الفهرس 
ContentsOnly 14 pages are availabe for public view
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Abstract
Two soil column experiments were conducted using wheat plant ((Triticum aestivum L.), cv Sakha 8, during the winter season of 2000 at the Agric. University (laboratory experiment). The first experiment aimed to study the dynamics of nitrogen, while the second one was conducted to study the dynamics of phosphorous. Two soil types were used (clayey and sandy soils). We could concluded that a broad knowledge of the specific nutrient dynamics in soils of semiarid regions is necessary. The reactions of fertilizers applied have to be considered with respect to economic production and environment. Proper agrotechniques have to be practiced to optimize economic benefit and to minimize environmental pollution. The goal must be to sustain or increase soil fertility in sound and practicable integrated production systemsWith respect with former topics we must avoid the ground water pollution, by frequent application of light rates of N fertilizer which must be done to minimize the losses of NO3 through soil profile. Thus careful matching of fertilizer nitrogen application rates to crop needs can reduce nitrate leaching. The more efficient technology to reduce the NO3 leaching is using the nitrification inhibitors and by using of addition a part of organic matter as slow release fertilizer beside the mineral fertilizer. In order to minimize the risk of P pollution, addition of excess P to soils should be avoided. Also, band placement of P reduces the contact between the soil and fertilizer, with a subsequent reduction in P adsorption.