Soil acidification is a slow natural process that occurs during pedogenesis and can be either accelerated or slowed down by farming practices. The causes of soil acidification in agricultural systems have been attributed mainly to an imbalance in the carbon and nitrogen cycles [1,2] (see Chapter 2). The major processes leading to soil acidification include (1) net H excretion by plant roots due to excess uptake of cations over anions; (2) removal of alkalinity in farm products such as grain, hay, meat, and wool; (3) accumulation of organic anions in the form of soil organic matter; (4) mineralization of organic matter, nitrification of ammonium, and subsequent leaching of nitrate, and (5) input of acidifying substances such as NH4-based fertilizers.