الفهرس 
Introduction
Soil - water contentOnly 14 pages are availabe for public view
 |  | from | 143 |  |  |
| | | from | 143 | | |
Abstract
Objectives: The main objective of the present study is to identify the most effective tillage method using subsoiling plough, which leads to the most enhancement for the physical properties known well for the heavy clayey soils, such as (infiltration rate, water holding capacity and drainage conditions).This is, in order to, the deluge of irrigation water which is applied using the surface irrigation system during the first sowing irrigation, be infiltrated from the soil surface in a shortest time and finally, be protected from evaporation. Hence, the water conservation to be achieved, this protected portion of irrigation water should be discounted from the irrigation requirements later. Methods and Results: The experiments attended in the present study were conducted on a heavy clayey soil of an area (1800m²).This area was divided into four plots, each one of them of an area (450m²) and allocated only for one treatment. The treatments were as follows: (T1)- sub-soiling plow at a depth of 40cm together with a lateral spacing of 150cm. (T2)- sub-soiling plough at a depth of 60cm together with a lateral spacing of 150cm. (T3)- sub-soiling plow at a depth of 40cm together with a lateral spacing of 300cm. (T4)- sub-soiling plough at a depth of 60cm together with a lateral spacing of 300cm. In all preceded tillage treatments, the subsoiling plough was followed by chisel plow at a depth of 20cm two crossed times and each plot was leveled at the dead level using the laser controlled scraper. All plots of the tested soil were irrigated at one time using the flooding surface irrigation system. Only, one irrigation was applied on a bare soil and an equal amount of irrigation water (22.5m³) was added for each plot. Regarding only, the mean values of the top layer (0-20cm) of soil profile for comparing the different treatments. It found that, the mean values recorded before tillage for the whole area of the tested soil were (0.7mm/h, 2.63MPa, 22.67%w/w and 1.22g/cm³) for the infiltration rate, soil strength, water content and bulk density, respectively. On the other hand, after tillage, the second treatment (T2) achieved the lowest mean values of (2.38MPa, 17.14%w/w) for soil strength and water content, respectively. Furthermore, it recorded the highest mean value of the infiltration rate of (2.2mm/h) after tillage and also, the highest mean value of water content of (65.76%w/w) at saturation and its water flux at the tenth day from saturation was (3.29mm/day). Inversely, the third treatment (T3) achieved the highest mean values of (2.52MPa & 21.23%w/w) for the soil strength and water content, respectively, after tillage. It also, achieved the lowest mean value (57.88%w/w) of water content at saturation and the lowest mean value (4.24mm/day) of water flux at the tenth day from saturation. On the other hand, the plot of soil which was selected apart to be as reference field achieved the lowest mean value of the infiltration rate (1.1mm/h) after tillage under all the different treatments. It also, achieved the highest mean values (2.55MPa & 21.86%w/w) for the soil strength and water content, respectively, after tillage. Inversely, it achieved the lowest mean values (54.98%w/w & 4.57mm/day) for its water content at saturation and its water flux at the tenth day from saturation, respectively. It can be concluded that, the second treatment is the most effective tillage method using sub-soiling plow for enhancing the well known physical properties of the heavy clayey soils to maintain a considerable portion of irrigation water from evaporation.