Species combination determines whether forage mixtures gain in dry matter yield or crude protein concentration. A meta-analysis

Abstract

Cereal/legume intercropping is gaining attention due to its potential contribution to achieving sustainable intensification of forage production. Productivity and quality of cereal/legume fodder mixtures are expected to vary among species combinations. However, for intercropping with different species combinations, the impacts of management practices on productivity and fodder quality have remained largely unexplored. We report a meta-analysis (with 467 data records from 49 publications) to evaluate options for improving forage yield and quality (%crude protein) in cereal/legume fodder mixtures through management (e.g., varying crop density and species combination). Our findings indicate how much forage mixture gains in yield or quality varied among 16 species combinations with ≥ 8 records. The net effect ratio for dry matter yield of barley/vetch (1.18±0.061), maize/cowpea (1.33±0.160), maize/soybean (1.66±0.188), and triticale/pea (1.41±0.139) intercrops was positive (> 1). The net effect ratio for % crude protein of barley/faba bean (0.87±0.025) and triticale/pea (0.85±0.026) intercrops was negative (< 1). In addition, intercropping design (replacement (relative density = 1)/additive (1 < relative density ≤ 2)) influences the size of effects without affecting their direction. Oat/pea intercropping in an additive design had a higher net effect ratio for %crude protein than that with a replacement design. Both maize/cowpea and sorghum/cowpea intercrops with additive designs had positive net effect ratios for dry matter yield, while those with a replacement design had net effect ratios similar to one. Here, we report a quantitative review demonstrating for the first time how yield and quality performance of cereal/legume intercropping for fodder production differs between species combinations and how management practices influence the size of the effect. Our findings support the design of intercropping systems for specific agro-ecological settings and production aims of target animal farming systems, thereby contributing to the forage production literature.