ABSTRACT
A filed experiment wasconducted at the experimental farm of Nubaria Agricultural Research Station (30° 54´ N, 29° 57´ E, and 25m above sea level), Agricultural Research Center (ARC), Ministry of Agriculture and Land Reclamation (MALR), El-Behiera Governorate, Egypt, during 2016 and 2017 seasons.The objective of this investigation amid to study the effect of three water regimes (100%, 80%, and 60% ET_o), two compost rates (0 and20m³fad^-1),and five intercropping  patterns(Millet sole stand, cowpea sole stand , millet/cowpea 1:1, 1:2, and 2:1patterns) on some growth traits,forage yield, protein percentage,amounts of applied irrigation water and water utilization efficiency in calcareous soils.
Results can be summarized as follows:

Water regimes, compost rates and intercropping patterns significantlyaffected thetested growth traits, forage yield, and protein percentage.
Maximum values of studied traits were obtained with irrigation by 100% ET_o, while minimum values were recorded with irrigation by 60 % ET_o.
All growth traits, and yield,except for protein% were increased significantly due to applying compost compared with the control.
Growing of pearl millet with cowpea significantly increased plant height than sole cropping, and increased the number of tillers of pearl millet, while the increases of cowpea branches reached maximum number under sole cropping.
Water utilization efficiency reached the maximum values under 80% ET_o compared with the other two regimes.