Zeolites

Zeolites are aluminosilicate lattices, derived from volcanic ash, that hold up to 55% of their weight in water in the small cavities of their crystal structure. If one tablespoon of zeolite crystals were unfolded, they would cover an entire football field! Negatively charged, the lattices hold the cations of essential elements.
Zeolites can improve the productivity of any texture of soil, improving water and mineral retention in sandy soils and improving aeration and minimizing compaction in heavier soils. Added to compost, zeolites retain ammonium ions and prevent their transformation to ammonia gases, keeping the nitrogen from escaping into the air.
Add 2–3# for each 10# of potting soil. In gardens add 15–20#/100 sq ft to the top 6" before planting. Spread 1–2½ tons/acre. Water thoroughly after application so the zeolites will absorb the moisture, holding it in a thin film on their surfaces until needed