Performance of Maize-Soybean Intercropping under Various N Application Rates and Soil Moisture Conditions in Northern Mozambique

Abstract

Soybean has attracted increasing attention as a cash crop while subsistent maize production is the first priority for smallholder farmers in southern Africa. Our study examined the performance of maize-soybean intercropping system at three sites across northern Mozambique. Both monocropped and intercropped maize received three levels of N application, while soybean was grown without additional fertilization. The grain yield of monocropped maize applied N at three rates and that of monocropped soybean ranged 1.6 – 2.1 t ha–1 and 0.57 t ha–1, respectively, in Nampula; 1.7 – 3.9 t ha–1 and 1.87 t ha–1, respectively, in Gurue; and 2.8 – 4.5 t ha–1 and 2.01 t ha–1, respectively, in Lichinga. Relative to these values, maize-soybean intercropping demonstrated advantageous productivity over monocropping in terms of the land equivalent ratio (LER) at 1.15 – 1.49 across the experimental sites. LER above 1 was mainly attributed to the consistently superior growth of intercropped maize than the monocropped maize. Under moist field conditions, the LER values were particularly high in the non-fertilized plots because maize plants became more competitive and depressed the intercropped soybean yields to greater degrees with increasing N application rates. When exposed to a dry spell, intercropped soybean showed an apparent benefit in drought avoidance, as shown by the slow depletion of the soil water potential and leaf stomatal conductance and by the retention of the aboveground biomass relative to the monocropped soybean. These results indicate that maize-soybean intercropping can be beneficial to introduce soybean while ensuring subsistent maize production in the low-N-input and drought-prone environment that prevails in the region.