Clipping Forage Sorghum Twice and Nitrogen Topdressing Offer an Option for Dual-Purpose Use for Cover Cropping and Fodder in Mixed Crop/Livestock Farming Systems

Abstract

Management practices that promote dual-purpose use of cover crops as forage and soil cover can encourage adoption in mixed smallholder (SH) farming systems. This study investigated the feasibility of dual-purpose use of forage sorghum (Sorghum bicolor x Sorghum bicolor var. sudanense) by testing the effects of clipping frequency and nitrogen (N) topdressing on the root biomass, crude protein (CP), acid detergent (ADF), and neutral detergent fiber (NDF) in the greenhouse and vegetative biomass on the experimental farm station. Four levels of clipping were tested: not clipped (C1), clipped once (C2), twice (C3), and thrice (C4). Nitrogen topdressing had two levels: with (N1) and without (N0) recommended supplementary N. Results show that absence of N topdressing significantly (p < 0.05) increased root biomass in C2, while increasing clipping frequency significantly (p < 0.001) decreased root biomass. During the growing period, N topdressing significantly (p < 0.001) increased CP content in C3 and C4 and NDF (p < 0.01) content in C4. At the termination stage, there was a significant interaction between clipping frequency and N topdressing on the biomass yield obtained in both 2016–2017 (p < 0.05) and 2017–2018 (p < 0.001), respectively. Clipping twice and N topdressing emerged as the best management practice for the dual-purpose of soil cover and livestock feed.