It seems everyone has a “package” that gives an extra bump in yield. Many of these packages contain micronutrients. In Ohio, because we generally have clay in our soil and reasonable levels of organic matter, we don’t regularly see a yield impact from applying micronutrients. So should we be concerned about micronutrients?
Our soil tests are most reliable for pH, phosphorus and potassium. We usually use a combination of soil and tissue tests to determine micronutrient deficiencies. Soil pH can also help us know where to look for deficiencies. Table 1 outlines some situations in which to watch for these deficiencies.
Table 1 Crop and soil conditions under which micronutrient deficiencies may occur. This taken from Table 23 of the Tri-State Fertilizer Recommendations.
|Boron (B)||Sandy soils or highly weathered soils low in organic matter||Alfalfa and clover|
|Copper (Cu)||Acid peats or mucks with pH < 5.3 and black sands||Wheat, oats, corn|
|Manganese (Mn)||Peats and mucks with pH > 5.8, black sands and lakebed/depressional soils with pH > 6.2||Soybeans, wheat, oats, sugar beets, corn|
|Zinc (Zn)||Peats, mucks and mineral soils with pH > 6.5||Corn and soybeans|
|Molybdenum(Mo)||Acid prairie soils||Soybeans|
Typically we will see deficiencies occurring in small isolated areas of a field first. When these are noted, pull both a soil and a tissue sample. You can also consult a previous yield monitor map for losses. Nutrient deficiencies I have seen of late are potassium from the dry early conditions we had in 2012 and occasionally sulfur — neither of these are micronutrients however.
Two sources for information on micronutrients are the Tri-State Fertility Recommendations for Corn, Soybean, Wheat and Alfalfa (http://www.extension.purdue.edu/extmedia/AY/AY-9-32.pdf) and the Field Guide for Corn, Soybean, Wheat and Alfalfa (http://estore.osu-extension.org/productdetails.cfm?PC=2845) a for sale item. The Field Guide also has excellent pictures of deficiencies.