Effect of tile drainage spacing on wheat production in heavy clay soils
Agriculture and Agri-food Canada
Manitoba Ag Staff
This study investigated the effects of three tile drainage configurations (15’, 30’ and 45’ spacing) on the behaviour of the water table (WT), volume of drainage outflow, quality of drainage outflow and nutrient transport, as well as wheat growth and yield.
Between May 15 – August 21, PESAI site got 157mm of rainfall which was 70% of the normal for this time of year. Excess moisture was not a limiting factor in wheat production this season, meaning that it was difficult to assess the effect of tile drainage on crop production. Yield was statistically not affected by any tile drainage spacing treatment.
Neither moisture stress nor drought stress were limiting factors in production this season, meaning that it was difficult to assess the effect of tile drainage on crop production. As well, all plots were seeded on the same day instead of seeding when the field was actually ready for planting. This was due to the fact that PESAI relied on custom seeding for this project.
In dry seasons, tile at 15’ in this soil type will still lower the water table (WT) more effectively than surface drainage alone (45’ will not). This may be a concern if the crop is not receiving enough water for production. However, this can also be alleviated with the use of control structures to prevent drainage when it is not desirable. Similarly, if the tile is between 2-3 feet from the surface, this rapid lowering of the WT in this space may not be a large concern, considering the tile drainage does not generally affect the groundwater below it.
It is recommended to repeat this study to collect data during a year when excess moisture stress affects plant growth.
Manitoba receives significant amounts of snowfall and sub-zero temperatures during the period between November and March. This leads to accumulation of snow over the ground and frozen soils. As temperatures rise during the month of April, melting of snow and frozen soils can cause excessive moisture in agricultural fields. Excessive soil moisture delays agronomic operations, such as field preparations or seeding, during the early cropping season. These delays can result in a shorter cropping season and sometimes a reduced yield.
The presence of heavy clay soils in the Interlake contributes to the presence of high moisture content, particularly during the spring. The province of Manitoba has identified the importance of surface drainage in peat areas of Interlake and built drains (Provincial waterways) for proper runoff after rainfall. In regions with heavy clay soils, removal of surface water alone might not be a solution to excess moisture if the soil below the surface remains saturated.
Draining water from the root zone is important to gain access to a field and to avoid loss of moisture-sensitive crops. Subsurface drainage systems help to remove excess soil moisture from the root zone. The amount of water removed daily is dependent on the drainage rate of the system, which must be carefully considered during the design process. The drainage rate determines the capability of the system to prevent soil saturation during high intensity rainfall events. Other parameters affecting the drainage rate are soil type, topography, tile installation depth and spacing of tile drains.
The Prairie East Sustainable Agricultural Initiative (PESAI) research site has various configurations of subsurface drainage installed and was used for this study. Soil at this site is classified in the Fyala (FYL) soil series as Class -3 agricultural capability due to limitations in high moisture conditions. Fyala soil is considered as poorly drained soil due to presence of clay particles throughout the profile. This site was chosen to investigate the effects of subsurface drainage in on water quality, yield, water table, and drainage volume outflow.