I first published this article in November 2011, but with better cameras, and a flurry of tests being undertaken this year in various community gardens, it seemed like a good time to update it.
Why? Getting to know your soil is half way to determining how well your plants will grow.
Soil texture describes how soil feels. It can influence how plants grow as it affects water and nutrient efficiency. If you can identify your soil type, whether it’s clay, sand, peaty or loam, you can work with the soil you have and grow plants that prefer the growing conditions, rather than constantly fighting against them.
How to find out what your soil texture is
A fun experiment you can carry out at home (and a great one for the children to help with too) is to place about a cup full of your soil (preferably) into a straight sided clean jar, removing any larger pebbles or stones first.
Add a tablespoon of laundry detergent and a tablespoon of salt to the soil then fill the jar with water to the top before screwing on a lid tightly.
Shake the jar for five minutes or so (you may need help!) then leave the jar undisturbed where you can see it. After a couple of days the soil particles will settle into layers.
Reading the Results
As the sand particles are the heaviest they will sink to the bottom first, followed by silt then clay. The thickness of each layer will help to determine how much of each is contained in your soil.
As you can see from the results of this soil sample taken from a community garden and marked on the jar, a layer of sand has settled at the bottom, then a layer of silt, followed by a small layer of clay at the top. We have estimated that this sample is 65% sand, 30% silt and 10% clay. If you follow the lines in the soil texture chart below to cross reference, you can see that the soil sample is considered sandy loam.
Source: USDA Soil Texture Triangle
You can often identify your soil type by looking at it and feeling it, without the need for an experiment (this was just for a bit of fun). Sandy soil is lighter in colour than clay for instance and peat much darker again.
How to determine soil without the experiment
Grab a handful of dry soil and add a few drops of water, mixing well until it become pliable. Try rolling the soil into a ball.
If it feels gritty, if it crumbles when you try to roll it into a ball then your soil is sandy.
Course sand feels like granulated sugar when rubbed between fingers. Medium sand feels like table salt when rubbed. Fine sand is harder to detect unless you hold your fingers near your ears as you rub it.
Sandy soils are easy to dig but water and nutrients flow through them easily, meaning they dry out quickly and will have to be replenished regularly. Sandy soils warm quickly and retain their heat (just think of a warm beach) which some plants especially like, particularly carrots and their roots will swell.
If, when you try to roll the soil into a ball in your hand it holds together well, or if it feels much finer than sand, then your soil texture will be silt or clay. If it feels like plasticine then its fine clay whereas silt particles will leave it feeling like icing sugar. If you can roll the soil into a sausage and it forms a ring, its clay. If it forms a sausage but breaks up as you try to make a ring and feels silky, its silty loam.
Clay soils are described as heavy and can be very sticky to dig. If you try digging when clay soil is wet you can damage the structure of it. Clay soils are slow to warm up but retain water better in the hotter months and therefore keep their valuable nutrients for longer. Because their particles are so tiny they tend to pack together tightly which creates poor drainage and aeration and can contribute towards roots rotting.
Silty soils feel silky or soapy when moist. Clay soils feel sticky when moist.
How to improve your soil texture
You can improve your soil texture and structure by adding well-rotted organic matter. It will help to bind the particles in sandy soils and separate them in clay soils, providing space for air, water, nutrients and organisms to travel.
If you’d like to delve deeper into soils, Teagasc, the Agricultural and Food Development Authority in Ireland have produced a comprehensive soil map that you can find here.
3 Essentials to Help You Get Started in the Vegetable Garden
Have you been planning to grow your own vegetables but haven’t started yet? Perhaps you’ve begun growing your own but aren’t sure if you’re doing the right thing? With all the good intentions in the world, sometimes it’s difficult to take the first steps or spend the time to learn more. Perhaps you’ve just been too busy to start a new project, or you simply don’t know where to begin. If that sounds familiar, here are the three most useful things I learnt when we began working in the vegetable garden that may help you to grow your own successfully.
1. Start Small
Our original vegetable garden eventually became too high maintenance
Even if you’d like to grow lots of veggies, don’t attempt to be fully self-sufficient in the first year. Plan big but start small, only clearing enough space or building enough beds to get you started.
If you clear too much land at once you may find it daunting to keep up as the weeds begin to grow. One of the busiest times of the year isn’t springtime as you might expect with all the sowing and planting, but later during the summer and autumn as you start to harvest and then have to find time to pick, preserve, pickle or freeze your produce. Starting small will allow you to see how much time you have to grow your own food and whether it’s something you’d like to do more.
We began with two beds, increasing ever year until we had 17, but that eventually got too much for us and we’ve had to resort to a smaller growing space again with raised beds for easy maintenance. Don’t be afraid to admit defeat if you’ve overstretched yourself. Learn from it.
2. It’s all about the soil
What we add to the soil now will repay us in produce later. As you can see in the short video clip above, fertile soil is vital to our existence. Did you know it takes 2,000 years to create just 10 cm of topsoil? We ignore it at our peril. Adding well-rotted organic matter to the soil in the form of garden compost or old farmyard manure will help to feed it with vital nutrients as well as help with soil texture and drainage.
Autumn/Fall is a good time to prepare for the following year as it will allow the microbes, organisms and worms to do their job over winter, incorporating all the goodness you’ve added, back into the soil.
Don’t worry too much if you miss the opportunity to get some winter preparation done, it’s not too late to do it in the springtime. Just leave three or four weeks between preparing the soil and sowing time, which will allow weed seedlings to grow and you to remove them, a technique that’s known as a ‘stale seed bed’. Remember, don’t work the soil when it’s too wet or frozen or you can do more damage than good.
A general guide for adding organic matter is to add about one, big bucketful of well-rotted organic matter per square metre to the top of the soil. If you’re doing this in the autumn, cover with cardboard, weed membrane or black plastic and leave it be until the springtime. Once you’ve removed the cover, if you’re not following the ‘No Dig’ method of gardening, lightly fork any remaining organic matter in, before raking the surface of the soil flat.
One essential soil tip before we move onto the third point, and especially vital to remember if you’re visiting a garden or you could attract a fierce look of displeasure from the gardener: avoid walking on garden soil at all costs as over time it will damage the soil structure and compact. Soil and plants need air for healthy growth. If you have to walk on your soil, place a wooden board down first which will help to distribute your weight more evenly. You can find more soil tips here.
3. Vegetables live in families
Garlic – a member of the Allium family
It’s generally easier for gardeners if we don’t split up and scatter our vegetables all around the beds. Where possible, plant them in their families. You may have heard of Alliums (onions, garlic, leeks) and Brassica (cabbage, kale, broccoli) but there are several other families too. Here’s a PDF of the most popular that you can print off and keep handy. If you plant vegetables in their families, they will be easier to feed, care for and protect from pests and disease. Planting vegetables in families will also help you to plan and remember where they have grown before as you move them around from year to year in what’s known as crop rotation.
When I started growing food in the earth as opposed to container gardening, one of my first conundrums was how to treat the soil. I remember gazing around, thinking that if I’m taking plants out, surely I must have to put something back in. But I didn’t know how much or what. Everything I read pointed to adding fertilisers, (chicken pellets, blood, fish and bone etc.,) but they fed the plants: add this for extra nitrogen for your cabbages or that for potassium for your tomatoes. What about the soil? I knew that worms were great, but what should I be adding to keep them happy? Alongside that, magazines were talking about organic matter, manure, soil conditioners and compost as if I knew what they were talking about. I didn’t.
Hoping to learn more about soil was a primary reason that I enrolled as a mature student to study horticulture. As it transpired, soil science was the module I had to work the hardest to get to grips with given its ions, cations and anions. Chemistry was a subject I’d barely looked at 30 plus years ago, never mind one I’d be tested on in middle age. I almost quit on the first day.
If, like me, you’ve ever wondered what the common terms are in relation to organic matter (OM), you might find the following guide helpful. In no particular order and with links and tips to some interesting videos and slideshows I’ll be looking at:
Soil conditioners or improvers
Well rotted manure
Green manure and cover crops
Top soil, sub soil and soil horizons
and a brief foray into soil structure and texture.
I hope this helps to dispel some of the confusion. Adding well-rotted organic matter to soil is a more holistic and sustainable approach to gardening and one of the underlying principles of ‘organic’ growing methods.
One of the simplest definitions for OM is that it’s something that was once alive. Organic matter is derived from a living thing. Whether that’s us, farmyard manure, twigs or leaves, over time the materials will rot down to become organic matter. When gardeners talk about adding organic matter, they can mean anything from garden compost, animal manures and leaf mould, to the remains of plants that have been planted as cover crops (green manures), as well as some soil conditioners.
OM adds nutrients to the soil that will feed the plants, and organic materials that will feed the soil microorganisms. It’s great for soil structure. No matter what soil you have, clay, loam, peat or sand, organic matter helps to break it up, increase drainage or improve porosity, allows oxygen to move around and plant roots to find water and nutrients. Organic matter also prevents the erosion of top soil, protecting it from the elements.
Soil Conditioners or Improvers
Soil conditioners or improvers can be made from organic material that is added to the soil to improve plant growth and soil health such as organic matter above, or fertilisers. Examples include compost, manure, coir, green manures and peat. Soil conditioners can also include inorganic minerals such as clay, sand, lime or silt and some can adjust the soil pH.
Just like ourselves who need proteins, carbs and vitamins to keep our bodies functioning healthily, several nutrients are necessary for plants to grow and fight off pests and diseases. The major elements they need in various quantities depending upon the plant include Nitrogen (N), Phosphorous (P), Potash(K), Sulphur (S), Calcium (Ca) and Magnesium (Mg) and the trace or minor elements essential for plant growth but in much smaller quantities include Baron (B), Manganese (Mn), Molybdenum (Mo), Copper (Cu), Zinc (Zn), Iron (Fe), Chlorine (Cl) and Nickel (Ni).
Compost is a synthetic manure that can be made from various amounts of decomposing organic matter, fertilisers and soil. Usually sold in bags, some composts contain top soil, most contain peat, despite the knowledge that the later is not a sustainable source of organic matter. Peat bogs take hundreds of years to create and are fantastic carbon sinks. Its extraction releases carbon dioxide into the atmosphere, a major greenhouse gas.
If you’re planning to garden under strict organic guidelines, avoid using store bought compost unless it carries a symbol to say that it’s organically certified. Some manufacturers are misguiding shoppers by printing ‘organic compost’ on their bags. It may have been derived from an organic base, but unless certified, compost is not ‘organic’ as we think of it and you’re wasting money buying organic seeds to plant into it. Research your source carefully.
Composting your own waste materials is a great way of creating organic matter that will add nutrients to your soil and help with soil structure. If you’re planning to start composting this year, or you’d like some tips on how to do it better, head over to Stop Food Waste for more information. The image in the top photo is of our own home made garden compost made from uncooked kitchen scraps, coffee grounds, grass clippings, animal bedding, twigs and garden waste. It took over a year to make but felt great to be making our own and the soil benefits immensely from its addition.
Is what it says on the tin. Manure primarily derived from herbivores: cattle, horse and poultry that’s been left to rot until it no longer smells or resembles it’s original form. Do not use manure from meat eaters (dogs etc) as it can contain harmful bacteria. It takes three months to a year or more for manure to rot down sufficiently for garden use depending upon the type and heat of the pile. If the manure is too fresh when you add it, it can harm the roots and microorganisms within the soil. Be careful where you source the manure from too. The chemical aminopyralid hit the headlines in recent years when it was found that residues could pass through animals in sufficient quantities to cause damage to many crops.
Leaf mould is made by collecting leaves in the autumn, placing them in a container separate from the normal garden compost (they take longer to rot down), and patiently waiting. Different leaves can provide more nutrition or less and some take longer than others to deteriorate (anything from one to three years), but leaves are a great soil conditioner and you can make your own potting compost with them as a base. The RHS have a handy guide to leaf mould here.
Phacelia in flower
Green Manure and Cover Crops
Cover crops or green manures are plants that have been grown specifically to protect the soil by covering it (nature tends not to leave soil bare) between crops. Usually before they flower, green manures are cut and dug in to the soil which helps with soil structure and provides food for bacteria, worms and microorganisms. They can also be cut and left on the top of the soil to act as a mulch. Cover crops are a great way of adding organic matter to soil if you don’t have ready access to compost or manures. A PDF containing some of the more popular green manures can be found here. Green manures include plants like Alfalfa, Phacelia, field beans and Hungarian grazing rye. Seeds can be brought online or from garden centres.
Humus is more than the organic matter that’s added to soil, humus includes decaying insects, animals, microbial bodies and fungus. It’s a dark organic material that builds up over time. Think of the soil beneath leaf litter in a forest to envisage humus. It’s rich, dark and earthy. It can occur naturally or is the result of a well managed compost pile.
Top Soil, Sub Soil or Soil Horizons
Soil is divided into layers known as horizons. These include: O – organic matter, A – topsoil, mostly minerals with organic matter incorporated, E – eluviated, missing in some soils, B – subsoil, where the minerals that have leached down from the higher horizons settle, C – parent material from which the soil developed, R – bedrock such as granite, limestone or sandstone that forms the parent material for some soils. If you stick a spade into the soil and dig down, you can see the different colours and textures of the horizons.
The importance of soil
It takes around 100 years to creat 2.5cm of topsoil and the majority of the world’s food is grown in this horizon. In 2015, the Food and Agriculture Organisation of the United Nations published a technical summary of the World’s Soil Resources. They summarised that ” the overwhelming conclusion from the regional assessments is that the majority of the world’s soil resources are in only fair, poor or very poor condition.The most significant threats to soil function at the global scale are soil erosion, loss of SOC [soil organic carbon] and nutrient imbalance. The current outlook is for this situation to worsen unless concerted actions are taken by individuals, the private sector, governments and international organizations”. Using sustainable soil management techniques which includes adding organic matter to soil will help to reverse this trend.
This is a layer of organic or inorganic material that sits on the top of the soil. Made from straw, compost, wood chips, dried leaves or pine needles, mulch can also be an aggregate such as pebbles, slate or stones. Mulching adjusts the temperate of soil, insulating the ground against cold or heat, helps with moisture retention, and the spread of plant disease can be reduced by its application. More information about garden mulches can be found in this archive guest post from Jerry Day.
Soil structure refers to the architecture of the soil, or the arrangement of all the particles (clay, sand, silt etc) within it. In heavily compacted soil there will be little drainage or oxygen available to plants and soil biodiversity. A more detailed explanation of the A, B, C’s of soil structure can be found in this Teagasc guide.
Soil texture is the type of soil you have, sand, clay, peat etc. Knowing your soil texture can help you to determine what plants to grow. An example is carrots that prefer a looser, sandier soil if they’re to develop the long roots of say, an Autumn King variety. If you’re gardening in a clay soil, choose shorter or round varieties of carrot seed such as the Chantenay. Work with your soil where possible rather than fighting against it. I’ve shared a simple experiment to learn your soil texture in an archive post here.
How much Organic Matter Should I Add?
Now we’ve established what the definititons are, how much organic matter should you add? Unfortunatrely that’s a million dollar question as it depends on what gardening method you’re following and what soil you have. As a rule of thumb I use two parts top soil to one part organic matter when creating raised beds. No Dig guru Charles Dowding recommends a layer of around 15cm or 6″ of well rotted organic matter mulched on top of the soil to create a new No Dig bed. An early organic, Gardeners World presenter Geoff Hamilton used to recommend a bucket full per square yard. I aim to add around 10kg per square metre in our clay soil.
For a closer look below the soil surface, here’s a lovely short video ‘The Living Soil Beneath Our Feet’ from the California Academy of Sciences. We need to stop treating soil like dirt and look after it. Our lives may depend upon it.
If you really dig your soil or would like more information on regenerative agriculture, some great resources that include videos, podcast and peer reviewed papers can be found:
Don’t Ignore the Warnings, Start Monitoring Soil in Your Changing Climate
It’s difficult to ignore the impacts of a changing climate yet easy to ignore the warnings. The words ‘climate change‘ do not grab people’s attention in a way they should. We’ve jumped from extraordinary winter snow events, to a forgettable spring, then straight into a summer of drought with land that is yet to recover adequate soil moisture levels in the south of Ireland. Talking to friends and colleagues across the globe, these unusual weather patterns are being replicated and scientists are telling us that we are to expect more of the same.
Unusual snow event in Co. Carlow 2018
Where does that leave food growers, land owners and gardeners? Do we invest in expensive irrigation systems or not? Do we cover our land in polytunnels or glasshouses? Should we be changing our planting practices and choosing different varieties of seeds and plants? How can we predict the sowing and harvesting dates of the crops we choose to grow? How do we adapt?
Joining eight other GROW Places in Europe, Joanne Butler from OURGanic Gardens and I, have been provided with the opportunity to help people gain a greater understanding about their soil in the Changing Climate Mission. We are doing this by distributing free GROW Observatory soil moisture sensor to people with access to land and supporting them in their endeavors.
Soil Moisture Levels at 305m above sea level in Co. Carlow
A constant talking point, the weather has offered us the opportunity to show real-time soil moisture data, light and ambient soil temperatures, collected fortnightly on our mobile phone apps, from our gardens. We’ve been able to share the news about the exciting Horizon 2020 European Citizen Science project and encourage more people to get involved, place soil moisture sensors in their own soil, and begin sensing their land.
(The GROW Observatory Introduction to Citizen Science: From Data to Action)
Thanks to this exciting European citizen science project, we can learn to understand our soil and its needs, help to provide climate change scientists with real-time data that will help to predict floods and droughts, provide policy makers with factual information based on verified data, and offer numerous entrepreneurs the opportunity to develop innovative ideas that can help growers in the future.
“Soil . . . scoop up a handful of the magic stuff. Look at it closely. What wonders it holds as it lies there in your palm. Tiny sharp grains of sand, little faggots of wood and leaf fiber, infinitely small round pieces of marble, fragments of shell, specks of black carbon, a section of vertebrae from some minute creature. And mingling with it all the dust of countless generations of plants and flowers, trees, animals and – yes – our own, age-long forgotten forebears, gardeners of long ago. Can this incredible composition be the common soil?”
– Stuart Maddox Masters, The Seasons Through
3 Ways to Be a SenseAble GROWer In a Changing Climate
In summary, here’s three ways that can help you and others make sense of your soil now in the changing climate.
No. 1: GROW Missions.
The GROW Observatory currently have two missions taking place. In the Ireland GROW Place, The Changing Climate mission is taking place in Donegal and the South-East of Ireland.
Joanne and I are encouraging people with access to land in those areas, to deploy soil sensors that will take soil moisture, light and ambient ground temperatures. We will be supporting volunteer citizen scientists with sensors to take soil samples that will help to validate Sentinal 1, a European Space Agency Satellite, giving European scientists and themselves, a better understanding of the soil beneath them.
The Living Soils mission involves data collection without the sensor. It involves experiments to test regenerate growing techniques and can be done from anywhere in the world.
No. 2: Join the Forum.
The GROW Observatory have created a forum that all gardeners and growers can join to share their experiences, connect with others, ask questions and perhaps come up with solutions. With links to an educational and informative blog, as well as offering information on other European wide citizen science projects such as the Edible Plant Database, the forum offers us all an opportunity to connect and help one another.
No. 3 Sign Up for the MOOCS – Massive Online Open Courses
The free MOOCS give everyone an opportunity to develop their knowledge and skills on soil and growing for food, while taking practical steps to preserve the soil for future generations. The GROW observatory courses, affiliated with the University of Dundee in Scotland, are for any scale of food grower – from back garden to commercial. You can sign up now to be alerted when the next course is about to begin.
Soil is home to billions of living microorganisms that help to provide the growing conditions for our food. Taking more than 500 years to make two centimeters of topsoil, it’s essential that we learn as much as we can about it and practice regenerative land practices.
Are you in? Contact me if you’re interested in placing soil moisture sensors in your soil or visit The GROW Observatory and sign up for their newsletter for more information about the various missions. Whatever you do, don’t delay. We need healthy soil to grow great food! We absolutely need to gain a better understanding of it and stop treating it like dirt.
It’s not often I reach out and ask people to sign a petition but time has almost run out for Ireland to register 8,250 signatures for the European People 4 Soil campaign and we’ve still a way to go to reach that target.
The campaign that launched a year ago is calling for the European Union to create a soil directive, similar to the air and water directives. If successful the Irish government would have to assess the condition of the soil beneath our fields and feet and take action where needed. Soil, the foundation of our existence, is currently unprotected.
If 1 million signatures are received from at least 7 member European states by mid September, the European Commission will have to react within three months. Can we do it? With your help yes, but please click the button below and share the petition with your friends, families and colleagues today.
What is soil?
Soil has been described as the skin of the earth and it’s incredible to consider that without this shallow layer, life on this earth as we know it would not exist. Formed slowly from thousands of years of physical and biological processes, soil provides a habitat for billions of living things. Soil holds and purifies water, it processes and stores carbon and it acts as a medium for plant growth.
Every teaspoon of soil is full of living organisms. Just 1 gram can hold up to a billion bacteria, nematodes, protozoa and fungal filaments. It’s not simply dirt, soil is alive! When we understand that we begin to understand why artificial fertilisers, pesticides and herbicides are so damaging to it, why it’s so important that we protect soil from erosion, and why we continue to study and educate people about it.
This clip from David R Mongomery explains how important the symbiosis between plants and the hidden mycorrhizae living beneath us is to soil fertility, plant health and subsequently our own health.
Recently I was gifted a beautiful 1946 revised edition of “The Living Soil – evidence of the importance to human health of soil vitality’ by E.B. Balfour. Within the book the author quotes Professor N. S. Shaler of Harvard University who in 1896 wrote:
“If mankind cannot devise and enforce ways of dealing the with earth, which will preserve the source of life, we must look forward to a time – remote it may be, yet clearly discernible – when our kind, having wasted its great inheritance, will fade from the earth because of the ruin it has accomplished.”
Yet here we are, over 120 years later, still not protecting the very substance we came from and one day will return to. Soil is the mother of all things. Please honour and protect her.
I felt honoured to be asked to model for an interesting project recently that celebrates the soil. I joyfully accepted this photographic opportunity as for once the camera wasn’t aimed at my face, far from it in fact for the photographer wasn’t looking to capture images and expressions of people, he was looking for the story of our hands.
Just for a moment close your eyes and picture Planet Earth as if you were looking down from space. The globe is covered with oceans and mountains, forests, rivers and deserts. In among that whorl of colour are pockets of land that are farmed. Those patchwork fields that cover the Earth’s crust are covered with just a few feet of fertile soil and to some degree or another, they feed the entire population of our planet.
How precious a resource that we barely give a second thought to.
Next time you glance down at the place where the plants grow, spare a thought for the earth. It’s so much more than the muddy, brown stuff that sticks to our boots. It’s the core of our very being.
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