Forage yield and nutritive value of summer legumes as affected by row spacing and harvest timing

Authors: BAATH, GURJINDER - Agrilife Research; SARKAR, SAYANTAN - Agrilife Research; SAPKOTA, BALA RAM - Agrilife Research; Flynn, Kyle; Northup, Brian; Gowda, Prasanna

Submitted to: Farming System
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2023
Publication Date: 12/13/2023
Citation: Baath, G.S., Sarkar, S., Sapkota, B., Flynn, K.C., Northup, B.K., Gowda, P.H. 2023. Forage yield and nutritive value of summer legumes as affected by row spacing and harvest timing. Farming System. https://doi.org/10.1016/j.farsys.2023.100069.
DOI: https://doi.org/10.1016/j.farsys.2023.100069

Interpretive Summary: Winter wheat is an essential, high-quality forage used for grazing stocker cattle from fall to spring in the US Southern Great Plains (SGP). However, the lack of nutritious forages during summers limits grazing by stocker cattle. To fill this quality gap, a short season species capable of producing significant yield and quality of forage is necessary. A two-year experiment was conducted to evaluate the performance of three legumes: soybean as a control, mothbean, and tepary bean, at different harvest dates, in response to row spacing (38- and 76-cm) and moisture regimes (rainfed and irrigated). Results showed forage yield by all legumes planted at 38 cm spacing was higher than at 76 cm spacing. Soybean was the most productive while mothbean had the highest relative feed value. None of the tested legumes performed consistently best at providing both high forage yields and nutritive values. While soybean produced more forage, mothbean and tepary bean provided high quality forage in terms of neutral detergent fiber, acid detergent fiber, and in vitro true digestibility. Future research should explore mothbean genotypes to identify cultivars with greater yield potential and develop agronomic practices that effectively utilize those cultivars.

Technical Abstract: Winter wheat (Triticum aestivum L.) is an essential, high-quality forage used for grazing stocker cattle from fall to spring in the US Southern Great Plains (SGP). However, the lack of nutritious forages during summers limits grazing by stocker cattle. To fill this quality gap, a short season species capable of producing significant yield and quality of forage is necessary. A two-year experiment was conducted to evaluate the performance of three legumes: soybean [Glycine max (L.) Merr.] as a control, mothbean [Vigna aconitifolia (Jacq.) Marechal], and tepary bean (Phaseolus acutifolius A. Gray), at different harvest dates, in response to row spacing (38- and 76-cm) and moisture regimes (rainfed and irrigated). Results showed forage yield by all legumes planted at 38 cm spacing (4.5 and 3.9 Mg ha-1) was higher than at 76 cm spacing (3.4 and 2.4 Mg ha-1) in 2018 and 2019. Soybean was the most productive while mothbean had the highest relative feed value (RFV) in both 2018 and 2019 (160 and 118, respectively). None of the tested legumes performed consistently best at providing both high forage yields and nutritive values. While soybean produced more forage, mothbean and tepary bean provided high quality forage in terms of neutral detergent fiber (NDF), acid detergent fiber (ADF), and in vitro true digestibility (IVTD). Future research should explore mothbean genotypes to identify cultivars with greater yield potential and develop agronomic practices that effectively utilize those cultivars.