Administration of Natural Resources Research-
General Comm. for Scientific Agri. Research
Faculty of Agriculture, Damascus University,
The effect of polyacrylamide (PAA), organic manure (OM) and phosphate solubilizing bacteria (PSB) on some physical and chemical properties of gypsiferous soil has been studied. The experiment has been conducted with (15) treatments and three replicates under greenhouse conditions. The OM and the soil has been described before seeding. The field capacity (FC), permanent wilting point (PWP), crust strength, available water content (AWC), saturated capacity, hydraulic conductivity (HC), available phosphorus, total nitrogen, available potassium have been estimated post-harvest. The results have shown a significant increase in (AWC) in OM-treated plots 44% (weight) in comparison with the blank, and the same for (FC). However, the increase in PAA-treated plots was relatively low. The PAA-treated plots was higher than the blank in terms of (HC) especially for (PAA+ N (nitrogen) + P (phosphate) + PSB), (158%). The crust strength of blank was higher than that of OM/ PAA- treated plots.
Moreover, no significant difference among the treatments in saturation and PWP.
The phosphorous, and soluble, available potassium have been estimated in plots. The available phosphorous increased significantly in the treatments which contain OM, PAA, PSB, P, together in comparison with the blank. The available potassium increased by 34 % over blank when OM and PAA added to soil. The available potassium decreased in all PAA- treated plots.
The total phosphorous, nitrogen and potassium have been estimated in plant. The plant-N decreased in OM-plots in comparison with N-plots. The plant potassium increased when the OM and PAA added together, whereas PAA- plots were superior to blank apparently. Plant phosphorous increased significantly when super phosphate, PSB or OM added.
The Egyptian clover has been cultivated. The productivity has been estimated post-harvest, and it was significantly superior to the blank at different rates due to addition of fertilizers and soil conditioners.
Gypsum has been estimated in plots, showing no significant differences among the treatments because the gypsum has not been leached.
The PSB population has been estimated in plots post-harvest, the population increased in treatments containing PSB and OM in comparison with other treatments.
The PAA had a role in motivating PSB and increasing its effectiveness in phosphorus availability, as well as increasing the efficient use of super phosphate.