Assessment of Nitrogen Dynamics in an Acidic Sandy-Loam Soil: Impact of Varied Nitrogen Sources and Incorporation of Chabazite Zeolite Tuff

Volcanic tuffs containing high percentage of zeolites have been extensively studied, both in their natural state or enriched with nitrogen, as a means of enhancing soil properties and fertilizer efficiency. Limited data however exist on their application in acidic sandy soils and in conjunction with organic fertilizers. This work consists of a 50-day laboratory incubation study wherein the nitrogen dynamics in an acidic sandy-loam agricultural soil fertilized with various nitrogen sources were investigated. These sources included urea, nitrogen-enriched chabazite zeolite tuff, and pelleted composted manure. Additionally, the nitrogen sources were tested in combination with the addition of chabazite zeolite tuff in its natural state to act as a soil improver. The results revealed distinct behaviors among the various nitrogen sources, particularly affecting soil pH and nitrogen dynamics. Mineralization was very slow in manure-fertilized soil, whereas nitrogen-enriched zeolite exhibited a more balanced behavior in terms of net nitrate production and ammonium consumption. Nitrogen-enriched zeolite and urea demonstrated a temporary "liming" effect, while pelleted manure promoted a prolonged shift of soil pH toward neutral values. In conclusion, nitrogen-charged chabazite zeolite tuff proved to be a valuable nitrogen source in acidic sandy-loam soil, serving as a viable alternative to synthetic fertilizers and an effective means of nitrogen recycling.