Garden soil: a handy list of everything you need to know

Maybe you have just got your first garden or maybe you are trying to grow the best veggies and flowers? Whatever the reason, it helps to know what kind of soil you have in your garden. The good bits and the bad bits and everything in between.

Who am I to talk about soil?

For those of you who don’t know me, hi, I’m Annette. I’m a second year postgraduate researcher at the University of Aberdeen. I’m researching how we can use root diversity interactions to engineer soil structure. Basically what combinations of plant root types can we use to help generate healthy and structurally stable soils? We have the best soil science department in the UK (ok a little biased I’m sure). We just won the 2021 Queens Anniversary Prize for Soil Science (less biased opinion). If you fancy coming here to join us in the study of soil and plants, then we’d love to see you.

It is one of my aims over the following year to come up with a variety of my own resources to help you understand more about the soil in your garden, park or even in your houseplant pot. But for now I’ll scour high and low across the web-iverse to find you some of the most helpful guides, books, blogs and videos. I’m so excited to bring these to you over the coming months. I hope that you’ll find them exciting and useful too. My aim is for one every couple of months, so do look out for them on Twitter; @annetteraffan.

I’m going to split them into subject area and focus on one aspect at a time. There will also be lots of cross-over as you’ll soon learn that everything in soil is interlinked!

The list of everything about garden soil

The broad areas I will be covering, in no particular order are:

(If I’ve covered them, there will be a link to the page):

1. Texture – how much sand, silt and clay do you have in your garden soil? Why does this matter?
   1. Soil additives like gravel, perlite and vermiculite – what’s their purpose and what’s the difference?
2. Organic matter – such a hot topic right now and a BIG post as there is so much to highlight! Including:
   1. Carbon – what role do gardens have in all this talk about carbon and carbon dioxide?
   2. Compost – what happens when you use compost that isn’t well rotted? How do you make compost?
   3. Peat – this series would not be complete without discussing Pete. I mean peat.
   4. Humus – is it a thing or isn’t it? Humus might be a mainstream term used by gardeners but it causes a division of opinion in soil scientists.
3. pH – is your soil acidic, neutral or alkaline and what does this mean? How can you tell? What happens when soil is towards the extremes?
4. Water – how to use it, conserve it and why a plant needs it.
5. Temperature and light – why is this important for soil?
6. Air and other gases – air is essential for life in soil, but what happens when it turns smelly like that thick layer of grass clippings you put on your compost heap?
7. Nutrient overview – the different options to test for them and why they are important in soil.
8. Nitrogen – Arguably the most important plant nutrient as it is the largest nutrient component in plants. How do we get it? What does it do?
   1. Nitrogen-fixing bacteria found in legumes like beans and peas
9. Phosphorus – important for so many plant functions like energy production and roots.
10. Cations like calcium and sodium but also iron and aluminium – what are they and how do they contribute to soil?
    1. Potassium – The most important cation for plant growth – it’s important for fruits but how does it work in soil?
    2. Sodium – is it always bad? Why do we need at least some in garden soil?
11. Other micronutrients – essential for plant growth. How do you make sure you get enough of these and how can you lose them?
12. Heavy metals and other contaminants – the nasty stuff that is important to be aware of in your soil particularly if you live in old mining or industrial areas.
    1. Plastics – should you be concerned about plastics and microplastics in your soil?
13. Soil porosity and the matrix – important to understand how these work together so you can build healthy garden soil that is both functional (e.g. absorbs water) and productive (e.g. doesn’t remain water-logged).
14. Earthworms and nematodes – ooh, the not-so-hidden wriggly engineers of our soil. They are most definitely your friend and occasionally not for some, but most definitely essential.
15. Other bugs and beasties – there are so many beasties in soil, which, in balance are essential for the soily food web.
16. Microbes (excluding fungi) – there are billions of bacteria in just a teaspoon of soil; it’s mind boggling actually. These are essential in your soil and a healthy population of these make for happy plants and therefore happy you too!
17. Fungi including mycorrhizae – did you know that almost all trees in a forest are connected by fungal hyphae? There’s no reason why this would not be the case for the plants in your garden too! How cool is that?
18. Plant parts – how do these influence the soil in your garden?
    1. Leaves and needles – part of the circle of life, but what’s in a leaf and what effect does that have on soil? Why is leaf mould so darn good?
    2. Roots – a hidden world of interactions that literally powers the world. The few mm to centimetres around plant roots are probably the most biologically active and diverse in the whole world. Cool or cool?! Find out more about these to make your soil a super powerhouse too!
    3. Wood – food of the fungi and home of the beasties. Why you need dying wood, twigs and sticks above and within your soil.
19. Weeds and their purpose – understand weeds, why you get them and their purpose in the circle of life. Should you remove them or keep them and how can you reduce them. What’s the best methods?
20. Plant pathogens and invasive species – with globalisation and unbalanced food webs these can get out of control. What can we do to help? What should we look out for?
21. To dig or not to dig that might be your question. A super interesting topic and in my eyes, quite eye-opening… but it’s not for everyone – why?
22. Sustainability – can gardening actually be truly sustainable? Why not and what part does soil play?
23. Design – garden design is so important to think about in regards to your soil. After all it’s not the best idea to put your shed on your nicest soil and be left with a quagmire…or is it?

There’s so so much to discuss isn’t there? Over the coming months we’ll work through them one-by-one, not necessarily in order and I may add more, but I’ll adapt this list accordingly. I’ll pepper in some research, popular You-Tubers, book authors and bloggers in there. All to give you a nice rounded and entertaining view of the subject. This is partly so I can put my possibly excessive You-Tube-watching and Twitter-scrolling to good use. I’ll drop in some influential researchers in there too, so you can follow what they’re up to. I hope that you will find this a useful series you can apply to your own (and others’) garden soil.

I’d love to know what you’d like to find more about! Is there something that I haven’t mentioned here?

Let me know in the comments!

Coffee I’m drinking: Horsham Coffee Roaster: Costa Rica, Aguilera Brothers

Books I’m currently reading: The Kindness Method by Shahroo Izadi and Killing State by Judith O’Reilly

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