Effects of Combined Application of Plant Residues and NPK Fertilizers on the Yield of Yam (Dioscorea rotundata ‘c’v’ Ewura) in the Derived Savanna

of Ogbomoso
ADEGBENRO, R.O.1, BABATUNDE K.M.2., OJETADE J.O.1 AND FATUROTI O.M2
1Department of Soil Science and Land Resources Management,
Obafemi Awolowo University, Ile-Ife, Nigeria.
2Department of Agricultural Technology,
The Polytechnic Ibadan, Saki Campus.
E-mail: Kemiadegbenro@yahoo.com, mbabatundekayode@yahoo.com,
Abstract
The field experiment was carried to determine the effect of Pueraria, Soyabean and NPK fertilizer combination with urea and Muriate of potash on the performance of yam (Dioscorea rotundata). The gap between plots was 1m while that between replicates were 2m.The plant residues were incorporated two weeks before planting, fertilizer rate of 90-50-75kg N.P.K/ha and 45-25-37.5kg N.P.K/ha was achieved using NPK 15-15-15 compound fertilizer and excess N and K rates were met using urea and muriate of potash respectively. The fertilizer was applied in ring method to the growing yam at 2 months after sprouting.
The experimental design was Randomized Complete block design with 4 replicates. There were nine treatments namely; Control (no residue, no fertilizer), No residues + 45-25-37.5kg N.P.K/ha (50% of the recommended NPK rate for yam in the zone),No residues + 90-50-75kg N.P.K/ha (Recommended NPK rate for yam in the zone), Incorporation of soybean residue alone, Soybean residue + 45-25-37.5kg N.P.K/ha, Soybean residue + 90-50-75kg N.P.K/ha, Incorporation of pueraria residue alone, Pueraria residue + 45-25-37.5kg N.P.K/ha, Pueraria residue + 90-50-75kg N.P.K/ha. There were significant differences between 90-50-75kg N.P.K/ha rate fertilizer application compared with control alone (no residue, no fertilizer) in terms of % N of yam leaves. Incorporation of pueraria with 45-25-37.5kg N.P.K/ha rate increased %
N of yam leaves compared with pueraria alone and pueraria with 90-50- 75kg N.P.K/ha. Analysis of variance indicate that Soybean incorporated into the soil alone and soybean with 90-50-75kg N.P.K/ha recommended rate fertilizer slightly increased %P compared with soybean with 45-25.37.5kg N.P.K/ha (50% recommended rate).