Impact of biochar, cattle manure and mineral fertilizer on soil properties and grain yield of maize (zea mays l.) In the Guinea Savannah zone of Ghana

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JULY, 2016
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The use of biochar as a soil amendment is being promoted due to its long term ability to improve soil physical and chemical properties. The aim of this work was to improve maize productivity by using different levels of synthetic fertilizer with farm yard manure and biochar in the Guinea Savannah zone of Ghana. A field experiment and laboratory incubation study were conducted at Kpongu in the Upper West region of Ghana (Guinea Savannah Agro – ecological Zone) and the Soil Science laboratory of KNUST respectively. Eighteen treatments including three levels of biochar (0, 2.5 and 5 t ha-1), three levels of mineral fertilizer(0, 50 and 100 % of the 60-40-40 kg ha-1 recommended rate) and two levels of manure (0 and 5 t ha-1 recommended rate) were applied in a factorial experiment arranged in split - split plot design with three replications. In the laboratory incubation study treatments were applied at 153.6 g to the field soil on mass basis in a 56 day incubation study period to determine the effect of treatments on soil pH, urease activity, ammonium nitrate (NH4-N) and nitrate nitrogen (NO3-N). The use of manure at 5 t ha-1 gave the highest plant height at 2 weeks after planting (17.39 cm) and 4 weeks after planting (60.1 cm) while the use of NPK (60: 40: 40: kg ha-1 )gave the highest plant height at 6 weeks after planting (123.7 cm) and 8 weeks after planting (194.6cm) respectively. The highest grain yield (1347 kg ha-1), biomass dry matter (2865 kg ha-1), nitrogen uptake in both biomass (28.68%) and grain (20.4 %), phosphorus uptake in grain (2.09 %) and nitrogen use efficiency (29) was obtained with the use of 30:20:20 kg ha-1 NPK while the highest phosphorus uptake in biomass (3.47 %) was obtained with the use of manure at 5 t ha-1. Laboratory soil analysisafter harvest showed that none of the soil amendments had significant effect on the examined soil properties. However, biochar amended plots at 5 t ha-1 was found to have the highest soil organic matter of 1.722 percent. Manure application at 5 t ha-1 gave the highest soil nitrogen content (0.667 %) while mineral fertilizer at 30:20:20 kg ha-1 had the highest soil P of 6.55 %. The applications of 30:20:20 kg ha-1 NPK and 5 t ha-1 Manure + 30:20:20 kg ha-1 NPK was the most economically viable imputs (VCR > 2) among the treatments. 5 t ha-1manure increased the soil pH from 5.4 to 6.22 while urease activity was highest with 2.5 t ha-1 biochar + 5 t ha-1 manure. NH4-N was highest at 56 DAI following the application of 2.5 t ha-1 biochar + No fertilizer and at 42 DAI, NO3-N was highest with 5 t ha-1 manure + 100 % RR NPK. Extensive research based on agro-ecological zone evaluation of biochar should be carried out to ascertain its effectiveness on maize productivity.
A thesis submitted to the Department of Crop and Soil Sciences, College of Agriculture and Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfilment of the requirements for the degree of master of philosophy in soil science By Ezike Ogechukwu Blessing Msc Unilorin July, 2016