Residual Effects of Organic and NPK Fertilizers on Maize Performance at Different Soil pH Levels

Abstract

Acid soils are highly weathered and are usually excessive in soluble aluminum and manganese and deficient in phosphorous, calcium, magnesium and molybdenum, which may cause their reduced uptake and lead to nutrient imbalances in plants. To address this problem, a field study was carried out in 2012 to evaluate the residual effects of combined rates of poultry manure (PM) and NPK 15-15-15 fertilizers on responses of maize (Zea mays L) in a soil limed to different pH levels. The treatments were four levels of soil pH: pH 5.5 (control), pH 6.0, pH 6.5and pH 7.0 and six levels of combined PM and NPK 15-15-15 fertilizer: T1 (200 kg/ha NPK + 6 t/ha PM); T2 (300 kg/ha NPK + 4 t/ha PM), T3 (400 kg t/ha NPK + 2 t/ha PM); T4 (400 t/ha NPK only), T5 (8 t/ha PM only) and T6 (Control) arranged in a 6 x 4 factorial in randomized complete block design (RBCD) with three replications. The results showed that Treatment T2 (8 t/ha PM only) significantly (P < 0.05) gave the highest dry matter yield while T2 (300 kg/ha NPK + 4 t/ha PM) had the least dry matter yield. Liming also increased the maize dry yield with soil limed to pH 6.0 having the highest dry matter. It was therefore concluded that for second season planting, maize can be efficiently produced in sandy loam ultisols previously applied with treatments T5 (8t/ha PM) and limed to pH 6.0.