What causes acid soils?
• Losses of calcium and magnesium from soils by leaching and erosion are much more rapid under row crop conditions than in natural forests or grasslands. As rain moves through the soil, it absorbs carbon dioxide, present in the soil atmosphere, forming weak carbonic acid. Weak organic acids are also formed when water moving through the soil comes in contact and reacts with humus. These acids remove calcium and magnesium and are replaced by hydrogen and aluminum, making the soil more acid. • Decomposition of organic matter is an acidifying process. The rate of decomposition, and hence acidification, is much higher in cultivated than in natural soils and more rapid under higher temperatures. • Fertilizers, particular those containing ammonium (NH4+), acidify soils. When NH4-nitrogen is converted to nitrate (NO3) by nitrification, the net result is the release of free hydrogen into the soil solution, lowering soil pH. For example, it requires 84 lbs of calcium carbonate (lime) to neutrali
