Estratégias de correção da fertilidade do solo para a produtividade e desenvolvimento radicular no capim Marandu

Abstract

In the tropical environment, the low soil's natural fertility and forage yield seasonality are significant challenges for animal production on pasture, especially in sandy soils. Thus, the aim of this study was to evaluate the contribution of gypsum (0, 200, 750, 1500, and 2250 kg ha -1 ) combined with liming + NPK fertilization, in addition to the treatments only NPK and the control (without fertilization or correctives), on forage production and root development of Marandu grass (Urochloa brizantha). The experiment was conducted under field conditions, in a randomized block design, with seven treatments and four replications. 3000 kg ha -1 of dolomitic lime was applied and for the NPK we used 100 kg ha -1 of N (urea), 50 kg ha -1 of P 2 O 5 (triple superphosphate) and 100 kg ha -1 of K 2 O (chloride of potassium). Soil fertility improvement strategies promoted changes in soil chemical attributes at six and twelve months. In the soil surface layer, the lime and gypsum increased pH and calcium content, in addition to reducing aluminum saturation, in addition, the fertilization increased phosphorus and potassium levels too. In the subsurface layers, from 50 to 110 cm, calcium and magnesium contents increased and aluminum saturation decreased due gypsum addiction. The Marandu grass root mass increased, in the soil profile, with NPK and gypsum application. In the first and second years of evaluation, the strategies of combining or not gypsum + lime and fertilization showed greater height, tiller density, and forage mass per cycle and total compared to the control. Only in the second year was observed difference between the strategies, and the application of gypsum allowed greater increments in height, tiller density and forage mass per cycle and total. The strategy that involves limestone and gypsum promotes better benefits on surface and subsurface soil fertility and stands out for minimizing the seasonality of forage production by stimulating forage growth in the wet-dry and dry-wet transition periods. Fertilization with NPK and gypsum increases Marandu grass root mass in the soil profile. The combination of fertilization with NPK plus lime and gypsum presents better performance on production and pasture recovery.