Soil Nurturing And Soil Health

Understanding soil nurturing is important for a gardener, as a healthy soil gives better harvests and healthier plants. By taking steps to reduce the disruption to the soil ecosystem caused by growing fruit, vegetables, and herbs, and by replenishing nutrients that are lost from the soil when crops are harvested, it’s possible to get better results and grow in a more sustainable way.

Watch the YouTube video below, or continue scrolling to read the full article on soil nurturing.

Step By Step Video

YouTube Video

A healthy soil for growing fruit, vegetables, and herbs is one that preserves the balance between the soil ecosystem below the surface, that keeps the soil healthy, and the plants growing above it. There is a symbiotic relationship between plants and soil, with plants effectively feeding and nurturing life within the soil through their roots, and in turn, the soil ecosystem providing back the nutrients a plant needs to grow.

This relationship between soil and plants appears to be crucial for soil and plant health. Growing food on an allotment plot is a destructive process to the health of the soil. When plants are removed for harvest, it takes away nutrients permanently from the soil, and can disturb the soil and soil life living within it. By taking steps to reduce the disruption to the soil ecosystem caused by growing fruit, vegetables, and herbs, and by replenishing nutrients that are lost from the soil when crops are harvested, it’s possible to get better results and grow in a more sustainable way.

Why Soil Nurturing Is Different To No-Dig Gardening

Soil nurturing is different to a no-dig approach, although many of the techniques are the same. The first difference to highlight is that soil nurturing does not rely on putting large amounts of soil, or compost, on top of existing beds to save work. Whilst both approaches look to avoid digging, and both add compost to growing beds, the emphasis of ‘no-dig’ is often on saving work for the gardener, which can mean regularly importing, or buying, large amounts of compost to put on top of beds. By contrast, soil nurturing focuses on the health of the soil and techniques to promote it, rather than an emphasis on saving work. Or put more simply, it relies less on dumping compost on top of existing beds.

Soil nurturing is about growing techniques that stop nutrients being lost from the soil, and growing in a way that helps sustain the soil ecosystem and life living within it. Adding compost, or well rotted manure, is also important to replace nutrients lost by harvest. Therefore, the focus of soil nurturing is on overall soil health, and a no-dig approach is actually a part of this, and is just one technique amongst others, that helps to achieve this goal.

What Is A Healthy Soil?

Whilst scientists are still discovering new insights about the relationships within a soil ecosystem, a few areas appear to be particularly important. One place to start is the UK Government website, specifically the Department of Agriculture, Environment & Rural Affairs, which in September 2022, states that the five elements of a healthy soil are:

• Soil Structure
• Soil Biology
• Organic Matter Content
• Soil Chemistry
• Water infiltration, retention, and movement through the profile

This website goes on to say that an unhealthy soil will have at least one problem area, which may impact the others. So what exactly does this mean? Let’s take each one of these in turn.

Soil Structure

Soil structure is how the solid, physical parts of soil are arranged, and perhaps most importantly, the air spaces between them. This has a direct impact on how air and water is held by the soil, and how they travel through it, which impacts the life living within the soil.

Some of the soil structure is inherited by a gardener, and relates to what a soil is made from. Clay soils are naturally compact, as the small clay particles are relatively tightly packed together, and these soils are often described as heavy or wet. Soils containing a high sand content are at the other end of the spectrum, the large gaps between particles allow water to pass through easily, meaning the soil is described as both light and dry. In the middle are silt soils, made from medium sized particles, that can provide a good balance of air and water content, without being too wet or too dry.

Whatever type of soil a gardener has, the soil life, or soil biology living within it, can help shape and improve the soil structure to make better growing conditions for plants.

Soil Biology

Soil biology includes everything that is living in the soil, from bacteria to insects. Gardeners often comment that a soil containing earthworms is a healthy soil, but earthworms are only a visible part of the whole soil ecosystem, that includes millions of fungi and bacteria in every gram of compost, and in a square metre of soil, hundreds of thousands of single celled organisms like protozoa, and the slightly larger nematodes or roundworms, and mites, all of which are less than a millimetre in length.

The larger wildlife which a gardener can see without a microscope, includes springtails, woodlice, millipedes, potworms, and earthworms, and these depend on the availability of food from the whole ecosystem to thrive. The ecosystem of this biology, helps create the optimum soil structure for plants.

Organic Matter Content

Life within the soil is also affected by the amount of organic matter. This originates from living material like plants, and if organic matter is available, the organisms within the soil break down and release the nutrients it contains through a process called composting, and these nutrients become available for new plants to help them grow.

This composting process is vital to the fertility of a soil. The really important point is that the fertility of the soil is directly related to the health of the soil biology, as without this life, plants would not have the nutrients they need to grow.

But, it’s not only dead and decaying organic matter that is important to life in soil. Living plants also feed the life within the soil through their roots. It has been estimated that around a third of the carbon captured through photosynthesis is released, or secreted, by plants through their roots. It appears that the compounds released by plants help to sustain soil life, and in return, the soil life helps make nutrients and proteins available to plants to help them grow.

Soil Chemistry

The soil chemistry of soil also has an impact. If the environment is acid or alkaline, this will influence the type of life living within the soil. Other influences are the amount of minerals naturally found in a soil, and the presence of pollutants. These will all affect the chemical reactions happening, and impact on soil life.

Water Infiltration

The final area to consider is water infiltration. In a healthy soil, the soil biology will create a network of airways within the soil to help it retain water, whilst also allowing gases to enter and be released. If a soil is too loose, for example after being disturbed by digging, there is the potential for water to pass through the soil too quickly, removing with it organic matter and minerals.

A soil which is too compact is also a problem. This can happen through the absence of rain, which can cause the soil to shrink and dry out, or by compression from heavy machinery, or constantly being walked over. When a soil is too compact, rain is not able to enter the soil, and is instead lost through surface run off.

Summary Of A Healthy Soil

Therefore, because of all these relationships, soil can be described as a complex living ecosystem, that will naturally sustain itself as all the elements interact with each other in balance. In particular, sustaining the soil life, or soil biology, appears to be crucial in maximising the fertility of a soil, and supporting this is the key goal of soil nurturing.

And with this understanding, the next natural step is to consider what plants need to grow, and the relationship they have with the soil ecosystem.

How A Healthy Soil Helps When Growing Crops

With this understanding of what makes a soil healthy, the next question is how this knowledge helps to grow fruit, vegetables, and herbs. Plants can be seen to need two things from the soil:

1. Firstly, the raw ingredients, specifically water and nutrients, that they need to grow
2. And secondly, the ability to easily access these nutrients in the soil

The Availability Of Water

As described above, a healthy soil has a good soil structure created by the life within the soil, and this natural soil structure is the ideal environment for holding moisture. Said another way, soil that has not been dug over is excellent at holding water, and plants growing in this soil will need less watering.

By contrast, if a soil is dug, the natural soil structure is destroyed, and water will more easily flow out of the soil. A plant’s roots will likely have less moisture surrounding them, as the soil structure will be less good at holding water. Therefore, a gardener will need to water more often in a soil that has been dug over, which is more work and requires more water, or rely on more rainfall to help give their plants the moisture they need to grow. Therefore, the less often a gardener digs their soil, the better it will be at holding moisture, and the more water will be available to plants.

The Availability Of Nutrients

The availability of other nutrients is a little more complicated. The reason this is important is that a gardener growing fruit and vegetables is constantly removing plant matter, by harvesting fruit and vegetables, and discarding the remains of plants to the compost heap. Without addressing this issue, over time, the amount of nutrients in a soil will deplete.

The four major nutrients plants need to grow are hydrogen and oxygen in the form of water, combined with carbon and nitrogen. Of these four, rainfall will replenish the water, and plants obtain carbon from the air through photosynthesis. However, whilst the air we breathe contains a high percentage of nitrogen, air is nearly 80% nitrogen, airborne nitrogen is different to carbon in that plants are not able to process it. Plants depend on absorbing nitrogen from the soil through their roots.

The Importance Of Nitrogen

Nitrogen is particularly important for plant growth, as without it plants cannot create proteins, and therefore cannot grow. In total, nitrogen can account for around 3 to 4 percent of a plant’s above ground dry mass. If a soil is lacking in available nitrogen, plants will not grow well.

For this reason, the availability of nitrogen is often the primary focus when looking to boost plant growth, but in fact there are many other nutrients a plant needs from the soil, including phosphorous, potassium, calcium, zinc, magnesium, and copper to name a few, but these are required in much smaller amounts. Like with nitrogen, the amount of these nutrients in the soil will gradually reduce by harvesting plant matter, unless they are replenished in some way.

Returning to nitrogen as an example, the process by which plants absorb it is a little complicated. As already mentioned, plants cannot access nitrogen in the air. What is key is that soil, when not disturbed by a gardener, will naturally recycle nitrogen through a composting process. As old plants are broken down through composting, the organic nitrogen they contain is made available for new plant growth in the form of ammonium ions and nitrates. This process is called mineralisation.

A key point is that for composting to happen quickly, there needs to be a thriving ecosystem of life in the soil, of the type described earlier, from the smallest bacteria to the more visible garden worms. It is the presence of this life, and their action in digesting and releasing organic matter, that ultimately results in nitrogen becoming available to plants. And just as important, this soil life needs a combination of living plants to supply nutrients through their roots, and dead plant material to feed upon during the composting process.

It’s worth noting that composting is not the only way nitrogen is added back to the soil, even though this is the most important. Some plants, particularly legumes like peas, beans, and clovers, are able to take nitrogen from the air by using bacteria contained in their root nodules. There are also bacteria that live in the soil that can fix nitrogen directly from the air.

And a gardener can also take action directly to boost nitrogen and other nutrients, by adding artificial fertiliser to their soil, often in the form of a liquid feed, or by slower release pellets that gradually dissolve when moist.

Summary Of Plant Nutrients

So, to summarise, nitrogen is very important for plant growth, and when a gardener cultivates their soil, nitrogen levels will gradually reduce. And as I’ve already mentioned, this is also the case for other minerals too, which are required in smaller amounts. To replenish the nutrients that are lost from the soil through cultivation, there are two key factors:

• The first is a healthy soil biology, that includes bacteria, fungi, and living creatures
• Secondly, a source of organic material for this biology to feed off.

With this understanding of how nutrients are naturally returned to a soil, the next question is what are the best ways for a gardener to promote soil biology and supply the organic materials it needs?

The Use Of Artificial Fertilisers

The big advantage of using artificial fertilisers is their convenience. Fertilisers are easy to dilute in water, and can be given to plants as part of a watering regime. These fertilisers have been developed to make the nutrients they contain as easy as possible for plants to absorb, and have the right balance of nutrients for optimal plant growth.

There are some disadvantages to using artificial fertilisers too. The first is the additional cost, and another is wastage. Once fertilisers are diluted in water, it is easy for the minerals to be washed away before they are absorbed by plants.

If too much fertiliser is added to compensate for run off, it can end up damaging the soil ecosystem and the life living in the soil. On a large scale, for example in farming, excess nutrients can create problems for wildlife in rivers.

The usage of artificial fertilisers is a big topic, but the focus of this page is about soil nurturing. One of the joys of gardening is to learn to grow things naturally. The next section discusses principles to follow to sustain soil health.

Soil Nurturing Principles

1) Minimising Bare Soil

The first principle I follow is to minimise the amount of bare soil on my plot, and the length of time any bed has any bare soil on it. This is because life within the soil depends upon the nutrients provided by plants through their roots. Also, plants block direct sunlight that can cause the soil to heat up and dry out. And, if the soil is bare, there is no new material available for the composting process.

The next three principles are ways to avoid bare soils, to help keep the soil ecosystem in balance.

2) Sowing Green Manures

Sowing green manures on beds that are not in use is an excellent way to retain nutrients in the soil. There are two main types of green manures. The first is nutrient lifting types. These are so called as they lift nutrients out of the soil and store them in their leaves. The nutrients are returned to the soil when the plants are cut down, with the cuttings left on the soil to be broken down through the composting process.

Whilst the plants are growing, the nutrients cannot be leached away by heavy rain, as they are safely stored in the plants. The roots of the plants help keep the soil in place, and provide nutrients to soil life.

The second type of green manures have the same advantages as the first, but are called nitrogen fixing green manures because of their ability to fix nitrogen from the air. Once the plants are cut down, this additional nitrogen returns to the soil through the composting process.

3) Companion Plant Crops

The third principle is to companion plant crops that do not compete with each other, to help ensure that there are no empty areas of a growing bed. For example, runner beans that grow tall can be surrounded by winter squash plants that spread around the bed at ground level. Similarly, low growing green manures like clover can be planted between rows of vegetables.

Aside from making the most of the available growing space, companion planting feeds life in the soil over the whole bed, and helps retain moisture by preventing the sun drying out bare soil.

4) Spreading Homemade Compost & Manure

My fourth principle is to add nutrients back into the beds by spreading homemade compost and well rotted manure over them after crops are harvested. Depending on what’s growing next, I decide whether to spread a mulch, or choose to sow a green manure instead. Using green manures means that I don’t need as much homemade compost, which is good, because I cannot generate enough homemade compost to cover all my beds every year.

In terms of making homemade compost, I’ve found hot composting to be very efficient, which is a method that greatly speeds up the composting process by keeping heat, and air, inside the composting container. This makes it possible to create a bin’s worth of compost in 4 to 6 weeks, which allows for several bins worth of compost to be made through a growing season. I’ve created a separate video on hot composting, and I’ll link to this in the video description.

5) Avoid Digging

And my fifth principle is to avoid digging my soil as much as possible. Instead, by using green manures and mulches, as well as by regularly hoeing during the growing season, I can avoid the need to dig over beds to control weed growth. This prevents disturbing both the ecosystem of the soil, and the structure of the soil that is important in retaining moisture.

However, for some crops, I think it is still better to dig, for example when growing potatoes. My preferred method is to grow potatoes in a trench, which disturbs the soil when digging the trench, and a second time at harvest when I dig the potatoes up. But after growing potatoes in a bed, I’ll avoid digging the bed again for a few years to allow it to fully recover, by rotating where I grow potatoes around my allotment.

Techniques To Avoid

And finally there are two techniques that I try not to do when nurturing soil. The first is to avoid using shop bought compost on my growing beds. I like to avoid this because of the cost and effort involved of moving large amounts of compost to my allotment. I have discovered that by following my five soil nurturing principles, and creating my own compost by hot composting, I can supply the compost I need from what I make myself.

And the second technique I avoid is buying artificial fertiliser for my beds, as the beds don’t need these extra nutrients. A combination of green manures and occasional mulching supplies enough nutrients to replace what the beds lose through harvesting.

However, I do feed the plants that I grow in pots inside my polytunnel, for example my tomatoes, cucumbers, and peppers.

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