Evaluation of Water Sources for Sawah Management in the Restoration of Degraded Lowlands and Sustainable Rice Production in Southeastern Nigeria

Abstract

Agricultural productivity in Nigeria fluctuates, mainly because the country’s agriculture is rain-fed and subsistence farmers rely on the rain as the main backbone of farming in the country. Consequently, traditional water management systems in the lowlands rice production in Ebonyi State that is regarded as a major rice producing State in Nigeria  who also rely on the rain, are characterized by the fact that farmers focus on storage of water in the rice field, without any possibility to divert water from one place to another. In an attempt to arrest the declining productivity of the inland valley soils in these zones due to poor water control and fertility management, four different organic sources, including the control (Rice husk; Rice husk ash; Poultry droppings at 10 t/ha and NPK 20:10:10 at 400 kg/ha and 0 t ha^-1) were used in three different water sources (sawah types) (rain-fed, pump-fed and spring-fed sawah) 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. A split- plot in a randomized complete block design was used to asses the two factors at different levels. Three sources of water (sawah types); rain-fed sawah, spring type and pump type constituted main plot, while the amendments, that constituted the sub- plots were applied as follows: 10 tha^-1 rice husk (RH); 10 tha^-1 of rice husk ash; 10 tha^-1 of poultry droppings; 400 kgha^-1 of N.P.K. 20:10:10 and 0 tha^-1 (control). The treatments were replicated three times in each of the subplots. The results of the study showed that the soil pH was significantly improved by different water types in the two locations. As the pH was improved statistically upon by different soil amendments in the two sites, the interaction of water sources and amendments only significantly improved the pH in Ikwo location. The results also indicated that soil organic carbon and total nitrogen were positively influenced in the two locations by both the different water sources and amendments. The result shows a significant improvement on the CEC by both factors in Ikwo site. It was also recorded that available phosphorous were positively improved by different water sources and amendments in different forms in the two locations. The result equally indicated that rice grain yiled was positvely increased in both locations by the studied factors.