Mixed rotational systems explained

31 May 2021
organic crop rotation crimson clover

“The wet weather has been great for our grass clover fertility building leys. This is a picture of crimson clover (In flower) mixed with vetch and rye grass. This part of the field was our courgette patch last year. The grass clover got sown in September and it’s now knee high!”

This process, mentioned above by Sarah at Ripple Farm, is an essential part of what they call a mixed rotational system. This is a crucial way of maintaining healthy fertile soils on a farm and an ancient farming practice that has mostly become abandoned in the race for intensification. 

 

How it works

After a cropping season, the field is left ot go "fallow", which means it is rested for two years. To help return fertility to the soil, our farmers sow 'green manure' – mixes containing clover, grasses and other beneficial plants - also known as “herbal leys” that add nutrients and organic matter to the soil as well as providing food for pollinators. These are then either grazed Cancelby sheep or mowed before they set seed. When they’re ready to use the field again, the leys are ploughed back into the soil, where all the nitrogen from the plants is “fixed” into the soil, boosting the fertility. In addition, that two-year fertility-building period allows for carbon to be sequestered into the soil – the plants take carbon dioxide out of the atmosphere and store it underground.

The grazing animals, like Sarah Green's small herd of sheep, not only help to clear the land but they add extra fertility with their dung droppings. And the sheep get a better quality of feed as well. The mineral content is much higher than a ryegrass mix and can carry 60% more calcium. This whole process brings more microbial life into the soil. Studies have shown that these mixed rotation systems are actually more productive in the long run as healthier soils create more abundance.

What's the pay-off?

How can a farmer afford to leave fields un-cropped for two years? For organic growers its part and parcel of caring for and feeding the soil. But for many farmers, margins are so tight, particularly If they’re selling to supermarkets, they may not even get paid the price of production for their crop so they have to use every bit of land they have to keep their heads above water. This underpayment of farmers is at the heart of unsustainable farming practices as it means farmers cannot allow the land to rest and are more likely to turn to artificial fertilizers and pesticides to manage the land. At Crop Drop, paying farmers properly is one of our core guiding principles.  In the long-run it pays off. Crop rotation brings more microbial life into the soil. Studies have shown that these mixed rotation systems are actually more productive in the long run as healthier soils create more abundance.

Protection from drought and deluge

Another advantage of sowing herbal leys is help to reduce flooding and drought, as they improve soil structure. Herbal leys include plants with deeper penetrating roots, so during heavy rainfall water is absorbed more readily and is stored in the water table to be used during droughts. This is particularly significant for livestock grazing, which takes up a significant proportion of farmed land. Modern pastures are sown with monoculture ryegrass which in comparison to herbal leys, don't help to absorb water so fields get very flooded and water-logged in very wet weather or water runs off into drains, carrying precious top soil with it.  In light of climate change and the increasing pattern of drought and deluge, the switch to herbal leys is ever more urgent. We need more farmers to embrace these simple, ancient practices. It's encouraging to know that  a number of prganisations are working with farmers to make these changes, such as Pasteur for Life, the the Soil Association is leading a programme called FABulous Farming that works with conventional (non-organic) farmers to reduce reliance on external inputs, like chemical fertilisers and pesticides, by encouraging methods such as these mentioned above to improve biodiversity and soil health. This is having a positive impact as farmers are making the changes and seeing the results.

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