STUDIES ON SOME FACTORS AFFECTING THE SOLUBILIZATION OF P IN THE RHIZOSPHERE

Abstract

This study was carried out to explore the effect of some factors i.e. CaCO3, pH, organic matter (Humic acids) and clay mineral (Bentonite) on the availability and behavior of phosphorus in rhizosphere and nonrhizosphere zone as well as dry weight and P content of phaseolus plant grown on calcareous and noncalcareous sandy soils. The study involved three experiments, an incubation experiment, a split medium technique experiment and pots ones. The experiments were conducted at the faculty of agriculture, Ain Shams University. 5.1. Incubation experiment The experiment was conducted using 50 g of acid washed sand as pure media that were placed in plastic bottles (100 ml), mixed with the used treatments plus solution of soluble P as KH2PO4 containing 16 mg.kg-1 of P and incubated at laboratory conditions for 4 weeks at room temperature- ̃25°C after adjusting the water content to 70% of field capacity and then adjusting the moisture content daily. The treatments were applied as follows: Calcium carbonate (CaCO3) in the levels of 0 , 6 or 18%, Humic acid (H.A) in the levels of 0, 1 or 2%., Bentonite in the levels of 0, 20 or 40% and pH of the sand medium was adjusted to 7, 7.8 or 8.6. Samples from the incubated materials were taken after one, tow, three and four weeks for evaluating NaHCO3 extractable P.