Location: Soil Dynamics Research2022 Annual Report
1. Determine weed suppression, soil coverage, and agronomic and economic benefits for monoculture and mixed species high-residue cover crops in conservation tillage for diverse crop production systems of the southeastern U.S. 1a. Evaluate monoculture and mixtures of cereal, legume, and selected Brassica cover crop species on weed dynamics in corn, cotton, peanut, and soybean. 1b. Evaluate and develop integrated weed control systems to diminish herbicide resistant and troublesome weed yield loss in cotton. 1c. Evaluate cover crop management across single species and mixtures to compare soil health benefits, while improving biomass production. 2. Integrate new equipment, high residue cover crops, and conservation tillage into cropping systems that foster sustainability and resiliency, increase efficiency, and reduce risk by promoting soil health and yield stability. 2a. Evaluate effects of different planting factors in a no tillage cotton system with a rye cover crop. 2b. Develop a no tillage equipment system compatible with a modular tractor for vegetable production. 2c. Determine the effects of cereal rye seeding rates and timing of termination methods on soybean production in a no tillage conservation system. 2d. Determine cash crop performance across high residue conservation tillage systems and different agronomic management factors. 3. Increase environmental sustainability of pasture and forage-based beef production systems. Research can include, but is not limited to, incorporating broiler litter into pasture-based grazing systems; cropping systems with beef cattle production through grazing cover crops utilized in soil conservation programs; production of forages adapted to local growing conditions and resilient to a changing southern climate to improve production efficiency and environmental benefits; and lowering fertilizer and energy inputs and associated production costs to maximize profitability.
Research objectives are designed to develop conservation systems that will improve soil quality, conserve natural resources, and increase production efficiency, increase environmental sustainability of pasture and forage-based beef production systems, while reducing risk for producers. These objectives will be accomplished by examining cover crop benefits (agronomic and economic) for single species and mixtures across diverse cropping systems of the southeast. In addition, we will also examine how integrating cover crops with management strategies designed to maximize benefits for cropping systems will promote soil health and productivity. Major areas of focus include: (1) examining weed germination across single species cover crops and mixtures for popular row crops grown across the southeast; (2) integration of cover crop mixtures into herbicide resistant weed control strategies; (3) comparisons of cover crop management strategies across single species cover crops and mixtures to identify how to maximize benefits; (4) evaluation of cover crop seeding rates, termination timing, and cash crop planting speeds on cash crop productivity; (5) development of equipment for a modular tractor suitable for vegetable production; (6) evaluation of cash crop performance across high residue cover crop systems; and (7) identifying tillage and seeding rate guidelines for a carinata biofuel crop. In addition, the research will focus on incorporating broiler litter into pasture-based grazing systems; cropping systems with beef cattle production through grazing cover crops utilized in soil conservation programs; production of forages adapted to local growing conditions and resilient to a changing southern climate to improve production efficiency and environmental benefits; and lowering fertilizer and energy inputs and associated production costs to maximize profitability.
Experiments, data analysis, and manuscript synthesis have been accomplished or are ongoing for multiple experiments designed to examine how cover crop management affects cover crop benefits. Experiments, data analysis and manuscript synthesis are also on-going that include comparisons between single cover crop species and multi-species cover crop mixtures for soil carbon (C) levels, microbial activity, and weed suppression across various cropping systems. Research has concluded for carinata, a potential biofuel crop for the Southeast, that involved investigating interactions between carinata seeding rates and conventional and conservation tillage systems. Other tillage comparisons include an examination among different forms of surface tillage across different nitrogen (N) rates for winter wheat production. Cooperative research with Auburn University to examine how single and multi-species cover crops affect soil properties is also continuing, as well as determining how cover crop grazing duration affects soil and crop productivity. In addition, experiments evaluating cover crop termination and transplanting machinery design and subsequent design refinement continue. Technology transfer activities have continued, which are related to many facets of all the previously described research.
1. Cover crop grazing in southeastern U.S. cropping systems. Grazing livestock on winter forages in the Southeast U.S. raises questions about the possibility of these forages also serving as cover crops. Extended grazing periods may benefit livestock but diminish surface residue and subsequent soil health benefits. Auburn University collaborators and ARS researchers at Auburn, Alabama, examined winter grazing impacts on soil health indicators for three cattle removal dates and an non-grazed control in a cotton/peanut rotation. Increasing soil organic content (SOC) and improving soil health with winter grazing of cover crops exists for producers with row crop and livestock operations. After two years, microbial biomass carbon (C) was highest in the control treatments, likely due to greater cover crop biomass on the soil surface at termination. No differences were observed between treatments for other soil health indicators that suggests integrating winter grazing livestock does not negatively nor positively impact selected dynamic soil properties in the short-term. More time under grazing treatments is needed to thoroughly evaluate how winter grazing livestock impact soil health.
2. Soil health changes minimal from short-term cover crop use. Soil health restoration is crucial to maximize productivity in historically eroded soils of the southeastern United States. Cover crops are one management strategy to improve soil health and future productivity. Auburn University collaborators and ARS researchers at Auburn, Alabama, examined various soil health indicators following 2 years of cover cropping before cotton in fine-textured soils of north and coarse-textured soils of south Alabama. Monocultures, which may cost less, produced equal biomass to potentially more expensive mixtures. However, soil health indicators seldom differed between monocultures and mixtures after 2 years of cover crop treatments, although soil carbon (C) increased on the fine-textured soil. Our results demonstrate that long-term cover crop use may be required to produce documentable, consistent changes in soil health properties.
3. Sunn-hemp cover crop management in a no-till corn system in Cambodia. Conservation agriculture (CA) is gaining popularity in Cambodia to sustain soil fertility, productivity, and profits. However, the adoption remains low due to the insufficient engagement of local equipment services into CA machinery and knowledge. Kansas State University and Cambodia Royal University of Agriculture collaborators and ARS researchers at Auburn, Alabama, compared different no-till seeders and sunn hemp residue retention methods for corn sowing and to determine their effects on growth and yield. The results show plant population, plant diameter, and kernel characteristics were greater with the ‘Brazilian’ seeder, when compared to the ‘Morrison’ seeder. Soil moisture was also significantly affected by residue retention with higher volumetric moisture content following rolled and crimped residue compared to disked/incorporated residue. Our study demonstrates that using rollers/crimpers and no-till planters is feasible in Cambodia’s small farming CA systems although more research is needed to study long-term effects on crop yield and soil health.
4. Cover crop termination methods on no-till cantaloupe. In a no-till system, there are many methods to terminate cover crops including mechanical termination by rolling and crimping or mowing, but mowing can result in cover crop re-growth and loose residue interfering with the planter during subsequent cash crop planting. ARS researchers at Auburn, Alabama, conducted research to determine the effects of different cover crops and termination methods on cantaloupe yield in a no-till system. Crimson clover, cereal rye, and hairy vetch cover crops were terminated using two different roller-crimpers, including a two-stage roller-crimper attached to a traditional four-wheel tractor and a powered roller-crimper attached to a two-wheel walk-behind tractor, and evaluated weekly for three weeks after rolling. Three weeks after rolling, higher termination rate was found for flail mowing compared to lower termination rates for a two-stage roller and powered roller-crimper. There were no significant differences in cantaloupe yield among the rolling treatments; however, yields were higher for cereal rye and hairy vetch cover crops compared to crimson clover.
Kornecki, T.S., Kichler, C.M. 2022. Effectiveness of cover crop termination methods on no-till cantaloupe. Agriculture. 12(1):66. https://doi.org/10.3390/agriculture12010066.
Singh, R., Prasad, R., Guertal, E., Balkcom, K.S., Lamba, J. 2021. Effects of broiler litter application rate and time on corn yield and environmental nitrogen loss. Agronomy Journal. 114:415-426. https://doi.org/10.1002/agj2.20944.
Crowell, H., Gamble, A., Feng, Y., Balkcom, K.S., Yang, A. 2021. Impacts of winter grazing on soil health in southeastern cropping systems. Agrosystems, Geosciences & Environment. 5:e20240. https://doi.org/10.1002/agg2.20240.
Johnson, A.M., Gamble, A., Balkcom, K.S., Hull, N.R. 2021. Influence of cover crop mixtures on soil health in southeastern crop production. Agrosystems, Geosciences & Environment. 4:e20202. https://doi.org/10.1002/agg2.20202.
Korres, N.E., Loka, D.A., Gitsopoulos, T.K., Varanasi, V.K., Chachalis, D., Price, A.J., Slaton, N.A. 2022. Salinity effects on rice, rice weeds, and strategies to secure crop productivity and effective weed control. A review. Agronomy for Sustainable Development. 42:58. https://doi.org/10.1007/s13593-022-00794-4.
Greene, W., Tredaway, J., Price, A.J., Monks, D. 2022. Cotton (gossypium hirsutum) cultivar response to glufosinate plus s-metolachlor applied post using two nozzle types. Weed Technology. 35:1023-1028. https://doi.org/10.1017/wet.2021.102.
Hin, L., Kornecki, T.S., Reyes, M., Tivet, F., Hok, L., Buntong, B., Lor, L., Leng, V., Suos, V., Clemmons, H. 2021. Effects of different management methods for sunn-hemp cover crop on corn production in a no-till system in Cambodia. Applied Engineering in Agriculture. 37(5):805-818. https://doi.org/10.13031/aea.14345.