Influência do manejo da pastagem do campo de altitude nas características do solo e na produção forrageira

Abstract

Inadequate pasture management causes land degradation and decreases the economic efficiency of livestock activity. This research aimed to evaluate physical and chemical soil attributes and to quantify plant biomass production in four native field management systems in the Água Doce/Palmas (SC/PR) high grasslands, Brazil. The experiment was carried out in a field, a Bruno Humic Cambisol, with the treatments of natural field mowed, natural field burned, natural field with introduction of oat and ryegrass species and natural field without any interference. The experimental design was randomized blocks with four replications in 10 x 10 m plots. Soil collections were carried out at 0 – 143 days intervals after the initial management of the area in the 0- 20 cm layers. To determine soil resistance to penetration, an impact penetrometer was used, assessing to a depth of 0-40 cm, with three sampling points for each repetition. To evaluate the production of green and dry vegetal biomass samples were collected at 0, 3, 7, 14, 28 and 35 days after the implantation of the treatments. Leaf area index was determined with a ceptometer, and three readings per plot were taken at intervals of 0, 3, 7, 14, 28 and 35 days after management. Data were submitted to analysis of variance, being performed multiple comparison test of means or regression analysis, as appropriate, when observed difference (p <0.05) between treatments. The distinct management of the grasslands natural pasture influences the soil fertility, both in macro and micro nutrients. The practice of burning natural pastures does not improve forage quality, reduces plant production potential, exposes soil to erosion by reducing soil cover and increases its density. On the other hand, over-season management of annual winter species or mowing natural vegetation results in better general soil fertility conditions and higher forage yields compared to fire management.