ABSTRACT

The principal adverse effects of acidity on soil fertility occur at soil pH values below 5.5 due to acid dissolution of aluminum (Al) and the onset of Al phytotoxicity to susceptible plants [1]. Aluminum phytotoxicity results in rapid inhibition of root growth due to impedance of both cell division and elongation [1]. This results in reduced volume of soil explored by the root system and direct interference with uptake of ions such as calcium and phosphate across the cell membrane of damaged roots [2]. These phytotoxic effects are unimportant in moderately acidic soils with pH values of 5.5 to 6.5 when the concentration of toxic forms of Al is normally negligible. Manganese toxicity and deficiencies of phosphorus, calcium, and magnesium are common in acidic soils. Soil nutrient deficiencies exacerbate the problem of inefficient nutrient uptake due to restricted root growth and root damage [3]. In drier environments, poor water use due to poor root development is considered to be another adverse effect of Al phytotoxicity.