Disponibilidade do nitrogênio do solo em condições de pré e pós-pastejo em sistemas integrados

Abstract

Was aimed to evaluate the influence of grazing on the availability of NH4 + and NO3- on the soil. So that, layer of 0,00-0,10 m was collected in four picket points before, during, and after grazing of milky cows. Availability of íons was evaluated in four areas formed with grass Ipyporã and Eucalyptus urograndis: B- 260 trees hectare-1 in two doble rows; C- 340 trees hectare-1 in three triple rows; D- 130 trees hectare-1 in two doble rows; E- 120 trees hectare-1 in three simple rows. The pasture was formed in between rows of 50 m on B and D, and of 15 and 21 m in C and E treatments, respectively. The design was completely randomized, with four repetitions. The data were submitted to ANOVA and average test. Before the grazing there was lower averages, with, respectively, 5,63, 0,09, 1,89, and 0,33 mg N-NH4+ kg-1 and 10,58, 4,55, 8,85 e 4,12 mg N-NO3- kg-1 on treatments B, C, D and E. The grazing raised the availability of íons, with, respectively, 22,52, 17,8, 20,25 and 2,86 mg N-NH4+ kg-1 e 17,24, 5,44, 10,13, and 6,76 mg N-NO3- kg-1 on treatments B, C, D and E. After the grazing, the contents were, respectively, 7,91, 0,68, 2,83 and 0,72 mg N-NH4+ kg-1 e 4,38, 3,40, 9,57 and 2,25 mg N-NO3- kg-1 on treatments B, C, D and E. The entrance of animals on pickets made possible increase on availability of NH4 + and NO3- , however, the answers were different according the systems arrangement.