In Henry’s Handbook we had this to say about micronutrients: “I do not suffer under any illusion that we have discovered all the micronutrient deficiencies that exist in Western Canada. It is best to maintain an open mind when the question of a new deficiency comes up. Micronutrient research is expensive and often not exciting because a lot of ‘nothing’ results are often obtained.”
“Pet” crops
Copper deficiency of wheat was well documented in Kenya in the 1950s. Manganese deficiency in oats, zinc deficiency in beans and lentils and boron deficiency in alfalfa are other examples of crops most likely to show deficiencies.
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With the advanced agronomy of recent decades and very high crop yields, the removal of micronutrients is much greater. It will not be a surprise to find new examples of micronutrient deficiencies but documenting where and when will not be easy.
Go where the problems are
There is little point in a co-ordinated field research program on micronutrients with sites selected on current and former public research stations. Most of those stations are on the best local soils that are not likely candidates for the problem.
The same principle applied to macronutrients. Phosphorus was easy. A few decades of fertilizer-free farming of our rich Prairie soils left most of them deficient of phosphorus.
Nitrogen took a bit longer. With the wheat-summerfallow rotation, the mining exercise lasted much longer. When soil testing started in the 1960s, some U.S. labs received samples. They did not use the nitrate soil test and used only organic matter to recommend nitrogen rate. They gave the same nitrogen recommendation for stubble and summerfallow!
Potassium was very tricky. In the early days, the University of Saskatchewan Soil Science Department and Ag Canada research stations had filing cabinets full of data that said our soils had lots of available potassium. When the Saskatchewan Soil Testing Lab opened in 1966, it included potassium in the regular test.
Lo and behold, the Carrot River soil association in the Carrot River area of northeast Saskatchewan had soil tests as low as any in the world. A few simple strip tests soon proved the soil test was right — no potassium fertilizer equals no crop.
Those with Henry’s Handbook can check out page 58 for all of the details about potassium. That experience drove home the fact that in soil fertility field work go where the problems are.
Sulphur was also tricky, but we now know that sulphur deficiency is common, especially for canola.
Varieties and micronutrients
This is an area where a co-ordinated field research program needs to include plant breeders. Most Co-op variety trials are on research stations where micronutrients are not a problem.
In 1974, I was working on the Tanzania-Canada Wheat Project on the slopes of majestic Mount Kilimanjaro in Tanzania. There was a good field plot program at several local farm sites to check out varieties that had been bred in nearby Kenya. A promising variety was provided to the Tanzania seed increase farm where soils were developed from the leavings of volcanic Mount Meru. The new variety died when planted at that site.
A field experiment sorted it all out. The photo above shows the result.
Those with Henry’s Handbook can check out page 62 for the entire story. Keener PAg or CCA types can check out the journal Plant and Soil: Volume 52, pages 437-444, for the complete details.
Glacial till soils and micronutrients
It has been my experience that our soils developed from the direct leavings of a glacier (i.e., glacial till) rarely, if ever, have micronutrient deficiencies. Soils developed from water-laid deposits have undergone a sorting process that removes or leaves small quantities of some micronutrients. If a reader has an example of a micronutrient deficiency on a glacial till soil, I will be happy to retract that statement.
It is particularly true in Saskatchewan. If one looks at the soil map of Saskatchewan, the most common soil parent material is glacial till.
Micronutrients, a recent significant advance
In the past decade, the Jeff Schoenau group at the U of S Soil Science Department have done some very good work on micronutrients. Ryan Hangs collected soils from 48 sites scattered throughout the ag area of Manitoba, Saskatchewan and Alberta. Sites were selected with advice from other research folks, but a major information source was agronomists in private practice. The sampling sites were targeted.
Once collected, the soils were subjected to a thorough screening with various laboratory tests. Twenty soils were used for further detailed pot experiments in glasshouse and detailed work on the specific chemistry utilizing the synchrotron. That process identified specific soils with serious micronutrient deficiencies for wheat, field pea and canola. Glasshouse experiments proved up several micronutrient deficiencies.
The stage is now set for an ongoing field-based program that goes where the problems are to provide improved soil and crop-specific recommendations. In some cases, crop variety will also be an issue.
To be able to extend the data to the field will require use of soil maps to advance the geography of a specific micronutrient problem. It does not have to be a random process.
An extended-term co-operative program will be required but one agency or person will need to lead the way and keep the program on track.
Our Western Grains Research Foundation would be an appropriate funding source for such a venture. The foundation is in the process of establishing special chairs to ensure that real-world problems at the farm gate are dealt with.
Case studies
In recent years, case studies on farms have moved the needle on micronutrients. Many micros can be highly variable within a single field. The simple procedure of careful sampling of both soil and plants in good and bad areas can often quickly solve the problem. Plant analysis is often the more definitive.
Such case studies can even identify micronutrient toxicities. Lyle Cowell of Nutrien Ag Solutions in northeast Saskatchewan recently sent me a PowerPoint presentation showing manganese toxicity in both canola and wheat at two locations in northeast Saskatchewan.
Some mechanism to assemble and publish such case studies would be a valuable asset for micronutrient work.
