Growth responses of mesquite (Prosopis juliflora (SW) DC.) during establishment stage to planting methods and amendments were studied in a highly alkali soil (Aquic Natrustalf, ESP 94), at the experimental farm of the Central Soil Salinity Research Institute, Karnal in July, 1984. Six combinations of planting methods and amendments with and without Karnal grass (Diplachne fusca Linn. P Beauv) in the inter-row space were compared in a four times replicated field experiment in randomised block design. The mean plant height (MPH), diameter at stump height (DSH), diameter at breast height (DBH), lopped biomass 16 months past planting and total biomass attained in 2 years period were significantly less when inter-row space was planted with Karnal grass. The MPH (cm), DSH and DBH (mm) attained in 2 years period were 319, 43.4 and 15.1 in with grass as compared to 405, 53.4 and 20.3 in without grass treatments. Similarly, the total biomass attained in 2 years was about 3 times more where inter-row space was not planted with grass. Growth was better when mesquite was planted by auger hole and pit methods than in trench plantation, when the original soil was treated with gypsum at 3 kg plant−1 and then refilled. However, using trenches of dimensions 30 × 30 cm and filled with a mixture of original soil, 3 kg gypsum and 8 kg farm yard manure plant−1 appeared to be promising method for establishing mesquite plantations on highly deteriorated alkali soils. The effect of amendments on growth decreased in the order gypsum + FYM, gypsum + rice husk, gypsum, control. In two years period, 37 percent mesquite died in the trenches in which the original soil was left unchanged. Effect of treatments on nutrient concentrations and total accumulations in different segments of mesquite is discussed. Karnal grass gave 25.3 t ha−1 green forage yield in 8 cuts without amendment in a growth period of 26 months proving its great potential as a folder crop for the adverse sites. The inorganic chemical composition of the shoots, including trace elements Fe, Mn, Zn and Cu, is such as to make this species a highly promising plant for the exploitation of alkali soils. Growing Karnal grass with mesquite for a period of about 2 years reduced soil pH and EC significantly and improved organic carbon and available N contents. The grass improved water infiltration rates and moisture storage in the lower layers of the profile.