Posted By: Paul 08/12/2009 09:40:00
Over the past few weeks I have been working on a garden project where I have had to remove a large amount of dead trees.
The trees used to make up a hedgerow across the back of the garden and defined a boundary between the garden and a field. As with most hedgerows the boundary was also defined by a raised hump where the trees where and a ditch on the field side. Sadly over the past two years the hedge, which was full of Hawthorne and Blackthorn has gone from being the picture of health to being dead as a Dodo. What's more, the hedgerow continues in the gardens to the left and the right without any sign of dying off. Now if I hadn't know the people who own the garden better I would have assumed the dead hedge was a result of judicious use of a weed killer. But they where distraught over the dead trees and wanted to restore the hedge to it's former glory. Clearly the damage had been caused by something in their garden which had not reached anyone else's, so my first job was to clear back all the old trees, leaving the one remaining live hawthorne tree. I wanted to make sure there was no sign of any fungal infection or disease in the soil, so I planned to dig down at least a spades depth and remove all the soil from the surrounding area. To be honest I was not sure what I was going to find, but I may have had to have the soil analysed if I could not find any signs of disease or fungal threads. In the end it was much simpler than that to work out what had happened to the hedge. The bad weather we've had over the past couple of weeks gave me the first indication of the problem. As I started to remove the top soil on the mound of the hedge I found at least a foot depth of compost on the ridge line of the hedge, at some points it was almost 2 feet deep. The hedgerow had become a dumping ground for old compost. After a bit more digging I found the foundations of a greenhouse which had been removed about five years ago. So putting two and two together I guessed the compost had been the remains of grow bags which had bee dropped in the hedge. However toxic the Tomato compost can be I couldn't see it killing off a hedgerow. So I started to look at possible fungicides and pesticides which may have caused a problem. It was about this time when the weather broke and I had to stop work for a few days. After three days of heavy rain (about 2.5 inches), I returned to the garden to finish of removing the compost. It was then I found the jelly like substance in the compost. It was the swell gel used to keep the compost moist which had absorbed the rain. What's more it seemed to have absorbed all of the rain and not let any pass through the layer of compost. I decided to test the theory and turned the hose onto a section of the ground which had not been disturbed yet. After 15 min's I water moderately pouring out I then dug down through the compost layer to discover the soil underneath was only just starting to get wet. It would seem the mystery has been solved, the combination of the compost layer with swell gel, and the lack of rain for the past few years had resulted in the hedge dying from a lack of water, and the one remaining tree was far enough from the compost layer to not have been affected.