Wednesday, December 30, 2009

Wet, Wet, Wet

I haven’t been in the garden for weeks. It was incredibly wet here (Welsh borders) for practically all of November and well into December – and now it is so cold not much can be done outside either.

The rainfall is high here,nearly  2,000mm per year, and the soil, overlaying Old Red Sandstone has enough clay/silt content to slow down water absorption – so it gets saturated very quickly. When really wet, springs appear, and water can actually flow over the surface of the soil. Pooling for several days after rain is normal. In areas where subsoil or near-subsoil is exposed, it is even worse. The whole garden is on a gentle south-facing slope however so there is constant water movement through the soil and no long-term waterlogging.

So, given all of this, and the fact that we have had three cool, exceptionally wet summers, it is amazing what survives – or put another way, how little fails. Even Mediterranean plants like santolinas and lavenders flourish in sticky poor-quality soil with pools of water around them for days. It is hard to think of any failures: Lilium regale definitely, and I think the raspberries, although there was a complicating factor here, as we dug in loads of manure to ‘improve’ the rather poor-quality soil and I think phytophthora may have killed them.

The year before last there was an exceptional period of high rainfall, in, I think, June. A friend, who lives not so far away, Charles Chesshire, had huge losses, despite being also on a south-facing slope – but in his case, springs or at least great upwellings of water from underground (he has the very substantial Clee Hill just behind him) must have completely de-oxygenated the soil, and at a crucial period of very active growth. Thinking about places where you see plants in the wild, wet slopes are often a good habitat for a wide range of species. The conclusion I think must be that plants do not object to very wet conditions at the roots so long as there is dissolved oxygen in the water, so that they can respire, and that means that the water must be moving. This is more crucial during the growing season than the dormant.

Anyway, we’ll probably have a terrible drought this year, which’ll give us something else to think about.

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