Eficiência do uso da água e nutrientes da palma forrageira sob diferentes regimes hídricos e sistemas de plantio

Abstract

Forage cactus is a crop widely used in Brazilian semi-arid region animal production systems, since it presents great adaptation to this region. Thus, the objective of this work was to analyze water efficiency and nutrient use of forage cactus submitted to different water regimes and planting systems. The experiment was carried out in Serra Talhada - PE, from 11/2014 to 11/2015, with "Orelha de Elefante Mexicana" clone forage cactus and cv. SF-15 forage sorghum distributed in randomized blocks, with 4 replications, in a 5x4 factorial arrangement, with five water blades (0%, 25%, 50%, 75% and 100% of reference evapotranspiration - ETo) and four planting systems (exclusive forage cactus, exclusive sorghum, forage cactus-sorghum consortium and palm with cover. The crops productivity was obtained at harvest time and then, efficiency indicators of water use were calculated relating crop productivity in water blade systems, and nutrient use efficiency, relating nutrient productivity to water blades. There was no interaction between water slide and water and nutrient efficiency planting systems use for N, P, K, B, Mn, Zn and Na, however it was observed that higher efficiency of water use at water blades occurred in dry or irrigated condition based on ETo 25% and between the systems, exclusive forage cactus has lower efficiency. In relation to nutrients when influenced by slides under lowest water conditions (dryland and ETo 25%) highest efficiencies are obtained, and when it comes to planting system exclusive forage cactus has the lowest efficiency. There was interaction between water blade and planting system for nutrient utilization Ca, Mg, S, Cu and Fe, being observed a greater influence of the planting system than of water blade system. Considering the water use efficiently based on dry matter, even when there was no interaction between planting systems and water blades, forage cactus planting, forage cactus intercropped with sorghum and forage cactus with cover systems are more efficient than exclusive forage cactus since forage cactus should not be fed to animals as an exclusive diet, the forage cactus-sorghum consortium becomes an efficient alternative to overcome this limitation. The application of 208.3 mm of complementary water distributed regularly during greatest deficit period promotes an increase in forage cactus green matter yield and green and dry sorghum matter. It is indicated its use mainly in forage cactus- sorghum system, since the sorghum has less water use efficiency. Mulching use, consortium with sorghum, as well as complementary irrigation with 208.3 mm in forage cactus cultivation Opuntia stricta (Haw.) Haw., are efficient strategies to promote forage production improvements. The Mulching use promotes greater extraction of nutrients by forage cactus, as well as promotes increased productivity.