The Impact of Different Phosphorus Fertilizers Varieties on Yield under Wheat–Maize Rotation Conditions

The global phosphate (P) rock shortage has become a significant challenge. Furthermore, the misalignment between crops, soil, and P usage exacerbates P rock wastage in agriculture. The distinctions among various types of phosphorus fertilizers influence the phosphorus cycle, which subsequently impacts biomass, the number of grains per ear, the weight of a thousand grains, and, ultimately, the overall yield. In a four-year field experiment conducted from 2017 to 2021, we assessed the impact of various P fertilizer types on crop yield in a continuous wheat–maize rotation system. Prior to planting the crops, P fertilizers were applied as base fertilizers at a rate of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Additionally, nitrogen (N) was applied at rates of 120 kg ha−1 for wheat and 180 kg ha−1 for maize. The P fertilizers used included ammonium dihydrogen phosphate, ammonium polyphosphate, calcium–magnesia phosphate, ammonium phosphate, and calcium superphosphate. Urea was used as the N fertilizer with a split application—60% at planting and 40% at the jointing stage for wheat or the V12 (twelve leaf collar) stage for maize. The results showed that different P fertilizers increased the average yield of wheat and maize by 21.2–38.0% and 9.9–16.3%, respectively. It was found that ammonium polyphosphate, calcium superphosphate, and monoammonium phosphate were more suitable for application in a summer maize–winter wheat rotation system on loess soil.