Effect of perlite and moisture content on the availability and movement of phosphorus in calcareous soil cultivated with Sudan grass plants

الملخص EN

A pot experiment was conducted under greenhouse condition at the Experimental Farm, Faculty of Agriculture, Zagazig University.

The experiment aimed to study the effect of two phosphate fertilizers i.e., ordinary super phosphate (OSP) and rock phosphate (RP) combined with or without perlite under different soil moisture levels (80, 65 and 50% of saturation point) on sudan grass (Sorghum vulgare var.

sudanense) plant as well as available P behavior through the investigated calcareous soil.

Soil samples were taken from the surface layers (0-30 cm) from El-Noubaria Research Station, El-Noubraria District, Egypt.

Results showed that the application of various phosphorus source i.e.

OSP or RP as individual application or combined with perlite under different soil moisture levels increased fresh weight, dry matter and phosphorus uptake of sudan grass compared to untreated soil.

The highest value of each of fresh and dry weight, P-uptake and available P was found in calcareous soil treated with OSP combined with perlite under 80% moisture level, while the lowest ones were obtained with untreated soils under 50% moisture level in absence of perlite.

Application of OSP showed greater values of fresh weight, dry matter and P-uptake by sudan grass plants than RP.

The promotive effect of different soil moisture levels on available phosphorus after three cuts in the two layers follows the descending order: 80>65> 50% under the application of ordinary super phosphate or rock phosphate in presence of perlite.

Treatments under OSP gave higher values of available phosphorus after cutting than those under RP.

These increases represented as much as 9.2, 8.8 and 29% after the first, second and third cuts, respectively in the first layer (0-5cm) as well as 10.1, 8.6 and 23.4%, respectively in the second layer (5-10 cm).

Available P were higher in the first layer (0-5 cm) than in the second one (5-10 cm) after all cuts under different treatments.