New Findings Advance our Knowledge of how Struvite and Natural Zeolites Affect Soil Microbial Communities and the Nitrogen Cycle

Nutrient recycling in agroecosystems is of paramount importance for agricultural sustainability. Recently, ZeoTEAM published the results of a series of experiments conducted in collaboration with the BOKU University, Institute of Soil Research (Vienna, Austria) to investigate the effects of Struvite (a nitrogen, phosphorus, and magnesium-based mineral fertilizer) and nitrogen-enriched Zeolites, both produced by a wastewater treatment system patented by ZeoTEAM and the University of Ferrara, for nutrient recovery and reuse.
The short-term effects immediately following their application were investigated, primarily evaluating processes related to the nitrogen cycle, climate-changing emissions, and effects on the soil microbial communities. For these experiments, agricultural soil with a predominantly silty-sandy texture and acidic pH was selected.

 

The effects of zeolites and struvite on soil pH were fundamental and influenced many of the measured parameters. The increase in pH (liming effect observed with both zeolites and struvite) primarily caused complete solubilization of struvite, which released nitrogen, phosphorus, magnesium, and other micronutrients into the soil, potentially bioaccessible to plants and microorganisms.
Zeolitic minerals demonstrated the ability to reduce gaseous emissions of nitrogen oxides (NOx), which are precursors of nitrous oxide (N2O), a highly impactful greenhouse gas that is over 200 times more potent than CO2 in terms of global warming potential (GWP), and for which agriculture, particularly the use of nitrogen fertilizers, is responsible for over 40% of global emissions.
Two natural zeolites - or zeolite-rich tuffs - were tested, with different geographical origins and mineralogical compositions (one was rich in chabazite-type zeolites, while the other was rich in clinoptilolite). In the first (chabazite zeolite), we observed a significant increase in nitrogen assimilation by microorganisms, which was about 90% higher than in unfertilized soil. This result is particularly encouraging as crops could benefit from this new reserve of nitrogen, which is rapidly immobilized by microbial biomass, as an available resource for plants.
However, when high doses of zeolites were used in the soil, especially in the presence of ammonium-based fertilizers, nitrogen losses were observed in the form of ammonia (NH3) emissions, where these losses were controlled by the soil pH, increasing where the pH was higher.
Soil pH is indeed a fundamental parameter that must be considered in agroecosystem management, and it is necessary to understand how different practices can modify and influence changes in the short, medium, and long term.

 

In summary, this study, conducted in collaboration between ZeoTEAM (University of Ferrara) and the University of BOKU (Vienna), highlighted the effectiveness of struvite and nitrogen-enriched zeolites, produced from the treatment of agricultural effluents, in potentially reducing nutrient losses from agricultural systems and improving soil resilience. However, this study also reminds us that environmental solutions are not simple and universally applicable. pH control is necessary at the farm level to minimize nutrient losses, effectively mitigating pollution by nutrients.
Knowing how different practices modify key aspects of the agricultural ecosystem is essential to achieve optimal results and effectively reducing environmental impacts. Applying strategies capable of mitigating N2O emissions and its precursors, such as potentially using zeolites, is fundamental and will be increasingly important in the coming years to ensure a sustainable future for the well-being and health of not only the planet but also humanity.
Finally, we must remember that to effectively contrast agricultural pollution and reverse climate change, we must consider soils and agroecosystems as complex systems, but at the same time, we must also be able to effectively transfer this knowledge into practice and common sense, always respecting ecosystems, natural cycles, and the proper functioning and health of our soils.

 

Link to the paper: https://www.sciencedirect.com/science/article/pii/S0045653523001480