The importance of good soil management5th December 2019
Happy World Soil Day! Here at Outerspace we’re a strange bunch who love nothing more than to discuss our passion for soil! What better day to shout out for this unsung hero of ecology than today, World Soil Day!
Why are soils important?
Soils are often overlooked. Think about it, when you’re in a beautiful forest, marveling at the trees how much attention do you really pay to the soil under your feet?
However soils are essential for life; they provide the medium for plant growth, they act as a water filtration system, they provide a crucial habitat for many insects and billions of other organisms and they act as a carbon store helping to maintain the delicate balance of atmospheric gases.
It is for these reasons that it is vital for us to preserve soils and to give soils the primary importance that they deserve.
Interesting soil fact: Pick up a handful of soil. In your one handful you will be holding more microorganisms that there are people on earth!
In order to provide their full benefits, soils need to be healthy. Soil health is influenced by a factors, such as climate or human activity. Whilst, as individuals, we cannot affect the climate we can improve or damage soils through decisions we make on how we use and manage our land. Soil damaged to such an extent that it can no longer carry out its functions can influence the wider environment, for example greenhouse gas emissions from soils can contribute to climate change.
Interesting soil fact: On a global scale, soils contain about twice as much carbon as the atmosphere and about three times as much as vegetation.
We need to look after our soil to ensure it continues to provide us with the benefits we expect and so that it can continue to do so for future generations.
Why are soils at risk?
Bianka Schneider, one of our Associates at Outerspace holds a special place in her heart for soil: “During my landscape architecture studies, we were asked to dig soil pits in the forest to learn about soil profiles. It was fascinating to see all the different levels and changing colours of the soils; from the dark organic rich soil on top, to the sandy and rocky layers at the bottom and to see reddish iron veins running through. What impressed me was how LONG soil has been there, quietly developing under the trees and how UNIQUE it was. The production of the soil had taken place over hundreds (if not thousands) of years and it was IRRETRIEVABLE!!! You cannot bring it back and you cannot recreate it. It pains me to think about how careless planning of construction projects can use up or damage precious ‘virgin’ soil and how there is still a lack of understanding of just how important it is”.
Interesting soil fact: The top layer of soil is usually darker than subsoils due to the high concentration of decaying organic matter and can take anywhere from 200 years to as much as 1000 years to form a single inch. This top layer is becoming increasingly endangered and is disappearing much faster than it can form. The United Nations considers soil degradation one of the central threats to human health in the coming decades.
How can good construction practices save soil?
One key thing construction firms can do to help preserve precious soil is to have a clearly thought out soil management plan. During construction, the top layer of soil is typically removed and can be used in other locations or sold, however poor management can result in some of the soil becoming compacted by the heavy equipment used. Without a soil management plan there is a risk of losing, damaging or contaminating valuable soil resources. A site manager should always keep in mind that topsoil is a finite and valuable resource and it is essential that it is removed, stored and replaced with care.
Interesting soil fact: Worms enrich topsoil by feeding on organic material in the soil and converting it into nutrients for plants. As they move through the soil it becomes more absorbent and better aerated too. Soil is at the bottom of the food chain, yet it is the cornerstone of life on earth.
How can soil management affect landscape architecture?
Antony Geddes, one of our Associates here at Outerspace notes that “It isn’t possible to exaggerate how important soil is to a thriving landscape. Over the years I have watched trees get planted, only for them to be taken out again 12 months later once they have died. There is always a plethora of opinions as to why they died, such as poor tree specification or bad nursery stock. Whilst this can certainly be true, on closer inspection the reason is almost always the soil, specifically soil compaction.”
In the rush to get a development finished, soil (and trees) are too often brought to site too early and as a result are continually tracked over, inverting the subsoil and topsoil layers and irreversibly damaging the soil structure. With the philosophy of ‘you can never have too much soil’, the answer seems to be to bring in more topsoil to hide the damaged material, which again requires the existing material to be tracked back over, further compacting the ground and forming an impenetrable layer. This often isn’t picked up until problems are found and usually when the construction team has moved on to the next site, leaving it to the maintenance team to resolve.
As landscape designers we need to appreciate the constraints of a site. Of course we should always push to maximise the ‘greening’ of a new development, but equally we need to be realistic and advise our clients against planting trees if it is simply to ‘tick a box’, especially if the soil conditions do not allow. We need to look to the long-term and for this, the soil needs to be up to the job. We might not always look at it, but soil needs as much care and attention in terms of specification, sourcing, protecting and installing as anything else, as the nice green fluffy bits are nothing without it.”
Interesting soil fact: Soils typically have six layers called ‘horizons’ ; O ,A, E, B, C and R. Each horizon has certain characteristics. Horizon O is the topsoil and R is bedrock.
With all this in mind maybe us Outerspacer’s aren’t such a strange bunch after all…lets ALL get talking about soil!
By Bianka Schneider (Associate), Antony Gedded (Associate) and Kate Kershaw (Practice Manager)