The researchers aimed to develop formulas to predict how much water soil can hold and how much is available for plants in southern Brazil. They collected soil samples, tested their properties, and created formulas based on these properties. They found that the formulas accurately estimated water retention at different tensions, but availability was harder to predict. Existing formulas from other studies were only moderately accurate for southern Brazil soils. Formulas specific to the region were more reliable than ones from different climates.