الفهرس 
IntroductiionOnly 14 pages are availabe for public view
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Abstract
Anincubation and pot experiments were conducted in soil Dept., Fac. Of Agric., El-Mansoura Univ. during seasons of 2008 – 2009 to investigate the effect of soil additives on phosphorus mobility and P-fertilizer use efficiency in calcareous soil. Seven treatments were arranged in a split-block design which were the simple possible combination between three treatments of compost, Pultary manure and humic acid as a main plots and four treatment of soil additives; Control, Bentonite, Vermiculite and Sulpher. The obtained results could be summarized as follows: Incubation experiment: Concerning the effect of organic manures, it could be observed that soil addition of humic acid was superior for increasing the mean values of Avail-P following with pultary manure and lastly the treatment of compost. Column experiment: Humic acid recorded the highest mobility of p. This could be an indication for increasing P-availability in soil matrix. The high performance of humic acid an increasing P-mobility could be attributed to various mechanisms Organic acids. Pot experiment:The heighest mean values of all plant growth parameters under study were realized due to an addition of humic acid as soil application followed by Poultry manure and compost, respectively. The difference between the mean values of such traits was significant for the two plants under investigation.