The effect of Different Tillage Managements on Soil Inorganic Phosphorus Pools

Tillage can significantly influence the productivity and sustainability of modern farming systems. In addition, the chemical nature of soil P is affected by tillage practice. The aim of this work was to determine changes of inorganic P fractions in a soil (labile, moderately labile, nonlabile, residual) under different tillage managements using Bowman and Cole (1978) procedure. Soil samples were taken from four different tillage treatments {conventional tillage (CT), Raised Bed Tillage (RB), Minimum Tillage (MT) and No-Tillage (NT)} from 0-8 and 8-16 cm depths with a factorial randomized complete block design with 5 replicates. The results showed that the tillage systems had significant effect on total P and all inorganic phosphorous except on nonlabile inorganic phosphorus. The change in soil tillage from conventional to conservation tillage significantly increased the amount of inorganic phosphorus forms (labile P, moderately labile P, residual P).  The most significant variation belonged to in labile inorganice phosphorus, in which the amount of labile inorganic phosphorus in conventional tillage (9.51 mgkg-1) increased to 21.37 mgkg-1 in minimum tillage (MT), indicating an increase of approximately 2 times compared to conventional tillage. No-tillage treatment showed the highest amount of moderately labile P (678 mgkg-1) and the lowest amount (580 mgkg-1) was in conventional tillage. The highest and lowest amounts of total inorganic P (522.95 and 441.98 mgkg-1) were observed in No-tillage and conventional tillage, respectively. The results of this study indicated that the change in soil tillage from conventional to conservation tillagehas considerable effect on soil P reserve.