Search

Laboratory experiments were carried out to investigate the effect of operating pressure on wetting pattern in layered soil for subsurface point water source. This study helps to determine a suitable operating pressure and appropriate spacing between emitters and drip lateral pipes. The layered soil profiles were prepared using two types of soil (clay and loam) in two combinations (clay over loam and loam over clay) . Three operation pressures (4.99, 9.99 and 16.14, m) with a nominal dripper discharge rate (2 l/hr) were used. The experimental results showed that positive back pressure around dripper outlet develops, when the water application rate is larger than the soil infiltration capacity , and the actual dripper discharges were less than the rated dripper discharges by about (10%-28%) due to back pressure effect . Furthermore, it has been observed that water start rising up to the soil surface (Chimney Effect) when the operating pressure is (16.14m) for the loam over clay soil profile, which occurs when water application rate exceeds the soil capability to spread the water. It is found that the total wetted area for both layers was not affected by the operation pressure for the same volume of applied water. In the relationship of the wetting advance (a tb) , it is found that , the constant (b) is not effected by operation pressure while the constant (a) increased with increased operation pressure . [ABSTRACT FROM AUTHOR]

The present study aims to obtain a relationship between the ultrasonic pulse velocity which is one of nondestructive method of material testing and some of soil mechanical and physical properties. In this study a relationship between the ultrasonic pulse velocity through the soil samples and the unconfined compressive strength, dry density and curing time was obtained in high plasticity clayey soil. The soil was compacted in the cases of natural condition in standard and modified compaction effort, and in the treated condition with ( 2,4,6,8 ) percent of lime, compacted with modified compaction effort for three percent of water content(O.M.C, O.M.C ±4) these samples cured in 25º)temperature in different curing time ( 0,2,10,20,42 ) day . After curing time end, all samples tested in ultrasonic device and unconfined compressive strength device. The results obtain from these tests, analyze and get a good relationship between the ultrasonic pulse velocity and the unconfined compressive strength, dry density and curing time with high correlation coefficient in all properties. [ABSTRACT FROM AUTHOR]

Five pesticides were selected match, polo, topas, Diazinon and alphacypermethrine which were belonging to various groups in its chemical structure, to assess their vertical mobility in two types of agricultural soils which have been taken from the surface layer (0 - 30) cm in Abu-Khasib and shiabah with two different texture clay soil and sandy loam soil respectively. The results illustrated non ability of pesticides on mobile in clay soil, so they tend to remain in it, as result these pesticides lost theirs ability of movement and reaching to ground water to pollutant it while alphacypermethrine and topas were showed the ability of movement in sandy loam soil, whereas diazinon showed least to absence of movement in that soil, as for the match was founded to be middle in its movement, on the contrary of polo which its movement was least. The studied pesticides demonstrated difference in humidity proportions for the soil with clay texture also values of Hydraulic conductivity which was considered the most variable characteristic in the soil, since its depending on the property of liquid and soil together. Where the ratio of humidity varied for clay soil by passing the different pesticides through it with high significant level at (0.01) for humidity as well porosity (f) and Hydraulic conductivity and the difference were significant at level (0.05) for Bulk density (pb) too. The results demonstrated, there was a positive direct relationship between Hydraulic conductivity and volumetric humidity (pv) by (0.44) degree as well as this study showed the stability of Hydraulic conductivity values after leaching the soil from pesticides with normally water. Two studies have been carried out to measure the standard Hy.Co. of two types of soils clay and sandy loam. First, the pesticides were passed through a column of soil and their Hy.Co. was measured. Second, the soil was dried and the pesticides were passed through it. Then the soil was washed by water for measuring the Hy.Co. [ABSTRACT FROM AUTHOR]