Qualidade do solo sob manejo de aplicação de cinza vegetal em manutenção de pastagem de capim Paiaguás

Abstract

Vegetable ash, also known as wood ash or biomass ash, is a promising alternative for the recovery and maintenance of national pastures, because it presents a great potential as a corrective and fertilizer, directly influencing soil quality indicators. The objective of this study was to evaluate the effect of wood ash doses and application managements, on soil quality attributes, in a Cerrado area cultivated with Urochloa brizantha cv. BRS paiaguás. The experiment was conducted in the field at the Federal University of Rondonópolis, MT. The experimental design was in randomized blocks in strips, with five doses of wood ash (0, 8, 16, 24 and 32 t ha-1 ) and two application managements (incorporated and non-incorporated), with four repetitions. Evaluations occur over two years of grass maintenance, 2020 and 2021, with two appraisement periods, before forage cutting (December) and after the third forage cutting (March). The variables evaluated were divided into physical, chemical and biological soil attributes and forage productivity. After variance analysis of the data, the Tukey test was performed for the management application factor and regression for the doses of wood ash, both at 5% probability of error. In general, the soil physical attributes were altered by the incorporation of the ash to the soil, which provided a reduction in bulk density, macroporosity and resistance to penetration of the soil. Isolated effects of ash doses were observed on the chemical parameters evaluated, with promotion of nutrient contents, increase of CEC and pH, and reduction of soil OM content. The chemical composition of ash and changes in soil pH reduced soil enzymatic activity, and increased soil respiration and metabolic quotient. The productivity of the forage grass presented an increase of 1.86 t DM ha-1 for each ton of ash applied, until reaching the dose of 23 t ha-1 . The wood ash acts as a soil conditioner, because it improves its chemical, physical and biological quality of the soil, providing acidity reduction, increasing the macronutrients contents and higher productivity of the Paiaguás grass, reaching this result when used the dose of 16 t ha-1 incorporated to the soil.