PRODUCTIVITY OF CENCHRUS-CILIARIS IN RELATION TO RAINFALL AND FERTILIZATION

Forage for livestock is always in short supply in the arid zone of Ind ia, Cenchrus ciliaris L. is one of the major forage grasses cultivated in this region, We studied its productivity in relation to rainfall a nd nitrogen (N) and phosphorus (P) fertilization in the Indian arid zo ne at Jodhpur during 1983 to 1992, Factorial combinations of 4 rates o f N (0, 20, 40, and 60 kg ha(-1)) and 3 rates of P (0, 15, and 30 kg h a(-1)) were applied annually, Twenty kg N ha(-1) was the most effectiv e fertilizer treatment, increasing average annual forage yields from 9 42 to 1,785 kg ha(-1) over the 10-year study with significant yield in creases occurring in 7 of the 10 years, Yield responses to N rates gre ater than 20 kg ha(-1) occurred only during the last 3 years of the st udy and then only at the 60 kg ha(-1) rate with either 15 or 30 kg P h a(-1). Yields reached maximum levels on both the nonfertilized and fer tilized plots with between 180 and 250 mm of growing-season rainfall.