Abstract from introductionSoil acidity is one of the most influential factors in limiting crop production around the world. Roughly 30% of the Earth's total land area and as much as 70% of potentially farmable land is affected by soil acidity (Rengel, 2003). Soil acidity is common worldwide and can be found across almost all soil orders. However, acidity occurs predominantly in soils formed from acidic parent material or areas where weathering has occurred over a long period of time, such as Oxisols, Ultisols, Alfisols and Andisols (Jayawardane and Stewart, 1995). As a soil naturally weathers in humid climates, it will often result in an increasingly acidic profile due to the loss of base cations. In addition to naturally occurring weathering, soils under degradative management practices will often lead to an increased in soil acidity (Adams, 1984). A highly weathered or degraded soil often results in an acidic soil environment with hard and infertile subsoils that prove to be resistant and sometimes impenetrable to plant roots (Sumner et al., 1986). Similar studies conducted by Marsh and Grove (1992) and Caires et al. (2008) found strong correlations between both corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) root growth and yield response to soil acidity
