Effect of Crop Residue on Soil Physical Properties and Rice Yield on an Acid Ultisol at Abakaliki, Southeastern Nigeria

A study was conducted in 2005 and 2006 to evaluate the effect of different types of crop residue mulch on soil physical properties and rice yield. The crop residue treatments were dry rice straw, burnt rice husk, legume residue and the control, while rice cultivars were ITA 257, Ex-China and ITA 315. The experiment was laid out as a 3 x 4 factorial in a Randomized Complete Block Design (RCBD), with three replications. Measurements of soil bulk density, total porosity, soil temperature, moisture content and water infiltration, and plant growth and yield were taken. The result showed that soil moisture, total porosity and water infiltration were significantly (p<0.05) higher on residue treated plots, where as soil bulk density and temperature were significantly (p<0.05) reduced by the residue treatments compared to the soil with no residue treatments. Rice growth and yield were significantly (p<0.05) better on the residue treated plots. There were average grain yield increases of 0.95, 1.00 and 1.00 t/ha for ITA 257, 1.05, 1.25 and 1.20 t/ha for Ex-China and 0.95, 1.30 and 1.24 t/ha for ITA 315 as a result of rice straw, burnt rice husk and legume residue mulched soil. The grain yields of ITA 315 and Ex-China were 1.10 and 1.00 t/ha significantly (p<0.05) higher than the yield of ITA 257 when valued across the two years and residue treatments. The highest grain yield of 3.07 t/ha in the study was obtained from ITA 315 grown on soil mulched with legume residue. The superior rice growth and grain yield on the residue mulched soil was as the result of the improved soil physical environment while the better performance and yield of ITA 315 and Ex-China were ascribed to genetic inheritance.