PRODUCTIVITY AND WATER USE EFFICIENCY OF MAIZE UNDER SURFACE AND SUBSURFACE DRIP IRRIGATION

An experiment was conducted using surface and sub surface drip irrigation to study the water use efficiency and root distribution and productivity of maize. The experiment was carried out in fall season of 2004 at Al-Raad Research Station (Abu-Ghraib). The experiment was carried out in a completely randomized block design with three replicates. Treatments included control in which the crop planted with furrow irrigation method with water requirement of 700 mm plus 15% for eaching requirement. Surface drip irrigation (DI) and subsurface drip irrigation (SDI) were used with three levels of water requirements, 80%, 60% and 40% of the water control treatments. The seeds of Zea mays L. was planted on July with density population of 53333 plant.h ''(1) and harvested in November. Average grain yield, root distribution in the different depths of soil, salt distribution pattern and water use efficiency was measured and calculated. The results of the experiment showed significant difference in grain yield among the treatments. It was 9.397 t/ha for the treatment SDI0.8 , , 8.009 t/ha for the control, and 1.826 t/ha for the SDI0.4 treatment. The results showed that more than 90% of the root system grown in soil volume of 30 cm horizontal and 40 cm in deep with drip irrigation. Weight of day roots were varied from 27.2 to 55.2 gm according to treatments. Highest water use efficiency for the treatment DI 0.4 was 2.237 kg.m ''(3) and with DI 0.6 1.807 kg.m ''(3). The treatments were from higher to lower water use efficiency were as follows :SDI0.6 > SDI0.8 > control > SDI0.4. The results of this experiment showed that sub drip and drip irrigation system could be used to reduce water losses. The drip and sub drip can leach the salts out of the root zone when only 60% of the water requirement used. High water use efficiency can be reached when maize watered with only 60% of the 700 mm of the water consumptive used that recommended in Iraq.