done). See pictures below.
6.	Contact farmers used some of the cover crops as a source of fresh vegetables. They shared their produce and production experiences with their communities.
1.	The greatest challenge has been the loss of two of our contact farmers. Mrs. Bradley died in August 2012, and Ms. Edward died in February 2013. Mr. Bradley completed the project for his wife. Ms. Edward completed the 2012 production activities before her short illness that claimed her life. Mrs. Bradley and Ms. Edward were very active and involved in their communities, and their experiences in sustainable production methods will continue to benefit those they interacted with.
1.	Analyze data and present third 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).
This project has evaluated and generated information about the benefits of adopting sustainable practices adapted to the Southern region that are cost efficient and promote stewardship of the farm land. 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/spring cover crops as part of their sweetpotato production system for two consecutive years (photo). 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, conservational tillage was not part of the on-farm studies and are needed for the farmers to experience the benefits. This may be beneficial to the processing industry which has expanded significantly in the last two years because of the health attributes of sweetpotato, but the high production cost is still acting as a barrier to further expansion. In the case of direct planting, development of suitable varieties would be necessary.
In Arkansas, all the four contact farmers understood the concept of sustainable production of sweetpotatoes using cover crops. They understand and also shared their knowledge on the benefits of use of cover crops in their vegetable crop production systems. The project’s contact farmers have added sweetpotato as a specialty crop in their farming systems. None grew sweetpotatoes before the project. The project’s contact farmers are now experienced master trainers in the use of sustainable production methods.
