Large sections of Alberta and western Saskatchewan are going into winter with dry soil, according to data from Environment Canada.
Ken Panchuk, soil specialist with Saskatchewan Agriculture, is encouraging farmers in dry areas to measure the subsoil moisture in all their fields next spring because of the variability of stored soil water.
Precipitation is the greatest limiting factor for plant growth in Western Canada, so the rain and snow that falls must be efficiently managed.
This moisture management begins in the spring by minimizing soil disturbance at seeding, and continues through harvest.
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Measuring the subsoil moisture in spring allows farmers to make final adjustments for spring seeding.
“For example, if the subsoil is dry and has only two inches (five centimetres) of plant-available water stored, the farmer may seed the crop but apply less fertilizer. He can then apply fertilizer later in the growing season if precipitation increases,” said Panchuk.
To measure stubble subsoil moisture, farmers should use a soil moisture probe. This can be made by welding a three-quarter-inch (two cm) steel ball on one end of a 3.5-foot-long (one metre), one-half-inch (1.25 cm) thick rod, and welding a handle on the other end.
Representative areas of the field should be sampled, avoiding saline areas, potholes and other problem areas. Depression areas, slopes and knolls can be measured separately for site-specific crop planning.
The probe should be pushed into the ground in a single motion. It will stop penetrating when it hits dry soil, a rock or, in the spring, frozen ground.
Panchuk said each field should be sampled separately because rainfall amounts can differ over short distances.
Also, crops and varieties differ in water use and crops mature at different times because of seeding date and different maturity dates.
At least 15 to 20 sites should be sampled in each field and the average depth of moist soil recorded.
Spring sampling may require more sites within a field because of the variability caused by water runoff, ground frost, snow trapping and drifting, and moisture migration within the soil.
“Soil texture and average depth of moist soil are used to calculate the plant-available water,” he said.
Information on how to make the calculations and to determine how much soil water is enough, is available at Saskatchewan Rural Service Centres.
A Saskatchewan moisture map and additional information is also available at the agriculture department’s internet site at www.agr.gov.sk.ca/saf.
