Agronomic efficacy of fertilizer types on some soil chemical properties and sweet potato production in an ultisol environment

Abstract

Studies were conducted in 2014 and 2015 cropping seasons at the Experimental Farm of the Faculty of Agriculture, University of Benin, Benin City, Nigeria, to evaluate the effect of soil amendments on enhancing soil fertility status and relative agronomic efficiency of sweet potato yield in humid ultisol environment. The treatments were Cattle and Poultry manures at application rate of 15 t ha^-1 each, NPK fertilizer at 400 kg ha^-1 and control (no fertilizer) replicated three times. Data were collected on plant establishment, vine length, leaf area index (LAI), total dry matter and relative agronomic efficiency. The results obtained showed that the soil prior to the experiment was low in total N, available P and exchangeable cations, but moderately acidic and high in organic matter. The manures were rich in N, P, Mg, K, organic carbon and Ca concentration. The application of poultry manure, cattle manure and NPK to the soil improved the soil fertility status. The longest Sweet potato vines were observed in poultry manure (252.10 cm) and NPK (249.90 cm) treated plots. The highest LAI (5.15 cm) was observed from plots treated with poultry manure while the plots treated with cattle and poultry manures had the greatest total dry matter (TDM) and relative agronomic efficiency (RAE). TDM was positively correlated with vine length (r = 0.360) and RAE (r = 0.569). Vine length positively correlated with LAI and RAE with a coefficient of 0.416 and 0.360, respectively. Poultry and cattle manures at the application rate of 15 t ha^-1 are therefore recommended for sweet potato growers in the humid ultisols environment for better performance.