Subsurface banding poultry litter influences edamame yield, forage quality, and leaf greenness

Poultry litter is generated in large quantities throughout the southeastern United States and is an excellent nutrient source for increasing crop yields. However, surface applications result in nutrient losses to air, soil, and water. Subsurface banding poultry litter is a promising technology for reducing nutrient losses to surface and groundwater, but information is needed on optimum crop seeding distance from bands. This study evaluated edamame [Glycine max (L.) Merr. 'Edamame'] yield (residue, pod, and total plant), crop quality, and leaf greenness. Subsurface banded poultry litter and crop row distances (13, 25, and 38 cm) were compared with surface-applied poultry litter (all received 168 kg ha(-1) total N) under irrigated and nonirrigated conditions from 2019 to 2020. Both chlorophyll and edamame total yields were greatest (P <= .05) under subsurface banding litter, relative to surface applications, regardless of distance. Overall, greatest total crop yields were observed for 13- and 25-cm banding distances under irrigation and the 38-cm distance, irrespective of irrigation, relative to surface applications. Residue nutritive value for the 13-cm distance was greater under irrigation than dryland. Both systems provided high levels of nutritive residual mass, thus edamame could be used as a vegetable crop and a forage following harvest. Overall, subsurface banding poultry litter in conservation tillage systems is a viable replacement to surface applications for edamame production (vegetable and fodder), particularly in organic systems. Results can be used to develop nutrient management plans for organic edamame and other specialty crop production systems in the Mid-South.

Automated summary

Poultry litter is a valuable nutrient source for increasing crop yields, but surface applications result in nutrient losses. This study found that subsurface banding poultry litter can reduce nutrient losses and improve edamame yield and quality. The optimal crop seeding distance from bands was found to be 13-25 cm under irrigation and 38 cm under nonirrigation. The results suggest that subsurface banding poultry litter is a viable and sustainable alternative to surface applications for edamame production.