Soil Health

Intro to Jennifer Dungait: Soil Health Expert

Intro to Jennifer Dungait: Soil Health Expert 451 193 Soilmentor

We are honoured to have Professor Jenni Dungait as a soils advisor and ambassador for Soilmentor. Jenni is a leading soil scientist, Editor in Chief for the European Journal of Soil Science and also offers brilliant insights into how soil works in the field through her consultancy Soil Health Expert. Find out more at www.soilhealthexpert.com

Our planet may be the only place in the universe where the conditions are right for soil to form. We rely on this miracle substance to grow our food, and it doesn’t usually let us down. So, most people, even some farmers, rarely think about the soil as more than ‘dirt’. But, relentless pressure over several decades to produce more and more food, with little regard for the effect of increasingly intensive agricultural production on soil, has taken its toll on this irreplaceable resource.

There is now real worry that the degradation of agricultural soils, combined with the changing climate and competition for agricultural land for other uses, will affect our ability to grow enough nutritious food in the future. Already, rarely a week goes by without reports in the media about food shortages caused by unpredictable extreme weather events and disease that are seriously affecting human well-being somewhere in the world.

Over the last couple of decades, I have devoted my life to discovering the science behind the remarkable ability of soils to keep on helping farmers to grow food, and what can be done when they don’t.

As a Professor of Soil Biogeochemistry working in world-renowned agricultural research institutes and universities, I have been lucky enough to travel across the world to talk to farmers about their soils and the problems that they are facing in the hope that scientific solutions can be developed.

There are some very common themes amongst concerns expressed by farmers that I have recognised across all continents.

  • The weather is becoming more unpredictable, with droughts and flooding becoming more common.
  • Yields are stagnant or declining despite using the latest crops, technology and agrochemicals which are all becoming more expensive.
  • Breaking soil compaction is a major expense in time and money.
  • Top soil losses in run off are causing local pollution problems.
  • Weeds and disease are increasingly difficult to deal with.
  • Falling farm incomes are forcing farmers to sell land for non-food production and construction.
  • Farmers are expected to act as environmental stewards as well as producing food which seem to be opposing demands.

The innovative farmers who are successfully adapting to change and meeting these problems head on are those working in partnership with the life in our soils. These farmers say that getting the organisms in the soil to work with you is a win:win strategy that has reduced their workload and their expenditure on pesticides, fertilisers, irrigation, fuel and livestock medicines, whilst ensuring sustained yields and enabling them to meet their commitments to protect the environment. They recognise that Soil Health is the beating heart at the centre of their farming life.

Optimising Soil Health by managing the physics, chemistry and biology of agricultural soils is now recognised as a major part of the strategy for farmers to improve and sustain their businesses during the current period of intense change and to futureproof their livelihoods against the challenges to come.

What are the signs that soil is healthy? In recent years, I have been working with farmers’ groups in the UK and USA to find out which are the best and most reliable tests for Soil Health that can be easily used by farmers, but are also supported by the latest scientific evidence.

I am very pleased to be working as an independent Soil Health Expert with Vidacycle to develop the Soilmentor app using my knowledge. Watch out for a series of blogs from me on the Vidacycle website in the coming months, starting with ‘Soil Health – what’s it all about?’ as an introduction to the scientific basis for the individual soil health tests chosen for the Soilmentor app. If you have any questions you can email me at jenni@soilhealthexpert.com.

Soil Health Principles

Soil Health Principles 2000 1333 Soilmentor

The Soil Health Principles, thanks to soils advisor Niels Corfield:

  1. Living Root – for as Long/as Often as Possible

  2. Covered Soil – with Residues or Living Plants

  3. Minimise Disturbance/Compaction – Tillage

  4. Diversity – in Rotations/Plantings

  5. Feed Soils – w/Organic Matter (Between Cropping)

  6. Incorporate Animals – Ideally Adaptive Grazed

  7. Minimise Use of Chemicals/Synthetics

Soil testing: How to measure infiltration rate effectively

Soil testing: How to measure infiltration rate effectively 700 445 Soilmentor

When the rains come, have your tubes at the ready, because a day or two after is the perfect time to test your infiltration rate. Measuring the infiltration rate in Winter or early Spring can be challenging because the ground is saturated with seasonal rainfall, so it can take quite a long time! The main thing to consider when doing this measurement is you want to take the reading at about the same time/and in approx the same conditions each year to be able to compare year on year and see how it’s changing. Soilmentor makes it really easy to record your infiltration rate results alongside the date they were taken, and visually monitor your progress over time with personalised trend charts. 

Awareness of how well water infiltrates down into your soil is at the core of knowing your soil health and structure. A good infiltration rate indicates that the top soil has a ‘crumb structure’ and it is well aggregated. Essentially this means that each clump of soil is stuck together with glues and slimes from soil organisms and they are not broken down by water. Therefore the clumps (or aggregates) retain their structure when the water flows around them, also allowing water to quickly flow down into the soil depths. At the same time the clumps provide lots of nooks and crannies for droplets of the water to be stored in. So the water percolates easily, and some of it is stored along the way. This is what we want!

The infiltration rate is the speed at which water enters the soil, and is measured by monitoring the time it takes for a set amount of water to ‘infiltrate’ into the ground. Read the details in our infiltration rate guide here. Understanding how land works with water is highly beneficial for a farmer or any type of grower. It gives an idea of how much rainfall is soaking deep into the ground and how much could be running off and taking the soil with it. Soil washing off the land is like throwing money out of the window, our prime resource going down the drain. The image below of the UK clearly shows the seas brown with soil runoff after a heavy period of rain. Leaking away resources like this does not contribute to a profitable farming plan or an ecological farming system.

The extent of soil erosion in the UK is visible from space. Credit: NEODAAS/University of Dundee

To get a good sample of infiltration rate, you need to measure it at the same time each year, for each field. Do at least two tests per field, maybe one in the ‘best part’ and one in the ‘worst part’. Compare rates between your different fields. Why is the infiltration rate much quicker in one field than the next? Do you manage things differently in one field than the other? Where your infiltration rate is slower, could you look to the Soil Health Principles (cover soil, minimise disturbance, diversity in rotation or plantings, minimal chemical usage, living root in the ground as often as possible) to guide you in a new direction for your management strategy?

The equipment for this test is key to getting a reliable result, finding the right tube is essential! If it’s too narrow it will compact the soil inside it as you drive it into the ground and heavily impact your result (unfortunately we have found that baked bean tins don’t work). When the soil is compacted the infiltration rate will be a lot slower, as it’s harder for water to enter the ground. This will not give you a true reading for your infiltration rate. To avoid this happening we recommend finding some 150 mm diameter (6 inch) tubing or pipe; a flue pipe can work quite well. Cut it to about 15cm depth and make one of the circular edges sharp, so it’s easily pushed into the ground. Read more here for the full instructions.

There are impressive stats to show that even when we think the ground is saturated, there could be even more capacity for the ground to hold water. Healthy soil can hold up to twenty times its own weight in water and increasing soil organic matter by 1% increases the soil’s water holding capacity by 3.7%. So it’s worthwhile putting some elbow grease into improving your soil crumb structure and soil organic matter, because in times of heavy rain you’ll reduce flooding and soil erosion and in times of drought there will be more water available to your thirsty crops. Keeping an eye on your infiltration rate helps to understand how well you’re doing at this. Good luck!

Head over to our soil testing page for more info on how to measure your infiltration rate. And if you want to easily record your infiltration rates and other soil tests as you go then our app is your perfect helping hand you can buy Soilmentor here or get in touch with us for more information!

Building soil health: 5 Key Soil Tests to get you started

Building soil health: 5 Key Soil Tests to get you started 2000 1500 Soilmentor

The first thing to decide is where to do your soil tests. You might pick a few sample sites in 4 key fields and test them every 6 months. Most of these tests require a decent spade so you can dig 10-20cm depth into the soil profile in order to analyse it.

Soilmentor is made for farmers, to allow an understanding of the ‘pulse’ of the soils on their farm, so this is not a precise science – it’s about what works on your farm in order to monitor your soil health, better meet your management goals and ultimately have a thriving farm. So the key to all these tests is to be as consistent as possible with what works for you. We try to keep this as simple as possible to do, so for example, use a spades width and depth to ensure you dig up the same amount of soil each time you do your earthworm count, and use the same spade! Repeat the tests in the same field, at the same time of year (the app tracks this for you). Working with this simple principle you will build up an amazing picture of how your soil is changing, and hopefully improving!

We have more advice to help you make these decisions here.

1.The VESS test

This is where you get to dig in and really get a feel for your soil. We take a photo as soon as the soil is dug up to see its profile and initial structure (and so we can share it with others later to get their thoughts). Then we look to see if there is an obvious divide between a top soil and the subsoil below. On most farms we have visited the top layer of soil is as thin as 1-10 cm. This is where the aggregation* is happening and there are lots of roots so this is the layer we want to work on building up. Then the next 18cm is relatively uniform in colour and structure. We think it’s helpful to score topsoil and subsoil separately and record the depth of each – one indicator of better soil health is when the topsoil depth begins to increase, as roots reach further and further down and aggregation begins to happen deeper and deeper.

*aggregation: Soil aggregates are clumps of soil particles that are held together by moist clay, organic matter (like roots), gums (from bacteria and fungi) and by fungal hyphae. The aggregates are relatively stable and vary in size. This means that there are spaces of many different sizes in the soil and these spaces are essential for storing air, water, microbes, nutrients and organic matter.

Find full details about doing this test here.

2.Count your earthworms

Earthworms can be considered as the top of the soil food chain. They are engineers of their ecosystem, and provide some really amazing benefits to soil (learn more in our earthworm blog series here!). For this test, take the soil sample you’ve dug up and count how many earthworms are present. It’s important to note that this test is quite seasonal: on the farms we visited in the UK in November there were loads of earthworms but when we went out on the farm in Chile last week in the middle of Summer, we saw just one earthworm very deep, across 9 sample sites on 3 fields. When it is very dry earthworms tend to hide away! They also move around depending on heavy rains and other factors, so if you are going to do this test, then it’s best to do it across all the fields you are monitoring in one go. That way you can compare between fields.

Find full details about doing this test here.

3.The Slake test

This test is very easy to do – you just put a large pea-sized piece of soil in water and leave it. How much the ‘pea of soil’ breaks down indicates how much sticky stuff there is holding your soil together, thanks to the work of all those little microbes. Our three fields had soils that broke down completely differently. In one field where there was the most evidence of aggregation, the ‘pea’ did not break down at all over 24 hours. However, in another field, where the soil was very crumbly, red and easy to dig into but also not much evidence of structure, most of the samples broke down completely within 2 hours and all within 24 hours. As far as I understand this shows that the microbial activity and aggregation activity is very low in this soil. It was deep-ploughed somewhat recently which may explain the lack of compaction but its lack of aggregate structure suggests it’s lacking biological activity.

Find full details about doing the test here.

4.How much ground cover and bare soil is there? What is the percentage cover of weeds (undesirables), herbs, grasses?

For many of us, a key reason healthy soils is important is because we want healthy plants above ground, and importantly healthy plants that support the bottom line. For PFLA members that often means increased forage, more grass species, less buttercups. On our farm in Chile that means healthy vines and olives, and fostering warm season grasses and perennials for fire retardant ground cover in Summer.

This measure is a great way to understand the link between healthy plants and healthy soils. The 1st soil health principle is a living root, so lots of bare soil is not a good sign. What’s on the surface of our soils can tell us a lot about what is happening below, so for this test record % cover of undesirable species, herbs, grasses and bare soil. Our farm is not pasture-based but this is still helpful as a measure – one of our main tools for managing damage from fires is to shift our ‘undesirables’ to plants that remain green all Summer long.

To do this test you need to make yourself a quadrat. Full details on doing these tests here.

5.Measure the sugar content and health of your groundcover with a Brix reading

Brix is a measure of photosynthetic activity. The building block for production and plant immunity/health. Brix measures how much photosynthesis is occuring in the plant by showing the amount of sugar and dissolved solids in the sap. Higher values indicate the plant is photosynthesizing more rapidly, therefore growing faster, with a better immune response and a higher nutrient profile. Brix is already used by many fruit producers as an indicator of when their fruit is ready to harvest. Research has shown that Brix readings show the actual sugar content in pasture, as well as other plants.

I first heard about it from Australian farming advisor Graeme Saite as he explained if you take a Brix reading in the morning and then another in the afternoon, there should be a big difference in sugar content because late afternoon the plant moves all its sugar from its leaves (solar cells) to its roots to converse with the world below. If this isn’t the case then the system connecting your plant to the soil isn’t working.

We mainly use Brix as an indicator of plant health. We compare Brix readings across fields at the same time to see which plants have more sugars. It’s then interesting to do see how the Brix value evolves over time. An increase in Brix value could be a good indicator of improvements in soil health and healthier plants. Brix is very dependent on the time of day you do it (as explained above) as well as the season, so if you want to compare across fields you need to get round and do the Brix readings all in one go and then try to do them again, on more or less the same day and time a year later. Also, Brix doesn’t work in wet conditions as the rainwater dilutes the reading.

To perform a brix test you will need a refractometer and garlic crusher. Find full details on how to do this test here.

So, those are some ideas of soil tests to get you started! Keen to learn a few more? Head over to the free soil testing guide on our website to check out the full list, record some wildlife with the biodiversity tool, and learn more about our Soilmentor app here.

Getting started monitoring on our farm – Abby Rose

Getting started monitoring on our farm – Abby Rose 800 600 Soilmentor

 

Sunday morning early my dad and I went out to observe and investigate our soils on our farm in Chile. As you may know 2017 was a very difficult year for my family’s small farm as the mega fires in Chile consumed our farm, burning all our crops — olives and vines, just the buildings survived. Come November (Spring) it became obvious that most of the 8000 olive trees and 2ha of vines were dead or growing back from the ground. In terms of having a crop, it’s a bit like starting again.

Many of the old trunks stand bare, a reminder of what was there before the fire. The trees all starting again from the ground.

It is at times an overwhelmingly dire situation. But there is no point lingering on the negatives as this is what’s happened and mega fires are bound to happen again based on global trends, so we must rethink.

Where to start? The soils. If there is one thing I have learnt over the last year, it’s that soil health is the litmus test for the direction your farm is going in. For fire prevention we see two ways forward: Either we bite the bullet and plough between all the trees and build fire breaks around the whole farm (100m wide!?) — a disaster for soil health; Or, we make our 700ml of rainfall each winter go further and retain moisture on as much of the farm as possible, for as long as possible, allowing a green ground cover all year round. Neither sounds particularly easy, but as the realities of the changing climate and human impact on our landscapes intensify — we have little choice. So we are opting for the latter, as the first sounds like a barren nightmare.

To systematically observe our soils and document where we are at now we used Soilmentor, an app I recently launched, along with the Pasture-Fed Livestock Association and soils advisor Niels Corfield. I’ve used the app on a number of other farms in the UK (read more about them here) but this felt like a seminal moment using it on our own farm in Chile for the first time. This app is just part of my commitment to ensuring smaller-scale farming businesses around the world thrive, building a more resilient future for us all. In an odd way, it felt very moving to have this tool support our farm, especially at this moment of so many unknowns! I can’t explain but when you go out and really observe the soil, something happens, you become immersed in a whole new dimension of the farm. This is why I think farmers such as IanFidelity and Tim have also been so excited using the app, doing the simple soil tests themselves — we are empowering farmers to take the ‘pulse’ of their soils.

My dad on a mission to measure our soils 🙂 The best looking olive trees still standing near our house!

Back to our farm. Doing the tests. We went to 3 fields and dug a hole as best we could at 3 sites in each field. At first it felt incredibly daunting looking at the different tests in the app. I am still learning about soil science, so many things I don’t know! How deep should we dig? How many samples should we take? How can we tell where the top layer of soil ends and the bottom one begins for the VESS (Visual Evaluation of Soil Structure) test? And in fact how can we determine aggregates* from clods* in this incredibly arid soil? Luckily many of those questions are answered here.

We gave it our best shot, followed the notes on the VESS diagram and gave the top layer of soil a slightly higher score than the bottom, determining it was just 1cm deep — that’s where almost all of the roots were and some evidence of aggregation. We had to use a hammer to cut down into the soil, so Spading Ease was definitely 1 (the worst). As we moved on to the next hole it got easier to assess VESS and by Sector 2 we felt confident scoring our soil. Here, in Sector 2, things were quite different, the top 5–6 cm were top soil and showed definite signs of aggregation but then beyond 6cm the ground was almost impenetrable. In Sector 7, we were amazed the spade went in easy after the initial top cm or so. It was completely different again, a crumb-like soil all the way down, quite red, but oddly little sign of microbial life or root activity.

For each VESS reading we took two photos of the soil, one before breaking it up and one after. Later this week I will be talking through the results and photos with soils advisor Niels Corfield in the UK to better understand what it all means and how we might move forward in terms of management. Pretty exciting that we can so easily share the state of our soils with an advisor.

Our rather clodd-y soil, almost no spaces in each clump and incredibly dry!

We brought back samples from each field and did a slake test, Sectors 1 and 7 mainly disintegrated but as expected those from the top layers of Sector 2 stayed glued together. I did question whether the slake test would work for such dry soils, maybe they wouldn’t break down because they are baked into shape…or they would disintegrate completely because they have no moisture in them to keep their shape? Always so many questions and variables. But as we looked over the tests 24 hours later it seemed pretty obvious. Only Sector 2 had any real sign of the soil being stuck together thanks to microbial and root slimes (good stuff!) — it stayed completely intact. Sector 1 disintegrated partially and Sector 7 completely disintegrated. An interesting indication that the light crumbly soil in Sector 7 probably isn’t thanks to great soil creation from plants and microbes but a combination of other factors in the short term (it was dug up most recently of the 3). But I’m not sure on this one so will be asking in the group convo what others think!

Slake tests for sectors 1, 2 and 7 after 24 hours.

The whole experience was rather brilliant, my dad and I in conversation about our soils, really looking and recording whilst we go. We now have begun to understand what we are working with and that the mechanism for living soils is not currently in action on our land. The next step is how to get that mechanism in action as soon as possible. Currently we are considering direct drilling with multi-species herbal leys, grazing lambs in Spring, or maybe chickens all year round. We also want to use compost teas to move the soil health more quickly, as a short term input. If you have any other suggestions please let us know 🙂

How will we test if things are getting better? Well if our VESS top depth begins to increase and the score goes up in the bottom layer, if we start to see rhizosheaths, if we have even one or two earthworms and if we have all 3’s on the slake test then we will know our soil health is improving — it seems like a huge challenge but we believe it’s possible. Let the work begin!

Soilmentor is now available for anyone to use to investigate and monitor their own soils — find out more here. Join a community of farmers working together to monitor our soils and improve soil health!

*A few soil words:

  • aggregation: Soil aggregates are clumps of soil particles that are held together by moist clay, organic matter (like roots), gums (from bacteria and fungi) and by fungal hyphae. The aggregates are relatively stable and vary in size. This means that there are spaces of many different sizes in the soil and these spaces are essential for storing air, water, microbes, nutrients and organic matter.
  • clods: Soil clods are clumps of soil stuck together due to compaction. They often have very few spaces in them and can be very large. A sign of not as good soil health.