Abstract: Inputs of organic and inorganic compounds in agriculture have a strong influence on soil properties and productivity. This study investigated the influence of Rice mill Waste (RW) in combination with or without NPK 15:15:15 on some physico-chemical properties and productivity of an Ultisol cropped with cocoyam (Colocasia esculenta (L) schott) in Umudike, Southeastern, Nigeria. The study was laid out in a Randomized Complete Block Design (RCBD) comprising 11 treatments (2.5, 5, 10 and 20 t ha-1 RW combined with 200 or 400 kg ha-1 NPK, 30 t ha-1 RW alone, 400 kg ha-1 NPK alone and a control) in 3 replicates. Data generated were subjected to Analysis of Variance. Relative to the control, significant increases with application of 30 t ha-1 RW were 127.1% for available P, 87.5 for percent total N, 213.2 for percent Organic Matter (OM), 113.6 for exchangeable Ca and 138.5 for exchangeable Mg. Enhancements in other treatments in the chemical parameters, when compared to the control, were not significant except the applications of 20 t ha-1 RW + 200 kg ha-1 NPK on percent OM and 5 t ha-1 RW +400 kg ha-1 NPK on exchangeable Na. Similarly, applications of 30 t ha-1 RW and a combination of 20 t ha-1 RW +400 kg ha-1 NPK significantly enhanced Mean Weight Diameter (MWD). Improvements in saturated hydraulic conductivity (Ksat) and reduction in percent Dispersion Ratio (DR) were not significant. Also, amendments improved soil productivity indicated by non-significant increases in sucker numbers and plant height of cocoyam. These results indicate the potentials of RW in improving the physico-chemical properties and productivity of degraded tropical Ultisols.
P.C. Oguike , G.O. Chukwu and U.B. Ekere , 2007. Complementary Effects of Rice Mill Waste and NPK Fertilizer on Some Physico-Chemical Properties and Productivity of a Degraded Ultisol in Southeastern Nigeria. Agricultural Journal, 2: 121-126.