Chris Clark, a soil and nutrient management outreach specialist with the Division of Extension, tells Stephanie Hoff about her latest research looking into the micronutrients in manure. She explains that due to EPA air quality improvements, sulfur contributions from acid rain have dropped from 10 pounds per year to less than one pound. Long-term data comparison shows that while several nutrients were tracked, boron and sulfur are the two showing the most significant downward trends in manure. While farmers focus on N-P-K (nitrogen, phosphorus, potassium), this research highlights the importance of secondary nutrients like calcium and magnesium, and micronutrients like copper, zinc, and manganese. Many agronomists have already begun instinctively supplementing sulfur between hay cuttings because they noticed deficiencies in plant tissue and soil analyses years ago.