Strongly alkaline soils are sodic and dispersive, with slow infiltration, low hydraulic conductivity and poor available water capacity. Plant growth is severely restricted because aeration is poor when the soil is wet; while in dry conditions, plant-available water is rapidly depleted and the soils become hard and cloddy (high soil strength). The higher the pH in the soil, the less water available to be distributed to the plants and organisms that depend on it. With a decreased pH, this does not allow for plants to uptake water like they normally would. This causes them to not be able to photosynthesize.
Many strongly acidic soils, on the other hand, have strong aggregation, good internal drainage, and good water-holding characteristics. However, for many plant species, aluminium toxicity severely limits root growth, and moisture stress can occur even when the soil is relatively moist.