All gardening is an attempt to manipulate nature to give us the results we want. We want to make sure that the plants focus on providing the stage of their life that’s useful to us rather than follow their own agenda. We want tomatoes to produce fruit while we want lettuce, pak choy and other leaf vegetables to stay vegetative. We want onions to grow big enough to survive the winter but small enough so that they don’t reach “puberty” and produce flowers rather than bigger bulbs next spring.
However we can work with nature – or we can try and dominate her. We can make sure that we build soil fertility, minimise the use of artificial inputs and work towards producing a fertile climax ecology of soil earthworms, insects, bacteria and fungi. Or we can treat the soil as simply a hydroponic medium to hold up the plants – mine minerals and intensively add them and control weeds with weed killer. And we can cultivate the land intensively every year with heavy machinery.
We could build a shed like at Thanet Earth which covers 56 acres of formerly fertile land dedicated to producing cauliflowers and use hydroponics to produce about 15% of the UK’s supply of tomatoes, cucumbers and peppers. This gets quite a few ticks in the box for sustainability because it’s build round a Combined Heat and Power scheme (CHP) but whether the veg actually taste of anything is something that we’ll discover in due course.
However this kind of agri-business approach is not without its cost. Pesticides kill wild life and compromise water supplies. Excess fertiliser runs off, taints ground water and causes eutrophication and algal blooms. Intense mechanical cultivation damages soil structure and leaves it prone to erosion.
This is not a sustainable approach – and the mainstream business knows it. DEFRA’s chief scientist is talking on the Today programme about loss of soil structure. The Supermarkets in order to boost their Corporate Social Responsibility have reduced the amount of pesticide in produce they will accept from their supply chain. The EU has banned many substances from the supply chain and limits the amount of NPK that can be applied to the land – pretty much to replacement levels. So to an extent the mainstream is moving towards a more “natural” approach – at least in some respects.
However I’m not convinced that we really appreciate what we’re up against.
In Patrick Whitefield’s definitive book on PermaCulture he tells us that something like one third of all the soil that was in North America when Columbus arrived is now at the bottom of the sea thanks to erosion.
He goes on to observe that the rate of soil formation is 0.2 tonnes per hectare per year – 200lbs an acre – visualise 2 bags of cement! Erosion in the US is equivalent to 15 tonnes per hectare per year In the UK its considered that a 2 tonne loss per hectare per year is tolerable – given that that’s ten times the formation rate it begs the question of what is meant by tolerable.
So if we are going to rebuild the fertility in the soil, we need to take it seriously and work at it so that we are rebuilding the soil’s capacity and setting it out so that the plants can grow in the most effective way to provide a harmonious, garden environment.
And this is one of the themes we’re going to focus on in the intelligent garden.