So I’d just sown some Phaecelia at the allotment and bought some Winter Grazing Rye and then I picked up my copy of Grow Your Own magazine to find an article on green manure. The article unfortunately said there was little recent data to show that they were any good, but I had just seen Monty Don sowing some winter grazing rye and he had said it would be as good as manuring his ground. So had I just wasted my time and money or are green manures worth the trouble?
There’s certainly an awful lot of material out there in favour but I’m not sure whether the agricultural practice of allowing a field to go fallow can be suitable for small scale growing.
The problem for me is that this is my first year on my plot and I won’t have enough compost to mulch all of my beds. I have acquired some manure but I am still wary of manure after the problems with herbicide contamination. Also as a third of my beds are devoted to cutflowers these don’t need high levels of nutrients. So I thought green manures could fill that gap.
The Phaecelia I sowed has grown to form a feathery green carpet that certainly looks better than a patch of bare soil. It will, hopefully, provide some cover for beneficial insects over the winter, although it will equally provide cover for the creatures I don’t want. It should also protect the soil structure from heavy winter rain. It seems that it is the nutritional benefit that green manures provide that is the main area of dispute and one that is hard for the amateur gardener to measure. It seems that green manures need to be in the soil for much longer than is viable for the amateur grower to provide any significant nutritional benefits.
By next spring I will have areas that have been manured, areas that have been mulched with compost and ares that have been green manured, so I’ll try and keep some notes and see what I find.
I definitely think that soil benefits hugely from having something growing it. Plant roots have a beneficial impact on soil structure helping the break up the soil, forming channels that air and water can enter and leave, making the soil environment a better place for soil organisms to thrive and improving drainage. So I’m willing to give green manures a go and if nothing else, digging them in next spring will provide some welcome post-winter exercise.
For more information read October’s issue of Grow Your Own magazine or go to the RHS website.