Cover Up – Covered soil is protected soil

Cover up to maximise soil health! A healthy soil requires a healthy microbiome as written in our previous articles. For soil and its microbiome to thrive, it requires to be protected against water and wind erosion. It also needs to have a living roots system to ongoingly feed the soil bacteria and fungi. To achieve this, we have to cover up by maintaining (1) soil cover and (2) living roots

Soil Health Principle #3: Maintain Soil Cover

Cover up to maximise soil health by growing crops between main crops in space or in time. These crops ensure that the soil is covered by a protective layer of plants when the cash crops are harvested, and with an underground root system (Kharunga et al. 2023). Cover crops can be planted after harvest or can be under-seeding cash crops. Sometimes it may not be feasible to plant cover crops, a layer of biological materials such as mulch or crop residues can then be used to cover up the soil. They may have no living roots, but at least there is a protective layer that can keep the soil in the best condition for the next plants to grow.

Why it matters – sticking together

When soil remains covered it remains protected against erosion by water and wind. Firstly, the soil cover forms a physical protective layer. Secondly, if the soil cover exists out of living plants, the roots trap soil particles and keep them in place. Moreover, the fungi that live symbiotically with the roots can process root exudates into glomalin. This sticky fluid glues the soil together to create water-retaining aggregates.

For your reference, the disastrous 1930s United States Dust Bowl was caused by prolonged drought on poorly managed soil, which led the soil prone to wind erosion (Lee & Gill 2015). Blown away soil by strong winds formed massive dust storms covering vast areas of the Great Plains, causing economic, social and environmental harm.

Why it matters – flourishing below and above ground

Covered soil does not only stay in place, but it also thrives thanks to the provided organic matter when plants or crop residues decompose. Soil organic matter feeds the microbial biomass (White 2020; LaCanne & Lundgren 2018) while increasing water infiltration rates (Lehman et al. 2015; Khangura et al. 2023).

This flourishing soil microbiology and maintained plant cover combined are important pathways in sequestering carbon (Kharunga et al. 2023) which is critical for plant growth and increased soil organic matter (LaCanne & Lundgren 2018), closing the cycle. Lastly, adding cover crops can increase crop diversification, of which the beneficial processes are described above.

The top benefits

Cover crops protect the soil from wind and water erosion while providing the perfect feeding ground for its underground microbiome. Protected against wind and water, while provided with diverse and abundant organic matter, the soil microbiome flourishes sustaining agricultural productivity (Zhang et al. 2020).

1. Protection against soil erosion.
2. Thriving soil microbiome.
3. Increased soil organic matter by increased carbon sequestration thanks to the combination of above ground plants and thriving underground micro-organisms.
4. Enhanced crop productivity. Soil organic matter together with a thriving microbiome leads to increased mineralisation of nitrogen and carbon which are critical building blocks for plants and hence increase crop productivity (Kharunga et al. 2023; LaCanne & Lundgren 2018).
5. Carbon sequestration. The increased plant cover and underground micro-organism activity enhances carbon sequestration. If cover crops would be adopted widely, they could reduce agricultural greenhouse gas emissions by 10% (Kaye & Quemada 2017). Even if it could take several years for soil carbon to increase significantly (Ghimire et al. 2018).
6. Increased productivity and biodiversity, reduced pests, pathogens and weeds, and enhanced water and soil quality are all co-benefits achieved by crop diversification which happens if crop cover is provided by a different variant than the cash crop (Beillouin et al. 2021).

The benefits of cover crops depend on the typical variables, such as climate, soil texture, initial soil organic carbon levels, and the timeframe since the cover cropping started (Jian et al. 2020). Hence, let’s cover up to maximise soil health.

Principle 4 Maintain Living Roots

If cover crops aren’t possible, there are other ways to maintain living roots between harvests. Cover up soil with stubbles or perennial crops to maximise living roots all year long, and protect soil health.

Why it matters – water and carbon management

Like the processes described under the principle of soil cover, living roots protect against soil erosion and water run-off. Roots physically trap soil particles, while glomalin – produced by the mycorrhiza fungi in exchange of the root exudates – glues soil together in water-retaining aggregates which enable water infiltration (Kharunga et al. 2023).

At the same time, living roots introduce carbon – captured and photosynthesised by the plant – in the soil which feeds the soil microbiome. In exchange for this carbon, soil bacteria and fungi fix and cycle nutrientsthat are critical for plant growth, such as nitrogen, phosphor and potassium, and of course … carbon. By making these elements available for plants, plants can grow and thrive, in return photosynthesising even more carbon (Kharunga et al. 2023).

The co-benefits listed

1. Carbon sequestration. Maintaining roots keeps the symbiotic relationship between plants and the soil microbiome going, which enables the sequestration of soil organic carbon; combined with other regenerative practices that enhance the biodiversity and reduce soil disturbances, the capacity to sequester carbon is even higher (Kharunga et al. 2023).
2. Nutrient cycling & crop productivity. Similarly, in exchange for the maintained supply of carbon, the symbiotic soil microbes and fungi fix, cycle and provide nutrients such as phosphor, nitrogen and sulphur to the plants (Jacoby et al. 2017), which enable their growth and hence crop productivity. Particularly legumes are known for their nitrogen-fixating capabilities (Kharunga et al. 2023).
3. Soil organic matter. The increase of root biomass enhances the level of soil organic matter (Kharunga et al. 2023).
4. Erosion protection. Maintaining roots, when provided by perennial grasses etc. provides ongoing soil cover which as described previously protects against soil erosion (Giller et al. 2021).

Hence, living roots have the capability to cycle nutrients and carbon, especially combined with other regenerative agricultural practices that increase plant diversity and reduce soil disturbances (Kharunga et al. 2023). These practices ensure that roots and their dependent soil ecosystems thrive, critical for the cycling of carbon and nutrients between plants and soil. When the root cover is continuously provided by the same species, additional weed, pest and disease controls should be put in place to avoid the same risks as monocultures may have (Snapp et al. 2019).

Cover up to maximise soil health

In a nutshell, cover up soil to protect it from water and wind erosion and maximise soil health. Add a cover up solution like perennial crops, stubbles or cover crops to ensure the soil is not only protected but also flourishes. Moreover, keeping the living root system in soils alive all year long has many benefits from sequestering extra carbon to optimising water infiltration.

To work with the soil, understand soil at the deepest level and validate and inform existing and new practices, start by measuring, analysing and mapping the soil by using our soil data intelligence solutions. Let’s cover up the soil to optimise below- and above-ground soil health.