Produção e extração de nutrientes pelo capim-Tifton 85 submetido à aplicação de dejeto líquido de suíno

Abstract

Applying liquid pig slurry (LPS) in pastures and crops is the most accepted destination from an agronomic and environmental point of view. In this way the objective of this work was to evaluate the response of the Tifton 85 grass to the application of LPS accounting for morphological, productive and nutrient extraction. The experiment was carried out in a field at the Rio Verde Research Foundation in the city of Lucas do Rio Verde-MT, in a very clayey textured Yellow Red Latosol, the design was in randomized blocks with five treatments and four replicates. The treatments were defined in volumes: 0, 10, 20, 30 m³ ha-¹ of LPS for each application and a treatment with mineral fertilization. In total, ten applications of LPS totaling 0, 100, 200 and 300 m³ ha-¹ and seven total harvests were performed from March 2014 to January 2015. Before each harvest, the height of the plants was measured and after cutting the plant material was collected, dried in a drying oven, weighed and ground for the determinations of N, P, K, Ca, Mg, S, Fe, Zn, Cu and Mn contents. The nutrient extraction was calculated considering the content of each nutrient contained in the plant tissue and the amount of dry matter produced. The results were extrapolated to the area of one hectare. The effect of LPS doses was analyzed to the plant height, dry matter production and nutrient extraction, in each harvest, through analysis of variance and regression. Differences between harvests were submitted to analysis of variance and Duncan's test. To compare the effect of LPS doses with mineral fertilization, the Dunnett test was applied. The nutritional efficiency and nutrient extraction efficiency were evaluated by analysis of variance and the Scott nott test was applied, at 5% probability. The LPS influenced dry matter production and extractions of N, K, Ca, Zn, Mn, Cu and Fe, however, it provides lower yields than mineral fertilization, providing insufficient amounts of K, Fe, Cu and Zn. Thus there is the need for mineral supplementation to meet the plant demand. The nutritional efficiency was higher at the dose of 100 m³ ha-¹ of LPS for all nutrients; for the macronutrients the sequence was: K> P> Mg = S> N = Ca and for Cu and Zn micronutrients had higher nutritional efficiency than Fe and Mn. However, the order of efficiency is: K> Mg = N> P = Ca = S, for micronutrients the sequence is Fe> Cu = Zn = Mn and the most efficient dose was 200 m³ ha-¹ of LPS.