Productivity and profitability of intercropping systems involving sugarcane and short-duration pulses

Abstract:

Sugarcane monoculture in the Free State province of South Africa has expanded steadily since the 1990s, but farmers increasingly report declining soil nitrogen levels and narrowing profit margins tied to volatile sugar prices. Intercropping sugarcane with short-duration pulse crops may offer a practical route to address both problems at once. This research evaluated three intercropping combinations—sugarcane + mungbean, sugarcane + lentil, and sugarcane + cowpea—against a sole sugarcane control at the research farm of the Free State University of Agricultural Sciences, Bloemfontein, from October 2022 to September 2023. The experiment used a randomized complete block design with four replications. Sugarcane (cv. Co 86032) was planted at 90 cm row spacing, and pulse crops were sown in two rows between cane rows at 30 cm spacing. Cane yield, pulse grain yield, cane quality (Brix, pol %), land equivalent ratio (LER), and economic returns (net income per hectare) were measured. Sole sugarcane yielded 78.4 t ha⁻¹, while intercropped cane yields ranged from 71.8 to 74.6 t ha⁻¹—a 4.8-8.4% reduction that was offset by pulse grain harvests of 0.47-0.83 t ha⁻¹. All three intercropping systems recorded LER values above 1.0 (range 1.19-1.34), confirming a land-use advantage over monocropping. Sugarcane + mungbean gave the highest net income at ZAR 68,470 ha⁻¹, which was 23.7% above sole cane. Cane quality traits were not significantly affected by any intercrop. These results suggest that short-duration pulse intercrops can raise total system productivity and farmer income without harming cane quality, while also contributing biological nitrogen that may sustain long-term soil fertility.