Gaus Azam and Chris Gazey
Conventional surface application of agricultural lime takes many years to increase pH deeper in the soil profile. This is a barrier for the adoption of liming as crop growers want a quick-fix to the subsurface soil acidity. We conducted a small-scale field trial where agricultural lime was incorporated at various depths to re-engineer soil pH profiles for quick improvement of grain yield and water use efficiency (WUE). Results show wheat grain yield was more than doubled due to combined removal of compaction and lime incorporation compared to the untreated control. Removal of compaction only also increased grain yield by 72% over the control. WUE was as high as 24 kg/mm due to deep amelioration of soil compared to 11 kg/mm in the control. Deep incorporation of lime increased soil pH by more than a unit and decreased Al concentration to below the critical toxic level within two months of lime incorporation. Wheat plants produced root systems 60-65 cm deep with amelioration of compaction and acidity compared to 20-25 cm deep for the control. Deeper roots allowed plants to extract water and nutrients from deeper soil horizons and avoid moisture stress, in the absence of sufficient rainfall, during the grain filling in 2018 season.