|
چکیده
|
Variable rate (VR) phosphorus (P) fertilization aims at improving fertilizer use efficiency and environmental impacts by varying fertilizer rates according to the needs of each zone within a field. This study evaluates the profitability of an on-the-go VR fertilization of phosphate (P2O5) in grain corn yield using visible (VIS) and near infrared (NIR) soil sensor-based VR applicator. This evaluation was considered in two different soil phosphorus levels (high & very high with minimum & no fertilization, respectively), which are the common phosphorus levels in Belgian agricultural fields. A previously developed VIS-NIR model was used to predict the extractable phosphorous (Pal). An experimental field divided into two zones according to soil P levels, namely, Zone 1 (high Pal level of 55 mg 100 g-1) with 2 plots and Zone 2 (very high level of Pal of 63 mg 100 g-1) with 3 plots. In these five plots VR of phosphate (P) was adapted using the VR applicator. For each plot, the amount of uniform rate (UR) P need was also obtained using the traditional soil test phosphorus (STP). The overall P application in each plot using the VR approach was compared with the corresponding UR. Amount of P applied with VR fertilization depended upon the initial level of Pal. Compared with the STP recommendation for UR application, in Zone 1 with high level of P, VR provided a positive fertilizer return of 1.5 kg P ha-1, (0.96 € ha-1), whereas in Zone 2 with very high level of P, VR led to a negative fertilizer return of 16.37 kg P ha-1 (10.52 € ha-1). Compared with the UR fertilization plots, 305 kg ha-1 corn net return was obtained in Zone 1, which introduced a revenue of 33.54 € ha-1. However, in Zone 2 there was a loss of 324.6 kg ha-1 introducing a cost of 35.73 € ha-1. The results showed that the on-the-go VR fertilization of P based on a VIS-NIR sensor is profitable in fields with high level of phosphorus. However, the profitability of this system should also be investigated in fields
|