Atributos Químicos em Dois Tipos de Solos com Pastagem de Capim Mombaça sob Diferentes Doses de Fertilizantes.

Abstract

The choice of the best strategy of nitrogen and phosphate fertilization that influences the characteristics chemical allowing the maintenance or recovery of the soil and providing the productive increase for pastures allows the rational use of productive areas. The objective of this work was to find a better fertilization option in Neossolo and Argissolo that contributes to improve the chemical characteristics and the productive increase of the mombassa grass. The experimental design was randomized blocks with four nitrogen doses (0, 40, 80 and 120 kg ha -1 ) and two doses of phosphorus (100 kg ha -1 and 200 kg ha -1 P 2 O 5 per year ), with four replicates, the results were submitted to a test of variance and significance (t-student test at 5% probability) and the effects of the N and P doses compared by means of a linear or quadratic regression equation . It was evaluated the spatial dependency index in the areas, using the Geo statistic tool in a regular grid with 64 points. For the Neossoil, the phosphate fertilization with 100 kg ha -1 of P 2 O 5 increased in organic matter content , and the dose of 2 00 kg ha -1 P 2 O 5 caused the opposite effect. Phosphate fertilization with 200 kg ha -1 of P 2 O 5 associated with N doses resulted in a gradual increase of pH. Forage production and stem (kg MS.ha -1. cycle -1 ), linear effect was observed with higher averages related to the doses of 0 and 120 of N, total forage yield and Leaf blade (MS.ha kg -1. Year -1) obtained quadratic effect on P 2 O 5 doses, agronomic efficiency and dead material had no significant effect to leaf ratio leaf, stem and dead equipment (%) was observed quadratic effect, best response to doses of 100 kg ha -1 of P 2 O 5 per year . The leaf and stem ratio (kg MS.ha -1 .cm -1 ) linear regression with effect for N and dose of 200 kg ha -1 of P 2 O 5 , respectively the number of tiller and LAI did not present effect for N and P doses. Organic matter (OM), K, Aluminum (Al), aluminum saturation (m%) RP10 and RP15. The attributes Al, pH, H + Al, CTC and V%, presented spatial dependence being the adjustments with strong IDE. For the Neossoil, the variables MO, P, K, Ca, Mg, Ca + Mg and CTCe showed pure nugget effect. The spatial variability showed the dynamics in the evaluated area, where soil characteristics (sand fraction and relief) influenced soil moisture and CTC, indicating a correlation between these variables. The resistance to penetration showed heterogeneity being influenced, mainly by the soil moisture, presenting greater resistance from 10 cm. Base saturation suggests that the low values of basic cations may have influenced the increase of acidity and reduction of pH. The degree of spatial dependence in Argisol for all variables was considered moderate to strong. The variables potential acidity, P, pH and humidity had influence of the relief, therefore the regionalized evaluation of the factors influencing the fertility of the soil, allows a precise management with reduction of cost and increase of productivity.