Perfilhamento de azevém anual em sistemas integrado : do estabelecimento ao pastejo

Abstract

Crop-livestock integrated systems have been highly important as a model to sustain the agriculture production. Crop fields of soybean (Glycine max L. Merril) or corn (Zea mays L.) established in the summer and Italian ryegrass (Lolium multiflorum Lam.) in the winter are widely cultivated in Southern Brazil because the Italian ryegrass has agronomic attributes that allow its wide adaptation to these systems. Some of these important attributes is its establishment by natural re-sowing and the high-quality nutritive forage production. The tiller density, demographic patterns of tillering and the forage mass of Italian ryegrass were evaluated during the ryegrass establishment and the grazing period by lambs. The sward was submitted to rotational and continuous grazing methods at the intensity levels of 2.5 and 5.0% of the lamb intake potential. The on farm experiment was carried out from August to October in agriculture fields where the annual ryegrass was established after cropping soybean or corn. The experimental design was the randomized complete block in a factorial arrangement of treatments (2x2x2) with four replications. The fields cultivated with soybean showed earlier increases in the forage mass and tiller density than the fields cultivated with corn. The stability index had some values lower than 1.0 but without compromising the pasture stability. Therefore, both grain crops are suitable for further establishment of Italian ryegrass, but with soybean there is an earlier establishment. The grazing methods had no influence on the tillering. In contrast, fields established after corn with high grazing intensity affected the establishment of the Italian ryegrass. For tiller density, there was interaction only between the grain crops and time, time and grazing methods (P<0.005). Only areas cultivated with corn had increases over the evaluation time for tiller size/density compensation, tiller density and forage mass. The other area had a decrease in tiller density and increase in forage mass, and these values were affected by the boom of the fertile tillers. The stability index was reduced only at the end of the grazing period when the tillering was also reduced.