Performance of four intercropping systems under variable monsoon onset conditions in rainfed semi-arid region of Rajasthan

To provide a contingency cropping plan for the rainfed areas of hot semi-arid region of south-eastern Rajasthan a four seasons (2003 to 2007) kharif field experiment evaluated four intercropping systems viz. sorghum [Sorghum bicolor (L.) Monech] + pigeon pea [Cajanus cajan (L.) Millsp] (1:1), pigeon pea + black gram (Vigna mungo L.) (1:2), castor (Ricinus communis L.) + green gram [Vigna radiata (L.) Wilczek] (1:2) and soybean [Glycine max (L.) Merr.] + pigeon pea (4:1) under three dates of sowing, viz. first (normal) and third week of July, and first week of August. Four years mean pigeon pea grain equivalent data showed that sorghum + pigeon pea is the most remunerative cropping system under normal monsoon conditions but the crop yields sharply decline with the delayed onset of monsoon. The two week delayed planting of castor + green gram system did not show any yield reduction while four weeks delayed planting reduced yield by 16% only as against corresponding yield reduction by 9 and 54%, 25 and 46% and 28 and 57% for sorghum + pigeon pea, pigeon pea + black gram and soybean + pigeon pea intercropping systems respectively. Results indicated that if the monsoon onset is delayed by two weeks either castor + green gram or sorghum + pigeon pea should be the preferred cropping systems, whereas under four week delayed onset of monsoon situation only castor + green gram intercropping system has potential to maintain acceptable yield levels.