Just following the science

A month ago I wrote a blog about giving up composting, https://wp.me/p6bCCa-2Ft largely because I had a hunch that what was happening on the compost heap would be better happening in the soil. Today I looked at The Garden Professors™ – Advancing the science of gardening and other stuff since 2009 and there was the vindication I needed for my cranky behaviour. In an article about mulching, the nugget that compost offers very little nutrition for soil microbes; the labile carbon which the microbes would use for their food supply has already been consumed by the microbes in the compost heap.

I love Garden Professors and have dipped into it at intervals over the years. Recently though, I looked on YouTube at a video that Linda Chalker-Scott had posted about mulching. Mulches, the Good, the Bad and the Really, Really Ugly. There’s nothing like having an image of the person talking to bring an article you’re reading to life. I started reading a lot more of the blog with that image of a person behind the words. Made a big difference.

On the subject of mulches, hers is an American perspective, mainly a very different climate from mine. Conserving moisture is more important, but weed suppression, soil protection and improvement are the same. If you mulch you should watch the video. If she’d been a speaker at your garden club you’d have thought it the best value ever.

I’m not aware of a UK equivalent to what she and her colleagues are doing as part of their University Extension Service, getting science based gardening and landscape information and advice out to the public. I just looked at the RHS website at what they had to say about mulching. Some of their advice is in stark contrast to Garden Professors and it is the latter who are backing up their advice with references to relevant recent research.

I seem to be on something of a science kick at the moment. I’m currently reading “Acquiring Genomes” by Lynn Margulis and Dorion Sagan, explaining where the variation that gives rise to new species comes from, and it’s not from mutations. I’m just at the beginning but it strikes me as a fierce and fearless book, not at all a tone I was expecting and I can’t wait to read more. With only a Cormoran Strike tale betwixt them, I’d just read Frank Ryan’s Virolution, a more recent book than Margulis’s, explaining the contribution of viruses to evolution. Margulis is rather dismissive of viruses, Ryan makes it clear that we cannot afford to be. He was writing before the current pandemic and it shows all too clearly how predictable it was.

A picture of no relevance to the article.

12 thoughts on “Just following the science

  1. As long as you can look back at mulching arguments and say, “I told you so,” you’re doing the right thing! And now I have to run off and start reading more stuff by these professors.
    Are you planning on running a test – grow a plant with ‘traditional’ compost and one with the carbon uneaten?

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    1. I feel like I should be running a trial but it really needs to be done on a larger scale than I have time or room for, with several replications and a lot of thought given to excluding other variables. The other thing I should do is to try to quantify the quality of my soil now and see if it improves over the next few seasons. Need to do some serious thinking here, soils are not an easy research subject, too complex.

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  2. Jim, thanks for this. A long talk, and just listened to five minutes: I shall be back in the morning to listened when I am bright eyed etc. Hope you do a resume of Ryan’s ideas for us. What can be done or what do you suggest regarding the slugs and snails that lurk beneath all the mulch, and want to go out to taste the plants in full growth that we would prefer to remain unnibbled?

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    1. I get more reluctant to use slug pellets with every year that passes but will probably give in with a few plants. I think the evening patrols with secateurs and a torch helped and will start that a little earlier this year. I’m convinced the key to slugs is reducing their daytime hiding places or making a point of checking them by day and massacring the occupants, notably the leaf canopies of primroses and foxgloves. I think I will clear more leaves next autumn, shred them and spread just a thin protective layer which I will refresh as it becomes incorporated during the winter. There are large areas of the garden where it doesn’t matter but that’s my plan in the vicinity of slug vulnerable plants like Dahlias.

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  3. I can’t remember how I “know” but after listening to someone talking or reading something about mutations happening because of viruses, I am with Ryan and think that viruses are underestimated. So much to learn and so little brain (sigh) I will watch the mulches video with interest

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  4. Was there any reference to the consumption of nitrogen, or other elements, in the soil by the process of decomposition when material is left directly on the soil surface to decompose? It is something I have heard regularly – that piling material from the garden directly onto the beds would lead to the consumption of nitrogen, in particular. I simply could not spread the material that comes off the garden back immediately onto the beds as there is too much. The compost bin system is the only way I can deal with it and then return it as a mulch or as an addition when planting new plants.

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    1. Nothing in that particular article but it comes up elsewhere in their blogs. It seems that the effect on soil nitrogen is negligible if the mulch material is left on the surface but if incorporated can be significant, depending on the material. The material I shred is a mix of green and brown, the green will break down quickly and add to soil nitrogen and the woody bits will stay on the surface to protect it against the elements and break down gradually while encouraging mycorrhizal fungi. That, at least, is the theory.

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  5. I’ve just listened to the whole of the lecture. What a treat of information, very well presented too, proven with experiment etc. I’ve emailed a link to your blog and the lecture to my fellow gardening club committee members. I know at least two who will sit through to the end! Thanks again.

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    1. I’m glad you enjoyed the video. The blog is full of nuggets but for me, it makes a real difference to visualize the person behind the words. As we have all learned from daily Covid briefings, a speakers appearance and demeanour have a big bearing on how what they’re saying is received.

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  6. America is a very big and diverse place. Heck, California alone is very diverse. We all have distinct reasons for composting or not composting. My main reason is that so many neighbors want it. Really, I could do without it. (I just happen to be using quite a bit of it now for healing in plants than must be relocated, but that is another story.) Only a minor portion of debris from our landscapes gets composted, along with contributions from horses and the big cafeteria type kitchens (while they were operating). Yet, even that minor portion is a big pile. So much of our debris gets recycled as greenwaste, or simply dumped out in the forest that produced most of it. Mulching happens to be important here because of the chaparral climate, which lacks rain for more than half of the year. Leaving debris from the forest on the ground where it fell works like mulching, both for moisture retention, and weed suppression. (Redwood debris is very effective for limiting proliferation of weeds!) We do a lot of that, not because it is a good idea, but because we lack staff to clean up so much of the mess. It also creates less debris that we must dispose of.

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