In this study under clay soil conditions during two seasons 2008 and 2009, built in emitter type was used to irrigate pepper crop with 96h irrigation interval. In order to increase the benefits of water and energy units using water depletion strategy, three amounts of applied water 80, 90, and 100% of gross irrigation requirements (IRg) were studied with two different soil coverage cases, 1-rice straw mulching(RM) 2- normal (NM) conditions. Rice straw mulching with abundance (500g/m2) was used to decrease the effect of water depletion on pepper crop productivity. In general, increasing the amount of applied water led to increase crop productivity. The results showed that rice straw mulching led to increase the pepper crop productivity with all the amounts of applied water. The treatment (RM80) gave the maximum water use efficiency while the maximum water use efficiency under normal conditions was at (NM90) treatment. The two former treatments gave also the maximum productivity of energy unit. The study recommended using rice straw mulching if compared to normal conditions in order to increase crop productivity in addition to the increase of water and energy units' productivity. Using 80% of IRg with rice straw mulching and 90% of IRg will give the maximum water use efficiency and energy use efficiency at the two cases under experimental conditions.