Sojicultura de precisão no Cerrado de Mato Grosso

Abstract

The market competitiveness of soybeans has increased, creating the need for a comprehensive management of all stages from procurement of inputs. Factors such as soil fertility and plant parasitic nematodes may also raise the production cost. In this sense, precision farming practices can contribute to the success of production, mainly in Mato Grosso Cerrado region, the place where the land relief contributes to agricultural mechanization. Thus, this research was divided into three chapters, the first of which evaluated in a soybean field in Jaciara - MT the spatial variability of nematodes in two seasons (beginning pod formation and harvesting). Another study evaluated the influence of fertilization on variable rate on soybean yield in four areas of Campo Verde - MT and, the third chapter compares two interpolation methods to access the variability soybean yield in these five areas. Based on the results, there was spatial dependence for all attributes of the soil, the population of nematodes and plant. The nutrients levels between average and adequate contributed to lower nematodes incidence and higher grain yield. In the sample points with K contents above 77 cmolc/dm3 , affecting above 100 individuals of Pratylenchus brachyurus in the roots and Helicotylenchus sp. in the soil at the beginning of grain filling stage, there was a reduction in the grain yield. The severity of damage caused by nematodes in soybean yield is affected by the population of the P. brachyurus and Helicotylenchus sp. and the interaction with the texture and soil fertility. Comparing the costs with lime and fertilizer application between the fixed rate and variable rate, the farmer saves an average of R$ 77.76/ha, with variable rate. For the management of soil fertility precision is recommended to take account the peculiarities of each area, especially the texture, organic matter and topography. In areas with lower levels of clay and organic matter it is recommended to apply smaller doses of superphosphate and over limestone and potassium chloride. Areas with lower spatial variability of soil properties resulted in higher grain yield, compared to more heterogeneous areas. Fertilization in variable rate contributed to the increase in grain yield. Soybean yield maps obtained by ordinary kriging and the Bayesian analysis were similar in their spatial variability. The lowest spatial prediction errors of grain yield occurred in the maps of bayesian prediction. The spatial variability of the P. brachyurus and Helicotylenchus sp., of the soil attributes and soybean yield can be used to plan management practices for future harvests.