Download or read book Managing Subsoil Constraints for Increased Productivity and Water Use Efficiency written by Gary John Clark and published by . This book was released on 2010 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This was attributed to less decomposition of the wheat stubble, in comparison to the lucerne, resulting in a higher content of soil carbon. A further field study investigated the residual effects, after 3 seasons of crop production, of subsoil amelioration, with organic amendments, on the shoot growth, soil water-use and grain yield. In addition, soil structural changes were assessed in relation to the spatial pattern of samples, either being directly beneath a canola plant or away from the plant. Improved shoot growth and up to a 30% increase in grain yield was found in the organic treatments. Macroaggregate stability was found to be highest in the organic treatments. Furthermore, the presence of canola plants also contributed to a positive increase in macroaggregates. In conclusion, this thesis has demonstrated that the addition of organic amendments, or root growth, can improve the structure of sodic clay subsoil. Primarily, this is achieved through the stimulation of the soil microbial activity.