What is Soil Health?
Soil is complex. It incorporates elements of chemistry (chemical relationships between the environment, bacteria, animals, plants etc), soil physics (changes within the soil environment such as compaction etc) and biology or more specifically microbiology. Soil is a three-system state (consisting of solids, gases and liquids) consisting of organisms, liquids, gases, minerals and organic matter, that is changed by various chemical, physical and biological processes. We still have so much to learn about soil, with major discoveries such as glomalin (overleaf) only occurring in the last 30 years.
Conventional farming is often fighting against nature and trying to control natural systems. Historically science has taken a reductionist approach and simplified soil into needing a few key nutrients to be productive (such as NPK fertiliser). In reality there is a lot more going on in soil biology then the circulation of a few choice nutrients.
Resilience to Extremes
Following the four principles of soil health (overleaf) allows us to build resilience in our landscapes. Not only does it protect us against droughts by increasing the water storage capacity of our soil, this increase in storage also allows for higher rates of infiltration during floods.
Disease Resistance
The increased biodiversity in the system leads to a wider variety and availability of nutrients resulting in a stronger immune system in plants. While no system is 100% immune to diseases, having healthy crops helps alleviate the need for synthetic inputs, saving money in the long run and creating healthy produce for human consumption that has a more complex structure.
Soil Health, Human Health
Soil health is linked to human health in a number of ways. Likewise, soils can be contaminated in a number of ways, from industrial and commercial waste and runoff, mining and agricultural inputs, to the natural weathering of rocks. Contaminated soil has the ability to pass on dangerous toxins and pathogens to humans through water, dust and food contamination, while nutrient deficient soils can lead to nutrient deficient food and decreased gut biome health in humans.
Healthy soils act as a filter to draw contaminants out of water as it passes through pore space, reducing the risk of water-borne diseases, while offering nutrient rich foodstuffs. A recent review1 of soil health and nutrient density literature showed that organically grown crops had higher levels of anti-inflammatory properties and health protective antioxidants due to increased levels of phytochemicals.
The impact of soils on human health isn’t just at play through plants, with a recent study2 of regeneratively grown pork and beef compared to both conventional, and a health promoting brand found a better health related balance of omega-6 to omega-3 fats in regeneratively farmed meats. So, the benefits are clear, but how do we make soil healthy?
The Four Principles of Soil Health
- Minimize disturbances – Our soils are built up of arbuscular mycorrhiza (AM) and ectomycorrhizal (EM) fungi that form mutualistic symbiosis with plant root systems to help nutrient uptake.
- Maximise soil cover – Vegetation armours the soil against erosion. The root systems anchor soil in place and restrict its movement by environmental forces (rain, wind etc). This armour also protects the soil against the compaction effects of rain as the droplet energy is dissipated as it hits grasses and leaves.
- Continual living roots – Having living roots in the soil continues the movement of nutrients and minerals through soils and helps feed microorganisms. Having a mixture of plant species with different root types (e.g. tap roots and fibrous roots) allows for the circulation of nutrients at different levels in the soil profile.
- Increase biodiversity – Increasing the biodiversity of our soils increases complexity. This complexity allows for the intricate relationships between organisms to form increasing resilience. Often, we see the integration of livestock as a separate principle in soil health, here we include livestock as a part of the biodiversity required to improve soil health.
Glomalin
Soil Tests
While landscape literacy is an important way of understanding the health of your land, regular soil testing is key to getting down to the nitty gritty. The Environmental Analysis Laboratory (EAL) at Southern Cross University have a range of tools to help you conduct soil tests, and understand the results. It’s also important to remember we need to test for microbial activity as well as mineral deficiencies. Details are available in the want to learn more section.
References
1. Montgomery, D. R., & Biklé, A. (2021). Soil health and nutrient density: beyond organic vs. conventional farming. Frontiers in Sustainable Food Systems, 5, 699147.
2. Montgomery, D. R., Biklé, A., Archuleta, R., Brown, P., & Jordan, J. (2022). Soil health and nutrient density: preliminary comparison of regenerative and conventional farming. PeerJ, 10, e12848.
