Agricultural systems are under pressure to produce increasing amounts of food for a growing human population while preserving, and ideally enhancing, the capacity of soils to sequester carbon and provide a habitat for biodiversity. Regenerative agricultural practices have been put forth to address this challenge. One such practice is the application of non-harmful, cheap organic fertilizers in combination with additives.
In this study, we are working with the Nestlé Agricultural Institute to test effects of organic fertilizers in combination with selected additives on soil greenhouse gas emissions and crop productivity as well as parameters related to soil health and the carbon sequestration capacity on agricultural soils. This work will test two organic fertilisers, manure and digestate, in combination with two additives that have shown promising effects in laboratory studies. Field manipulations with these fertilizers and additives are being carried out in close collaboration with two farms in Switzerland.
The specific objectives of the this work are to
- determine effects of organic fertilizers in combination with additives on greenhouse gas emissions and crop yield,
- assess changes in belowground microbial diversity under organic fertilizer and additive treatments, and
- identify variations in the stabilization of soil organic matter under organic fertilizer and additive treatments.
To address these objectives, we will combine field measurements with molecular scale analysis of microbial community composition and functioning as well as soil organic matter and mineralogy. To determine effects of organic fertilizers plus additives on greenhouse gas emissions and crop yield (Objective 1), we are measuring greenhouse gas emissions after fertilizer addition and characterize crop yields at the end of the growing seasons. To assess effects on belowground microbial diversity and functioning (Objective 2), we are performing metagenomic (microbial diversity) and metatranscriptomic (microbial functioning) analyses of soils. To identify variations in the stabilization of soil organic matter (Objective 3), we are using state-of-the-art analytical techniques to characterize soil mineralogy and organic matter properties. Based on these data, we will estimate the carbon sequestration capacity of the investigated soils. We will further link the formation of recalcitrant soil organic matter (Objective 3) to microbial diversity and functioning (Objective 2) and greenhouse gas emissions (Objective 1).
We expect the proposed work to provide 1) estimates of global warming potentials (or decreases thereof) of the tested fields under various treatments with organic fertilizers and additives, 2) qualitative information on effects of various treatments on belowground soil microbial diversity, 3) estimates of the capacity to sequester carbon in mineral-organic associations for each tested field. These results will be key to inform regenerative agriculture practices and to scale up the application of organic fertilizers in combination with additives.
People: Camila Morales
Collaborators: Helena Wehmeyer, Adrian Ho
Funding: Nestlé Agricultural Institute