Effect of Deficit Irrigation and Nitrogen Fertilization on Cowpea Yield, Its Components and Water Productivity in North Delta of Egypt.

Abstract

Two field experiments were performed at Sakha Agricultural Research Station, (31° 05' N latitude and 30° 56' E longitude), Kafr El-Sheikh Governorate, during the two growing summer seasons of 2009 and 2010, to study the effect of deficit irrigation by watering after 50%, 70% and 90% of available soil moisture deficit (ASMD) and four levels of nitrogen fertilization at 10, 20, 30 and 40 kg N fed.-1 on cowpea yield, its components and water productivity in North Delta of Egypt. A split-plot design with four replicates was used. Mean values of seasonal water consumptive use were 42.17, 37.05 and 30.12cm in the 1 st season and 41.22, 36.51 and 29.67 cm in the 2 nd season for the 50%, 70% and 90% of ASMD, respectively and seasonal amounts of irrigation water applied for cowpea were 63.10 cm, 54.09 cm and 43.10 cm in the 1 st st season and 0.568 and 0.403 kg of seeds m-3 in the 2 nd season as a result of irrigation at 90% of ASMD and fertilization with 30 kg N fed.-1 in the both seasons. Irrigation at 90% of ASMD enhanced WP by 29.7 and 33.4% and PIW by 35.9 and 39.7% compared to irrigation at 50% of ASMD in the two seasons, respectively. W P and PIW increased by increasing N application up to 30 kg N fed.-1. It can be recommended that the best results under the experimental conditions were irrigating cowpea cultivars at 70% of ASMD and fertilization with 30 kg N fed.-1 .