How does ammonium sulfate compare with other nitrogen sources when it comes to soil acidification and liming needs?
While ammonium sulfate is more acidifying than anhydrous ammonia, urea, or ammonium nitrate, its acidifying effect on soil is significantly less than traditionally assumed. If applied to supply 100 percent of a crop’s nitrogen needs, ammonium sulfate would need 1.5 to 2 times more lime than the other sources, depending on the buffer capacity of the soil. Most commonly, though, ammonium sulfate is applied as a sulfur source (covering only a small portion of a crop’s total nitrogen needs), so its contribution to bulk soil pH acidification is significantly reduced.
As indicated in the charts below, assuming a sulfur rate of 20 pounds per acre and a lime cost of $20 per ton, the additional lime needed to neutralize a sulfur application would only cost between $0.47 and $0.63, depending on the buffer capacity of the soil.