Modeling of Phosphorus Nutrition to Obtain Maximum Yield, High P Use Efficiency and Low P-Loss Risk for Wheat Grown in Sandy Calcareous Soils

Fertilization with high levels of phosphorus increases the risk of environmental pollution. Identification of critical values of P in soil (SOP) and in plant tissues (PiP) is essential for achieving the maximum wheat yield without P loss. The critical value is the value of P which gives the optimum yield; the response of crop yield to P fertilization above this value is not predictable or nil. Here, a 4-year field experiment was conducted to identify the SOP and PiP for achieving maximum yield of bread wheat using 11 rates of P fertilization (0, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 kg P2O5 ha(-1)). The linear-linear and Mitscherlich exponential models were employed to estimate the PiP and SOP. The degree of phosphorus saturation (DPS) was used to assess the potential environmental risk; furthermore, phosphorus use efficiency (PUE) was also calculated under the studied fertilization levels. Phosphorus in soil and wheat plant was affected by the application rates and growing seasons. Increasing P fertilization rates led to gradual increases in soil and plant P. The SOP ranged between 21 and 32 mg kg(-1), while the PiP ranged between 6.40 and 7.49 g kg(-1). The critical values of P calculated from the Mitscherlich exponential models were 20% higher than those calculated from the linear-linear models. Adding levels of P fertilization & GE;90 kg P2O5 ha(-1) leads to higher potentials of P runoff and leaching, in addition, PUE decreased sharply under high P fertilization levels. The response of wheat yield to P fertilization in sandy calcareous soil is predictable below Olsen P values of 21 mg kg(-1). Identification of critical P values for wheat production is of great importance to help policy makers improve P use efficiency and attain optimum wheat yield under eco-friendly environmental conditions by eliminating the accumulation of excess P fertilizers in soil and water.

Automated summary

Identifying critical values of phosphorus in soil and plant tissues is crucial for maximizing wheat yield while minimizing environmental pollution risks. High phosphorus fertilization rates can increase phosphorus runoff and leaching, as well as reduce phosphorus use efficiency. Predictable responses of wheat yield to phosphorus fertilization were observed in sandy calcareous soil below certain phosphorus values.