Effects of Deficit Irrigation Regime and Interval on Chemical Properties and Paddy Rice Yield in Sudan Savanna of Nigeria

Strategies to improve water use efficiency of irrigated crops are among others deficit irrigation, precision irrigation technologies soil and water conservation practices. The study evaluates the effects of deficit irrigation regime and interval on soil chemical properties and performance of paddy rice in Sudan Savanna agroecosystem. The treatments include water application depths of 100, 85, 70, 55 and 40% of Total Available Water (TAW) capacity and 4, 8, 12 and 16 days irrigation intervals. Water was conveyed from field ditches into each basin through a pair of polyvinyl chloride pipes using surface irrigation method. Routine methods of chemical analysis were employed. Results showed that the highest organic carbon was recorded in treatments irrigated with water depth of 85% TAW at 4 days interval. Significantly higher total nitrogen, cation exchange capacity, sodium, pH (H2O) and pH (CaCl2), exchangeable sodium percentage and sodium adsorption ratio were recorded with TAW and 4 days interval treatments. Treatments irrigated at 40% TAW and 16 days interval got higher available P, Ca, Mg and potassium as well as base saturation. Treatments with 85% TAW (4772.0 kg ha-1) and 8 days interval (4442.3 kg ha-1) gave the highest yield. Based on stepwise regression analysis, potassium, organic carbon and cation exchange capacity were the major determinants of the yield. Hence, sustainable utilization of such land under irrigation requires regular application of organic matter and 85% of total available water at 8 days interval for more efficient use of irrigation water and acquisition of high paddy rice yield.