Crop rotation, soil cover management and integrated pest management

Disadvantages can include the fact that benefits may vary with local conditions, the greater amount of knowledge (about different crops and their interactions) required on the part of the farmer, as well as the need to have a greater variety of machines available on the farm (BIO Intelligence Service, 2010).

Crop rotation is beneficial to wildlife and biodiversity because different crops are sown and harvested at different times. For instance, crops such as sugar beet and potatoes are spring sown, which leaves bare stubbles from the previous crop through the winter providing food for farmland birds at a time when food from other sources is limited. Crops such as oilseed rape and sunflowers are flowering crops which support pollinating insects. Crops such as linseed and field beans are late harvested providing crop cover into the autumn when cereal crops have been cleared. Where crops within the rotation are distributed in the landscape, rather than grown in single blocks, species such as birds and brown hares adapt their foraging ranges to food availability.

Cover crops provide a range of benefits for wildlife and biodiversity. Mixtures of mustard and rye sown as autumn cover crops not only mop up nitrate which might otherwise be leached over winter, but provide protective foraging habitat for birds. Spring sown green covers, such as vetches and phacelia produce pollen and nectar for bees and other pollinating insects.

All cover crops are eventually destroyed either by ploughing or the use of herbicides. Crop root structures help bind the soil over winter months when soils are vulnerable to erosion. Reducing soil erosion reduces the loss of phosphate and sediment to adjacent water bodies which improves water quality in aquatic habitats. This has been shown to be greatly beneficial to the aquatic ecosystem. (Lane et al, 2006).

Organic matter returned to the soil benefits soil structure and permeability, which in-turn improves conditions for soil fauna. Chopped cropped residues and cover crops both add organic matter and are a fundamental pillar of Conservation Agriculture (www.ecaf.org) in helping to protect soils. Studies have shown combined benefits of reduced tillage and cover crops with earthworm populations increasing twenty fold compared with ploughing and bare soil over winter (Longhurst, 2010).

IPM focuses on preventive strategies and the use of non-chemical alternatives for control, like mechanical and biological solutions. Many of these are fostered by the creation of refuge areas or by the deliberate cultivation of crops known to favour beneficial predatory invertebrates. Beetle banks are raised permanent structures measuring 2.0 m wide and 0.4 m high installed by some IPM farmers through the centres of large fields and sown with tussocky perennial grasses. These provide an ideal habitat for overwintering for Carabid beetles with scientists reporting up to 1500 per square metre (McCloud et al 2004). Similarly Conservation Headlands, a 6.0 to 12.0m strip around the outside of the field where selective weed control is practiced provides an enhanced habitat for insects (Sotherton et al 2005). Providing habitat and reducing sprays can have significant benefits to the food webs within arable ecosystems and can reduce reliance on manufactured pesticides (Sotherton 1991).