ABSTRACT

Field experiments were carried out to determine the effects of palm bunch ash (PBA) on soil nutrient dynamics, growth and yield of cassava during the 2003/2004 cropping season at the Research and Teaching Farms of Michael Okpara University of Agriculture Umudike, Abia State and Federal College of Education (Technical) Omoku, Rivers State respectively. The experiments were laid as split-plot fitted into a randomized complete block design (RCBD) with four replications. Two cassava varieties, NR8082 and Nwaebibi, (Bitter and sweet varieties respectively), served as the main plots, while five levels of PBA (0.00, 1.25, 2.50, 3.75 and 5.00 t/ha) served as the subplots. Fertilizer at the rate of 600kg/ha NPK 15:15:15 which is the recommended rate for cassava production on the soils studied was included as a check. Plot size was 8 x 6m with buffer zones of im apart. Cassava cuttings were planted on crest of ridges at a spacing of 1 m x 1 m. Palm bunch ash and fertilizer were applied at two months after planting (2 MAP). Weeding was manually done thrice at 2, 5 and 10 MAP respectively. Prior to experimentation soil analysis was carried out. Soil nutrients (N, P, K) were monitored at 3, 6, 9 and 12 MAP. Plants were also sampled and analyzed for N, P and K at 3, 6, 9 and 12 MAP. The following agronomic parameters were also measured: plant height, stem diameter, Leaf area index, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, root number, root diameter and root length. Data were subjected to Analysis of variance and means separated by LSD at 5% level of significance. The soil nutrient (N, P. K) dynamics monitored at three monthly intervals up to 12 months after planting indicated that for both sweet and bitter cassava at Omoku, palm bunch ash did not significantly affect soil nitrogen content between 3 and 9 months planting. However, at 9 months after planting and thereafter soil nitrogen increased tremendously. At Umudike, palm bunch ash consistently increased soil nitrogen. For sweet cassava at both Omoku and Umudike, palm bunch ash significantly increased soil phosphorus content between 3 and 6 months after planting. But at 6 months after planting and thereafter, palm bunch ash did not significantly affect soil phosphorus content. For bitter cassava, palm bunch ash significantly increased soil phosphorus content between 3 and 9 months after planting at both Omoku and Umudike. However, at 9 months after planting and thereafter, palm bunch ash did not significantly affect soil phosphorus content. Soil potassium content under sweet and bitter cassava at both Omoku and Umudike was significantly increased by palm bunch ash between 3 and 12 months after planting. Tissue N, P after and K were also increased by application of PBA. Leaf N and K concentrations were increased significantly with application rate of PBA up to 5.00t/ha, while leaf P concentration was increased with 3.75t/ha PBA over time than the control. Application of PBA at the rate of 5 .00t/ha increased significantly cassava height, stem diameter and shoot fresh weight. Palm bunch ash application rates of 2.50 and 3.75t1ha increased leaf area index, root number, root diameter and root weight of sweet and bitter cassava, respectively. It was concluded that PBA can be utilized as a fertilizer for cassava production.