Biobeds are a good way of dealing with the disposal of dilute sprayer washings (more information from the VI website). When we installed the biobed at our Chishill farm some 5 years ago we knew that the substrate would have to be refreshed and that day arrived last July.
There is always something going on at the farm so it’s not easy picking the best time to dig out a biobed. As July is a quiet time from a spraying perspective it was felt that that would be as good a time as ever.
Then there’s the problem of actually digging the substrate out. If you have access to a digger then that can save a lot of sweat, otherwise it’s a case of grabbing a shovel and digging it out the old fashioned way. Whichever method you use, however, care needs to be taken not to damage the liner. It’s better to leave a small amount of substrate than damage the liner!
Now the digging is over, we need to store the spent substrate for 12 months. According to the Environment Agency, this storage must be away from any bore holes, surface water, ditches and drains. At the end of that year the substrate can then be spread on the farm. Looking at what came out today, this will be a great source of organic matter. I was also amazed at the huge number of worms!