Context of the Study
With nearly 25% of the Earth’s biodiversity, soils are the stage for numerous interactions that influence soil quality, resource availability, and carbon storage. Understanding these complex ecosystems is crucial, especially in agriculture, where these factors can significantly impact production.
This is one of the key principles of agroecology, a branch of agronomy that emphasizes the importance of scientific ecology knowledge in agricultural production.
In this context, the Domaine de Graux, located in Tournai, asked E-BIOM to evaluate the biodiversity of their soils and compare them with those from conventional agriculture. This analysis aligns with the Domaine’s mission to demonstrate that agroecology is possible on a large scale and provides greater resilience for farmers. Undoubtedly, this resilience is linked to soil health and quality.
Sampling and Surveys
To conduct this study, E-BIOM employed its Soil Kit, a sampling kit for analysing soil biodiversity using environmental DNA methods.
In practice, the study focused on the organic matter (OM) content and microbial molecular biomass (MMB), two parameters that are representative of soil biological diversity. To this end, soil samples were taken from the Domaine de Graux plots as well as from neighbouring plots outside the property.
Thus, the study aimed to:
- Quantify the correlation between OM and MMB.
- Quantify the impact of agricultural type on OM and MMB.
- Quantify the impact of land use type on OM and MMB.
The land use was noted for each plot, in order to evaluate its influence on soil biodiversity and take potential interactions into account. These uses included various crops (wheat, maize, alfalfa, etc.) as well as permanent grasslands and forests.
Results
Correlation Between OM & MMB
The organic matter (OM) content measured for all samples ranged between 2.47% and 6.91%, while the Microbial Molecular Biomass (MMB) for quantifiable samples ranged between 1.3 and 33.1μg DNA/g of dry soil. A 55% correlation was observed between OM and MMB, a correlation supported by scientific literature, as OM is one of the main factors influencing MMB.
Impact of Agricultural Type
Samples taken from permanent grasslands and forests showed the highest OM and MMB values, which can be logically explained by the absence of soil disturbance compared to crops.
Focusing on samples from different crops, it appears that agroecology has a significant positive impact on organic matter and microbial molecular biomass. Indeed, the OM content in agroecological soils is nearly 1.3 times higher, and MMB is nearly 8.5 times greater.
However, these values come from a limited number of samples. A larger sample size would refine the results and more precisely quantify the added value of agroecology.
Impact of Land Use
In addition to the fact that forests and permanent grasslands have higher OM and MMB values, the type of crop also has an influence. Analyses show that crops with high soil exposure, such as maize and potato crops, tend to have lower values.
Conclusion
The practice of agroecology, as carried out by Domaine de Graux, significantly boosts organic matter content and microbial biomass in the soil, indicating better biological quality. Soils cultivated according to agroecological principles host more pronounced biodiversity compared to conventional crops.
In general, this study highlights trends that would benefit from further exploration through more detailed analyses, such as microbial community composition, the fungal/bacterial ratio, etc., and by integrating other parameters like soil pH, texture, and nitrogen levels.
