INTERACTION OF SOIL ORDERS AND LEVELS OF APPLIED PHOSPHORUS ON P-STATUS OF SOIL CALTIVATED WITH WHEAT AT ELONGATION STAGE

A pot experiment was carried out during autumn growing season of 2016-2017 at the Gerdarasha field of College of Agriculture Engineering Sciences, to study the effect of three dominant soil orders (Mollisols (M), Vertisols (V) and Aridisols (A)), five levelsof applied triple super phosphate (TSP) fertilizer (0, 80, 160, 240 and 320 kg TSP ha-1) and combination between them on chemical availability of phosphorus (P) using solubility diagram at elongation stage and wheat yield. The factorial experiment was depended using a completely randomized design (CRD) with three replicates. The results indicated that the soil orders were affected on phosphorus status, it has appeared that the studied soil order was located between TCP and HA for both Aridisols and Vertisols it means the solubility of phosphorus is low. but in Mollisols is slightly more than Vertisols and Aridisols. It is the P-status and availability was very low since shifting towards TCP, it means precipitation of P in a non-available form then decrease in its availability. The application of phosphorus fertilizers caused shifting the points towards a more soluble form of phosphorus. The results indicated that the application of TSP fertilizer increased the solubility of P in the studied dominate soil orders. Then, the treatment combination (M, V, A) TSP0 were the nearest point to TCP falling between TCP and OCP which were the lowest soluble of phosphorus there less available, phosphorus application of phosphorus caused to shifting towards DCP In contrast, for treatment combination (M,V and A) TSP320 kg ha-1 were located between OCP and DCP the nearest point treatment combination for DCP