Zeolite-induced enhancement of soil cation exchange capacity reduces nitrogen gaseous emissions and improves nitrate retention under urea fertilization

Abstract

Zeolite has great potential as a soil amendment due to its unique porous structure and high cation exchange capacity (CEC). While its use in soil pollution control and heavy metal remediation has been widely studied, its effects on soil carbon and nitrogen (N) cycling—particularly greenhouse gas emissions—remain insufficiently explored. NZone Max is an additive for N fertilizers that containing proprietary surfactant-based and calcium-complex compounds. It aims to improve N availability and uptake. However, only a limited number of studies have been conducted, and no clear conclusions have yet been reached regarding its effectiveness. To address this, an incubation experiment was designed using normal soil (S) with a CEC of 12 cmol kg−1 and soil amended with 10 % clinoptilolite zeolite (SZ, target CEC = 29.8 cmol kg−1), along with the addition of a no-fertilizer control (N0), urea (U), and urea + Nzone Max (UNZ) treatments. NH3, N2O and CO2 were monitored continuously for one month, while soil mineral N (NH₄⁺ and NO₃⁻), dissolvable organic C and microbial biomass C were measured at the end of the incubation. The addition of 10 % zeolite reduced NH3 and N2O by approximately 50 %, while soil microbial respiration were stabilized, and the soil NO3- concentration at the end of the incubation was almost doubled in soil added with zeolite compared to no zeolite addition. In contrast, Nzone Max had no significant effect in any respect. These results highlight the potential of mineral-based amendments to regulate gaseous nitrogen losses, particularly NH₃ and N₂O, and promote soil microbial and chemical stability. These findings may inform nutrient management strategies in a variety of soil conditions, particularly in regions with low native CEC or under intensive fertilizer use.