Development of alternative basal and top dressing fertilizers in wheat cultivation

This study aimed to develop alternative basal and top dressing fertilizers by comparing the efficiency of urea-enriched nano-hydroxyapatite (U-nHAP), biochar-coated diammonium phosphate (BK-DAP) and biochar-coated urea fertilizer (BK-urea) with conventional DAP and urea fertilizers. Characterization of nano-hydroxyapatite (nHAP), U-nHAP and biochar was determined by SEM and XRD. In the first experiment, U-nHAP was applied from the base as an alternative to DAP. Urea or BK-urea was used for top dressing. In the second experiment, BK-DAP was applied at the base and urea or BK-urea was applied as top dressing. In the experiments, DAP was applied at 8 kg P2O5 da-1 as a reference, U-nHAP and BK-DAP fertilizers were applied at amounts equal to or lower than the reference treatment (8, 6 and 4 kg P2O5 da-1). For top dressing, 15 kg urea da-1 or 15 kg BK-urea da-1 were applied to the plots. In the first experiment, grain yields were lower than the reference in both years with U-nHAP treatments. In the first year, the lowest U-nHAP applications (4 kg P2O5 da-1) provided closer grain yields to the reference. In the second experiment, particularly in the first year, even the lowest fertilizer dose of BK-DAP provided close results to the reference with regard to grain yield. In both experiments, there was no significant decrease in grain protein content even at reduced doses of U-nHAP and BK-DAP fertilizers compared to the reference. In the first experiment, plant N concentration was higher compared to the reference, despite lower fertilizer doses. In the second experiment, there was no decrease in plant N concentration despite reduced fertilizer treatments. Similarly, plant P concentration did not decrease in both trials even when the applied dose was reduced to 4 kg P2O5 da-1. In both experiments, it was determined that the treatments were in the same group with the reference in terms of plant Fe concentration, while there was variabilities between experiments and years in terms of Zn concentration. In conclusion, it is thought that it is necessary to test the effectiveness of these fertilizers, which may be an alternative to depleting P sources, in different plants under different soil properties and climatic conditions.