Environmental and Innovative Fertilizer Development Strategies for Wheat Cultivation: Urea-Doped Hydroxyapatite, Biochar-Coated Diammonium Phosphate, and Biochar-Coated Urea in Basal and Top Dressing

The effectiveness of conventional fertilizers is quite low. This study aimed to develop alternative basal and top dressing fertilizers by comparing the effectiveness of urea-doped nanohydroxyapatite (UnHAP) and biochar-coated diammonium phosphate (BDAP), as well as biochar-coated Urea (BUrea) fertilizer, with conventional DAP and urea fertilizers in field conditions. In the first experiment, Urea or BUrea was used as a top dressing with UnHAP from the base. In the second experiment, Urea or BUrea was again used as a top dressing with BDAP from the base. In the experiments, a P rate of 80 kg P₂O₅ ha⁻¹ was applied with DAP fertilizer as a reference. UnHAP and BDAP were applied at rates equal to or lower than the reference (60 and 40 kg P₂O₅ ha⁻¹). All plots received 150 kg N ha⁻¹ of Urea and BUrea, in comparison to DAP + Urea, the first year the highest grain production (4456 kg ha⁻¹) with 80 kg ha⁻¹ of DAP + BUrea, and in the second year, an equivalent amount of grain yield was obtained. In the second experiment, particularly in the first year, despite a decreased P rate up to 40 kg ha⁻¹, yields were still comparable to the reference. Even at reduced doses of UnHAP and BDAP fertilizers compared to the reference, there was no significant decrease in the grain protein contents. High-efficiency UnHAP and BDAP have the potential to reduce fertilizer consumption. Conducting studies to determine the long-term effects of UnHAP under various ecological conditions would be advantageous.