Yields of most crops are increased as a result of reduced levels of aluminum and manganeseand improved availability of phosphorus and other nutrients. Very strongly acid Less than 5.1 Direct effects as outlined above for strongly acid soils. Indirect effects as outlined above for moderately acid soils. Yields of most crops are severely reduced unless the soil is limed. Very strongly acid soils are very infertile.
Crops also vary greatly in their tolerance to the various components of acidity.
As a result, the cause of soil acidity damage to crops is often rather complex. The following discussion and Table 1 describe the effect of soil acidity on crops at various pH levels. The effects of acidity on crops can be divided into two general categories - direct effects and indirect effects. Direct effects Acid soils often contain soluble forms of aluminum and manganese. Aluminum toxicity restricts root growth and phosphorous uptake.