Caution: before reading this piece please know that it is just thinking on paper. The objective is to plant the seed of an idea in the head of folks who are capable of making the equipment to make it all happen.
Reality forces us to think in the moment. The natural human tendency is to think that current conditions are the norm. But, the reality with weather and farming is that the only certainty about the future is uncertainty.
In many parts of Manitoba and Saskatchewan we have now had five “irrigation” years in a row. In recent years my Dundurn neighbours that irrigate from Blackstrap Lake have mostly moved the pivots to farm under. While many of us relish the irrigation supplied by Mother Nature, many excesses of water have also occurred. In many areas of the world excess water drains off in streams that lead to rivers that lead to big rivers that lead to an ocean. The glaciers left us with many areas with little or no external drainage. The excess simply fills the potholes (sloughs).
Sloughs that were bone dry in 2002 are now full and some overflowing. In 2002 I had zip for water in any slough on my Dundurn farm. Now on NW22-32-3W3 I estimate there is enough water sitting in sloughs to provide an inch or two of water to all of the cultivated acres. A large slough in an adjacent RM has several hundred acre feet of water. The locals suggest that the last folks to see that much water in the slough were the Indian people.
Handifacts in Henry’s Handbook of Soil and Water tell us that it takes 22,615 gallons of water to put one inch on one acre. So there is a lot of water sitting. Some of it slowly soaks in but in some sloughs with pressure underneath the water mostly sits there until it evaporates. In wet years that can take a long time.
But, we have no idea when the current wet cycle will end and dry years return. I often look at that water and wonder how we could use it to advantage when the need arises.
Farmers and irrigation equipment suppliers are an innovative lot. Portable, tractor-mounted slough pumps already exist. Big gun irrigation systems that irrigate significant areas already exist. What about marrying the two concepts to arrive at a system that could take the unwanted water from the slough and apply it to significant acres next to each slough?
Some caution would be required. Some sloughs that can appear very clean can be nearly as salty as the ocean. Many sloughs have a significant salt load that would preclude their use on a continuing irrigation basis. We assume that with extra runoff sloughs will be very fresh. Not always true. (See my Grainews article “Faith, snuff and slough water”)
The photo of the barley crop shown on this page comes from the Univerisity of Saskatchewan Goodale Farm. The well that provided the water is a flowing well. The pressure is the fundamental cause of the soil salinity.
One or two applications with that EC 3,200 S/cm water will do no harm. But, each inch of such water applies 700 pounds per acre of salts. So, if used very long the excess salts would have to be leached with excess water. In this case, and in most cases leaching is not an option so the water is not suitable for sustained irrigation. But a few inches of that water in a drought year could be a real game changer.
Such an idea would apply only to rolling land where the sloughs are deep. In flat land like Regina Plains a 50 acre slough may only have a foot or less of water — not practical to access.
Further caution: the use of slough water for crops will only be of value for a short term anyway, perhaps two years at most. After any length of drought the sloughs go dry all by themselves.
So, there you have it — a bit of thinking on paper. Maybe all a big pipe dream.