The Importance of Soil Stability and the Slake Test

The Importance of Soil Stability and the Slake Test

A soil stability test, or slake test, is one of the most straightforward yet revealing methods for assessing crucial indicators of soil health. It showcases how stable soil is when exposed to rapid wetting, with the most stable soils resisting breakdown. This resistance to disintegration helps prevent erosion from both wind and water, improving the soil’s water infiltration and retention properties.

Two soil samples from fields with different management histories can demonstrate the stark contrast between healthy and degraded soils. In particular, fields managed with conventional tillage practices often result in heavily degraded, unstable soils. These soils tend to be dry, crusty, and compacted, lacking the beneficial microbes necessary for healthy, functional soils.

The Impact of Tillage on Soil Microbes

Microbes play an essential role in maintaining soil health. Unfortunately, they are highly susceptible to tillage, which can greatly reduce their numbers. In soils affected by conventional tillage, the organic matter content is alarmingly low, and the soil appears pale and dry.

In contrast, healthy soil managed with practices such as reduced tillage and the use of cover crops looks dark, moist, and spongy. This living soil hosts a diverse microbial community known as the microbiome. The organic matter in this type of soil is retained, preventing the release of carbon into the atmosphere. The formation of soil aggregates, held together by microbial substances such as glomalin, helps maintain soil stability.

Glomalin and AMF: The Natural Microbial Glue

Glomalin is a microbial glue produced by arbuscular mycorrhizal fungi (AMF), which are naturally occurring beneficial soil fungi. Research has shown that AMF and glomalin contribute to the creation of stable soil aggregates and lock carbon within the soil. This process prevents carbon from escaping into the atmosphere as carbon dioxide, a greenhouse gas.

When soils are depleted of AMF, the balance of microbes is disrupted. Less glomalin is produced, and the soil becomes unstable. These disrupted soils lose their ability to retain carbon, water, and nutrients, which are essential for supporting healthy and productive crops.

The Slake Test in Action

To better understand the significance of AMF, glomalin, and carbon retention in agriculture, a simple experiment can be conducted by dropping two soil samples into water. In the case of the depleted soil, it begins to break down almost immediately. As the soil pores collapse, the lack of AMF prevents the production of glomalin, resulting in no stability. The soil disintegrates, which is why water, soil, and nutrients tend to run off from depleted agricultural land.

This runoff leads to a series of destructive environmental consequences and financial costs for farmers. In contrast, the healthy, living soil, rich with a diverse microbial community, holds together. The stable aggregates and pores in this soil remain intact, allowing the water to be absorbed without causing the soil to burst apart.

The Environmental and Economic Consequences of Soil Erosion

Imagine a large-scale rain event affecting acres of unstable land. The soil’s aggregates would erode, leading to a loss of nutrients and productivity. To restore depleted soils to their natural, balanced microbiome, and to sustainably grow healthier crops, many growers are turning to AMF inoculants like MycoApply from Valent BioSciences.

Over time, combining MycoApply with other soil management practices can help farmers reduce costs related to irrigation, nutrient loss, equipment operation, labor, and more. Healthy soils not only support better crop production but also contribute to a more sustainable and cost-effective agricultural system.

The test Conclusion

Maintaining soil health is critical for sustainable agriculture. The slake test offers an easy and revealing way to evaluate soil stability and its capacity to support crop growth. The presence of beneficial microbes like AMF, and the production of glomalin, help create stable aggregates, retain carbon, and improve water infiltration. By incorporating practices such as reduced tillage and using microbial inoculants like MycoApply, farmers can rejuvenate their soil, reduce costs, and support healthier, more productive crops.