Climatic change adaptation strategy for dry season amaranth cropping systems in the tropics: a case study from irrigated watermelon (Citrullus lanatus) as live mulch

As live mulch, crops like watermelon (Citrullus lanatus) could reduce soil temperatures and improve soil moisture levels in the dry off-season of sub Saharan Africa, resulting in reduced needs for irrigation and providing additional income to farmers from produce harvested in mixed cropping systems. This study therefore seeks to quantify the impact of watermelon live mulch on irrigation requirements, adaptation to climatic change and yield potential of an amaranth production system in the dry off-season. Grain amaranth was planted at 0.75×0.75 m spacing, and there were three sowing densities of watermelon: 1.5×0.45; 1.5×0.90; 1.5×1.50 m. Control plots were planted with only grain amaranth. Averaged over two consecutive cropping seasons, irrigation water requirement was optimally (P=0.05) reduced compared to the control plot. Amaranth grain yields were highest at 1.5×0.90 m watermelon plant spacing. Maximum soil temperature was reduced by the watermelon mulch relative to the control. Soil moisture content was also significantly (P=0.05) greater in the live mulch treatments compared to the control. Our research demonstrates that live mulch lowers soil temperatures; reducing water requirements for irrigation in the dry season, and provided opportunities in the adaptation of agricultural production systems under climate change scenarios.