With spring planting in full swing, the attorney general’s office is cautioning farmers to be skeptical of pitches for soil improvement products they don’t need. ISU extension agronomy professor John Sawyer says micronutrients are marketed as a kind of fertilizer.Sawyer says of 16 elements deemed essential for growing crops, many are micronutrients, called that because either there isn’t much in the plant or they’re not very important. Iowa has very fertile soil, and can supply adequate amounts of most of those micronutrients. Sawyer says there are a few exceptions in which a minor nutrient could have a bigger factor in a good crop.ISU does recommend one test, for zinc, in soil that’ll be used to grow corn and sorghum. Sawyer also says soybean farmers sometimes find they need to apply some iron to their soil.He says farmers should think about needs like that, and targeted situations where they might need micronutrients, rather than assume there’s a “blanket need.”