Drought Watch
Trapping Snow can Increase Yields
Roughly 30 per cent of all precipitation on the Prairies comes as snow. Trapping that snow can be an important tool in replenishing your soil's moisture. Depending on conditions, each inch of extra water conserved in the soil can mean an increase in wheat yields of between 2-4 bu/ac.
Snow management starts at harvest by manipulating crop stubble to trap more snow. Several methods of snow management are inexpensive and can fit conveniently into harvest.
Uniform standing cereal or oilseed stubble is the simplest method of snow trapping. The higher the stubble, the greater the potential to trap snow. An important advantage of uniform tall standing stubble is that it also reduces evaporation of soil water in the spring before seeding.
Where the crop is very short due to drought, leaving unharvested strips one foot wide every swather or combine width will improve snow catch significantly over stubble cut near ground level. Similarly, these "snow catch" strips can be left in hay crops to increase winter snow cover. The yield loss from such strips will be two to five per cent.
Straw deflectors and clippers have been developed to leave strips of taller crop when swathing. Where double swathing is practiced, every second pass can be cut higher and laid onto the first swath. The resulting, high-low stubble pattern will increase the winter snow catch.
The amount of water gained by snow trapping depends both on the amount of snow and the level of infiltration into the soil. Infiltration of snowmelt into the soil will vary. Typically, infiltration of meltwater increases the drier the soil and the better the soil structure. Deeply cracked clay soils have the best infiltration ability.
The effectiveness of the various snow trapping methods varies according to conditions. In some years, there may be no additional water gained by snow trapping. Under other conditions, the gain may be up to several inches of water. Long-term research has recorded average gains of about half an inch of extra water from snow trapping per year - equivalent to about two bushels of extra wheat per acre.
For more information on managing through drought conditions, contact your nearest PFRA office or contact the Agriculture and Agri Food Canada research scientists at Lethbridge and Swift Current research stations.