Exploitation of soil by roots as influenced by phosphorus applications

According to literature, the mechanism of P acquisition by roots is mainly through interception. Sufficient P uptake is only ensured by proper root development. Pot and field experiments were conducted to determine the percentage "exploitation" or "utilization" of the soil volume by roots and to study the influence of P on Zea mays root growth. For the two pot trials, four P levels (0, 20, 40, and 80 mg kg(-1)) were used, with additional N (100 kg ha(-1)) and K (75 kg ha(-1)). The field trial consisted of a high-P (Bray-1: 70 mg kg(-1)) plot and a low-P (Bray-1: 7 mg kg(-1)) plot, sampled to a depth of 80 cm. The Gompertz function was used to describe exploitation by roots as influenced by P application. Less than 5% of the soil volume was exploited by the root system for the pot and 0 to 10 cm depth in the field trial, with