PHONOLYTIC ROCK AS ALTERNATIVE SOURCE OF POTASSIUM IN SOYBEAN-CORN SUCCESSION SYSTEM

Abstract

Brazil is a world leader in the food production in a sustainable way. However, most part of the inputs used in their agriculture come from imports, such as fertilizers, for example, which makes their acquisition expensive and difficult to access for farmers. A local alternative for these fertilizers is the use of ground silicate rocks, such as K-feldspar phonolite, a source of potassium, which has shown great aptitude for partial or total replacement of Potassium Chloride (KCl). The present research project is part of an experiment that began in March 2019 and which aims to evaluate the effect of the application of phonolite rock as an alternative potassium fertilizer associated with the use of organic compost in soybean and corn crops intercropped with Urochloa ruziziensis in succession. The experiment is installed at the Experimental Lageado Farm of the College of Agricultural Science at UNESP, in Botucatu - SP. The treatments are constituted by 1) control; 2) KCl; 3) phonolite; 4) organic compound; 5) phonolite + organic compound. The K2O doses will be standardized for both fertilizers and will follow the recommendation according to the soil needs and for the respective soybean and corn crops. In October/November from 2022, soybean will be sown and, subsequently, corn intercropped with Urochloa ruziziensis (March 2023). The evaluations will consist of: nutritional status of crops, gas exchange, production components, and soybean productivity and corn, as well as the quantification of dry matter produced by soybean, corn and Urochloa ruziziensis.