05 Sep Cover crops and integrating livestock into arable rotations

The benefits of planting winter cover crops are wide ranging and very important for the health of the soil, water quality, wildlife and crops. This is a quick list of those benefits.

For Soil:

• Cover crops help to prevent soil erosion and run-off, keeping soil in the field
• Deep-rooting crops will help to improve soil structure in compacted soils
• Cover crops build soil organic matter which improves soil structure and water holding capacity helping to protect against extreme and prolonged rainfall and drought conditions
• Reduce water-logging and increase workability of heavy soils
• The presence of crops over winter sustains mycorrhizal fungi, and maintains soil biota which promotes healthy soil biodiversity

For water quality:

• Cover crops established early will put on a lot of growth, taking up nutrients, particularly nitrates, from the soil and prevent them from leaching through the soil profile, out of the rooting zone and into groundwater
• The green cover intercepts rainfall, reducing surface capping, and taking up water which can prevent soil erosion and run-off over winter and reduce sediment and phosphate pollution to surface water

For wildlife:

• The ground cover provided by the crops will provide shelter for wildlife over the winter months
• The soil is likely to be richer in soil invertebrates, feeding birds and other wildlife over winter
• Some early-sown cover crops can provide a late nectar source in mild autumns

Other agronomic benefits:

• Cover crops that establish well provide competition to weeds, helping to suppress them and reducing herbicide bills
• Cover crops also take up P and K therefore helping to maintain soil indices
• Mustard (in particular) contains glucosinolates which are released when the crops are rolled, cut or incorporated, which mixes with a naturally occurring enzyme and water to produce a fumigant that can be deadly to weeds, soil-borne pathogens and nematodes
• Deep rooting crops can bring up trace elements from deep in the soil profile
• Can result in healthier plants as a result of many of the factors above

This year on the farm we have planted a cover crop with 7 different nutritious species of plant (vetch, rye, crimson clover, Balansa clover, fodder radish, forage rape and phacelia), all suitable to be grazed by livestock. The cover crop was planted directly into the stubble (we chop the straw and leave it on the surface) on the day the wheat was combined off the fields. By the beginning of November the cover crops were knee high and ready to be grazed by the sheep and cows. The animals are rotated around the cover crops at intervals when they have ‘eaten a third, left a third and trampled a third of the greenery’ thus leaving plenty to protect the soil and feed the soil microbes. There will be more than enough fodder until January which reduces the quantity of haylage the livestock will need over the winter adding a further economic benefit.  The animals add to the fertility of the soil by their dung which in turn increases the number of important beetles. Grazing arable land also allows us to rest the permanent pastures reducing the damage to the sward from poaching.

The spring sown arable crops will benefit hugely from the cover crops. The high number of soil microbes maintained over the winter will quickly form beneficial bonds with the new crop and get the plants off to a good start and healthy plants supported by a diverse soil biota will be better able to withstand pests and diseases. All this amounts to reduced use of artificial fertilizers and sprays and cutting down on our reliance on fossil fuels and reducing our carbon footprint.