Synergistic Effects of Phosphatic Fertilizers and Cow Manure on Wheat Yield and Phosphorus Use Efficiency in Calcareous Soils

Abstract

Achieving sustainable phosphorus (P) is a critical for food security in calcareous soils, where P fixation limits crop productivity. This study evaluated the integrated effects of phosphatic fertilizers-single superphosphate (SSP), triple superphosphate (TSP), monoammonium phosphate (MAP), and management cow manure (20 t ha⁻¹) on wheat yield, P dynamics, and P use efficiency in a calcareous soil (pH 8.2, 50% CaCO₃). Seven treatment included: control (no P), SSP, SSP+manure, TSP, TSP+manure, MAP, and MAP+manure. Phosphorus was applied at 37.5 kg P₂O₅ ha⁻¹. Results demonstrated that MAP with manure significantly (p<0.05) increased grain yield (3.78 t ha⁻¹), biological yield (21.86 t ha⁻¹), and 1000-grain weight (47.6 g) versus the control. Available P in post-harvest soil was highest with TSP+manure (46.89 mg kg⁻¹) and lowest in the control (4.69 mg kg⁻¹). The MAP+manure treatment maximized phosphorus use efficiency, PUE, (27.7%), while SSP alone showed the lowest PUE (14.4%). Grain P concentration peaked in TSP+manure (0.46%) and MAP+manure (0.38%). Synergistic interactions between manure and MAP enhanced P availability by reducing Ca-P fixation, improving root uptake, and sustaining fertility. In conclusions: Co-application of MAP (37.5 kg P₂O₅ ha⁻¹) and cattle manure (20 t ha⁻¹) optimizes wheat productivity and PUE in calcareous soils. This integrated strategy mitigates P depletion risks and supports sustainable intensification.