Soil Fertility of Tropical Intensively Managed Forage System for Grazing Cattle in Brazil

Abstract

Most of the Brazilian cattle are maintained on pastures grown on acid and low fertility soils that do not receive any lime or fertilizer. This lack of nutrients input in the establishment and the maintenance phases, and the inadequate management of grasses are the main causes of pasture degradation in Brazil. Estimates point to approximately 80% of the 50 million hectares of pastures are degraded or under degradation process in the Cerrado region. Pastures degradation are the main causes of the Brazilian livestock low productivity. Stocking rate average of Brazilian pasture is 0.5 Animal Unit - A.U. per hectare (A.U. = 450 kg of live weight), with an annual productivity of meat and of milk around 50 and 2,000 kg per hectare, respectively. On the other hand, using appropriate technology in cultivated pastures it is possible to improve significantly animal production. Well established pastures that are properly managed and fertilized are the main source of food for cattle and most practical as a less costly source of feeding. In intensive cattle production the system allows increased rates of stocking and productivity, based on grazing rotation, forage availability in the dry season, and building up soil fertility by balanced fertilizer supply. In the summer, Panicum maximum or Brachiaria brizantha are used as grass forage, and in the winter, feed is based on chopped sugarcane or corn silage. Throughout the year, the feed diet may be complemented with alfalfa, as a high source of protein. This technologies set leads to increasing stocking rate up to 5 A.U. per ha (without irrigation) or up to 10 A.U. per ha with irrigation. Crop-pasture rotation and the tropical grass pasture management intensification allows meat and milk productivity of approximately 750 and 20.000 kg per ha per year. Of the controllable factors determining forage yield and quality, soil fertility including fertilizer treatment is one of the most important. On these tropical acid soils naturally poor in plant nutrients, soil liming and balanced nutrient supply (N, P, K, Ca, Mg, S, B, Cu, Mo, Mn and Zn) are therefore essential to ensure high yielding and high quality forage.In order to intensify cattle production and reach high animal productivity, the main point to be considered is the correction of soil acidity and the balanced supply of mineral nutrients.This chapter organizes and provides information regarding the management of liming and fertilization of intensively managed pastures (based on soil analysis and requirement of the grass). The information sources are scientific articles (most in Portuguese) and personal experience of experts in the field.