All gardeners are currently working with very wet soil and sadly some are dealing with flooding. There are different ways water can affect soil. There is the sudden deluge causing temporary and localised flooding before draining quickly away. Pooling of water is limited and soil is not immersed in water for long. This means it stays aerobic, containing oxygen in its pores and maintaining good levels of soil bacteria. Give the soil a feed with a general fertiliser in March to replace nutrients that have been washed away.
Another affect, and one I suffer from at home, is the raised water table. Here the water level rises and can’t drain away. You can’t put in drainage because the water has nowhere to go. You have to wait until rivers, becks and fields drain – sometimes miles away – clear away before the water table drops. Here pooling is problematic because if the pool stand for any length of time, oxygen within the soil is replaced by water. Within a couple of weeks the soil becomes anaerobic, the bacteria changes and the roots of plants die.
Once winter has passed and the water has receded you will be able to turn over the soil, add well-rotted organic matter to reintroduce good bacteria, and feed with a general fertiliser. If this is a regular event this land is more suited to growing annual summer crops of flowers of vegetables. In rural areas, flooding is often an annual event lasting a variable amount of time, not necessarily causing anaerobic soil conditions but bringing excess silt and debris with it. The silt needs to be removed otherwise over time your soil texture will change, leaving a poor sand and silt soil. Improve it with organic matter and apply a general fertiliser in March.
Then there is the serious flooding that we have seen in our urban areas. This flooding devastates homes as it usually carries with it sewerage that contaminates not only homes but also soil. But here our friend, good bacteria can help us. Flooding in urban areas is tackled swiftly and is unlikely to be for such length of time that the soil becomes anaerobic. Where you can dig the soil, aim to bury anything you think is contaminated. This breaks soil into smaller particles presenting a bigger surface area for bacteria to feed on. Add fertiliser, particularly nitrogen as bacteria grow on nitrogen. The bacteria will break down the organic matter in the sewerage eventually turning it into humus. Where soil that cannot be turned over, apply a general fertiliser and put a mulch of organic matter on top. There is less surface area for the bacteria to work on so it will take a little longer to recover, but any spoilt soil is covered. I personally would not grow root vegetables for at least one year. One final word of advice, stay off the soil whilst saturated as you will only compact and damage the soil structure. Waiting and allowing gravity and the March winds to dry it out will help your land recover.
Mike I’Anson – February 2016