PRODUCTIVITY OF HEAVY CLAY SOILS AS AFFECTED BY SOME SOIL AMENDMENTS Combined with irrigation regime.

Two field experiments were carried out at Sakha Agricultural Research station, Kafr El-Sheikh governorate during the two growing seasons 2015/2016 and 2016 to investigate the effect of irrigation regimes and soil amendments on some soil properties, some water relations and yields of wheat and maize. The experiments were conducted in strip block design with three replicates. The most important findings can be summarized as follows: Irrigation at 40% depletion of available soil moisture received the highest amount of irrigation requirements, consumed water and stored water. The highest values of irrigation application efficiency and water consumptive use efficiency were recorded with irrigation treatment at 55% depletion of available soil moisture during two growing seasons. Water productivity (wp) and productivity of irrigation water (PIW), were recorded highest values under (I2) for maize crop. While the highest values of wp and PIW for wheat and maize were achieved from the interaction between irrigation treatment (I2) and soil amendments . The electric conductivity, sodium adsorption ratio, exchangeable sodium percentage were clearly improved and reducing of soil bulk density and increasing soil basic infiltration rate with application of soil amendments. Irrigation treatments and soil amendments have highly significant effect on increasing of yield of wheat and maize. Economic evaluation recorded the highest values of total income, net income, economic efficiency and net income from water unit with application of compost at rate of 5 ton fed-1 under I2 for wheat and maize crops.