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Two field experiments were carried out in clay soil at the experimental farm of Gemmeiza Agriculture Research Station (Middle Delta, Egypt). during the two successive winter seasons of March 2007 and March 2008, to investigate the possibility of spraying compost extract and humic substances as foliar appliocation for maximizing the soil compost addition. For that purpose, kidney bean (Phaseolus vulgaris, L.) was planted in two successive seasons. The compost was added to all treatments except the control (100% mineral nitrogen fertilizer). Both compost extract and humic substances were added each alone twice or alternatively. The results clearly showed a positive effect of compost extract and humic substances on all plant growth parameters. The superior treatment was when compost extract was sprayed alternatively with humic in present of 75% of mineral nitrogen fertilizer with 10 Ton/fed of compost as soil addition, the following treatment was spraying of compost extract alone with 75% of mineral nitrogen fertilizer plus (10 Ton/fed) of compost addition. Generally, results pointed that usage of compost extract and humic as foliar application maximized the utilization of soil compost addition.

A laboratory incubation study was conducted to evaluate the effect of bensulfuron-methyl treatment on soil microbial biomass and N-mineralization of a loamy sand soil. The herbicide was applied at 0 (control), 0.01 (field rate), 0.1, and 1.0 microg g(-1), and soil microbial biomass carbon (C(mb)), soil microbial biomass nitrogen (N(mb)), and N-mineralization rate (k) were measured at different times after herbicide treatment. Compared to the untreated soil, C(mb) and N(mb) decreased significantly (p < or = 0.05) within the first 7 days after herbicide treatment at 0.1 and 1.0 microg g(-1), and the impact was greater for N(mb) than for C(mb). Nitrogen mineralization was significantly suppressed during the first 5 days of incubation when the soil was treated with bensulfuron-methyl at 0.1 and 1.0 microg g(-1). The overall impact of bensulfuron-methyl to the soil microbial communities was closely related to the application rate in the range of 0.01-1.0 microg g(-1). This effect, however, was found to be transitory, and significant impact occurred only at high application rates.