In any organic polytunnel garden, one of the most important jobs for you, as a gardener, is learning how to protect the soil. Protecting the soil includes both making sure that we do not damage it. And finding ways to build and improve it over time.
The soil in our polytunnel gardens is one of the most precious resources we have. Soil is far more than just ‘dirt’. It is an ecosystem that teems with life. In order to protect the soil, we have to understand that it is a complex and fragile system.
Unfortunately, around the world, large swathes of land have soil that is degraded or seriously degraded. Soil degradation is a huge environmental problem – and one that is often overlooked. Soil is so important. Without it, we could not grow most of our food. Soil also holds fresh water, and sequesters carbon. Carbon sequestration in soil is an important facet of climate change mitigation. As gardeners, we can do out bit in our climate crisis by protecting and improving the soil where we live.
Here are 12 important ways to protect the soil in your polytunnel:
First of all, it is very important to garden organically. Never use harmful pesticides, herbicides or fertilisers in your polytunnel. Toxic substances can do untold harm to the ecosystem in your garden, including the ecosystem that thrives below our feet. Work with nature rather than fighting it to keep soil healthy and its systems in balance.
Don’t Dig Unless Absolutely Necessary
If you are not yet familiar with ‘no dig gardening‘, look into the benefits of this type of gardening. The methods of no dig gardening involve taking steps to reduce our impact on the soil. In a no dig garden, we do not dig or till unless we absolutely have to. We leave the soil ecosystem as undisturbed as possible so it can function as it should.
Avoid Leaving Soil Bare
When soil is left bare, uncovered by vegetation, it is much easier for it to become degraded. Bare soil can become depleted of water more quickly in warm weather. It is also more easily eroded by wind and water. And nutrients can become depleted, or be washed away more easily. Of course, in an annual garden, there will sometimes be gaps in planting. But in order to take care of the soil we should try to fill gaps as soon as possible, and avoid leaving soil unplanted as often as we can. Good planning and organisation are key. Make a good planting schedule, plan for year round growing, and stick to your plans as much as you can.
When we walk on our growing areas, the soil can easily become compacted. When the ground becomes compacted, aeration is decreased. Not digging is one important step to avoid compaction. It will allow earthworms and other creatures in the soil to thrive. And they will aerate it more effectively for you. But it is also important to avoid walking on or compressing our growing areas. To avoid stepping on your beds, think carefully about your polytunnel layout, and always make sure you can easily reach all parts of the growing areas from pathways or access points.
Think About Water/ Soil Moisture
In a polytunnel, of course, we are less affected by the vaguaries of the weather. But this means that it is up to us to deliver appropriate levels of water. Water is obviously essential for plants, but water is also crucial for optimal soil health. In order to protect the soil in your polytunnel, it is important to think about water very carefully. You should always make sure that you are not watering too much or too little.
Consider Perennial Plant Options
Most polytunnel gardeners focus on growing traditional annual crops. But if you want to do best by your soil, you should also consider perennial plant options. Since perennial plants remain in place over the years, rather than being harvested each year, they help to protect the soil long term. Their roots anchor the substrate, and they will often add fertility naturally through natural die back in autumn. From fruit trees and fruiting shrubs, to grape vines, to perennial vegetables, herbs and flowers… There are plenty of great perennial plant options to consider for your polytunnel.
Use Nitrogen Fixers To Add/ Maintain Fertility
Whether they are perennial or annual, nitrogen fixing plants also play a crucial role in protecting and improving the soil in your polytunnel over time. Nitrogen fixing plants have a symbiotic relationship with beneficial bacteria in their root rhizomes. They take atmospheric nitrogen and make it available below the ground. Some of the nitrogen is used by the plants themselves, but some is also believed to become available to other plants grown nearby.
Use Dynamic Accumulators
Other plants also help to improve the nutritional composition of the topsoil. Dynamic accumulators include not only nitrogen fixing plants but also those with deep roots, or those which are particularly effective at ‘collecting’ certain plant nutrients. Growing, then chopping and dropping, or composting dynamic accumulators is one important way to recycle nutrients. And to add them to your polytunnel garden soil in growing areas.
Plant Green Manures/ Cover Crops
Green manures and cover crops can help you protect the soil in your polytunnel and enhance it over time. One thing they do is help you avoid areas of bare ground. They can also add fertility, or build better structure over time. Incorporating green manures and cover crops in your planting schedule is a good idea if you want to maintain fertility and a good quality soil over time. There are a number of different plants that you can use to provide various different benefits, both in the main growing season and over the winter months.
Rotate Annual Crops
Another area where good planning is essential is in crop rotation. Rotating annual crops will help avoid excessive nutrient depletion, and avoid the build up of diseases in the soil. It is best to rotate annual crops – tomatoes, potatoes and other members of that plant family, brassicas, alliums, and legumes should all be grown in different growing areas each year. Try to implement a three or four year crop rotation in your polytunnel if you possibly can.
When it comes to returning nutrients to the system, and maintaining the long term health and productivity of your polytunnel, one practice is perhaps more important than any other. Composting is crucial. You can compost in place. Or in a compost heap or bin. You can use cold or hot composting techniques. Composting can be aided by compost tumblers, or special worms in a vermicomposting system. However you choose to compost, you must make sure that you do have a system in place. Spreading that compost will replenish nutrients you have taken from it as you harvest your crops.
Mulch Soil With Other Organic Matter
Mulching is another very important practice to protect the soil in your polytunnel. You can mulch with your home-made compost. But you can also mulch with a range of other organic matter. Choosing the right mulches is important, not only to grow healthy and productive plants, but also to build and improve the topsoil in your polytunnel over time.
All of us need to look down, and think more about the soil. We should, in our gardening efforts, always remember just how much we rely on it, and just how important it is. Do you care for the soil in your polytunnel? How do you protect and improve it over time? Share your comments, tips and suggestions below.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.