Long-Term Effects of Chabazite-Zeolite Tuff Amendments on Soil Quality in Arable and Perennial Cropping Systems

The use of natural zeolites to enhance soil properties has gained popularity, but there are limited long-term data on its effects. This study evaluates the Soil Quality Index (SQI) in three agricultural soil systems, 6-10 years post-application of chabazite zeolite. These soils had different management practices: intensive arable (cereals), intensive perennial (pear), and organic perennial (olive).

In the arable system, chabazite was applied at rates of 5, 10, and 15 kg m^-2, compared to unamended soil. Perennial systems were tested at 5 kg m^-2. Analysis of 25 soil parameters related to soil health was conducted at each site, including soil physic-chemical properties (bulk density, pH, electrical conductivity, cation exchange capacity, C-N-P species), biological properties (microbial C-N-P, enzyme activity) and gaseous emissions (CO₂, N₂O and NH₃ fluxes). Principal Component Analysis (PCA) was performed to determine the SQI using a linear scoring method.

In the arable-cereal field, chabazite increased the SQI significantly from ~0.3 to ~0.6, but no clear dose effect was evident. The SQI also rose significantly in perennial fields thanks to the use of chabazite zeolites. Different indicators have been selected by the PCA at each site, suggesting that chabazite addition impacted soil quality differently in each cropping system.

Overall, this research underscores chabazite zeolite potential to boost soil health, indicating a substantial enhancement in soil quality post-amendment.