الفهرس 
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Abstract
Two field experiments were carried out and replicated in two seasons to investigate the possibility of spraying compost extract and humic substances as foliar application for maximizing the soil compost addition, for reducing usage of mineral nitrogen fertilizers. A complete randomized blocks design with three replicates was adopted and data were statistically analyzed. Field experiments: Two field experiments were carried out using two plant variety kidney bean (Phaseolus vulgaris, L.) and lettuce (Lactuca sativa, L.) each experiment was replicated in two seasons in alluvial soil. 1- Kidney baen experiments: Kidney been (Phaseolus vulgaris, L.) planted during the two successive winter seasons of March 2007 and March 2008. Treatments were as follows: Both of compost extract or humic substances was sprayed twice, the 1st after full grown plants, the 2nd after 2 weeks from the first spraying. But the treatment which included alternatively compost extract and humic substances, compost extract was applied after full grown plants, whereas humic substances was applied after 14 days from applying compost extract. 2- Lettuce experiments: Lettuce (Lactuca sativa, L.) planted during the two successive seasons of January 2007 and February 2008. Both of compost extract or humic substances were spraying twice, the 1st after 15 days of transplanting plants, the 2nd after 2 weeks from first spraying. The treatment which included alternatively compost extract and humic substances, compost extract was applied after 15 days of transplanting lettuce, whereas humic substances was applied after 14 days from applying compost extract. The results can be summarized as follow: Plant measurements: Fresh and dry weights, shoot height, number of pods were increased by application of 75% of mineral nitrogen fertilizer coupled with the addition of 10 ton/fed of compost jointly with compost extract alternatively with humic substances as foliar application. Chemical composition: N, P and K concentrations and their uptakes were increased with application of 75% of mineral nitrogen fertilizer coupled with the addition of 10 ton/fed of compost jointly with compost extract alternatively with humic substances as foliar application. CONCLUSION: from the obtained results, it can be concluded that, usage of compost as soil application led to reducing the mineral nitrogen fertilizer use. Also, spraying compost extract and humic substances separately or alternatively increased all growth parameters of kidney bean and lettuce in both seasons compared with recommended dose of mineral nitrogen fertilizer (control). That means, when compost extract or humic substances applied the utilization of soil compost addition was maximized.