Interactions of aerobically decomposed cattle manure and nitrogen fertilizer applied to soil |
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Authors: | J Nyamangara MI Piha H Kirchmann |
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Affiliation: | (1) Crop Nutrition Section, Chemistry & Soil Research Institute, Box CY 550, Causeway, Harare, Zimbabwe;(2) Department of Soil Science, University of Zimbabwe, Box MP 167, Mt. Pleasant, Harare, Zimbabwe;(3) Department of Soil Sciences, Swedish University of Agricultural Sciences, Box 7014, 750 07 Uppsala, Sweden |
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Abstract: | Inorganic N fertiliser may be applied to soil in addition to cattle manure by smallholder farmers in developing countries: (a) to complement fertilization; (b) to control a possible immobilisation of N by the manure; and (c) to eliminate the risk of yield depression due to lack of plant available N. The aim of this study was to find out if and how much N was immobilised by cattle manure, if and when remineralisation of N will take place and, if added N has an effect on decomposition of cattle manure in soil. A laboratory study was conducted applying inorganic N fertiliser to soil (NH4NO3 equivalent to 30, 60 and 120 kg N ha-1) together with four cattle manures with different C/N ratios (9–18). CO2–C mineralisation and changes of inorganic N in soil were determined over 60 d. Immobilisation of fertiliser N occurred with manure having the lowest C/N ratio but not with the manures having a higher C/N ratios. Maximum immobilization of fertiliser N (23–36%) occurred within 21 d and thereafter N was mineralised. Carbon dioxide evolution decreased in cattle manure-amended soil at increasing rates of N fertiliser, but decomposition was still higher than from the unamended control. None of the manure treated soils had significantly different contents of inorganic N after 2 months of incubation. It was not possible to use the C/N ratio of aerobically decomposed cattle manure as a tool to predict mineralization or immobilization of N. It was concluded that aerobically decomposed solid cattle manures do not contribute to the N supply of crops in the short term but can immobilize fertiliser N applied at the same time. |
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Keywords: | cattle manure composting N fertilizer rates N mineralization/immobilization depressive C mineralization effect |
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