IMPACT OF TILE DRAINAGE SYSTEM AND WATER QUALITY ON SOME SOIL PROPERTIES AND CROP YIELDS OF WHEAT AND MAIZE

Abstract

The current study was carried out in two successive seasons (winter 2015/2016 and summer 2016) on two areas (Mahallet Rooh and Saft Torab). Both areas belong to El-Santa District (about 13 km to Tanta, Gharbia Governorate, Egypt). This work was conducted in clay loam soils to study the feasibility of installing tile drainage at farm level and using fresh and mixed water (fresh and drainage water i.e.1:1) on some soil properties, wheat and maize productivity. Moreover, the obtained field data were used to evaluate the field drains through comparing the calculated drain spacing using Hooghoud equation with the actual drain spacing. Both areas have a covered drainage system. The laterals were constructed at 1.2 m depth and 30 m drain spacing with a length varies from 250-275 m. Five feddans in each area were selected to carry out this study. Moreover, non- tiled drained areas were selected in both two areas as control areas. The results of irrigation water analysis revealed that generally, both fresh and mixed water applied in this study could be used safely according to the standard guidelines of FAO (1994) which means that, using such mixed water safely can save about 50% of fresh water needed for crop water requirements. Also the results proved that, at Mahallet Rooh area where fresh irrigation water is used, the soil salinity reduced by about 30.7% as compared with the initial value in the area not provided with tile drainage, but the reduction in soil salinity was about 58.9% in the area provided with tile drainage system. The total amounts of leached salts from the top 60 cm of soil were 1850.4 and 2051.8 kg/fed for non- tiled and tiled areas of Mahllet Rooh area, respectively. Concerning Saft Torab area, where mixed water is used for irrigation, these amounts were 1222.1 and 1965.2 kg/fed for the top 60 cm of soil, respectively. The obtained results confirmed that, the tiled areas at Mahallet Rooh, where fresh irrigation water is applied, showed a relatively higher values of quickly drainable pores (QDP), slowly drainable pores (SDP) and consequently, the total drainable pores (TDP) as compared with that of Saft Torab area where mixed water is used for irrigation. On contrary, the water holding pores (I.e. fine and coarse capillary pores values) were relatively higher as compared with that of Mahallet Rooh area. The non-tiled areas in both Mahallet Rooh and Saft Torab showed almost the same values of pore size distribution components, but the fine capillary pores value (FCP) was slightly higher for Saft Torab as compared with that obtained for Mahallet Rooh area. The results showed that soil bulk density values were lower in areas provided with tile drainage either in Mahallet Rooh or Saft Torab area resulting higher total porosity values as compared with that not provided with tile drainage. The results indicate that water table levels during winter season were much deeper than that observed in summer season in both areas under this study. The tile drainage areas showed a pronounced effect on lowering water table level as compared with the areas that not provided with tile drainage system. The results indicate that using mixed irrigation water which has a relatively higher salt content caused a higher salinity of water table as compared with that of Mahallet Rooh area where fresh irrigation water is used. Drain spacing is calculated according to Hooghoudt equation using the field data measurements of soil hydraulic conductivity and water table levels midway between drains. The results revealed that, using the field data the calculated drain spacing was 27 m at Mahallet Rooh area, while it was to 30 m spacing at Saft Torab. The designed values were 30 m which is almost the same as the calculated values. These results indicate to the good performance of tile drains in both areas under the study according to the field actual measurements. The results revealed that, both grain and biological wheat and maize yields in drained areas and that irrigated with fresh water are higher than that obtained in non-drained areas and that irrigated with mixed water.