Take cover

With soil health under threat, it's time to ditch fertilisers for a gentler system. Cover crops and green manure can help restore Nature, feed insects and birds and add a splash of colour to the countryside, advocates Simon Lester

- Simon Lester

We have ploughed the fields and scattered the good seed on the land for centuries, reaping and sowing, sowing and reaping, taming Nature as we went along. With an evergrowing population, we have needed more food and the Agricultural Revolution of the mid 17th to late 19th century increased productivity through the innovative Norfolk four- course rotation, which effectively allowed a crop to be grown for four years on the trot, against the old system that had a fallow year.

British agriculturist Charles (‘Turnip’) Townshend promoted the system that allowed stock to be kept over winter through grazing of root crops. The use of cover crops and nitrogen-fixing clover kept the soil in good, fertile condition. Most farms at the time were mixed, with cattle and sheep providing the critical part of the four-course rotation—the provision of organic manure.

For soil to be in good heart, it needs organic matter, humus, to retain water, carbon, inver- tebrates and millions of bacteria in each gram. After the Second World War, however, farming changed with the advent of chemical fertiliser: suddenly, because of the growth in the petro-chemical industry, there was a ready supply of cheap, synthetic fertiliser (subsidised until 1974), which provided the all-important plant nutrients. It took much less effort and labour to use bagged fertiliser—soon, farms didn’t need livestock and could grow arable crops year after year, without any organic content, soil becoming a growing medium for continuous cropping. Until recently.