Acúmulo de massa seca verde e características anatômicas, químicas e biológicas das lâminas foliares de capim-massai sob doses de calcário e nitrogênio

Abstract

This study evaluated the effects of different doses of nitrogen and limestone in the herbage accumulation, chemical characteristics of the soil, macronutrients, nutritional value, anatomical features and in situ degradability of leaf blade of massai grass (Panicum maximum). The study was conducted from September 2009 to November 2011. Four doses of limestone with PRNT 100% (0, 2000, 4000 and 8000 kg ha-1), and five doses of nitrogen (0, 20, 40, 80 and 160 kg ha-1) were assessed. The experimental design was a randomized block in factorial arrangement, with repeated measures at the time. Four replicates of the plots of 3m x 5m were used. The data were submitted to analysis of variance and regression. The mean comparison was made through the Scott-Knott at 5% probability. For the regression analysis the answers were adjusted according to the mean, adopting only the significant coefficients by “t” test (P<0.10). Doses estimated near 580 kg ha-1 N- 1.year and 5.795 kg ha-1 of lime in the first year of evaluations resulted in the highest accumulation of dry weight green 15.260 kg ha-1year-1. Base saturation and pH were elevated by the effects of limestone and reduced by the effects of nitrogen. Liming increased the contents of Ca and Mg in the soil, and amended in the first year, during the rainy season the CP and IVOMD in leaf blades.The nitrogen increased the levels of N, Mg and Ca (g kg-1), crude protein (CP) and the in vitro digestibility of organic matter (IVDOM), whereas the neutral detergent fiber (NDF), the acid detergent fiber (ADF) and lignin (LIG) in leaf blade of massai grass were reduced. The nitrogen increased the speed (K) of in situ degradability, the width, the length and the total area of massai grass leaves. The adaxial epidermis was reduced as were increased levels of nitrogen in the dry season.