The soil is the substance on which we all depend for our flourishing and productive patches. Juliet Barber offers advice on its care through the winter months.
We all want soil that feels beautiful and crumbly and yet – slightly sticky in the hands when damp; ideally a rich darkish brown colour, full of nutrients, worms and generally easy to dig. Well, the principles for obtaining this perfect mix are essentially simple.
The millions of soil organisms, to an extent, depend on us and the way we choose to manage our land. Realising the importance of keeping our soil ‘alive’ can ensure good growing conditions.
Soil microbes, soil fauna and roots which make up the biological component are intimately associated with the creation of soil structure, in turn, their activities are governed by the soil, they have helped to create and so the cycle continues. Virtually all organisms found in the uppermost layers of soil contribute to the development of soil structure.
Winter as far as the gardener is concerned begins at the first indication of a freeze and ends at the last. In the northern hemisphere, we now have a seasonal and temperate climate. However, our seasons can sometimes surprise us, with uncharacteristically hot, cold, wet or dry weather when we least expect it. Add to orientation and vegetable gardening and this place can become quite a challenge. Perhaps your plot has a unique microclimate handily sheltered by a boundary of hedging and trees? Perhaps it really is protected by buildings and within a town?It could be exposed to the elements, on a hillside, facing the sea, be prone to waterlogging or is in a shady hollow. The soil is considerably affected by the position of our plots and the extent and severity of the seasonal weather that was chilly. If winter is brutal and contains a lengthy freeze, indications of life can appear limited as well as nonexistent.
So what happens during winter when temperatures drop? While soil can store up heat from the sun it will conduct heat faster back into the atmosphere when it is frozen. The carbon cycle is greatly affected by climatic variables, temperature and precipitation being the most influential at they govern the rates of chemical reactions and the growth and activities of organisms in the soil. In winter, the livelihoods of larger soil organisms like insects are under threat because they are reliant on external heat as they can’t generate their own. If they are to survive they must find dry hibernation places. Ladybirds, for example, share heat by hibernating communally often under rocks or bits of wood. Insects winch over-winter as adults and become dormant are in a slow metabolic state called diapause. When temperatures really dip the consequences can be fatal to larger soil organisms. Carbon becomes locked into frozen ground as microbial activity slows or stops completely.
Although soil can be slow to cool in the autumn, once frozen it quickly loses heat to the atmosphere after a sunny winter’s day.