Dry Patchy Lawns
Dry Patchy Lawns
Many lawns suffered in the heatwave of 2018 which wasn’t helped by the late, cold and wet end to the winter which dragged on into spring. This results in lots of cases with lawns that have bare patches which have not recovered.
The reasons for this are many and we do need to have a look to diagnose why and suggest remedial action. However, one to the more deep-rooted reasons is a phenomenon called (rather boringly named) “Dry Patch”.
In the soil, there are countless numbers of organisms that are quite happily going about their activities, breaking down organic matter and turning it into nutrition for other plants.
Whatever the size of your garden, there will be more organisms underground than above ground in a total rain forest! This means that you will have hundreds of millions of different bacteria and fungi living quite happily!
Many of these fungi produce “waxy” resins in their day o day activities and in some soils, and in some conditions, these can bind soil particles together causing the soil to become “hydrophobic” meaning that it will repel moisture.
If we look at this example, we can see that the soil to the left has started to recover and the soil has moisture within it.
To the right, the soil is still very dry. This is after substantial rain and the reason is the soil has become “hydrophobic”. This in effect makes the lawn look even worse as any rain ends up penetrating the soil in the “good bits” after running off the bad bits making the situation appear worse.
I have a habit of calling these soils somewhat “constipated” which is not a scientific term at all, but I feel it describes them well.
The solution is very simple. We need to apply wetting agents that contain detergents to the soil to help break up the waxiness in the same way that we would wash roasting pans!!
However, to get the chemistry into the soil, we need to open up cracks to help the moisture penetrate, otherwise, all the chemistry will be wasted.
To do this, we use a pedestrian aerator with very long tines which are very thin to penetrate the soil and create many cracks.
This means that we can then apply the right chemistry to help alleviate the problem and help the soil to regain a healthy status before overseeding.
If the lawn is irrigated, we can use a liquid formulation but where (as is often the case), watering is not possible, this is not a problem and we can use a granular formulation which will gradually be used as and when rain does occur.
Once we have dealt with this issue, reseeding is simple but if the soil is left in the hydrophobic state, the seed will not germinate.
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