After a recent trip to the library at RHS Harlow Carr in Harrogate, I started reading about how to handle clay soil. At the same time, I’ve been reading about the no-dig method of gardening. So, now there is lots of sometimes competing information going round in my brain.
There is no doubt that the soil is clay, which means it is fertile, or would be if it was in better condition. However, at the moment, a proportion of the nutrients appear to be locked to plants, either because the sods need to be broken up to make them more accessible or simply because the roots can’t get through the ‘concrete’. In other words, it would benefit from a large amount of organic matter to break it up. However, the question is whether to dig or not to dig.
The first disadvantage of digging (for me!) is that it would be very hard work. In fact, I think I would need a pneumatic drill to go into the subsoil, which is not far below the surface. Even if I wasn’t going to double-dig, this subsoil does need to be broken up to give roots more growing space as well as extra access to nutrition. In places, there has also been a considerable amount of compaction, particularly in the area which used to be lawn (no wonder the onions fared badly in this patch this year).
The second disadvantage of digging is that this brings up dormant weed seeds. (I remember it well from my time at the allotment.) To be fair, though, after the digging I have done since moving in, I haven’t had a particular problem in this direction.
On the other hand, I understand that beneficial microbial activity at the soil surface is also disrupted if digging is done. But mulching and green manures are not necessarily going to get into the clay at the same speed as they might on another, lighter, soil type if just left on the surface.
‘Necessarily’ appears to be the operative word. There are worms and other creatures which live in the soil, who would be happy to mix the mulch in with the clay. There are also green manures such as rye grass, whose roots break up the soil. The thing is the length of time this would take.
It seems to me, the best course of action is to in fact keep doing as I have been. In other words, no double digging as I just don’t have the strenth, but I will dig in compost and manure.
On the other hand, I have decided not to dig in green manures. If you do that, the decomposing matter will rob subsequent plants of nitrogen, unless left to rot for at least a couple of months before cultivating anything else. This negates the protective effect of green manure (ie the soil is once more exposed to the elements) and in a garden my size would actually reduce the amount of vegetables I would be able to grow, I think.
However, one thing I will definitely be changing is walking too close to the apple tree. In order to get part of the hawthorn bush out, I had to stand at the back of the tree – and fortunately the soil would have been dry, so compaction may not be too bad. It doesn’t need anymore assaults on it, though, otherwise the roots of the tree might become starved of nutrition. So, I’ll be standing on the path outside the fence to pick my runner beans!
© Helen Butt, August 2014