Clinoptilolite Zeolite Influence on Nitrogen in a Manure-Amended Sandy Agricultural Soil

Zeolite minerals may improve nitrogen availability to plants in soil and reduce losses to the environment. A study was conducted to determine the influence of clinoptilolite (CL) on nitrogen (N) mineralization from solid dairy manure (224 kg N ha(-1)) in a sandy soil. Clinoptilolite was added to soil at six rates (0 to 44.8 Mg CL ha(-1)), each sampled during 11 sampling dates over a year. Over time, nitrate (NO3)-N increased, ammonium (NH4)-N decreased, but total inorganic N increased. Clinoptilolite did not influence the nitrification rates of initial manure NH4-N or mineralization of organic N (ON) over time. It is possible that adsorption of manure-derived potassium (K) outcompeted the NH4-N for CL exchange sites. The ON concentration was constant up to 84 days and then decreased by approximately 18% over the remaining time of the study across all treatments. Clinoptilolite use in this sandy soil did not alter mineralization of N from dairy manure.