Cassava Yield as Affected by Sawdust Ash Siam Weed Residue and Npk Fertilizer

Experiment was conducted at Ayegunle and Oka South-West Nigeria to study effect of combined sawdust ash and siam weed residues and NPK fertilizer (NPKF) on soil nutrients and performance parameters of cassava. Plant parameters determined were number of leaves, plant height, stem girth, leaf area index, root weight, root diameter and root length. Plant residues NPKF and their combinations increased significantly soil OM, N, P, K, Ca, Mg and cassava performance parameters. NPKF at 400kg/ha reduced soil pH and gave least values of soil nutrients among treated soils, and OM and pH reduced with increased with rate of NPKF. Combinations of residues and NPKF increased soil pH, OM, N, P, K, Ca and Mg and cassava performance compared with NPKF. Performance parameters increased with rate of NPK when it is combined with residues. The 4t/ha SDA+10t/ha CR+300kg/ha gave highest values of cassava performance parameters and soil N,P.K, Ca and Mg.