These four steps will let you know whether you actually have a deficiency problem on your farm
Think you might have a micronutrient deficiency in your fields?
Take these four steps before spending any money on micronutrient fertilizer, says Ross McKenzie, who became the province’s best-known fertilizer authority during his lengthy career with the province.
“I always encourage farmers to walk their fields at least once a week looking for anything unusual. Sometimes diseases and micronutrients can be related. For example, copper deficiency is associated with stem and head melanosis. Also, look for deficiency symptoms that tend to affect wheat and barley in the vegetative growth stages and you’ll see that the flag leaves will actually start to twist and curl like a pig’s tail.
“If you see that in some areas in your field, that doesn’t mean conclusively that it’s copper deficiency. But that would be a clue that you might have some deficiency showing up and need to investigate further.”
2. Soil test
“That works fairly well for copper, iron, manganese and zinc. I don’t put a lot of faith in the boron or chloride soil tests. We don’t really have a good soil test for molybdenum and we’ve never seen a response to it.
“Boron is the one I’m most concerned about. The present soil test we use for boron is called the hot water soluble method and we’ve found it doesn’t really do a good job of predicting the need for boron.
“In fact, probably a third of our soils in southern Alberta would test low for boron, but field research has not shown any benefit when applied.”
In some cases, a tissue sample may be necessary as well.
“If you see areas that might be suspicious during the growing season, tissue sample and soil sample those areas separately to see if you can notice anything uniquely different between the poor growth area in the soil test and the tissue test versus the good areas.
“Remember that tissue testing is also not that reliable as it depends on the stage of plant growth and plant parts sampled. Also, most tissue research data that is available to labs is 30 to 40 years old.”
3. Get a second opinion
Some labs and agronomists have different ideas of what defines a “critical deficiency” of micronutrients.
“A lot of the micronutrient salesmen and soil testing labs will use a higher critical level for making recommendations. For example, some people will use two parts per million (ppm) as the critical level for soil copper on wheat and barley while others use one ppm.
“Most of the work done in Alberta and Saskatchewan has shown that as long as your soil test levels are above 0.5 ppm, then there’s really no need to put on copper. Depending on your soil type, the micronutrient and the crop you’re growing, you want to carefully interpret the soil test to decide if a micronutrient is really required.”
Producers should get a second or even third interpretation of their soil test from someone who is not in the business of selling micronutrients, said McKenzie.
“Call the Ag-Info Centre at 310-FARM (3276). Also, most of the agronomists with P.Ag (professional agrologist) or CCA (certified crop adviser) designations out there are also very reputable.”
4. On-farm trials
Finally, if you think there’ a micronutrient deficiency on your fields, do a real-world test.
“Rather than do your whole field, start out by doing some test strips because sometimes the soil test might be in the marginal range. Do your own on-farm trial to see if you get a response or not before you start spending a lot of dollars on a lot of acres.”