What is soil health and how is it measured?

What is soil health and how is it measured?

Why is soil health important?

95% of our food is produced on the soil and by 2050 agricultural yields must increase by 60% to meet the global food demand of our growing population. FAO has estimated that sustainably managing the soil will lead to improvements in soil health, resulting in an increase of up to 58% in food production.  It is obvious that soil health is key for food security and to guarantee food supplies for the upcoming generations. However, over the last 50 years, intensive crop production has exhausted our planet’s soils, endangering their ability to meet the future food demand. Meaning that now we need to start taking care of the wellbeing of our soils to improve agricultural yields and guarantee the food supply.

The UK government has recognised the importance of soil health to protect the conservation of agricultural lands for future generations. As a matter of fact, on the 12thSeptember the Agricultural Bill was introduced into the House of Commons for the first time in history with the objective amongst others of ensuring that the health of UK’s soil is preserved and improved. Over the past years, soil health has become a trending topic, and this is due to the realisation of the upcoming crisis of soil health fertility that we will face. This crisis could be devastating for agricultural yields, if no preventative measures are taken in time. In fact, the UN predicts that there are only 60 harvests left before our planet’s soils are depleted and become too degraded to feed us.

However, do we really understand what soil health means?

The United States Department of Agriculture defines soil health as the capacity of soil to function as a vital living ecosystem that sustains plants, animals and humans. This definition implies that the soil isn’t an inert growing medium, but it is a living ecosystem with billions of fungi, bacteria and other microbes that create an intricate and elegant ecosystem providing the foundation of agricultural activities. It is not surprising, that as a living system, only soil that is healthy can perform optimally its functions of: regulating water; sustaining plant and animal life; filtering and buffering pollutants; cycling nutrients; and providing physical stability and support. Therefore, by understanding the health of the soil we can assess and manage it to ensure that it performs optimally and safeguard its conservation for future generations.  (Source)

Similarly, FAO defined “soil health as the capacity of soil to function as a living system to sustain plant and animal productivity, maintain or enhance water and air quality and promote plant health and animal health.” Moreover, FAO recognised the necessity of healthy soil to support a diverse community of soil organisms (fungi, bacteria, earthwors, etc.) to control plant disease by creating a positive symbiosis with the plant roots. Interestingly, this definition acknowledges the role of a network of living organisms within the soil to ensure healthy crops and optimal agricultural yields. (Source)

From the definitions of soil health by USDA and FAO one can conclude that soil functions as a living ecosystem with billions of organisms that interact with plants to form a complex network of interactions and if this living ecosystem is healthy, it results in healthy fields.  However, if a soil is sick, the networks within the ecosystem of this soil organisms are damaged, impairing the normal function of the soil, resulting in diseased plants and a concomitant reduction in crop yields.

But to what extent do we understand the health of a soil?

In order to answer this question, the methods used to measure soil health currently should be investigated. Due to the realisation of the importance of soil health for agricultural yields, over the past years, there has been an increasing interest in understanding how to measure and monitor the health of our soils. For example, some of the methods that the Agriculture & Horticulture Development Board recommends for soil health assessment are (Source).

1. Spade diagnosis or a subjective visual soil assessment. This consists of digging up the soil, and checking its compaction, colour and smell. Similarly, the soil structure is usually evaluated by soil pit/profile informs about the location of compact layers. This method is very useful to gauge for worm presence and to assess the drainage of the field, both of which are important for root establishment and crop development.

2. Plant health monitoring, by visually checking crop deficiencies. However, this method is not suitable for predicting upcoming risks that will likely impact the yield of the fields, as the problems are diagnosed after seeing damages in the crops.

3. Total soil organic matter. This test is carried out in laboratories and it simply indicates the ratio of organic matter in the soil. However, it does any inform about the nature of the organisms living in the soil ecosystem and it totally ignores the pathogenic or pro-biotic nature of the microbes within the ecosystem.

4. Visual soil assessment tools following recommending guidelines to obtain an overview of the health of the soil by inspecting the roots, worms, soil structure or colour. This method can be a good indicator of short-term soil health; however, it does not indicate underlying risks triggered by environmental changes. For instance, some pathogenic microorganisms can remain in the soil in a resting state until there is a change in weather conditions that triggers their infectious activity. Also, pathogenic microorganisms can cause disease in crops if supressing beneficial microorganisms, within the soil ecosystem, are eliminated by external factors (i.e. fungicide applications).

5. Standard lab tests of macronutrients, micronutrients and pH. However, the information provided by these tests about the health of the soil is very superficial and minimal. The soil is a living ecosystem of organisms, and these tests (pH and macronutrient composition) are not suitable to understand the network of microbes populating the soil. Also, these laboratory tests cannot describe the relationship of the soil biota with the plant roots or alert of any risks of crop disease.

6. Microbial profiling tests, which informs of the bacteria, fungi species and diversity within the soil. These soil health assessments methods are the only tests that can properly describe the network of microbes present in the soil. However, currently there are no standards for these tests, and they often require skills for adequate sampling and for interpretation of the results.

How does FungiAlert contribute to our soil health knowledge?

FungiAlert has developed a method of microbial profiling that does not require any skills for sampling and interpretation of the results. This system samples the ecosystem of microorganisms in the soil, in-situ, in the field. Sampling the microbial network in the field eliminates the possibility of imposing artificial laboratory conditions on the soil ecosystem. Some laboratory tests for microbial profiling require soil samples to be sent to the lab, where the samples are manipulated to be able to identify the microbes present. This manipulation of the soil ecosystem in laboratory conditions will affect the profile of the microorganisms in the soil and will lead to a miss-interpretation of the true health of the soil. Therefore, currently only FungiAlert’s soil health test allows for a true profiling of the soil microbiome.

Furthermore, some methods for soil microbial profiling are specific for certain microbes, missing out the wide range of the species that can inhabit soils. FungiAlert’s method is unbiased with the potential to scout all the species in the field sampled. This unbiased method provides information about both the beneficial and pathogenic microorganisms for the crop. Undoubtedly, this knowledge truly allows for an assessment of the soil health as a living ecosystem. Moreover, FungiAlert delivers the results in a meaningful simple-to-read report, which does not require skills to interpret it.

In conclusion, FungiAlert’s soil health test offers a revolutionary tool, that will transform the understanding of soil health. This field-testing tool provides an innovative method to disentangle the complexity of the soil for the first time.

Angela de Manzanos Guinot, CTO

19th November 2018

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