Productivity of solid and intercropped soybean with corn under low irrigation water levels

A three-year study was carried out at Giza Agricultural Experiments and Research Station, Faculty of Agriculture, Cairo University, Giza, Egypt during the summer seasons of 2018, 2019, and 2020 to evaluate the effect of low irrigation water levels on the productivity of corn and soybean under different solid and intercropping systems. This study included 18 treatments. Three levels of irrigation water (7140, 5712, and 4284 m 3 /ha) were expressed as 100 "I Sa ", 80 "I Sb " and 60%"I Sc ", respectively. Six cropping systems that included alternating ridges 2:2 (A a ), mixed (B b ), solid corn ridges (Soc a ), solid corn beds (Soc b ), solid soybean ridges (Sos a ), and solid soybean beds (Sos b ). Corn cultivar S.C.132 (white grains) and soybean cultivar Giza 111 were used in this study. A split plot design in randomized complete blocks arrangement with three replications was used. All soybean and corn traits were negatively affected when received I Sc . However, there were no significant differences between I Sa and I Sb for all soybean traits in all seasons. A significantly higher seed yield per hectare for soybean was recorded for solid plantings than for intercropping systems. Intercropping system Bb had high kernel weight and grain yield per hectare. Irrigation water use efficiency (IWUE) was increased by decreasing the applied irrigation water level from 7140 to 4284 m3/ha. The intercropping system Bb recorded high values of IWUE. Land equivalent ratio (LER) was not significantly affected by applied irrigation water levels, while intercropping system Bb recorded high LER in all seasons. Most interactions were significant throughout the seasons of the study. It can be concluded that intercropped soybean cultivar Giza 111 with corn in raised beds that received irrigation water of 5712 m3/ha recorded higher productivity values (IWUE and LER), as well as total and net returns, than the other treatments.