Effect of paraplowing on soil properties and crop yield under irrigated management
Limitations on water infiltration and soil aeration through compaction processes have the potential to limit production in irrigated agricultural fields. This project was conducted to determine the impact of sub-soiling with a paraplow (Howard Rotavator) on soil physical properties and processes that are important in affecting soil-water relations and productivity. The paraplow was the subsoiler selected for use in this study because of its ability to loosen the soil at the depth of plowing while producing minimal surface disturbance. The research plots were located on Chernozem and Vertisol soils in the Brown soil zone in the Lake Diefenbaker irrigation district near Birsay, SK. Irrigated and dryland sites were used for comparison. Sub-soiling was able to consistently reduce bulk density of the soil and effects persisted for one to two years under normal precipitation conditions. Excessively wet conditions (2010 and 2011) reduced the effectiveness of the sub-soiling. Tillage induced porosity in the soil was associated with a greater infiltration capacity measured in the field. Yield benefits in crops grown (canola, flax, wheat) from sub-soiling were variable under the wet conditions of 2010 and 2011. A greater benefit was observed under the normal precipitation conditions of 2012 on sites that were paraplowed in 2011. Subsoiling at a depth of 45cm and a row spacing of 45cm (manufacturer’s recommended configuration) was more effective than shallower depth and wider row spacing treatments. A significant yield benefit was only observed at the dryland site established in 2011, and limited yield benefit was observed in the irrigated sites. Over the three years of the study, annual yields from sub-soiling were on average about 5% higher than the un-tilled control. However, yield benefits were variable depending on crop and year. Given an estimated cost of subsoiling of ~$30 per acre, a benefit of sub-soiling that lasts one year would produce close to break-even conditions, and sub-soiling benefits that are consistent and last longer than one year are needed to be cost effective.
Soil Science, Tillage, subsoiling, paraplow, agriculture, bulk density
Master of Science (M.Sc.)
Agricultural and Bioresource Engineering