Evaluation of a Layered Double Hydroxide (LDH) mineral as a long-term nitrate exchanger in soil (PDF)

The leaching of nitrate is an important way of N losses in crop production particularly during autumn and winter. Since nitrate as an anion is not adsorbed to the soil particles, it remains mobile in the soil. An efficient way to reduce nitrate leaching would be to control its movement in the soil by adsorbing it from the soil solution in the same way as clay minerals do it for cations like potassium and ammonium. The layered double hydroxide (LDH) minerals have anion exchange capacity, in contrast to the common soil clay minerals, which have cation exchange capacity. The LDH minerals are not often found in soils, but they can be synthesized at industrial scale.
The present work evaluated the potential use of a specific LDH mineral as a long-term nitrate exchanger in the soil to adsorb nitrate if its concentration in the soil solution is higher than needed for optimal growth and to release it when the crop requires it. The LDH mineral acted as a long-term nitrate buffer in soil. The nitrate adsorbed on the mineral was efficiently protected against leaching, and was available for the crop. Also, the long-term stability as well as the structural changes of the LDH mineral under soil and cultivation conditions was investigated.