New high performing crop varieties are making greater demands for nutrients than ever before.
However, those nutrients are not always replaced in adequate amounts.
“Deficiencies are becoming more common as a result of the new varieties we are using pushing for maximum yields,” said Michelle Nutting, an agronomist with Agrium Inc.
Plants need 16 essential nutrients to properly grow. Within that group are four trace elements that can make a huge difference in crop production.
A 40 bushel per acre wheat crop is a heavy feeder on soil nutrients. It removes per acre, 85 pounds of nitrogen, 32 lb. of phosphorus, 72 lb. of potassium and nine lb. of sulfur. On a smaller scale it takes 0.1 lb. of copper, 0.1 lb. of boron, 0.3 lb. of zinc and iron and 0.8 lb. of manganese.
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Western Canadian soils tend to be low in copper, boron, zinc and manganese.
Wheat, oats and barley are most sensitive to a copper deficiency. Copper is necessary for protein development, seed production and chlorophyll.
“Sometimes visual symptoms may not be present or can easily be confused with other problems,” Nutting said.
A copper deficiency is most noticeable when leaf tips are yellow, die, then bend over and twist.
This is known as “pigtailing” and can be mistaken for frost damage in the early spring.
Later in the season, kernels may appear black at the base or they may shrivel.
Head and stem melanosis in a crop shows up as a black patch in a field.
“If you were to pinch those plants between your fingers, you would likely feel empty heads or poorly filled heads,” she said.
Copper-deficient fields tend to lodge. Nutting recommends soil tests to determine a copper deficiency.
Soil tests are crucial
Copper deficiencies and ergot may be linked. Adding copper will not preclude an ergot infecting a field but it can help lessen damage.
Copper is taken up by the plant roots so it can be blended and applied with other fertilizers. However, fields that have received a heavy manure application may inhibit copper and zinc uptake.
Boron deficiencies are most noticeable in alfalfa and canola. It aids pollen grain germination, protein production, reproduction, cell division and better uptake of phosphorus.
Canola suffering from a lack of boron displays yellow or reddish bronze mottling on the leaves. The plants are stunted and occasionally the pods are aborted or poorly filled.
This can also be confused with a sulfur deficiency.
Alfalfa that needs boron has stunted stems and new leaves are yellow, brittle and thick. Flowering is poor.
To detect micronutrient deficiencies, have soil tested and keep samples from different areas of the field separated.
Consider having a plant tissue test run. Provide good and bad samples so the lab has something for comparison.
When looking for symptoms, check eroded knolls or areas with coarse textured soils since there is more likely a deficiency in these spots.
Try planting a test strip with extra nutrients and compare it to the rest of field.
“It takes some extra time but it is time well spent,” Nutting said.
“The cost of micronutrient application for the entire field may not be your best investment. Test the micronutrient in a test strip.”
All situations require individual attention and various products react differently depending on the crop, equipment and soil types.
“The economics of micronutrient application will depend on an accurate diagnosis of a mild deficiency,” she said.
If the diagnosis is correct, there should be an improved economic return.
