Abstract :
Field experiments were carried out in the Indo-Gangetic plains of India during 1997-98, 1998-99 and 1999-2000 with the objective to identify alternative crop sequences that are more productive as well as remunerative than the rice-wheat cropping system. The results indicated that the highest mean sunflower seed yield was obtained in the soybean-sunflower rotation followed by the rice-sunflower rotation and the lowest in the maize-mustard-sunflower crop rotation. Similarly, the sesbania-toria-sunflower rotation had the highest biological yield followed by the soybean-sunflower and urd-toria-sunflower rotations. The mean highest harvest index was found in the cowpea-toria-sunflower rotation (35.1%) followed by the urd-toria-sunflower (33.2%) and rice-sunflower (32.7%) rotations. A significantly high oil content in sunflower seeds was observed in both the soybean-sunflower and sesbania-toria-sunflower rotations that was similar to that in the urd-toria-sunflower and cowpea-toria-sunflower rotations. The maize-potato-sunflower, maize-mustard-sunflower, cowpea-toria- sunflower and rice-sunflower rotations had significantly higher sunflower seed yield equivalents (201, 17, 15 and 4% higher, respectively) than the rice-wheat rotation. Similarly, the maizepotato-sunflower rotation produced the highest net income followed by cowpea-toria-sunflower, rice-sunflower and maize-mustard-sunflower, that was 351, 37, 14 and 4%, respectively, higher than the net income of the rice-wheat rotation. The benefit : cost ratio was also observed to be significantly highest in the maizepotato-sunflower rotation (1.60). After 3 years of field experimentation, soil organic carbon, available nitrogen, phosphorus and potassium were observed to be highest in the urd-toria-sunflower, soybean-sunflower, cowpea-toria-sunflower and soybean-sunflower rotations, respectively. The mean value of total available nutrients was greater in soybean-sunflower than rice-wheat rotation. It can be concluded that the cowpea-toria-sunflower, soybean-sunflower and rice-sunflower crop rotations may be preferred for greater sustainability over the rice-wheat system not only in the Indo-Gangetic plains of India but also in the whole of Asia, and these findings may be a very useful reference for future research on Australian crop diversification.
