Q: While we have little control over available moisture for crop production, how can it impact the final result? What is meant by the term “Water Use Efficiency (WUE)?”
A: When we consider inputs that are essential for crop growth we tend to think of fertility. However, there is one ingredient that every single cropping system is absolutely dependent on — water.
Many factors such as soil texture, crop rotation, stubble management and even stand establishment can all impact how much water will be available to a crop in a given year. A focus on proper stand establishment and maintaining crop residue can help to reduce evaporative losses from the soil, thereby giving the crop more available water.
Water Use Efficiency (WUE) of a plant is defined as the amount of dry matter produced by a plant for a given amount of water. Crop species differ in their WUE, and the timing of moisture stress on a crop has a large impact on end yield. In general, the most crucial period of development where moisture stress can impact yield is during reproductive growth. In determinate crops such as wheat, barley and oats flowering occurs over a relatively short period of time, so a short duration of moisture stress can be very detrimental. Indeterminate crops such as canola or pulses flower over a longer period and may be able to recover some yield if favourable conditions return after short-term moisture stress.
In dryland farming operations water is an input that you can’t control. While we can’t control how much moisture will fall from the sky, there are strategies we can incorporate to maximize our production on a given amount of moisture. When in a moisture- deficit situation, adopt practices that limit potential evaporative or run-off losses where possible. In addition, crop growth factors such as proper nutrition must be optimal so that we make the most of each drop of water.
Scott Anderson is a manager of agronomic services with Crop Production Services in northwest Saskatchewan.