Application of variable rate fertilizer in a commercial apple orchard

The spatial variability of yield in an apple orchard is high due to the inherent soil variability and the impact of the environment on the trees. One practice of precision agriculture is the variable rate application (VRA) of inputs, which gives farmers the opportunity to manage field variability. The objective of the present study was to demonstrate how the use of variable rate fertilization in an apple orchard can change the farmer’s profit. For every other row, in a commercial apple orchard in central Greece, VRA was applied while the remaining rows were used as reference and received a uniform rate similar to the rate typically used by the farmer. The VRA rates of nitrogen were based on the literature which suggests that for every t/ha of apple yield, 2.45 kg/ha of N are removed from the soil in one growing season. The comparison of the results between VRA and reference treatments showed that the amount of fertilizer used in VRA treatments was reduced by 32.4% while the farmer’s profit increased by 21%. More years of research are required to give more reliable results.