Precision agriculture applied to soybean: Part III - Spatial and temporal variability of yield

Abstract

The Brazilian Savannah is an important production center of grains despite the presence of low fertility soils. In this agricultural scenario, the delineation of management zones for the application of lime and fertilizer seems to be promising for a high potential for success and may result in the reduction in production cost with an increase in the yield. The objective of this work was to evaluate the spatial and temporal variations in soybean yield in the Brazilian Savannah involving the delineation of management zones based on the apparent soil electrical conductivity (ECa). In an agricultural field in the Brazilian Savannah, 160 sampling points were taken as the references for the mapping of soybean yield in the crop seasons of 2011/2012, 2012/2013, and 2013/2014. In 2012/2013 and 2013/2014, the soil fertility was managed according to the classes set on the basis of measurement of ECa in 2012. The fertilizers were prescribed on the basis of soil sampling in each class. The class management resulted in an increase in the yield of each area. Over the three years of study, 1.2% of the area reported an unstable yield (with a coefficient of variation greater than 30). This low inconsistency may be attributed to the prediction error (the difference between predicted yield values and actual values) in non-sampled sites. The regulation of soil fertility using the management zones based on the apparent soil electrical conductivity is likely to reduce the spatial variability of the yield in the study area.