Soil Health Indicators

What is Soil Health?

1. Chemical Comparisons. Sheffield University compared allotments and arable farms "measured a range of soil properties, including soil organic carbon levels, total nitrogen, and the ratio between carbon and nitrogen (which are all directly related to the amount and quality of organic matter in the soil) as well as soil bulk density, an indicator of soil compaction."

2. I mentioned in an Food Ethics Council Blog for Soil Day 2014 Save our Soils that 'Soil Organic Matter' is probably a better measure than 'Carbon content' when trying to assess the health of the soil. Can we use soil animals as an indicator?

Soil Health and Soil Animals "Soil animals have an important role in the formation of soil structure. Soil animals improve soil structure by forming - along with roots, worms and fungi, channels and pores. Aggregate formation is a crucial soil characteristic where concentrating fine soil particles together into aggregates, by fragmenting and mixing organic matter through soil."  "Plant-stimulated soil pore formation appears to be a major, hitherto unrecognised, determinant of whether new C inputs are stored or lost to the atmosphere. Unlike monocultures, diverse plant communities favour the development of 30–150 µm pores." Nature

3 'Soil health' describes how well soil performs all of its functions now and how those functions are being preserved for future use. Soil health is not determined by measuring only crop yield, water quality, or any other single outcome. Soil health cannot be measured directly, any more than we can do that for ourselves. So we use Soil Quality Indicators.

Indicators are properties of soil or plants that can be measured in order to provide clues about how well the soil is functioning. Indicators can be physical, chemical, and biological properties, processes, or characteristics of soils. They can also be morphological or visual features of plants. USDA

Indicator Examples and Relationship to Soil Health

Soil organic matter => nutrient retention; soil fertility; soil structure; soil stability; and soil erosion

Physical: bulk density, infiltration, soil structure and macropores, soil depth, and water holding capacity => retention and transport of water and nutrients; habitat for soil microbes; estimate of crop productivity potential; compaction, plow pan, water movement; porosity; and workability

Chemical: electrical conductivity, reactive carbon, soil nitrate, soil pH, and extractable phosphorus and potassium => biological and chemical activity thresholds; plant and microbial activity thresholds; and plant available nutrients and potential for N and P loss

Biological: earthworms, microbial biomass C and N, particulate organic matter, potentially mineralizable N, soil enzymes, soil respiration, and total organic carbon => microbial catalytic potential and repository for C and N; soil productivity and N supplying potential; and microbial activity measure

The Dollars & Cents of Soil Health 

In the US, many farmers are incorporating soil health management principles into their operations. Conservation practices such as cover crops and no-till are widely recommended to build soil health over time, but do these practices actually improve crop yields and lead to stable profit margins? To answer this question fully, a recently-completed Natural Resources Conservation Service (NRCS) Conservation Innovation Grants project shows promising results for farmers interested in adopting soil health management practices. Conducted by the National Association of Conservation Districts (NACD) in partnership with Datu Research, the project provides economic case studies focusing on four corn and soybean producers in the Upper Mississippi River Basin"

In the UK, there is an ongoing Soil Health Partnership, organised by the AHDB, consisting of 8 scientific partners and 6 industry ones. They say: "A healthy soil optimises the physical, chemical and biological properties of soil and AHDB has made several key investments in these areas in recent years. While the former two are now relatively well understood, biological properties are not." Quite.  The 5 yr 

£1 m project aims to improve farmers' understanding of soil health as a way of improving their production.

Soil Health Assessment Guidelines

"Guidelines for Soil Quality Assessment in Conservation Planning" describes a step-by step process for assessing soil health. It will help you decide whether to do an elaborate or simple assessment, which tools to use, and what management practices to use to address soil health concerns. While the guidelines are presented in the context of the NRCS 9-step conservation planning process, they are also useful in informal assessments, or as an educational resource for teaching soil health concepts. This guide uses the terms soil health, soil quality, and soil condition interchangeably. I don't think we should - we would not do that in other areas, such as 'public health'. Health is about wellbeing and life - ie biology, quality could be just chemical, and condition just physical.

Soil Health Indicators for Educators "Each guide includes an introduction to the soil property, discussion of the inherent and management factors influencing it, and explanation of the property's relationship to soil function. The educator's guides also include detailed information on a method to measure the soil property and interpretations of the test results. "

Techniques to improve soil health

Proposal for Popular indicator of Soil health

Application of National Sustainable Agriculture Indicators

Report of Workshop for Sustainable Soils Alliance that looked at "the ‘soil health’ indicator, and in particular: • What data sources should be included/excluded in a ‘soil health’ Indicator • Spatial and temporal scale and gaps in knowledge • Relevant existing and ongoing R&D activities that aim to develop a ‘soil health’ Indicator • The use and availability of soil-specific data sources which might be relevant to the framework and any of the proposed Indicators"

New Test of Soil Health created by Sustain members.  " A standardised, manageable and meaningful system of on-farm soil health monitoring metrics can be used to establish a baseline quality for farm soil and decide what actions should take place to maintain or improve its health. These metrics and methodology have been recommended to Defra for inclusion in the development of the new Environmental Land Management Scheme (ELMS). 

But remember DEFRA says  that soil is NOT a public good (target for future subsidies) but a natural asset out of which  public goods grow.

My Indicators

I've been asked by several people to come up with popular indicator of the health of our soils. So here goes..

The idea of indicator species is well founded. Here in UK the Biodiversity Action Plan sets out priority species’ that we need to keep an eye on', and they are usually called BAP species..

So why don’t we do the something similar to indicate the state of our soils – or soil health’?

Three easy tests for Soil Health. "The infiltration rate test, earthworm test and slake test require basic equipment which can be found on most farms. They will give you a good idea of your soil structure, organic matter content, and how much biological activity is happening".

The Global Soil Biodiversity Atlas

There are many ways to provide indicators soil quality, using physical chemical and biological methods. But they are at best dull, and some dubious. They don’t bring the soil to life – the element we are wanting to attract attention for.

Cranfield carried out study for DEFRA to find which Soil Quality Indicator (SQI) was best for determining quality of soil using physical indicators. Out of the top 7, they could not identify any particular one.

So why don’t we have indicators of the LIVING Soil? We need one that is visible an easy to communicate with people and represent what is going on in the soil. This is a way of shining a light on what otherwise is a dark and unseen world – almost the last environment to be explored. We know more about planets billions of miles away than we do about what is under our feet. So we want people to

a. Propose indicators of living soil

b. Vote on them (we will set up an online voting system)

It is part 1 where you come in. We want you to propose an indicator creature , that you believe demonstrates a ‘healthy soil’. You then have to explain why and how, taking this opportunity to explain more of the workings of the soil – the main point of the exercise

Here are some possible indicators

What constitutes 'Soil Health?

USA Soil Health

250 Soil health Bills been introduced into USA in last 2 years. "Planting trees, cover cropping, no-till farming, and rotational grazing were once in the relatively niche purview of environmental activists and advocates. But as epochal floods and droughts sweep farmland away, the notion that those techniques could actually help keep the land together—and make for more productive farming—is picking up steam."

"What’s interesting is how the language and goals of those bills subtly shift once they move away from the coasts and towards the Heartland. New York and Washington, for example, are currently considering carbon farming bills—a term that refers to the sequestration of carbon dioxide, and which is most readily apparent in the form of permanent vegetation. But Nebraska, citing the costs saved on less irrigation and fertilizer, recently established a “healthy soils” task force that would coordinate a statewide push for cover cropping, among other strategies. The bill to establish a task force does not mention climate."

Impact of US Farm Bill (2018) on soil health. spells  out "detailed summary of almost 60 provisions that may affect soil health...."It will be a valuable time saver for those who wish to gain information quickly, providing a brief description of each provision, how it impacts soil health, and links to the respective USDA agency responsible for implementing that provision. ..plus authorized funding levels for the 2018 Farm Bills compared for several programs in the Conservation, Research, and Forestry titles."

Is soil health related to human health?  

Soil can infect us, heal us, contaminate us, nourish us, and determine what we breathe. Even the gene used to create herbicide (Roundup) tolerant GM crops - Agrobacterium sp., comes from the soil - it is a pathogen of roots. Increasingly academics are looking at soil eco-services and how they provide us with food, building materials (eg wood & clay), water purification, clothing materials and how much these are worth to us. For each service we should value good soil health.But this is to treat the soil like some sort of factory producing services we do not pay for.

Whereas, we need to see it more as a living entity, with a ‘vitality’ (life force) of numerous connections between plants and animals, many of which we are yet to understand that enable our lives to be better. Perhaps the greatest exponent of this was Eve Balfour in her book The Living Soil, the bible of the organic movement, where she spells out how vitality is not the same as productivity. In it she spells out how living organic matter, in the  form of humus, compost or dung, provide for improved plant growth and also farm animal health. It is harder for her to demonstrate how we humans may directly benefit as the science is all but impossible – and has never really been tested. She gives some examples of how various ailments –  colds, rheumatism may well be improved by composted vegetable consumption, and makes the point that palatability – perhaps a good indicator of what is good for us –has been lost over the years. What she could not distinguish is whether good palatability is determined just by composted growing or by freshness of the produce. Certainly, fresh vegetables taste better and are better for us than mangled process mash we eat later.

Loss of nutrients in our food - The level of every nutrient in almost every kind of food has fallen between 10 and 100 percent. This is an incredibly sobering fact. An individual today would need to consume twice as much meat, three times as much fruit, and four to five times as many vegetables to obtain the same amount of minerals and trace elements available in those same foods in 1940. Good soils will have wide variety of minerals – rather than just the big 3 fertilisers – Nitrogen, Phosphorus and Phosphates

While many people who believe in organic farming - where there is reduced pesticide usage, and usually better rotations and compost usage, it is harder to prove that the healthier soil makes for healthier food. A massive study at Stanford in 2012 found "found little significant difference in health benefits between organic and conventional foods. No consistent differences were seen in the vitamin content of organic products....There was also no difference in protein or fat content between organic and conventional milk, though evidence from a limited number of studies suggested that organic milk may contain significantly higher levels of omega-3 fatty acids." None of the studies looked at were longer than a couple of years" However, these studies are only over a few years, and look at nutrition in its present day form - reduced to separate elements rather than as a whole. This  also reflects the way ‘organics’ has now been ‘commodified’ over the last 30 years - what is quite 'natural; is now sold as a commodity. There are no studies to examine the actual possible improvements in health, the sort Balfour was looking at all those years ago. They were hard for her to measure then, and nobody seems to have tried since.   

The best link for soil health and human health  may be digging soil over. Gardening is probably the best exercise for mind and body.

CANDIDATES for Soil Indicators

Springtail Watch

The springtail Folsomia candida is also becoming a genomic model organism for soil toxicology.[66][67] There is even an ISO standard Soil Quality Inhibition of reproduction in Folsomia candida by soil pollutants. And another one F candida Avoidance Test. That is why we want to highlight them, and celebrate them as saviours of our soil. They keep our plants healthy. There is another good reason. They didn’t like dry. We extract them by making their soil dry, so they come out easily (oribatids role up in a ball and sit still). They are easy for people to extract.. just a cola bottle tin can..see DIY

Biology of Collembola National History Museum    Where Springtails fit in the soil web    Collembola.org Where found

Collembolans are everywhere around the world. They like plant litter. There are less in arable soils..Countryside Survey. As there is less and less devris..so less and less carbon on the soil. Collembolans don't 'like' herbicides (weedkillers) like 'Roundup'. Collembola are very sensitive to herbicides and thus are threatened in no-tillage agriculture, which makes a more intense use of herbicides than conventional agriculture.[65] But these tests were in the lab. Whereas my PhD thesis on the 'Effects of Herbicides on Soil Animals' was in the field. Basically I couldn't find any toxic effects - and admit to being disappointed. It was 25 years later while sitting on the ACP (Advisory Committee on Pesticides) that  I realised it didn't matter how the soil animal numbers were reduced, they just were.  It was not the 'direct' toxic effects which  bumped them off. It was the lack of any food source. It did what it says on the tin - -'weedkiller'. I never published the work, which I now regret and want to do so, especially as the toxicity of Roundup is causing a major argument.

[[Here I have to confess that while E O Wilson is probably the greatest evolutionary biologist on the planet, I have problems with him. When I was a 'radical scientist' in the mid 1970's we used to slag him off because he promoted something called 'sociobiology' a science trying to link evolutionary mechanics (eg genes) with social behaviours - like altruism. We argued that he was being 'biologically reductionist' - trying to explain everything in terms of molecules, rather than life overall. I thought he had a re-think..BUT

He is in the middle of another controversy where we are trying to get our heads round whether 'group' or 'kin' relationships are the more important in passing on these nice behaviours like Altruism (how do you measure that for scientific purposes?). I just don't think 'nice behaviours' are genetically determined. I feel like the author of 'E O Wilson Please retire or stick to ants' - referring to his research on ants eating oribatids. He still  doesnt seem able to believe that we humans affect each other enormously - and we need to understand that better, rather than looking at ants for help]]

Mesostigmatid Mites

Since then I have watched a lot and realise a better indicator is the main predator of these Springtails - those Mesostimatic mites. Just like the presence of buzzards tells us prey is around, these mites tell us there are lots of springtails that indicate healthy roots of the plants. Those mesostigmatic mites are also very easy to spot and identify. Here one mite polishing one off a Springtail...mp  Romanian study of Mesostigmatic mites as urban soil indicator