Soil zinc availability varies among different cropland soils in China. A study looked at six types of soils from northwest and southeast China to understand how they adsorb and release zinc. They found that the amount of zinc in the soil increased with the initial zinc concentration added, and the soil's ability to release zinc also increased with the amount already in the soil. Soils with more organic matter tended to adsorb more zinc. Overall, soils from southeast China could hold more zinc than those from the northwest. Calcareous soils had higher zinc adsorption capacity than acidic soils. Red calcareous soil had the highest zinc buffering capacity and fixed the most zinc compared to other soils.