Cover crops and glyphosate

Dear Bill,

Your story about vetch was great ( FW, 9 November)! It’s good to know that cover crops are a great asset to a farm’s future. I run 1 500ha of cover crops for my cattle near Belfast. For more than five years, I’ve planted over 50 species of cover crops. It’s great to see that after 17 years, my lands are returning to a forest of freshness! If you’re ever down near Middelburg, please come visit!

Could you give me some advice about burning cover crops? Also, I have a lot of kweek that damages my cash and cover crops. Does glyphosate hurt the soil organisms, and what are its effects?

Gary Murphy, Fountain Valley

Dear Gary,

Cover crops can really improve the soil and soil biology very rapidly. There is a tendency these days to make complex mixtures with as many species as possible. The rationale is that by doing this, there is greater diversity. This is certainly true, but it is unnecessary. The species that occur are there because the environment suits them, and the amount and diversity of species is dependent on the soil environment.

I believe in using just the right number of cover crop species that will give me the maximum amount of biomass and formation of humus and nitrogen. When mixing species of both leguminous and non-leguminous cover crops, the biomass should collectively have a C:N [carbon:nitrogen] ratio of 30:1, or narrower, in order to maximise the amount of humus that can be formed. For me, grazing vetch is the most suitable crop.

I am totally against burning residue as carbon is then transferred into the air instead of transforming into humus. If you leave the residue, it will feed earthworms, which are a valuable asset to our soils, as it decays.

Here are two valuable tips: keep hadedas out as they destroy huge quantities of earthworms; and legumes decompose much more rapidly.

Glyphosate does not diminish soil microbes, but changes their composition. It will reduce the amount of fungi and increase bacteria. I don’t like using it, but there are occasions where it is the best way to go. Kweek is difficult to control, and repeat application may be necessary. Kind regards, Bill