Transition strategies for an organic peanut-grain cropping system

Transition strategies for an organic peanut-grain cropping system

Summary

The two grain crop rotational years have been completed. The final year of the 3-year transitional certification period will take place in 2010, when all plots get planted to peanut for performance evaluation and pest incidence, plus a final organic certification (at on-farm locations; research station locations could not officially be certified for this project due to nearby conventional production plots). Both cowpea and pearl millet have performed well in the rotation thus far, however they have each had some disadvantages as well. Cowpea has done an excellent job of canopy closure and shading of weeds, keeping most weed problems minimal except for a few escapes (such as aggressive early season pigweed). Some limitations of cowpea thus far have been its viney growth habit, which makes it hard to cultivate except for a short timeframe after planting before the vines begin to overlap into row middles. The intertwined vines also make it very difficult to harvest. As for pearl millet, its upright/erect growth does not provide good row coverage, thus weeds have a greater opportunity to grow since more light can penetrate the canopy to the base of rows and row middles. However, this type of growth is more conducive to operating cultivation equipment to remove weeds fairly close to the base of the plants. But weeds directly within the drill, especially grasses have been difficult to suppress. Pearl millet also has been fed upon heavily by birds, which are hard to keep away, even with commercial deterrents.

The other rotation being evaluated in this project (aside from the fallow control treatment) is two consecutive years of bahiagrass prior to peanuts. Bahiagrass has historically proven to be one of the best rotational crops for peanuts because of its ability to suppress many diseases common to peanut. The first year of bahiagrass growth was minimal, as it had to compete with numerous weeds for establishment, with no means of controlling the weeds other than close mowing. Bahiagrass plots proved much more successful in the second year, after rhizomes had a chance to develop more robustly. This grass is aggressive and will often out-compete most weeds after the initial year of growth, which tended to be the case in this trial.

Objectives/Performance Targets

Determine effectiveness of organic transition strategies to manage weeds and improve soil quality in three prior land-use types.

Evaluate the impact of transition practices and weed management strategies on organic peanut production, pest management, and returns on investment.

Determine how management characteristics (physical and human) of farms relate to crop yield and economic returns of organic transition strategies across the transition period.

Accomplishments/Milestones

Progress remains steady. Cover crops for 2009 were well established. However, the very wet harvest season for summer 2009 crops delayed planting of winter 2010 cover crops, and soil conditions continued to be poor for planting until January 2010. Cold soil temperatures caused slow growth and minimal cover was in place for the winter 2010 phase. All plots for Hort Hill, CASE Farm, and Martin Farm locations have had soil tests run to determine nutrient needs before each summer crop, and have been fertilized with Nature Safe OMRI approved fertilizers based on soil test results/UGA recommendations. Untreated peanut seed has been reserved for the upcoming 2010 final phase of the rotation/certification period (peanut planted to all plots).

Weed seed-bank populations have been difficult due to heavy densities. Soil micro-organism activity has been assessed on one occasion, and will be conducted again toward the end of the project.

The Martin Farm location in Dodge County, GA was a feature stop on the 2008 Georgia Peanut Tour where project coordinator Scott Tubbs and project cooperator/Pulaski County Extension Coordinator Ronnie Barentine gave a presentation on the project. Also, a poster presentation of the project was displayed at the 2008 SARE Summit at Fort Valley State University in June 2008. A field day on organic peanut production is planned for June 11, 2010 at the Lang/Rigdon and Ponder Farms in Tifton, GA, to be hosted by University of Georgia, USDA-ARS, and Georgia Organics, which will feature this research project at the Ponder Farm location.

Impacts and Contributions/Outcomes

Organic peanut production has been centered in less-humid peanut producing areas where disease is less prevalent than in the southeast. New disease resistant cultivars have opened new opportunities for organic markets in peanut production in the southeast. To become certified for organic production, land must go through a 3 year transitional period in which no inorganic inputs can be used, but growers will not receive price premiums since these are not certified crops during the transitional period. Developing cropping systems/rotations that will get growers through the transition period with some economical crops and minimal pest incidence heading into peanut production and land certification will be beneficial in opening up new acreage and market opportunities for peanuts and alternative grain crops such as pearl millet and cowpea.

Other research experiments have evaluated peanut cultivars for their potential success under organic management. At least two of the most promising commercially available peanut cultivars will be evaluated at each location for this project to determine potential for maximized success and marketability.

Collaborators: