Lixiviação de nitrato em Latossolo cultivado com milho após aplicações sucessivas de lodo de esgoto Nitrate leaching in a Typic Haplustox planted with mayze after successive applications of sewage sludge

O objetivo deste trabalho foi avaliar a lixiviação de nitrato causada por aplicação de lodo de esgoto e adubo mineral, em Latossolo cultivado com milho. As doses de N da adubação mineral (AM), em cinco cultivos, foram: 51, 90, 100, 90 e 100 kg ha-1. Nos tratamentos com lodo (L0N, L1N, L2N, L4N e L8N), as doses de N disponível corresponderam a zero, uma, duas, quatro e oito vezes às de AM. Ocorreu lixiviação em todos os tratamentos, na seguinte ordem de intensidade: AM<L0N<L1N<L2N<L4N<L8N. As perdas médias totais de N na forma de nitrato (N-NO3-), nos tratamentos L1N, L2N, L4N e L8N foram de 430, 1.020, 2.400 e 3.970 kg ha-1, respectivamente (28, 42, 54 e 45% do N total aplicado, respectivamente). Nos tratamentos L2N, L4N e L8N, no quarto cultivo, ocorreram os maiores teores de N-NO3- na solução do solo, com picos de concentração entre 86 mg L-1 (L2N) e 464 mg L-1 (L8N). Nos tratamentos AM, L0N e L1N, os teores de N-NO3- na solução variaram entre 5 e 9, 19 e 36, e 33 e 71 mg L-1, respectivamente.<br>The objective of this work was to evaluate nitrate leaching caused by applications of sewage sludge and mineral fertilizer in a Typic Haplustox cultivated with mayze. N aplication rates in five crops, in the treatment with mineral fertilizer (AM), were 51, 90, 100, 90 and 100 kg ha-1. In the sludge treatments (L0N, L1N, L2N, L4N and L8N), the rates of available N applied to each crop were equivalent to zero, one, two, four, and eight times those of AM. N-NO3- leaching occurred in all treatments, following the order AM<L0N<L1N<L2N<L4N<L8N. Mean total losses of N-NO3- in treatments L1N, L2N, L4N and L8N reached 430, 1,020, 2,400 and 3,970 kg ha-1, respectively (28, 42, 54 and 45% of the total N applied, respectively). Treatments L2N, L4N and L8N showed the greatest soil solution N-NO3- concentrations during the fourth crop, with peak values varying between 86 mg L-1 (treatment L2N) and 464 mg L-1 (treatment L8N). In treatments AM, L0N and L1N, soil solution N-NO3- concentrations during the fourth crop varied from 5 to 9, 19 to 36, and 33 to 71 mg L-1, respectively.

Abstract licence: CC BY

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