Smallholder Irrigation for Climate Mitigation and Cacao (Theobroma cacao L.) Performance Improvement in the Rainforest Tropics

Climate change poses significant threats to agriculture, including food security, livelihoods and economic growth. Based on the importance of cocoa, there is a need for sustainable crop production and resilience to anticipated changes in rainfall and temperature in the future. Irrigation is an important climate-smart practice for alleviating abiotic stress and enhancing crop productivity, and irrigation is seldom practiced in the cacao orchards of West Africa. Studies were conducted to examine the effects of dry season gravity drip irrigation on the rootzone moisture, tree water use (evapotranspiration), leaf area index and yield of cacao in a rainforest zone of Nigeria. Irrigation treatments were based on water application at 5- and 10-day intervals and 50, 70 and 100% Pan evaporation, which was applied using point source emitters on drip lines. The soil moisture content, photosynthetic active radiation, leaf area index and extinction coefficient differed among the irrigation treatments. Deficit irrigation (10-day and 50% EPan) enhanced water use efficiency by 25–44% (30 and 50% water savings), while full irrigation enhanced soil moisture, cacao ET, and pod and bean yields. This study established irrigation and water requirements for cacao in the dry season and confirmed the relevance of irrigation for enhanced cacao performance and climate mitigation.