13/08/2024
I'm seeing a lot of compacted soil while out doing assessments this month so let's talk about it! I'll start simple and work up to the technical.
A compacted soil is hard to the touch, it doesn't give way and can't be dug into very easily. Compacted lawns are often patchy and host to moss and weeds like ragwort and dandelion. Water will also run right off compacted soil, leading to flooding. It's often water that partly causes this compaction in the first place, as most compaction is formed by people walking or driving over wet soil. It's probably no coincidence I'm seeing more compaction given the record rain earlier in the year.
So, compaction inhibits water infiltration, and makes it harder for roots to spread. The bigger and thicker the root the more successful the plant will be in compacted soil, this is why you're seeing those particular weeds: They have taproots! It also reduces the amount of surfaces available for soil life to live on, as the soil is now a fairly homogenous mass rather than a bunch of little clumps called aggregates. These aggregates can be thought of as houses for your microbes to live in.
You can think of taproot plants as natures way of breaking up compaction; over time they will do so and make way for more delicate species. How can we accelerate this? The typical way is through tillage, which means manually breaking up the soil. You may have heard of No-Till growing, but despite the name even its biggest proponents will agree that in situations of heavy compaction a certain amount of tillage is necessary. No-Till is a bit more of a practise to avoid *having* to till, but Till-once-never-till-again is less catchy a name...
What are some more natural methods? We can plant taproot cover crops such as comfrey and red clover, or possibly root vegetables like beetroot or carrot (though don't expect a good sized crop). These crops will grow, bust the compaction, and then can be killed off and mulched into the soil to avoid nutrient loss. For a lawn, however, I would recommend simply broadforking and adding a soil improver (then replacing the grass with clover but that's another post).
I hope you feel more equipped to preserve your soil, fix your stubborn issues, and continue your green journey. If you've any questions or come up with any solutions I haven't mentioned please share them!
