Improving fertility of an acid Alfisol and maize (Zea mays L.) yield performance with integrated application of organic and inorganic soil amendments

Abstract

In view of the limitations or inadequacies of sole use of organic or inorganic fertilizers to improve soil fertility, as well as high cost and scarcity in Nigeria, of inorganic limes, commonly used for reducing soil acidity. There is a dire need to critically assess the potential of combined application of readily available and cheap organic and inorganic fertilizers, as nutrient sources to improve soil fertility, and the use of organic limes to reduce soil acidity, and thus, ensure balanced crop nutrition with attendant high crop yield. To this effect, a two – year study was designed to evaluate the influence of wood ash – based soil amendments on chemical properties of an acid Alfisol and grain yield of maize (Zea mays L.). The experiment was carried out at the Teaching and Research Farm of the Ekiti State University, Ado – Ekiti, Ekiti State, Nigeria, during 2011 and 2012 cropping seasons. The experiment was laid out in a randomized complete block design with three replications. The wood ash – based soil amendments included: sole wood ash (SWA); wood ash + NPK (15 – 15- 15) fertilizer (WA+ NPK); wood ash + ammonium sulphate fertilizer (WA+AS); and no fertilizer (NF) (check), which served as the control treatment. The results obtained indicated existence of significant (P = 0.05) differences among the wood ash – based soil amendments as regards their effects on chemical properties of the Alfisol and maize grain yield. At the end of 2011 cropping season, application of the wood ash – based soil amendments resulted in significant (P = 0.05) increases in soil organic carbon (SOC) from 0.61 g kg^-1 for NF to 1.47, 1.32 and 1.09 g kg^-1 for SWA, WA+ NPK, and WA+AS, respectively. Similarly, at the end of 2012 cropping season, application of the wood ash – based soil amendments resulted in significant increases in SOC from 0.43 g kg^-1 for NF to 1.65, 1.51 and 1.17 g kg^-1 for SWA, WA+ NPK, and WA+AS, respectively. At the end of 2011 cropping season, application of the wood ash – based soil amendments significantly increased total nitrogen from 0.26 g kg^-1 for NF to 0.40, 0.57 and 0.51 g kg^-1 for SWA, WA+ NPK, and WA+AS, respectively. At the end of 2012 cropping season, the wood ash – based soil amendments significantly increased total nitrogen from 0.14 g kg^-1 for NF to 0.51, 0.66 and 0.60 g kg^-1 for the respective SWA, WA+ NPK, and WA+AS.  Means of maize grain yield data across the two years of experimentation indicated that, the wood ash – based soil amendments significantly increased maize grain yield from 0.86 t ha^-1 for NF to 2.26, 2.57 and 2.47 t ha^-1 for the respective SWA, WA + NPK and WA + AS. Of all the fertilizer combination treatments, wood ash + NPK fertilizer gave the highest maize grain yield and yield components in both years, and therefore, a judicious and balanced combination of wood ash and NPK fertilizer is recommended for maize cultivation.

Key words: Acid, alfisol, fertility, inorganic, maize, organic, soil