Sawah Rice System, a Technology for Sustainable Rice Production and Soil Chemical Properties Improvement in Ebonyi State of Southeastern Nigeria

The soils in Ebonyi State agro-ecological zones of southeastern Nigeria are plagued with characteristics that impede optimal crop production. Failures in agricultural development in this part of southeastern Nigeria may have been caused by the inability of the farmers to develop the abundant inland valleys for such crops like rice using appropriate water management systems. In order to arrest the declining productivity of the inland valley soils in these zones, four different organic sources (Rice husk; Rice husk ash; Poultry droppings at 10 t/ha and NPK 20:10:10 at 400 kg/ha) were used in four different sawah environments including farmers environment (Complete sawah; Incomplete sawah; Partial sawah and farmer’s environment) in two inland valleys in southeastern Nigeria to evaluate their effects on some soil properties and rice grain yield. Sawah is generally described as a controlled water management in the field where the soil is expected to be puddle, leveled and bunded in order to impound water provided by rain water or by rise in the level of a river in an inland valley. The field layout was Split-plot in a randomized complete block design (RCBD) in which the five treatments (including the control) were replicated three times within the four sawah environments including the farmer’s field. The field was demarcated into four main plots with five sub-plots in each using 0.6m raised bunds except in the main plot used as farmer’s field. The four main plots were prepared and managed according to specifications of the study. The bunds have inlet and outlet channels through which water is introduced into the field from a water source and excess drain from the field, respectively. The test crop was a high yielding rice variety (Oryza sativa var. FARO 52/WITA 4). The rice seedlings were transplanted at the age of three weeks after nursery. Soil properties tested were soil organic carbon, total nitrogen, pH, CEC, EA and Base saturation, while the grain yield of rice was also measured. The results showed that soil pH, OC and TN were statistically improved within sawah managed environment in both locations. The amendments also improved the pH, TN, CEC and base saturation during the period. Also rice grain yield was statistically increased by both sawah managed environments and the soil amendments, with complete sawah environment amended with poultry droppings giving the highest significant increase in the yield of 7.5 tons per hectare.