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Know your soils #8: The most important thing you can do for your soil

Know your soils #8: The most important thing you can do for your soil 1600 900 Soilmentor

Welcome to the eighth instalment of our Know your Soils series sharing practical tips for monitoring the soil health on your land. Keep an eye out for our bitesize videos and fact sheets on simple tests you can do yourself on farm.

“If you can’t measure it, you can’t improve it.


Try 3 easy soil tests to understand your soil health

After almost a year of supporting farmers with soil testing, the Soilmentor team share insights on empowering farmers to monitor and build soil health for themselves.

It’s clear that we need to build more resilient soils, both for the future of our farms and for the long-term health of the land. Satellite images of muddy waters spilling out of brown rivers after heavy rainfall are hair-raising. Soil health advisors are certain this scenario is avoidable, it’s all down to how land is managed.

If this is the case then building soil health should be one of the top priorities on every farm, but how do farmers do this? It starts with soil testing and monitoring, going out into the fields and seeing for yourself how your soil is doing.

Monitoring how your land is changing with different management practices and what works to build healthy soils and crops is the core of successful farming. This is why dedicating just one day to do a few simple soil tests on your land is the most important thing you can do for your soil this year.

Spring and Autumn are the best times to do soil tests.
Here’s the 3 most important AND EASY tests you can do now using equipment already on your farm.

Do the Soil Test Challenge!

 

1. Slake Test (Wet Aggregate Stability)

The Slake test allows you to really see how well your soil structure holds up in water. It is also an indicator of biological activity. Well structured soil is composed of aggregates, so in the slake test you put a few small pieces of soil in a sieve, submerge them in water and then shake them around quite vigorously. If the small pieces survive without breaking down at all they are true aggregates. The water around them will also remain totally clear. So after heavy rainfall, your soil would retain its structure and even keep little droplets of water in the nooks and crannies of the irregularly shaped aggregates. For non-aggregates there is considerable break down of the pieces and the water can become murky. This implies that the pieces of soil are only held together because of compaction, and as soon as there is a heavy rainfall the soil structure just falls apart and then what’s left re-settles and compacts further – no air gaps anywhere.

You score the breakdown on a scale of zero to eight, eight indicates a soil full of microbes and made up almost exclusively of aggregates. You can then easily record your observations and results using the Soilmentor app – including notes and photos all automatically assigned to the field you are in. Here is a step-by-step guide of how to the test and the simple equipment you need.

We are working with Soil Health Expert Jenni Dungait and have adopted the method she used in her research with farmers on multiple farms in Cornwall and Cotswolds regions. An additional benefit of this test was highlighted by Jenni’s research (soon to be published) which shows that the slake test is an excellent proxy for Soil Organic Carbon.

 

2. Earthworm count

All growers inherently understand the value of earthworms as we see them physically move nutrients around the soil profile. Earthworms are one of the larger organisms in the soil food web, so lots of earthworms is a good indicator of plenty of life in your soil. In the UK, an average of 15-20 worms in a 20x20cm soil pit is considered good. Taking a spade, digging a pit and counting earthworms is a very easy and valuable test and if you are using the app, it will automatically record which field the count was in and give you an average for each field at the end of the day. It’s also easy to look back and compare when you do the count again next year. Here is a step-by-step guide of how to do the test and the basic equipment you need.

There is a more detailed earthworm count you can do based on the work of soil scientist Jackie Stroud at Rothamsted. There are three main types of earthworm: the litter-feeders which break down organic matter on the surface of the soil; the top-soil worms who work on soil aggregation and nutrient mobilisation; and then the deep-burrowers that keep water flowing from the soil surface to deep pools below, as well as increasing aeration and root development. Jackie’s research shows that if you identify numbers of each type of worm, it can tell you what the worms are working on and uncover any changes you might need to make in your soil management to encourage all types – ideally you want to have all three types of worm working in harmony. Take Jackie’s Worm ID Quiz, which is a brilliant way to learn how to identify types of worm for yourself. If you are in the UK, you can also choose to be part of her #30minworms nationwide worm survey, building up a picture of the worm situation in fields all over the country. You can find out more about it here, or we can also send her your results from the app, at your request.

 

3. Infiltration rate

The Infiltration rate test clearly shows how ready your soil is to soak up water when it comes, and indicates the ability of your soil to hold water when it’s dry for long periods. Imagine if every farmer and grower around the land had a clear idea of the average infiltration rate in each of their fields. We would definitely be better equipped to prevent those muddy rivers and top-soil losses. To do this test we use a 150mm diameter pipe and hammer the pipe 75mm into the ground (We have pre-marked this on the side). Then we pour in 444ml of water and time how long it takes the water to infiltrate. If you use the app, it will automatically tell you the average infiltration rate for each field, each year, so you can easily compare between your fields as well as from year to year. Here is a step-by-step guide and list of the basic equipment you need to do this test.

Originally we used a much smaller diameter baked bean tin to do the infiltration tests but we were finding it took over 20 minutes for the water to infiltrate which made it impractical to do in the field. One thought was forcing such a small diameter cylinder into the ground was causing artificial compaction in itself, which is why we have moved to a larger diameter cylinder. We have found this size to be much more reasonable in terms of the amount of time it takes, our aim is that this method that takes a maximum of five minutes in most soils.

 

4. Bonus! Photo Diary

We are going to sneak in a 4th here because it’s not really a ‘test’. Farmers have told us that a photo diary of each field above and below ground is very helpful alongside the soil tests. You can see from the example on Fidelity’s farm below what this can look like in the Soilmentor app. And thankfully the app automatically adds a date and time to each photo and assigns it to the field you are in, plus you can add notes, so it’s all organised for you automatically when you get back home. No more scrolling through photos endlessly trying to find the right one or what exactly it was your were photographing!

The Soilmentor app makes it easy to record these observations in the field as you go, and then turn those observations into graphs and insights. Just a few taps and you have everything recorded, alongside photos showing what you saw both above and below ground. Essentially you can build up a visual diary for each field combined with numerical results from the tests. All those results are easily searchable (no more shuffling through piles of papers to try and find those scribbled notes) and quickly show how your soil health is changing over time. What do you reckon? Are you on board? What’s stopping you? If you have any questions at all just email us! We are here to help.

We believe that if we all take this on the UK can be world-leaders in healthy soils and clean waterways!

 


See our free online soils guide for soil tests you can do at home and find out how our app Soilmentor helps you record & learn how your soil is changing.

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.