Role of Residual Organic Materials on Productivity of Zea mays L. for Sustainable Soil Fertility Restoration in the Guinea Savannah Zone, Ghana

Abstract

A field experiment was conducted at Nyankpala, near Tamale, Ghana, during the 2014 cropping season and continued during 2015, to investigate one year residual effects of indigenous organic materials (biochar, groundnut shell, rice husk and rice straw) on the growth and yield of maize. It was a 4×3×3 factorial experiment consisting of 4 organic materials at 3 levels (2.5, 5 and 7.5 t ha-1 on dry matter basis) and 3 nitrogen (N) levels (0, 45 and 90 kg/ha N) laid out in a Randomized Complete Block Design with four replications. The study revealed that integrated management of one year residuals of the organic materials with inorganic N supported increased plant height and grain yield, and moderated time of flowering to promote production of maize variety “Wang Dataa”. Application of 7.5 t/ha biochar + 45 kg/ha N, similarly 5 t/ha biochar + 90 kg/ha N supported tallest crop of 200 cm, whilst early flowering ranged 47 to 50 days with 2.5 t/ha biochar + 90 kg N/ha, 5 t/ha biochar + 45 kg N/ha, 7.5 t/ha biochar+ 90 kg N/ha, 2.5 t/ha groundnut shell + 90 kg N/ha and 7.5 t/ha rice straw + 45 kg N/ha. Grain yield was maximised with 7.5 t/ha biochar + 90 kg N/ha, 5 t/ha groundnut shell + 45 kg N/ha, 7.5 t/ha groundnut shell + 90 kg N/ha and 7.5 t/ha rice husk + 90 kg N/ha in the range of 3000 - 3600 kg/ha. The results also showed strongly that either residual nutrients and other plant growth conditions obtained from the organic materials or application N determined LAI, height of cob attachment, cob length, cob weight, 100 seed weight and stover biomass. Residual conditions provided by 7.5 t/ha of biochar gave the highest LAI. The more increased height of cob attachment ranged from 90 to 100 cm, provided by as low as 2.5 t/ha of biochar. Best cob length of 15 to 17 cm was obtained from 2.5 t/ha biochar and 5 t/ha groundnut shell. Cob weight under residual organic materials was in the range of 125 to 165 g/cob with 5 t/ha biochar or groundnut shell and 7.5 t/ha rice straw adequate to maximize the trait. Residual organic materials impacted on 100 seed weight with 5 t/ha of biochar and 7.5 t/ha groundnut shell impacted largest grain size of 25.5g. Stover weight was both highly significantly determined by residual effects of organic materials and N. Application of 5 t/ha biochar or 5 t/ha groundnut shell or 7.5 t/ha rice husk was adequate for highest stover weight. In this study, application of 45 kg N/ha was overwhelmingly sufficient to optimize leaf area index, height of cob attachment, cob length, cob weight, 100 seed weight and stover weight. Pearson correlation coefficients of grain yield with other traits exhibited robust relationships signifying strong impact of integrated soil fertility management of one year residual organic materials and N on maize production in the Guinea savannah. Grain yield prediction indicated treatments were best fitted in polynomials with 7.5 t/ha biochar + 90 kg N/ha for optimum grain yield.