Everyone is talking about no dig gardening right now. There is plenty of information on how to do it. Here, we will look at why no dig gardening works and the important reasons you should use this method in your garden.
No dig gardening is the practice of laying organic matter on the surface of the soil and allowing the organisms that live within the soil to do the digging.
This style of gardening and growing has been used for many hundreds, if not thousands, of years across the world. It has many different names and suggested methodologies. How you practice it depends greatly on the environment within which you garden. In this article, we will focus on why no dig gardening works from a scientific point of view, digging (pardon the expression) into the fascinating world of soil.
Why does no dig gardening work?
No dig gardening is backed by science in a way that conventional digging is not. In the last few decades, we have begun to understand more and more about soil and how it interacts with our plants. No dig gardening treats the soil like a living ecosystem that exists in perfect symbiosis with our plants. Which, of course, it is.
The soil life is essential for the health of our plants. It helps to protect plants from pests and pathogens and helps create good soil structure. Soil microbes help plants take up nutrients in the soil that are essential for plant growth. Bacteria help to release nutrients from the sediments in the soil, and fungi help to transport them and deliver them to our plants. These nutrients contribute to our food, making it more nutrient-dense, healthier for us and tastier!
No dig gardening works by replicating natural cycles. Leaves fall to the ground in autumn and feed the soil life dead organic matter. In no dig gardening, we seek to emulate this by laying compost on the ground once a year. This compost feeds the life in the soil, which in turn helps to feed our plants. Plants will also send root exudates down into the soil to feed the soil life. These are little packages of carbohydrates that plants produce during photosynthesis.
The combination of root exudates and dead organic matter feeds the life in the soil, creating healthier soil over time. There is no need to rest the soil. In fact, we encourage constant cropping to stop weeds from getting a foothold and keep exudates pumping into the soil.
NATURAL SOIL CARE
Before we look closer at the natural processes that allow soil health to build up and soil structure to improve without using a spade, I’d like you to take an imaginary walk in the woods with me. Imagine yourself pulling on your wellies and going for a walk in the woods. In spring, you will see lime green buds on the trees, bluebells crammed in impossibly close and ferns starting to uncurl their newest fronds. There is life everywhere. Birds are chirping, and the plants are thriving.
You must stick to the paths in summer because the vegetation is so dense. The forest feels cool on a hot summer’s day, and the soil feels soft and springy under your feet. By the time autumn comes, the greens of summer have turned to browns, yellows and oranges, and the ground beneath your feet is thick with fallen leaves.
The forest is incredibly productive because the soil doesn’t get too wet ot dry for the plants. The soil feels rich and healthy. But nobody comes into a forest once a year to dig it over. So how is this possible?
LET NATURE DO THE DIGGING
As with most problems, nature has a solution. An army of tiny microorganisms in the soil help to draw organic matter deep into the soil. Their constant movements through the soil churn up the particles and open spaces called pores. They secrete sticky substances which aggregate the soil and give it a good structure. Soil structure built in this way resembles a sponge and is important for our plants in many ways.
Earthworms are incredibly efficient at pulling organic matter into the soil. They are programmed to come to the surface to find dead leaves and other dead organic matter. When they go back down into the soil, they excrete this organic matter, putting it right where the roots of the plants are. Other organisms in the soil do the same. Others feed off larger organisms’ excrement or dead bodies (sorry – nature is gross!). This process breaks down the organic matter and incorporates it into the soil. This is why you don’t get a deep accumulation of dead leaves over time in forests.
Tiny bacteria can also help to break down sediments in the soil. This releases nutrients to our plants that roots alone cannot access. These bacteria and myriad other microscopic organisms in the soil are specially adapted for subterranean life.
WHAT HAPPENS WHEN WE DIG?
When we dig our soils, we expose the tiny creatures living in them to conditions they are not well suited for. The natural glues that hold soil aggregates together and give soil its structure are often broken down by sunlight. So, when we dig, we are creating something that feels like a good soil structure to us but is actually less stable and more susceptible to compaction. This is why if we are digging, it needs to be done annually to keep the soil well aerated.
Turning over the soil breaks down the habitat the organisms work tirelessly to maintain. Soil with good, naturally created structure holds water well, is well aerated and easy to move through (if you’re microscopic or an earthworm, that is!). We can think of this structure in the same way as we think of other ecosystems. It’s the trees in a forest or coral in coral reefs.
Shaking up the habitat by digging can actually cause a lot of the organisms within it to die. It breaks up fungal hyphae that are essential to our plants to transport nutrients. Water and chemical signals protect our plants from soil-born pests. It takes time to rebuild this ecosystem, though it will repair over time.
HOW DO YOU PLANT IN NO DIG GARDENING?
This is a common question. To plant in a no dig bed, you dig a hole and plant into it. In just the same way you would normally. The problems with digging (breaking fungal hyphae, breaking down aggregates, killing microorganisms) will still happen, but on a much smaller scale.
If you were to remove a single tree from the forest, creating a hole in the canopy, a smaller tree would soon grow up in its place. Or branches from the neighbouring trees would fill the hole. But, if you were to cut down the whole forest, it would take a lot longer to regenerate, and much more would be lost than just the trees. the same is true for the difference between digging a hole and digging over an entire bed, garden or allotment or ploughing a field.
WHY DOES NO DIG GARDENING WORK?
No dig gardening observes life in the soil as a precious resource. It recognises that the plants need the organisms in the soil to create a healthy growing medium and release nutrients.
In no dig gardening, we lay compost on the surface of the soil. This creates a protective layer over the soil, locking in moisture and protecting it from the elements. As the organisms in the soil come to the surface to feed on organic matter, they pull the compost down into the soil. This creates a good soil structure and delivers nutrients to the plant roots.
Additionally, fungi, bacteria, protozoa and nematodes that live in the soil can protect our plants from pests and diseases; They can form protective layers around the roots – as with fungi – or fight off organisms that might harm your plants. For every pest in the soil, hundreds of “good guys” are willing to defend our plants, as they are their main food source. Also, good aeration prevents soil-borne pathogens from thriving, as they do in anaerobic conditions.
WHAT ARE THE BENEFITS OF NO DIG GARDENING?
There are a number of benefits of no dig gardening. The first is that no dig builds soil health over time. The soil structure becomes more resilient, more able to hold water, better aerated and more teaming with life. We can walk on no dig beds without worrying about compacting the soil, and they are less prone to waterlogging or drying out and cracking.
No dig gardening is also easier on us gardeners. In fact, if you have been digging for your whole life, it can seem disarmingly simple to just lay the compost on the surface instead of digging it in. It takes so little time to set up a bed, and you can complete an entire allotment in a single day. And best of all, you can plant into it straight away.
Whilst there is no miracle cure when it comes to reducing pests, no dig gardening certainly does a good job. It works because soil-bourne pests or pests that overwinter in soil, such as slugs and snails, are predated by other organisms in the soil. Tiny nematodes can do a great job of controlling slug populations in healthy soil. Beetles also predate eggs of some pests.
In unhealthy, degraded ecosystems we often see a proliferation of pest species – organisms that are willing to eat almost anything, and
No dig also does not require the use of fertiliser. This is great for our bank balances and great for the environment. Run-off from liquid feeds can be incredibly damaging to waterways and aquifers. It causes algal blooms that choke rivers and streams. Liquid fertilisers interrupt the reciprocal relationship between plants and soil life. Because the plants have plenty of nutrients to eat, they no longer produce root exudates to feed the life in the soil. The result is that the life in the soil slowly starts to die out, and soil health decreases over time.
The wonderful thing about plants getting their nutrients from soil life is that they can request nutrients as and when they need them. Plants identify their own needs, and the soil life will deliver. Another great thing about not fertilising is that most conventional fertilisers only deliver the macronutrients NPK (Nitrogen, Phosphorous and Potassium).
When plants get their nutrients directly from the soil, they take in other micronutrients (nutrients they need in lower quantities). These include iron, calcium, manganese, copper, zinc and more. These micronutrients are then present in our food. This helps protect us from nutrient deficiencies and conditions such as anaemia that are more and more common in modern communities fed on conventionally grown and chemical-reliant agriculture.
Almost all plants we grow routinely in our gardens require good drainage. The reason for this is that plant roots need to respire. Respiration is the process of taking in oxygen and releasing carbon dioxide, just like we do when we respire. Plants are well known for photosynthesis takes in carbon dioxide and releases oxygen. This is essentially the opposite of respiration, but they do still respire in small amounts.
Plant roots can usually survive days with insufficient water but can drown in hours if there is too much water. That’s why good drainage in the soil is imperative to healthy plants. There are, of course, some plants that are adapted for life in bogs, ponds and other aquatic environments.
By adding organic matter in no dig gardening and aggregating soil particles, the life in the soil creates good drainage in the soil. This works well for the soil life, too, as most of the things that live in the soil also need to respire, so having tiny pockets of air throughout the soil is good news!
Better Water Retention
This might sound contradictory since I just said that no dig soil has better drainage. But good soil structure can do both. Air is held by the pores that open up with the movement of earthworms and other organisms, and the aggregates hold water. Water coats them and clings to them in much the same way as a sponge holds onto water.
Good no dig soil feels damp under the surface, even when it hasn’t been watered for a long time. This is because no dig soil allows water to permeate down through the layers. The pores act as pathways, and when water travels down through the layers in the soil, it creates a vacuum which in turn pulls down more air. This means that our soils are aerating themselves whilst it rains or we water them. It also means that water can permeate down easily, meaning that we don’t get as much runoff or soil erosion.
The spongy texture of no dig soil holds onto water well throughout the layers of the soil. This means that less water is lost from the soil into ground water and less is lost through evaporation at the surface. So water is more readily available to our plant roots.
Better Soil Structure
We have talked about how soil organisms create good soil structure, so I won’t go over it again, but it would be remiss of me not to mention it as a benefit.
Clay soils that have been dug turn to solid, cracked earth in a dry spell and heavy, claggy mud during a wet period. No dig soils are much more resilient, and they stay the same throughout the year – unless there is a serious flood. This is because of the improved soil structure. It means that the soil neither dry out easily nor becomes waterlogged easily.
No dig soils are also less prone to erosion. Because the particles in the soil are bound together, particles cannot easily be washed or blown away. Likewise, because of the aggregated nature of no dig soils, they are much less prone to compaction. You can jump on well-established no dig beds, and they feel springy and bouncy underfoot.
This one is obvious, but no less a significant benefit of no dig gardening. Digging over an allotment is no mean feat. Health conditions and poor fitness prevent many people from being able to do this. No dig gardening is a lot easier, quicker to set up and more inclusive.
No dig gardening almost feels too easy to those who have been digging for many years. If you need convincing, perhaps try a small section of your garden or allotment first as an experiment.
This is another benefit of no dig gardening. Fewer weeds. Whilst gardening in a no dig style will not eliminate weeds, it does make them a lot easier to manage. The loose soil on the surface of your beds, created by the compost, will be really easy to hoe. This means that you can easily keep on top of weeds, quite unlike trying to hoe them out of heavy, dry clay soil.
HOW CAN NO DIG GARDENING SUPPRESS WEEDS?
The cardboard and compost used in no dig (more on that here) act as a weed suppressant, which helps to keep weeds down at first. If you need to you can reapply cardboard and compost at any time. The good news is that by not digging the soil, we are not bringing seeds to the surface, so we are only dealing with seeds that are already on the surface or that arrive after we establish our beds. Weeds like creeping buttercup and couch grass can be more difficult to suppress, but regular hoeing will help; over time, they will grow weaker and die.
Soil organisms need plants as they are the primary source of food for the ecosystem. So, on bare soil, weeds are a valuable resource for soil life. In no dig gardening, the soil life can feed on compost when the beds are bare. But, because we do not need to worry about our soils becoming depleted, no dig gardening encourages constant cropping where possible. the use of cover crops, green manures and interplanting all help to keep the soil surface covered for as much of the year as possible. This means weeds don’t have the opportunity to thrive as our crops always sh shade them out.
On a more sciency level, weeds often feed on nitrates as their primary source of nitrogen. These come from nitrifying bacteria and allow the plant to grow quickly and go to seed quickly. In healthy soils, nitrifying bacteria cannot thrive, as fungi help to manage their populations. This means that healthy soil has a good balance of nitrates and ammonium. This is great for normal plant growth and not so good for weeds.
HOW CAN I BECOME NO DIG?
It’s so easy; all you need to do is stop digging and put down the fertilisers. If you have compost or well-rotted manure, lay this on the surface of your soil once a year. In the first year, it is a good idea to lay a thick layer of cardboard, too, to suppress weeds. If you don’t have any compost, your soil can do without it for a year or two whilst you make some of your own. But in the first year, you will need compost to establish your beds unless you are working on very rich, loamy soils (which most of us are not!).
We should dig out any perennial weeds (remember, removing a tree, not the whole forest) and suppress any annual weeds by hoeing or laying brown cardboard down under your compost. Cardboard will act as a weed suppressant and be broken down and incorporated into the soil, just like the compost. Then any more weeds that pop up through the year
For more information on how to implement a no dig system in a UK environment, I highly recommend this blog. The works of Elliot Coleman are excellent for US gardeners.