The rapid fixation of phosphorus fertilizers in soil with a high content of calcium carbonate requires efficient management methods for phosphorus fertilization, especially as regards the time of application. For this purpose, a field experiment was carried out in the summer season of 2006/2007 in the experimental farm of the Soils Department, Faculty of Agriculture, Mansoura University, Egypt to evaluate the best time for phosphorus fertilization to cowpea on Egyptian alluvial soil. The results showed that adding half the recommended phosphorus fertilization rate at sowing and the other half before the first irrigation was the best treatment to enhance phosphorus fertilizer use efficiency, contributing to an increased uptake of phosphorus by cowpea, reflected in the higher phosphorus concentration in the grains. Increased phosphorus uptake also caused an increase in the nitrogen and potassium concentrations in cowpea grains, whereas the zinc and iron concentrations decreased.

Soil surface photolysis can be a significant dissipation pathway for agrochemicals under field conditions, although it is assumed that such degradation ceases once the agrochemical is transported away from the surface following rainfall or irrigation and subsequent drainage of soil porewater. However, as both downward and upward water movements occur under field conditions, relatively mobile compounds may return to the surface, prolonging exposure to ultraviolet light and increasing the potential for degradation by photolysis. To test this hypothesis, a novel experimental system was used to quantify the contribution of photolysis to the overall dissipation of a new herbicide, bicyclopyrone, under conditions that mimicked field studies more closely than the standard laboratory test guidance. Soil cores were taken from 3 US field study sites, and the surfaces were treated with [(14) C]-bicyclopyrone. The radioactivity was redistributed throughout the cores using a simulated rainfall event, following which the cores were incubated under a xenon-arc lamp with continuous provision of moisture from below and a wind simulator to induce evaporation. After only 2 d, most of the test compound had returned to the soil surface. Significantly more degradation was observed in the irradiated samples than in a parallel dark control sample. Degradation rates were very similar to those observed in both the thin layer photolysis study and the field dissipation studies and significantly faster than in the soil metabolism studies conducted in the dark. Thus, for highly soluble, mobile agrochemicals, such as bicyclopyrone, photolysis is not terminated permanently by rainfall or irrigation but can resume following transport to the surface in evaporating water.

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Feeding millions of poor people depend on wheat for both diet and livelihood, two field experiments were carried out at Abo-Zaher, Sherbin, Dakahlia Governorate, Egypt during the two successive winter seasons of 2013/2014 and 2014/2015 under alluvial soil conditions. Different sources of inorganic nitrogen fertilizers at recommended dose including urea (U), ammonium nitrate (AN), ammonium sulfate (AS) and calcium nitrate (CN) were applied to soil with foliar application of zinc (Zn) and/or boron (B). Several parameters of yield and yield components were recorded including vegetative growth, grain yield, total N, P and K content in grain and straw, total Zn and B content in grain and straw as well as quality parameters in grain and straw of wheat plant. The experiments were conducted in split plot design which consisted of the main plot (inorganic sources of nitrogen including U, AN, AS and CN as well as control) and sub plots (four treatments of micronutrient compounds including control, Zn, B, and Zn + B). The results revealed that Zn and/or B as foliar application of wheat plant under different sources of inorganic nitrogen fertilizers cause highly significant increases in all studied parameters of wheat grain and straw yields. Most of these parameters gave the highest values treated with ammonium sulfate as a soil application followed by urea. Foliar application of Zn or B as an individual effect caused high significantly increases for all studied parameters of wheat grain and straw in compared with the control (untreated). Combine foliar application of zinc + boron gave the highest values of all studied parameters of wheat grain and straw followed by individual Zn foliar application. Foliar application of Zn +B in addition to ammonium sulfate or urea results recorded the uppermost all studied parameters of wheat grain and straw. Therefore, it could be recommended that, under these experimental conditions, foliar application of both Zn and B in addition to ammonium sulfate followed by urea as soil application at recommended dose for wheat recorded the uppermost of vegetative growth (plant height and tillering height), yield components (weight of 100 grain and grain yield), N, P and K content in grain and straw, Zn and B content in grain and straw, chlorophyll a, b, protein content in grain and straw of wheat plant.