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 theMitscherlich
exponential models were 20% higher than those calculated from the linear–linear models. Adding levels
of P fertilization 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 ofwheat 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