Amelioration some Physical and Hydrophysical Properties of Clay Loam Soil Using Compost at Different Depths and Nitrogen Fertilizer rates.

Field experiments were conducted on clay loam soil during two successive seasons. Summer season 2017 using maize plants and winter season 2017/2018 using barley plants at El-Gemmeiza Agricultural Research Station, El-Gharbia Governorate, to evaluate the effect and residual effects of compost rates placed in moles 30 cm depth, arranged in parallel orientation with respect to one another and spaced at 3 m apart or placed on the surface soil layers besides the nitrogen fertilizer rates on improving soil physical and hydrophysical properties. Furthermore, economical analysis was done by calculating the net income for every treatment to determine the economical value. The rates of compost were 0.0, 2.5, 5.0 and 7.5 t fed.^-1, while the nitrogen rates were 0.0, 50, 75 and 100 % of the recommended dose for every growing crop. The experiments were conducted in split-split plot arranged in a randomized complete block design (RCBD) with three replicates. Results can be summarized as follows:- 1- Soil penetration resistance significantly decreased with increasing the addition rates of compost and depths. 2- The soil bulk density (Db) significantly decreased under different compost rates and depths, while total soil porosity (E) and void ratio (e) took the opposite trend. 3- The settling percentage of the soil was significantly decreased with increasing of compost rates and depths, indicating a higher degree of structural stability. 4- The values of pore size distribution (large, medium and micro pores as a percent of total porosity) were significantly increased in the two growing seasons. 5- Soil hydraulic conductivity (Kh) and soil moisture content, i.e., saturation percent (SP), water field capacity (FC), wilting point (WP), available water (AW) and soil moisture content just before harvesting (θw) were significantly increased for the two seasons, with increasing the rates of compost. 6- Water consumption (Cu) was decreased and water use efficiency (WUE) was increased in all treatments of the two seasons. 7- Cost benefit analysis revealed that the most valuable treatment was adding compost (5.0 t fed.^-1) in 30 cm mole depth with 100 % of the recommended dose of nitrogen fertilizer for each crop, since it gave the highest net income. 8- From the above results, it is more useful to use of compost filled moles with different rates and nitrogen fertilizers to markedly improve both physical and hydro physical properties under clay loam soil.