Phosphate mineral weathering by carboxylic acids is driven by functional group composition and orientation

Phosphorus is an essential nutrient for crops, but it is not readily available to plants in alkaline soils because it forms insoluble calcium phosphate minerals.

Organic acids released from soil microorganisms and found in soil humus and organic amendments are known to induce the weathering of these minerals. However, mineral weathering by specific chemical functional groups (i.e., active part of organic acids that determine how they behave in chemical reactions) remains poorly understood.

In this study, six different organic acids, each containing distinct numbers and arrangements of important functional groups, were tested in mineral weathering experiments. It was found that the arrangement of carboxyl- and/or hydroxyl-functional groups was more important in weathering calcium phosphate minerals than their concentration.

These findings enhance our understanding of how organic acids in soils can improve phosphorus plant availability in alkaline soils.