Nutrients Concentration and Root Count of Cassava as Influenced by Residue and Npk Fertilizer

Experiment was conducted at two sites Ayegunle and Oka in South-West Nigeria to study effect of combined plant residues sawdust ash (SDA) and siam weed (Chromolaena odorata) (CR) and NPK (15:15:15) fertilizer on leaf N, P, K, Ca and Mg of Cassava. The parameters were evaluated at 3,6,9 and 12 months after planting (MAP) for nutrient concentrations and root count of cassava. The test soils are sandy loan and slightly acidic. Treatments replicated three times on cassava plants were (a) control, (b) 4t/haSDA+10t/haCR, (c) 400 kg/ha NPKF, (d) 4t/haSDA + 10t/haCR + 100kg/ha NPK F, (e) 4t/haSDA + 10t/ha CR +200kg/ha NPKF, (f) 4t/haSDA + 10t/ha CR + 300 kg/ha NPKF. The residues and NPKF, sole or combined significantly increased leaf N,P,K,Ca and Mg and number of roots at the four periods of determinations. Compared with NPKF, plant residues alone or combined with NPKF increased with rate of NPKF. Combination 4t/haSDA-10t/haCr+300kg/ha NPKF gave highest values of the measured parameters at 3, 6, 9 and 12 MAP. At 12 MAP its root count was higher by 109% compared with 400kg NPKF. Nutrients concentrations were higher at 9 and 12 MAP.