Okra cover crop management and poultry litter application effect on soil chemical properties in an organic system

Authors: HOLDER, TORRI - University Of Arkansas; SAVIN, MARY - University Of Arkansas; Nieman, Christine; Franco, Jose

Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 10/1/2022
Publication Date: 4/11/2023
Citation: Holder, T.E., Savin, M.C., Nieman, C.C., Franco Jr, J.G. 2023. Okra cover crop management and poultry litter application effect on soil chemical properties in an organic system. Arkansas Agricultural Experiment Station Research Series. 692;96-100.

Interpretive Summary: Cover crops, tillage, and fertility management are critical components of organic systems, yet organic crop production research in the mid-Southern US is severely lacking. This work reports on the results of a trial investigating okra as an alternative cover crop, and the impacts of different termination strategies and poultry litter application methods on organic small grain production. The results of this study showed that annual cropping systems that utilize organic matter-building practices such as cover cropping and poultry litter application exhibited K, Mg, and S availability that was not often different to perennial pasture systems. While nutrient availability varied between the perennial locations, soil nutrient concentrations during 1 year of summer cover crop followed by poultry litter application ranged between the control site with the lowest nutrient values and the control site with the largest concentrations. There were very few significant differences in Mg, K, and S between the first sampling date and the final sampling date across annual treatments, indicating the importance of long-term monitoring (> 1 year) in order to understand the impacts of management practices on soil nutrient availability and to make comparisons of annual cropping practices compared to perennial management. Though more research is needed, these results are relevant to organic producers interested in reducing soil disturbance and minimizing nutrient losses from poultry litter applications while maintaining crop yields.

Technical Abstract: This study investigated the effect of 1 year of cover crop termination strategy and poultry litter application method on soil chemical properties including electrical conductivity (EC) and Mehlich-3 extractable nutrients in relation to soil chemical properties of perennial management systems. Soil samples were collected from three perennially managed locations and from an organic cropping system where an okra (Abelmoschus esculentus L.) cover crop was terminated by roller crimper, disk, or hay mower followed by poultry litter application treatments including top dress unincorporated, top dress incorporated, subsurface applied, or no poultry litter. A significant interaction between treatment and time was observed for EC, K, Mg, and S across treatment types. Electrical conductivity was greater under annual management treatments than perennial systems until the end of year 1, and Mehlich-3 extractable K, and S averaged over all termination and poultry litter application treatments increased in the fall but were not different to the values observed under perennial management after 1 year. Mehlich-3 extractable Mg averaged over all termination and poultry litter application treatments were not different in the fall and were less than concentrations measured under perennial management in the first spring following the winter crop. These results are informative for understanding how nutrient availability may be affected by management in the first year after adding poultry litter and utilizing different termination methods following a cover crop in a summer rotation in the Mid-Southern US.