Efeito residual da gessagem e adubação fosfatada na cultura do milho segunda safra

Abstract

The use of gypsum and phosphatic fertilization are essential for the production of grains in Brazilian Cerrado soils, since they neutralize the toxic aluminum effect and provide important nutrients for plant metabolism. The objective of this work was to evaluate the residual effect of the agricultural gypsum associated with phosphate fertilization on the chemical characteristics of the soil, mineral nutrition, development and yield of second crop maize under direct sowing. The experiment was conducted at UFG, Jataí Regional, with an experimental design consisting of 15 treatments established in randomized blocks in a 5 x 3 factorial scheme, with 4 replicates. The first factor corresponded to doses of gypsum (0, 1, 2, 4 and 8 Mg ha-1

) and the second factor

corresponded to doses of phosphorus (0, 40 and 80 kg ha-1

). The following components were evaluated in the maize crop: second crop 16 months after the application of the doses referring to the treatments of the source of variation of the gypsum, the following components: dry root mass, macro and micronutrient contents in the leaves, production components and grain yield. In the soil samples collected in the 0-10, 20-40 and 40-60 cm layers the Ca, Mg, K, P, and S contents were evaluated. The residual effect (16 months) of gypsum did not increase efficiency of phosphate fertilization for second crop maize. Under water stress conditions, the yield of corn grains responds to the application

of agricultural gypsum in addition to the dose recommended by the formula NP = 5 x g kg- 1 of clay, which for this research is 2.93 Mg ha-1 of gypsum. Phosphorus provides

increases in maize grain yield only when 100% of the recommended dose is applied (80 kg ha-1 of P2O5).