The study looked at how adding calcium carbonate and clay to soil affects how well the soil can hold onto phosphate. They tested different soil samples and found that more calcium carbonate in the soil led to better phosphate retention. However, as the amount of phosphate in the solution increased, the soil's ability to hold onto phosphate decreased. Removing calcium carbonate from the soil also decreased phosphate retention. Overall, calcium carbonate played a bigger role in phosphate retention than clay did, with different soils showing varying levels of phosphate retention based on their calcium carbonate content.