What is the favored way to lighten & amend soil inside a raised bed? My raised beds are aluminum troughs with volumes of 220 gallons. They are 2 x 2 x 8ft. We've been using them for a few years to grow garlic, tomatoes, strawberries, etc, and I haven't really done any maintenance on the soil. I have sent samples to be analyzed to understand the nutrient picture but the soil is fairly dense and clumpy so I'm sure I need to lighten it in some way. We're in Seattle.
2 Answers
One solution I once saw (and it is not my idea, but seems to work) with raised beds is to designate a rotation pattern (say squash, potatoes, corn, beans, roots) and load all the manure onto the year 1 bed. The idea is that squash can tolerate a lot of fresh-ish manure, spuds can handle it after a year, corn after 2 years and so on. So in a given year only the squash bed gets the manure, and you pile it as high as you like without it collapsing and plant pre-germinated potted squash in the top. Over the 5 years the amount of manure diminishes until there is hardly a noticeable layer. There is never a need to turn the manure into the bed soil. Much goodness leaches down from the heaped organic matter into the bed underneath.
From a practical point of view probably best to move say 6 inches of soil from the intended squash bed to the year 5 bed, leaving a good space to start building up the manure.
Easy way is to remove some of the compost and add new compost and add some top soil too. This should make them go for a while. Compost gets heated up when the weather is hot, so better to add some top soil.