Effect of monoculture and intercropping on radiation use efficiency and yield of maize and soybean

Field experiments were conducted to investigate the effect of two intercropping patterns (maize-soybean 1︰3 and 2︰3) and corresponding monoculture on the capture and use of solar radiation and on yields of maize and soybean in two growing seasons (2006 and 2007). Results show that light extinction coefficients of monocultured maize and soybean, and 1︰3 and 2︰3 intercropping are 0.45, 0.60, 0.53 and 0.52 respectively. There is no significant maize biomass difference between the intercropping and monoculture before 79 days after sowing. After the 79-day period, maize biomass in 1︰3 intercropping becomes significantly higher than that of maize monocultured at 0.01 probability level. There is a significant difference in maize biomass between 1︰3 and 2︰3 intercropping at 0.05 probability level. Soybean biomass of intercropping and monoculture is significantly different. RUE value of 1︰3 (3.51 g·MJ^-1) and 2︰3 intercropping (3.49 g·MJ^-1) is about 2.8 times that of monocultured soybean (1.24 g·MJ^-1). However, it is slightly less than that of the monocultured maize (3.56 g·MJ^-1). Grain yields for monoccultured maize and soybean are more than those for intercropping treatments. However, total yields for intercropping treatments are 6.0% and 320% higher than the yields for monocultured maize and soybean respectively. Incomes from the two intercropping systems are 56% ~ 60% and 70% ~ 74% higher than those from monocultured maize and soybean. The findings suggest that intercropping may help increase crop production through more efficient utilization of solar radiation, hence increase farmers’ income.