There was a time when manure was the chief fertilizer on farms. It helped the crops grow, but was eventually replaced by technologically advanced, high-grade fertilizers.
These chemical-based fertilizers provide purer forms of nitrogen and other macronutrients, including phosphorous, potassium, calcium, magnesium and sulfur. But the elimination of manure and other organic fertilizers also robbed the soils of their main source of little-noticed but essential, micronutrients. With each bushel of beans or corns removed from the fields, these micronutrients are mined from the soils without being replaced, according to David Sasseville, a retired Missouri University Outreach and Extension plant nutritionist who now works as a consultant.
No-tillers are already in the habit of adding macronutrients such as nitrogen to their soils. In fact, the application of nitrogen and other macronutrients has become so routine that Sasseville cautions against using “cookbook” fertilizer programs because they don’t give the highest quality and best returns. Also, traditional fertilizer programs typically ignore the essential micronutrients.
When it comes to micronutrients, no-till soils might be in better condition than fields worked with conventional tillage due to the return of nutrients from decomposing residue. But depletion of micronutrients will still occur. All growers, no-tillers included, should monitor their soils for essential macronutrients and micronutrients. Essential micronutrients that frequently limit crop production include boron, copper, iron, manganese, molybdenum and zinc. Many, if not most, growers are unaware of problems with micronutrients, he says, and almost every grower who he has worked with has had…