The soil that I farm is naturally acidic, which mainly manifests itself in the form of aluminium toxicity to the crop and has to be limed to be productive. As lime is insoluble, it has to be incorporated throughout the soil profile to have the desired ameliorating effect.
This is, in theory, a one-off operation and once corrected one should be able to continuously no-till that field for many years. Unfortunately, acidity seems to creep back into the system, largely as a result of unused nitrogen fertiliser acidifying the soil.
The best way to incorporate this lime is with a plough, or shall I say “plow”, as to me it is a four-lettered word. I view this ploughing operation as a necessary evil. A bit like open-heart surgery, the doctor must saw through the sternum and crank open the ribcage to perform the life-saving procedure.
I am currently harvesting my soya beans and the chemical analysis of one field is showing acidity. As we have had a bit of autumn rain I decided to take the opportunity to apply lime and plough it in before the winter dry season.
Once ploughed, I sowed my cover crop mix. I am hoping there is enough moisture in the profile for this cover crop to grow and if we get an unseasonal shower or two this cover crop could add to my tight winter feed situation.
By ploughing in autumn and planting a cover crop, the soil will have time to consolidate and settle.
The winter cover will add roots to the profile and a protective blanket to the surface. Not only will this crop help to revive the biology that the mould-board obliterated, but it will also protect the soil from those aggressive African thunderstorms we are prone to.
Cover crops are relatively new to me and I am hoping they will also capture unused nitrogen and help to prevent this acidification in the future.
Ploughing has proved to be hard work and expensive. I now appreciate my no-till even more.
Bruce farms in Kwa-Zulu Natal, South Africa. He plants 320ha rain-fed summer crops. He also runs 2,200 weaner oxen on pastures, finishing them in a feedlot with maize grown on the farm.