Allotment Waterlogging Mitigation

In the last month, our City Council offered us a different allotment plot, one less windswept and possessing a thriving Allotment Association. Hurray!

The timing of this couldn't be better from the point of view of observing the pressures the ground faces from Devon's wet winter weather. The shallow sloping plot possesses a thin layer of heavy clay soil over what appears to be shillet. Bad for drainage, it must be said. After rain, the site becomes a quagmire of mud with pools of standing water. Not ideal, but equally not insurmountable.

The plot design must mitigate waterlogging while catering for the periods of dry summer weather we occasionally, yes occasionally, get too. This clearly requires careful consideration.

After contemplating this question over several nights of fitful sleep, this is the plan I'm actioning. A photo of my progress to date describes it nicely. As you can see, it's a lot of graft, but hopefully worth it.

The approach consists of building up a series of raised beds using soil from the surrounding trenches dug around them. I'm converting the trenches into paths by filling each with wood chips, many, many barrows of wood chips. Thankfully, tree surgeons keep our allotment site topped up with a regular supply. Maybe one day I'll get the chance to thank those guys personally for all that free organic matter. It would not surprise me if it is the lifesaver of my veggies.

Remembering the need to retain water as well as manage excess, I chose to position the raised beds in a staggered formation, again apparent in the photograph. This ensures that during large rain events the water can't simply travel straight along the trenches running vertically down the slope. Instead, the water must twist and turn between the series of alternating raised beds. This naturally spreads out and slows down the water as it navigates through this slalom. This simultaneously encourages maximum absorption while preventing pooling. A win-win.

I'm keen to ensure the raised beds themselves aren't forgotten either. I'm top dressing each with a layer of homemade compost capped with a layer of coconut coir to protect the soil. I'm really hoping my compost supply stretches far enough to cover all the beds, and my coconut coir costs stay in check. I buy those compressed blocks which helps.

Regarding the effectiveness of this approach, I have little time or harvest to go on yet. I've only held the plot a month. But I can report that the completed sections have held up nicely in the repeated deluges of rain and hail recently.

I'm hoping not to jinx anything by feeling quietly optimistic.