FONTES E FORMAS DE APLICAÇÃO DE FERTILIZANTES FOSFATADOS EM CULTIVOS CONSECUTIVOS DE SOJA EM LATOSSOLO DE ALTA FERTILIDADE

Abstract

The central region of Brazil has great economic importance in relation to grain production in the country. In these regions the soil has low nutrients availability, mainly phosphorus (P). Considering the importance of nutrient P for agricultural development of several crops, several studies have been developed in order to ensure greater efficiency in the use of phosphate fertilizers. Currently, the search for more sustainable systems is necessary, since P reserves are reducing. In this sense, the objective of this study was to evaluate the phosphorus dynamics in soil and the productivity of soybeans under sources of phosphate fertilizers and their application forms. The work was developed in an experimental area of the IF Goiano, in the 2016/2017 and 2017/2018 harvests, being part of a project with a history of two previous soybean harvests (2014/2015 and 2015/2016). The experimental design was in random blocks in a 4 x 2 + 1 factorial scheme, being four sources of phosphorus: Morocco Reactive Phosphate (FR); Monoammonium Phosphate (MAP); Simple Superphosphate (SS) and Triple Superphosphate (TS), two forms of application (in the sowing line and the haul), and the Control without phosphate fertilization, with four replications. This work was divided into two chapters. In Chapter 1, Mehlich I was used as an extractor to evaluate the P content in the soil and plant, soybean productivity and the efficiency of phosphate fertilizers and their forms of application were also determined In Chapter 2, the fractionation proposed by Hedley et al. (1982) was used, and modifications suggested by Chen et al. (2000) to evaluate the behavior of the P fractions in the soil in function of the phosphate sources and their application forms. It was observed that the soluble phosphate fertilizers, MAP, SS, ST increased the soybean productivity as well as the P content in the soil in labile fractions and lower lability. The FR application, even after four consecutive harvests, did not provide increases in soybean grain productivity, and with smaller increases in the P content of the labile fractions in the soil, compared to soluble sources.