By Dr. Tim Ball – Re-Blogged From WUWT
Two events provide the catalyst for this column. First, was the passing of a dear friend Elmer Stobbe, a soil scientist whose career at the University of Manitoba extended after retirement to consultation in Abbotsford BC. The second was my annual interview with a radio station in Yorkton, Saskatchewan, to discuss current weather patterns and expectations for the 2019 growing season. Elmer specialized in soil erosion and especially preventative measures including zero-till and minimum till. In Canada, this work was triggered by the work of Canadian Senator Herbert Sparrow. A farmer from Indian Head, Saskatchewan, also the site of a major agriculture research centre in western Canada. He lived through the dust storms of the late 1930s and witnessed first-hand images similar to a 1933 dust storm in Regina (Figure 1).
Figure 2 was a little closer to his home because it shows a dust storm at Lethbridge airport. I joked with Elmer about the most frightening thing in the world for a farmer was to see your neighbors’ farm coming at you vertically.
The Canadian Prairie is at the northern end of the Great Plains and has a triangular shape with the 49th parallel forming the base. It is called the Palliser Triangle (Figure 3) and named after the British scientist sent across western Canada in 1857 to determine the agricultural capability of the region.
The three soil zones also approximate the biozones, with red supporting Short grass prairie, orange is Tallgrass prairie, and yellow is mixed Aspen woodland and Tallgrass prairie.
Palliser’s Report was an excellent assessment of the situation partly because he previously travelled extensively on the US side and new the geology, geography, and climate well. You can read about him in Canadian historian Irene Sprye’s book The Palliser Expedition: The Dramatic Story of Western Canadian Exploration, 1857-1860. His report was remarkably objective because he knew from his US travels that he was traveling during a drought cycle and yet the government wanted positive results. He did not compromise. Rather, he said don’t be fooled by the soils that were very good for grain agriculture, but what dictated ongoing success were the low humidity and periodic droughts.
Palliser represented the British government who were in negotiations to take over the holdings of the Hudson’s Bay Company (HBC) and turn them over to the newly formed Canadian government in 1867. That government was not enamored of Palliser’s Report and in 1877 hired John Macoun to revisit the area. Macoun travelled during a wet cycle, and so he presented a very different report of the potential. Settlers quickly followed and like the German immigrant in Figure 4 broke the land.
Because there were no trees, soils are deep (mostly glacial till) and rock outcrops sparse, they built their houses from what was at hand (Figure 5). This picture is from Kindersley, Saskatchewan.
Figure 5 How did she get the dress so white?
Everything went well, with increasing yields, the arrival of the railway, and growing markets in the east and Europe. The drought cycle on the Prairies is approximately every 22 years, as Douglass and others showed through the correlation with sunspot cycles using tree ring data. My research showed these droughts alternated between Cold Droughts with low precipitation, lower temperatures, and low wind speeds, and Hot Droughts” with low precipitation, high temperatures, and very strong winds. The Cold Drought around 1910 had a small impact, but the Hot Drought of the 1930s exposed the problems of breaking the land.
After the devastation of the 30s, the government created the Prairie Farm Rehabilitation Act (PFRA) in 1935, that became the Prairie Farm Rehabilitation Administration (PFRA). Its goal was to counter the impact of the drought and later to “drought-proof” the region. One thing they did effectively was to take marginal land out of production. There is less land under cultivation in western Canada today than there was in 1930.
The Prairie region is the only moisture deficit region in Canada. This makes conservation of moisture extremely important. The practice of summer fallow began so as to remove any vegetation that would use up the moisture (Figure 6).
They also extended the practice of crop rotation. This involves growing a sequence of crops over a period of four or five years with each putting different demands on the mineral resources, so they let acreage ‘rest.’
While the practice was effective a major side effect was exposure of the soil to wind and water erosion. On the Prairies the natural annual rate of erosion, that is without human interference, was 5 tons per acre per year. A major factor in this was the frequent grass fires. A late 18th century entry in the HBC journal at Churchill says the Indians report the whole of the Prairies is on fire. By the 1930s when the first Hot Drought hit the land became desiccated, and the wind began to blow. Figure 7 is a beautiful painting of a Prairie grass fire in southern Saskatchewan around by Paul Kane
By the 1970s concern about the rate of erosion began to grow. Estimates put the rate at double the grassland levels, that is about 10 tons per acre per year.
“In the 1980s, the use of fallow and the land practices were creating soil drifting and loss as bad as it had been since the 1930s,” said the executive director of the Soil Conservation Council of Canada.”
By now Herb Sparrow was a senior Senator with the opportunity to act. In 1984 the government produced his report Soil at Risk.
It wasn’t long before people started considering an alternative to summer fallow. It has various names including zero till, direct seeding, and conservation tillage. As with everything there were costs. Three main benefits were a reduction in soil erosion, ground cover that simulated the natural conditions, and retention of snow cover in the winter. Costs include the high price of chemicals to control the vegetation cover, which made products like Roundup so valuable. A delay in the rise of soil temperature necessary to allow seed germination. People don’t realize that a major function of plowing is to mix the soil. It takes the warmer surface soil and the vegetation down to the seed planting level. The albedo is changed significantly with a much darker surface absorbing more heat with fallow. Figure 8 is a NASA satellite image of North Dakota showing the patchwork quilt effect. Remove the summer fallow, and it is all much lighter.
Think about the impact of all this on the global albedo, moisture regimes, and global climate.
I have done a few interviews a year for over 30 years with the Yorkton radio station but two each year that include an agricultural outlook for the next six months. During the last interview, the host and I talked about Professor Stobbe and his work. He reminded me that the first time he interviewed me was at a farm meeting in Swan River Manitoba. I began my presentation with an explanation of the factors that determine the weather in their region. They know the microclimate on their farm, so they can understand and better adjust to changes if they can put it in the larger picture.
My second issue was my concern about the impact of zero tillage since they are at the northern limit of agriculture in Canada. They have a very short growing season and the loss of even a few days is critical. At the time, they were introducing warmer weather crops, such as canola, made possible by the warming that began around 1980. I warned them that zero-tillage would reduce their growing season by delaying soil temperature increase. This occurred, but the continuance of warming up to 1998 masked the problem. A week before my most recent appearance on his program, the host told me a specialist spoke about the problem showing up with decreasing temperatures and the pattern of snowfall.
Canadian farmers always joke about never losing a crop in January. The trouble is it is not true. Winter snowfall is critical to the moisture availability in the spring. The best determinant of crop potential is Fall precipitation because it charges subsoil moisture. Early snowfall also provides insulating cover to stop the freezing level going too deep into the ground. I recall years across the Prairies when the level went 3 meters down. In addition, the Spring snowmelt mostly goes into ditches, ponds, and lakes across the land to become the major source of evaporated moisture for summer rainfall. A small portion of the melt stays on the field to recharge the average soil moisture content of 12 cm, sufficient for seed germination. The soil is a poor transmitting media for heat, so the water is important for quickly raising the soil temperature.
I will not continue this micro and meso-climate discussion any further, except to say you have a taste of the complexities. There is a great deal of research available, such as an article titled “Soil water conservation under zero- and conventional tillage systems on the Canadian prairies” and “How farmers on the Great Plains are changing the local climate” or, look at the number of weather variables required in the “Prairie Hydrological Model Study Progress Report.” This gives you an understanding of why the Intergovernmental Panel on Climate Change (IPCC) are wasting their time, especially when they write,
Unfortunately, the total surface heat and water fluxes (see Supplementary Material, Figure S8.14) are not well observed.
My good friend Elmer worked with farmers and agribusinesses in Canada throughout his academic career, and this continued in the post-retirement phase of his life. He was also responsible for establishing soil conservation and zero tillage programs in Africa and China. Elmer understood what Thomas Jefferson meant when he said,
“Agriculture is our wisest pursuit, because it will in the end contribute most to real wealth, good morals, and happiness.”
He also agreed with his observation that,
“Were we directed from Washington when to sow, and when to reap, we should soon want bread.”