Inorganic nitrogen in a tropical soil with frequent amendments of sewage sludge |
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Authors: | R F Vieira A H N Maia M A Teixeira |
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Institution: | (1) Embrapa Meio Ambiente, CP 69, 13820-000 Jaguariúna, São Paulo, Brazil |
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Abstract: | Accurate prediction of plant-available N release from sewage sludge is necessary to optimize crop yields and minimize NO3– leaching to groundwater. We conducted a 1.5-year study with three maize crops to determine N mineralization from an urban sewage sludge from Barueri, State of São Paulo, Brazil, and its potential to contaminate groundwater with NO3–. The soil at the experimental site was a loamy/clayey-textured Dark Red Dystroferric Oxisol. The treatments consisted of: plots without chemical fertilization or sludge, plots with complete chemical fertilization, and plots receiving four different doses of sewage sludge. Dose 1 was calculated at the agronomic N rate, while doses 2, 3 and 4 were, respectively, two, four, and eight times dose 1. The inorganic N addition increased with the rate of biosolid application. The high NO3– concentrations in relation to NH4+ were associated with intense soil nitrification. High N losses occurred for the first 27 days after soil sludge incorporation, even at the lowest dose, suggesting that land application of sewage sludge based on the N requirement of the crop may be overestimating the amount of sewage sludge to be applied. |
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Keywords: | Nitrate leaching Available N Nitrification Maize Denitrification |
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