Sawah Rice Farming Eco-technology Options for Enhancing Sustainable Nutrient Management and Rice Production in Degraded Inland Valleys of Southeastern Nigeria

The decline in agricultural productivity in Nigeria is merely because the rural farmers which constitute the bulk of Nigerian crop farmers rely on the rainfall for their agricultural activities. Rice farmers in Ebonyi State, regarded as a major rice producing State in Nigeria rely on rain-fed agriculture. The water management option among the rice farmers in their lowland rice production in the area is the use of grass materials in the demarcation of the fields into basins for water storage without any form of water diversion from one place to another as a way of controlling the field water. In an attempt to replicate the successful way of controlling water in the African agro-ecosystems, otherwise known as “Japanese Satoyama watershed management model”, sawah rice cultivation technology has been introduced to West Africa in the last decades.

Sawah is generally described as a controlled water management system in the rice field which involved mainly bunding, puddling and leveling with inlets and outlets channels on the bunds for irrigation and drainage purposes. The irrigation water may be provided by rain water or underground water discharge through seepage or springs, or by rise in the level of a stream and river in an inland valley, or using modern source from well pumps, taps, canal and storage of large quantities of water in reservoirs or ponds. The study was conducted in an inland valley at Akaeze in 2010, 2011 and 2012 cropping seasons, to evaluate the effect of different water sources for sawah water management system and amendments on soil chemical properties and rice grain yield. A split- plot in a randomized complete block design was used to assess two factors at different levels. Three sources of water; rain-fed, spring type and pond type constituted the main plot, while the amendments, that constituted the sub- plots were replicated three times and were applied in the following manner: rice husk (RH) @ 10 t ha-1, rice husk ash (RHA) @ 10 t ha-1, poultry droppings (PD) @ 10 t ha-1, N.P.K. @ 400 kg ha-1 and no amendment @ 0 t ha-1. The results of the study showed that different water sources significantly (p < 0.05) improved the soil pH in the location. Soil organic carbon, total nitrogen and cation exchange capacity were significantly (p < 0.05) increased within the period of study by both the different water sources and amendments. It was observed that the exchangeable acidity was statistically reduced by different water sources and amendments within the periods. It was also recorded that available phosphorous were positively improved by different water sources and amendments in different forms in the area. The result equally gave positive improvement on the rice grain yield by the studied factors for the three years. Generally, results showed a better performance of organic amendments over mineral fertilizer in some soil chemical properties and rice grain yield improvement. The interaction of a good water source in sawah water management and amendment practices was observed to be a good strategy for improving some soil chemical properties in the area.