Effects of irrigation regime and frequency on soil physical quality, water use efficiency, water productivity and economic returns of paddy rice

摘要

Talata Mafara is located in a semi-arid region in Sudan Savanna agro-ecosystem of Nigeria and regularly faces widespread drought. Given current water scarcity, the limited available water should be used as efficient and productive as possible. The influence of five regulated deficit irrigation regimes involving water application depths of 100, 85, 70, 55 and 40 % of total available water (TAW) capacity equivalent, referred to as TAW, 85 % TAW, 70 % TAW, 55 % TAW and 40 % TAW and irrigation intervals of 4, 8, 12 and 16 days on soil physical quality as well as paddy rice yield, water use efficiency, water productivity and economic return was studied. The study was conducted at Talata Mafara irrigation research station of the Institute for Agricultural Research, Samaru-Zaria. Water was conveyed from field ditches into each basin through a pair of polyvinyl chloride pipes using surface irrigation method. Routine methods of soil physical quality analysis were employed. Results showed that application of water depths of 40 % TAW and 16 days frequency significantly enhanced soil organic carbon (OC) content, and consequently, promoted macroaggregate stability measured by mean weight diameter and microaggregate stability measured by aggregated silt and clay and clay flocculation index as well as infiltration rate. However, yield, water use efficiency, water productivity and net revenue as well as gross profit rate were highest on application of 85 % TAW and irrigation at 8 days interval. Therefore, given the deterioration of soil physical quality on application of higher water depth, regular replenishment of soil organic matter is essential for sustainable use of the soil for production of rice and other irrigated crops.