Cover crops

Cover crops or green manures are an important part of soil management in conservation or regenerative agriculture. The general principle is that the ground should never be left bare as it is prone to erosion and compaction from heavy rain.

No-dig organic gardeners have been managing soil in much the same way for many years but usually with just one or two ‘green manures’. Many gardeners have used a variety of legume to fix nitrogen. The idea being that the nitrogen bearing nodules on the roots do the work of fertilizers. But research a few years back challenged the notion that leaving behind the roots of legumes fixed nitrogen and suggested that the whole crop needed to be incorporated.

Vetch and Rye mix Soils structure mix

With the rise of regenerative agriculture, the use of cover crops is as a way of avoiding soil erosion and improving soil structure. The crops are not incorporated by ploughing but left to die off naturally. The importance of not disturbing the soil is the key factor.

There are now many different seed mixes available and we are trialling two mixes from Kings Seeds; the Vetch and Rye mix and the Soils structure mix.  At the moment they are only available in agricultural quantities and we are grateful to Kings for finding some left-over test seeds for us to use.

The seeds were sown using the age old broadcast method, i.e. taking a small hand full and sprinkling the seed over the soil. There is always a temptation to sow too thickly which is exactly what happened especially with the soil structure mix. Also, we sowed a bit late in the year which did not give the plants time to establish before the cold weather. Having said that they Vetch and Rye mix looks good in early January 2020.

The soil structure mix should have been sown a lot early as it appears to be less hardy. It was also sown far too thickly. Lessons learned for next time.

What next? On the soil structure bed will we will cut down the foliage and cover with a layer of mature compost in the next couple of weeks. We will then sow directly into the compost in the spring. The other half of the bed that did not have a cover crop will be treated exactly the same. It will be interesting to see if there is any difference between the two.

The vetch and rye bed will be left until the next crop is sown or planted. The the foliage will be cut down and left on the bed. We are not yet sure what the next crop will be but are tempted to try no-dig potatoes.

It will be interesting to see how the beds perform. The page will be updated to record progress with the trial.

Update May 2020
The results of using cover crops was mixed. They certainly kept the ground covered over the winter but the beds showed signs of compaction and it was impossible to seed directly into them with first loosening the soil. There had been long periods of very heavy rain with some flooding of the site which did not help. This mirrored our experiences from the last garden. This year we will try an alternative ways of putting the beds to sleep over winter. More later in the year.