Ameliorating clay sub soils to improve crop yields : Final report 2013/072

Abstract

There are large areas of sodic duplex clay soils across the Australian sugarcane industry. Often, the sub soil on these soils is not conducive to sugarcane root growth and as a result the sugarcane roots can only explore the top 250-350mm of soil. This reduces the amount of water and nutrients available to the crop and reduces yield potential accordingly. An existing proof of concept trial showed that the sub soil can be ameliorated with organic amendments resulting in a 10% yield increase over a control. In this trial, the ameliorant was applied with a rudimentary applicator that was unsuitable for commercial use. Three questions were raised from this trial; firstly, what happened to the sub soil to produce this yield response, secondly can a commercially suitable applicator be constructed as they cannot be purchased from machinery manufacturers, and thirdly is sub soil amelioration a commercially feasible practice on a sugarcane farm? Through this project the DAG Group sought to answer these questions by testing the sub soil on the proof of concept trials for physical and chemical changes, constructing a prototype commercial applicator and establishing commercial sized trials.