Soil Health: #1 Minimise Soil Disturbance

Less is more

Less is more. When it comes to soil health, ‘less is more’: less tillage, less chemical inputs and less soil and water erosion. The  awareness that soil is the world’s most critical and strategic asset is growing. This fuels the need to preserve and improve soil health. Therefore, in this series of articles, you will gain a deeper appreciation of the importance of soil for the future of our planet. Moreover, we emphasise how agricultural practices can enable soil health. This first article dives into the first key agricultural principle on the path to making our soils flourish: minimising soil disturbance.

Minimising soil disturbance is the first key agricultural principle on the path to making our soils flourish.

What does ‘less is more’ look like? Minimising soil disturbance can be done mechanically (minimising tillage), chemically (minimising chemical inputs such as fertilisers and pesticides), and physically (minimising water and wind erosion) (White 2020). This article focuses on the minimal mechanical disturbance. Later articles will address chemical and physical disturbances.

Why it matters?

It is well known that the human microbiome (sometimes called gut flora) is critical for our digestion and overall health.  Similarly, soil health is determined by the health of the soil microbiome. In the same way that disturbing our gut microbiome through chemicals or poor diet can lead to health problems, disturbances to the soil microbiome can undermine soil health.

Tillage is the conventional agriculture practice that disturbs the soil structure and hence the protective tissue around the soil microorganisms (White 2020). This mechanical disturbance destroys critical fungal networks. As a result, the soil aggregate structure changes and becomes more compact. This prevents water and oxygen from flowing through it. This is bad news for microbes, earthworms and other soil microorganisms, who are critical to maintaining soil health.

Impacts on Carbon and Beyond

Even worse, when removing the topsoil and destroying the soil aggregate structure, soil organic carbon is exposed to the air (Kharunga et al. 2023), to wind and water erosion and can be released back in the atmosphere (White 2020). The carbon released back into the atmosphere contributes to climate change. The removal of carbon from the soil reduces crop nutrient availability, the water holding capacity of the soil and other physical properties of the soil that are influenced by soil carbon (Poulton et al. 2018).

Minimising tillage or eliminating it altogether, known as ‘low till’ or ‘no till’, produces other positive benefits beyond soil carbon. These “co-benefits” are a result of the undisturbed soil allowing the natural microorganisms, fungi and bacteria to thrive. Indeed, less is more!

Benefits

The first co-benefit of no till practices are the enhanced nutrient cycling including increased soil Nitrogen (N), Phosphorus (P), and Potassium (K) (Kharunga et al. 2023; Martinez et al. 2013). The nutrient cycle and resulting delivery of critical N, P, K and carbon to the plant are enabled by thriving mycorrhizal fungi and bacteria. By maintaining the aggregate stability of the soil instead of ‘ploughing it through’, no till practices avoid the exposure of these microorganisms to oxygen and other detrimental environmental factors. They also enable mycorrhizal colonisation and the build-up of microbial biomass.

Further, no till practices also lead to higher soil carbon levels (White 2020). Compared to conventional farming, no till practices were observed to have a higher fungi-to-bacteria ratio (Bailey, Smith & Bolton 2002). This is linked to more and better soil organic matter (Six et al. 2006). Fungal dominated soil communities have a higher-efficiency carbon use, therefore they turnover soil carbon slower and hence record a higher soil carbon rate (Kharunga et al. 2023). Moreover, because carbon feeds the soil’s microorganisms its increase creates a positive feedback loop while contributing to the natural soil-building process (White 2020).

Another advantage of protecting the soil aggregate structure, microbiome and carbon content is the protection of the soil’s water holding capacity (Kharunga et al. 2023). When humus is formed, carbon becomes a sticky protein, glomalin, which attaches to lose minerals and binds them together into aggregates that can fill with moisture. Over time these aggregates bind together and form underground water reservoirs (White 2020).

The Journey of Soil Health

In short, minimised soil disturbance leads to significant increases in organic carbon, Nitrogen (N), Phosphorus (P), and Potassium (K), soil water holding capacity, microbial biomass and fungo-to-bacteria ratio. These impacts are greater when combined with other regenerative agricultural practices which will be discussed in following articles.

Now that we have begun the journey towards saving the health of our soils by minimising soil disturbance, the next step is to measure and monitor that progress. This requires accurate and detailed soil data for farmers to map out the precise soil characteristics, health indicators and the best practices to improve them. These data can qualify and validate that less is more. To learn more about CAS’ soil data intelligence solutions, contact us or explore our website and continue reading.

Sources

Bailey, VL, Smith, JL & Bolton, H 2002, ‘Fungal-to-bacterial ratios in soils investigated for enhanced C sequestration’, Soil biology & biochemistry, vol. 34, no. 7, pp. 997–1007, DOI: 10.1016/S0038-0717(02)00033-0

Khangura, R, Ferris, D, Wagg, C & Bowyer, J 2023, ‘Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health’, Sustainability, vol. 15, no. 3, pp. 2338-, https://doi.org/10.3390/su15032338

Martínez, E, Fuentes, J-P, Pino, V, Silva, P & Acevedo, E 2013, ‘Chemical and biological properties as affected by no-tillage and conventional tillage systems in an irrigated Haploxeroll of Central Chile’, Soil & tillage research, vol. 126, pp. 238–245, DOI: 10.1016/j.still.2012.07.014

Poulton, P, Johnston, J, Macdonald, A, White, R & Powlson, D 2018, ‘Major limitations to achieving “4 per 1000” increases in soil organic carbon stock in temperate regions: Evidence from long‐term experiments at Rothamsted Research, United Kingdom’, Global change biology, vol. 24, no. 6, pp. 2563–2584, DOI: 10.1111/gcb.14066

Six, J, Frey, SD, Thiet, RK & Batten, KM 2006, ‘Bacterial and fungal contributions to carbon sequestration in agroecosystems’, Soil Science Society of America journal, vol. 70, no. 2, pp. 555–569, DOI: 10.2136/sssaj2004.0347

White, C 2020, ‘Why Regenerative Agriculture?’, The American journal of economics and sociology, vol. 79, no. 3, pp. 799–812, https://doi.org/10.1111/ajes.12334