Energy budgeting and productivity response of cotton-wheat cropping system to mechanical sub-soiling

In North India, sub-soiling is required to alleviate the problem of soil compaction raised due to the use of heavy machinery. We have emphasized energy auditing to understand the practical feasibility of sub-soiling in cotton-wheat cropping system. Four sub-soiling treatments (cross and single side sub-soiling at 1.0 m, 1.5 m under both cases) in addition to conventional tillage were compared with conventional tillage alone at two sites. Sub-soiling improved crop yield by 13.5-33.7% in cotton and 13.0-22.0% in wheat as compared to control. Net monetary returns earned with sub-soiling were 98-408 and 159-287 US$/ha higher under cotton and wheat, respectively over control. Energy auditing suggested that sub-soiling treatments consumed 489-1504 MJ/ha extra energy in cotton season, however, net energy gain was higher in cotton (by 11,518-29,715 MJ/ha) and wheat (by 19,861-32,594 MJ/ha) over control. Energy use efficiency was higher under sub-soiling treatments in cotton (5.36-7.25) and wheat (9.55-10.46), whereas corresponding values under control were 4.64-6.18 and 8.18-8.36. Similarly, lesser specific energy was observed under sub-soiling treatments as compared to control. The present study concluded that sub-soiling increased cotton productivity and energetic returns as well as had the significant residual effect on wheat crop. These results clearly suggest that sub-soiling is a sustainable practice for cotton-wheat system in north-western India.