How to Rewild

Arable and Horticulture

Habitat Management Plan

HomeGuides

Arable and Horticulture
Habitat Guide

Contents

Arable and Horticulture is a very broad category, taking in everything from intensive Christmas tree farms to organic field margins, bursting with biodiversity. Productivity can be artificially increased in the short term by pumping fertilisers and pesticides into land, but this can cause soil health to suffer. Government policy and subsidies have encouraged this approach for decades, but now we are beginning to see a shift towards regenerative agriculture.

Regenerative agriculture focuses on long term productivity, rather than short term yields. By restoring soil health, farm biodiversity, and water quality, we can safeguard the future of rural businesses. You’ll find that the health of livestock, quality of produce and climate resilience of the system benefit from this futuristic, holistic approach.

However, most regenerative and nature-friendly farming techniques tend to have lower yields (at least, in the short term), so it’s worth noting that switching away from intensive agriculture is not without its costs. While your farm itself, and the surrounding landscape may become more biodiverse, any decision to reduce productivity effectively means shifting your farmland footprint to another farm. This may result in biodiversity loss elsewhere – in places where the effect is hard to notice – other countries, perhaps, with less strict environmental legislation.

Sub Habitats

The edge of cultivated fields, where marginal zones have been left uncultivated, in the form of grass, or managed to promote biodiversity.

Rotational crop of grass or clover, intended to cover cultivated soils and restore nitrogen levels, and reduce erosion through winter months and/or fallow period.

A range of different productive grain crops, including barley, wheat and oats, typically grown as a monoculture.

Any other food crop of agricultural cultivated fields, including vineyards and biofuel (except fruit bushes).

Highly-managed orchards, which typically receive inputs in the form of fertilisers and pesticides, and are frequently mown.

A catch-all category for smaller scale, typically more diversified cultivation of plants, including a range of food and non-food crops from Christmas Trees to fruit bushes, allotments, and flowers.

Value

Arable fields are an essential part of our food system, and at How to Rewild, we do not support rewilding of productive arable systems. As people shift towards a plant-based diet, we may require fewer pastures, but our need for arable land will be maintained. We only recommend restoring nature on pasture, or severely degraded arable land – with a DEFRA Agricultural Land Classification of 4 or 5. It’s worth noting that offshoring arable production to create nature in Britain is a policy that disproportionately affects those in economically disadvantaged parts of the world.

That said, there is some biodiversity value in these fields, as certain crops and production strategies provide more benefits to nature than others. While intensively-cultivated annual crops and grasses have relatively low value for nature (Cereal Crops, Non-cereal Crops, Temporary Grass and Clover Leys); if they are under organic production this can improve biodiversity value significantly. Add-ons like Arable Field Margins (and less common wildflower or agroforestry strips) typically have much higher value for wildlife than the crop around them, especially given their linear form, which enables wildlife to disperse across the landscape.

While Intensive Orchards are not as biodiverse as Traditional Orchards (which are not a major habitat type in the UKHab system), they still create structural diversity that is of value to local wildlife. The value of Horticulture is hard to define, as this subcategory includes such diverse practices as Christmas tree farming and polyculture. A good rule of thumb is that biodiversity is highest in habitats with:

  • Less exposed soil
  • No pesticides used
  • Less, or no artificial fertilisers and muck spreading
  • A diverse mix of crops of differing heights and types
  • More perennials than annuals
  • High density of semi-natural features like scrub, ponds and hedges
  • Less mechanical soil disturbance
  • A low density, diverse mix of livestock raised alongside crops
Arable field
Winter cover crops can reduce the erosion and loss of soil health which often happens in fields left exposed over winter like this one.

Protect

Pesticides (which includes herbicides) are not just damaging to pests, but also to beneficial soil microorganisms and pest control species. It is not just the active ingredient in the pesticide which may be harmful, but also the formulants, which are documented to have toxic effects. For example, the most common weedkiller, Roundup (glyphosate), has negative effects on microorganisms living in the soil that are beneficial to plant growth. By liberally applying pesticides, farmers and horticulturalists could reduce the productivity of soil ecosystems over time.

Tilling or digging of soils destroys their quality by breaking up the soil structure and enabling erosion, while reducing organic matter in topsoil. Soil organic carbon (SOC) is essential for crop productivity; however, despite the popular belief that tilling reduces SOC, in fact research shows that it typically shifts the same carbon lower down in the soil. Only when no-till is combined with leguminous winter cover crops do we see an increase in total carbon. 

Nevertheless, carbon’s lower position in the soil under conventionally-tilled systems does have an impact on productivity, as it reduces beneficial biological activity – the downwards shift in SOC is bad for agriculture and horticulture. No-till systems are now in more widespread use, even on an industrial scale – these reduce erosion and soil compaction, and maintain SOC in the top fraction of soil, although occasional tilling may be necessary to maintain system health. In the long term, they may have lower yield than conventionally-tilled fields, and ‘reduced tilling’ can cause soil compaction on wet soils.

Artificial fertiliser is a complicated issue – correctly applied, it can maintain healthy crops and soils, but overdoses can cause the loss of soil organic matter through mineralisation effects. Without artificial fertilisers, our current stock of farmland would only support half of the global population. But fertiliser production is currently highly carbon-intensive, and, once applied, its breakdown creates further greenhouse gas emissions. The fertilisers are often packaged in slow-release granules, which are made from microplastics, and these were found to be a significant source of microplastic pollution in our waterways.

Runoff from fertilised fields also leads to algal blooms in rivers and streams, polluting drinking and bathing water both in rivers and coastal environments. However, it is worth mentioning that this runoff is, surprisingly, more of an issue in organic systems, where manure is applied with less precision than artificial fertilisers. Nutrient enrichment has caused many semi-wild habitats to transition away from biodiverse, nutrient-poor systems, instead becoming dominated by a few species (e.g. Modified Grassland) due to overspill of artificial fertilisers and muck spreading. Widening field margins along the edges of waterways (‘buffer strips’), and creating treatment wetlands in ditches can intercept nutrient pollution, to minimise this particular impact.

Monoculture crops are an essential component in most productive farming systems, producing vegetables, cereals and fruit, which are an essential part of all human diets. However, these uniform blocks of non-native habitat can present issues for nature, as the creation of large, machine-accessible fields often resulted in the removal of hedgerows, farm woodland and ponds.

Using farm machinery doesn’t mean wildlife has to be excluded, and many farms are now experimenting with in-field wildflower strips that offer additional benefits in the form of organic pest control. By diversifying the structure of the crop, and adding pollinator-friendly plants, polyculture – even with commercial crops – can also improve the biodiversity of an arable or horticultural system.

Poppies in arable field
Annuals like poppies can add additional biodiversity to cereal crops, though the flowers grown in these habitats are typically not native.
Alley cropped pasture diagram
This livestock-based alley cropping system can be repurposed without the fencing and cattle to be used for growing arable crops.

Restore

Huge farmland fields and large horticultural plots may suffer from crop wind damage and poor soil health, especially if tilling is used. In extreme cases, the soil may even be carried away by the wind. But growing tree lines through the centre of large fields, or even in regular strips across arable and horticultural land, can minimise wind damage. This ‘alley cropping’ system can be designed around standard-width farm machinery, with 24m lanes that are separated by 2-3m wide tree crops.

The combined effect of reduced wind speed and increased evapotranspiration from the trees does slightly dry out the soil, especially during drier periods. But wind damage is reduced and pest control is improved by the higher biodiversity. Alleys are typically oriented north-south to minimise the impact on crop productivity, though east-west can also be used, especially on hillsides or in wider systems. Though yield declines within 1-2 tree heights of the edge, the productivity increases for 8-12 heights beyond this, often resulting in overall yield increases.

Over the past few centuries, farms have faced increasing pressures to maximise field sizes and specialise in producing a limited selection of crops or livestock. This maximises profit, which is a high priority, as farm finances have been increasingly squeezed by supermarket pricing and reliance on government grants. It may be difficult to shift a farm away from this conventional system without substantial investment, but doing so can have enormous benefits for biodiversity.

Reducing your reliance on greenhouse gas-emitting artificial fertilisers, and switching instead to manure produced on site is one of the most effective ways of decarbonising your farm system. But this isn’t possible unless you have both livestock and arable within the same property, or are easily able to trade with neighbours. Some carbon calculators still treat greenhouse gas emissions from livestock (where the carbon comes from the grass they eat) as if they are the same as those from the production of artificial fertilisers (which come from carbon buried underground for millions of years). This will inevitably be fixed in the future, but in the short term is leading to a lot of bad advice being given to farmers.

Biodiversity is highest in mosaic landscapes – patchworks of arable, horticulture, pasture, woodland, wetland and other systems. This is what makes switching to a diversified farm system so valuable for nature – and rotating fields between these systems increases the value, allowing soils to recover their organic matter. Pasture can be added into a crop rotation cycle, and the livestock will condition the soil with their fertiliser, while grazing-off the stubble of old crop. Herbal leys can further-improve soil fertility and condition during this rotation – see the Cattle guide for more information.

As artificial fertilisers took over, crop rotation fell out of favour, but this practice itself is a relatively recent technological innovation. The three-field system was only invented in the late Middle Ages, and it can keep a soil in good condition, while minimising the need for fertilisers by using nitrogen-fixing legumes instead. Leguminous winter cover crops are another method which stand in for this system in modern farming, while reducing soil erosion and building back soil organic carbon over time.

Contents