I recall sitting in a room in the John Mitchell building on the University of Saskatchewan campus. First day in a soil fertility class.
The professor walked in and said, “just remember, the most limiting nutrient in crop production in Saskatchewan is water.” as he scrawled H20 under the heading “Key Nutrients”.
OK, let’s talk drought or crop limitations in a water deprived environment. This year is going to go down as one of the big ones. Everyone has their tales of “Remember 1961?” or “it was so dry in ’88.” Living through 2021 will add one more year to this long line of years to remember on the Canadian Prairies and Northern Plains.
In upcoming columns, I’m going to take a look at drought from three perspectives.
Today’s column will try to take a wider perspective on droughts and climate change.
Each crop has what is called a water use efficiency (WUE) or moisture use efficiency (MUE). WUE of a plant is defined as the amount of dry matter produced by a plant for a given amount of water. However, we usually think of it as the amount of grain produced by a given amount of water.
Crop types differ in their WUE, and the timing of moisture stress on a crop has a large impact on 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 will occur 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.
Drought is nothing new for prairie farmers. Tracing back using tree ring and other observations, there was a drought that lasted almost 100 years from about 1482. Periodic droughts have occurred to the present.
Of course, the 1930s are legendary. Nine of 11 years from 1929 to 1939 inclusive were drought years. This also corresponded with an economic depression that resulted in a tectonic shift in the social, economic and political dynamics of the region. It also started a major revolution in the way agriculture was practiced in northwestern North America.
Since the 1930s, there have been a number of memorable droughts. The most notable of these have a couple of things in common. Firstly, most of the most notable droughts such as 1961, 1988 and 2002 followed dry years. The other notable thing about these three droughts were that the summers of 1961, 1988 and 2002 were also very hot. Although I was just a young lad in 1961, I remember how hot it was and how the harvest was wrapped up by my birthday on Aug. 25.
This year, 2021, is following similar patterns. We have had drier than normal conditions for, depending where you are, the last three or four years and 2021 has been exceptionally hot.
In the 1980s, there were a number of drier than normal years but it wasn’t until the abnormally hot years of 1988 and 1989 that the drought really caused issues.
So there are two types of drought: hot season droughts, where significantly lower than normal precipitation is accompanied by above normal temperatures; and cool season droughts where significantly lower than normal precipitation is accompanied by normal or below normal temperatures.
From the above descriptions, the hot droughts are significantly more destructive than cool season droughts.
Only 1988 and 1961 were warmer. All data for this comes from the Meteorological Service of Canada and all recent data is still preliminary.
The drought of 1987-89 also caused a tectonic shift which resulted in the development of “conservation farming” or “no-till or min-till”.
The corresponding development of no-till seeding technologies, fertilizer placement and the introduction of cheap and effective herbicides in the late 1980s reduced the economic penalty of reduced tillage and in fact, showed increased profitability at the end of the year.
The adoption of no-till technology since the 1990s has been one of the most remarkable changes that have revolutionized the crop production system in Canada, especially on the Canadian Prairies.
In 1991, only seven percent of prairie producers used no-till to prepare land for seeding. Between 1991 and 1996, the use of no-till more than doubled with about 16 percent of producers using no-till in their farming operations. By 2001, the use of no-till doubled again to 31 percent. In 2006, half the farmers in Western Canada were using no-till, and 76 percent were using a reduced tillage or no-till practices.
The use of reduced tillage practices dramatically reduced the impact of the 2001-02 drought. While still devastating to yields, soil erosion was significantly reduced and in many areas, farmers reported 30 percent to 50 percent of a normal crop, whereas in 1988-89 they got nothing under similar conditions.
So that brings us to 2020-21. What has changed?
First, we have become sloppy with our soil and water conservation practices. I am seeing a lot more tillage, particularly in the black soil zones in the last 10 years. This is probably a result of having farmed through five of the wettest years on record (2010–14) and having changed practices, especially with reference to tillage and fertilizer practices.
Many growers now use vertical tillage equipment. While this equipment does have a fit, especially for repairing rutted fields and drying out wet fields, they also dry out drier fields. The dry winds that we have experienced for the last three years will dry the soil out to the depth of tillage. And every inch of soil moisture lost is an inch you will wish you had come June.
I have often heard soil moisture guru Les Henry state, “Moisture in the soil is like money in the bank.”
Heed this statement and do whatever you can to increase storage of winter snow and reduce losses due to tillage.
Roughly speaking, a foot of soil moisture equates to an inch of rain.
Review your practices this fall.
- Cut stubble as high as possible. The taller the stubble, the larger the snow trap potential. Remember, a foot of snow is equal to an inch of rain.
- Park vertical tillage equipment. They do too good of a job drying out the soil.
- If you must, harrow in the least aggressive settings to preserve the stubble.
- If you apply fall fertilizer, use narrow knives to apply anhydrous ammonia or urea. More on that next column.
Thom Weir PAg is a certified crop advisor and professional agrologist in the Yorkton, Sask., region. You can reach him at email@example.com.