Chapter 11: Environment
Updated 21 October 2022
Summary
- In 2021 utilised agricultural land use stood at 71% of the total area of the United Kingdom.
- Since the late 1990’s nitrogen and phosphate application rates have fallen.
- A comparison of soil nutrient balances (in kg per hectare) from the year 2000 to 2020 shows a 17% decrease for nitrogen and a 27% decrease for phosphate.
- Estimated greenhouse gas and air pollution emissions from agriculture have fallen between the year 2000 and 2020 (the most recent data available):
- Nitrous oxide emissions have decreased by 16%
- Methane emissions have decreased by 12%
- Ammonia emissions have decreased by 10%
- The farmland bird index has decreased significantly since 1970 with the index for all farmland species in 2019 less than half of 1970 levels.
Introduction
This chapter provides an overview of the change in inputs (fertiliser, pesticide and water usage) and environmental management over time as well as the monitoring of environmental impacts to which agriculture contributes.
Figure 11.1 Agriculture’s environmental footprint (%)
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per cent | Agriculture | Other sectors | Total |
---|---|---|---|
Methane emissions | 48 | 52 | 100% |
Nitrous oxide emissions | 69 | 31 | 100% |
Carbon dioxide emissions | 2 | 98 | 100% |
Total GHG emissions | 11 | 89 | 100% |
Ammonia emissions | 87 | 13 | 100% |
Phosphorus in rivers | 28 | 72 | 100% |
Nitrogen in rivers | 61 | 39 | 100% |
Water abstraction | 1 | 99 | 100% |
Area of land | 71 | 29 | 100% |
Source: Collated by Defra
Notes:
- All data are UK and for 2020 except for the following:
- Water abstraction is England and 2016
- Nitrogen in rivers is England & Wales, 2004
- Phosphorus in river is Great Britain, 2006 estimate
- Area of land 2021
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Whilst agriculture contributes less than 1% to the United Kingdom’s economy (see Chapter 4: Accounts), it provides around three-quarters of the indigenous food we eat (see Table 14.1) and is responsible for around 70% of land use (see Figure 11.1). As well as being vital for food production, agriculture helps to shape the landscape, providing important recreational, spiritual and other cultural benefits. This can be viewed in terms of delivering vital ecosystems services, with food production being a provisioning service whilst other environmental and societal benefits are delivered by, for example, cultural and regulating services.
Agricultural production and the associated land use and management are key drivers of the environmental impacts from the sector. A key challenge is to decouple production from its environmental impact so that production can be increased whilst reducing the overall environmental footprint.
Farm practices and the use of inputs (particularly fertilisers and pesticides) directly influence the environmental pressures from farming including the quality, composition and availability of habitats and impact on air, water and soils.
In recent years, the key drivers of change in terms of environmental pressures from agriculture are declines in the number of livestock, specifically ruminants, and reductions in fertiliser applications, particularly on grassland. Reforms to the Common Agricultural Policy, and in particular the decoupling of subsidy payments from production, have been instrumental to these drivers of change. As a result of these reforms, agriculture has become more responsive to market conditions which may influence both positive and negative environmental impacts.
Land use
Figure 11.2 Agricultural land use
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Source: June survey of Agriculture, Defra
Notes:
- Grassland includes temporary and permanent grasslands, sole rights rough grazing and common rough grazing areas.
- Set-aside was a scheme within CAP that required farmers to put land out of production.
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In 2021 the proportion of utilised agricultural land used for grassland was 72% with 27% used for crops. Grassland and crop land use have both remained relatively stable from 1990 to 2021 at around 12 to 13 million hectares and 4 to 5 million hectares respectively. The ending of the set-aside scheme in 2008 meant that the area of uncropped land fell sharply that year. From 2008 onwards the area of uncropped land has fluctuated around that level, mainly influenced by commodity prices and weather conditions.
Pesticide usage
Plant protection products (pesticides) are used to regulate growth and to manage pests and diseases in crops. They play a major role in maintaining high crop yields and therefore greater production from agricultural land. However, they can have detrimental impacts on the environment, particularly on terrestrial and aquatic biodiversity.
The need for pesticide usage varies from year to year depending on growing conditions, particularly the weather which influences disease, weed and pest pressures. In addition, longer term variations are due to changes in the range and activity of active substances, the economics of pest control, and resistance issues. In the United Kingdom the treated area of arable crops (number of hectares multiplied by number of applications) has remained relatively stable since 2008, whilst the total amount of pesticide applied (kg/ha) has shown an overall decline.
Figure 11.3 Pesticide use on cereals, Great Britain (kg/ha)
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kg/ha | Fungicides | Growth regulators | Herbicides | Insecticides | Molluscicides | Total |
---|---|---|---|---|---|---|
2010 | 0.12 | 0.52 | 0.25 | 0.06 | 0.19 | 1.16 |
2012 | 0.12 | 0.43 | 0.26 | 0.05 | 0.15 | 1.01 |
2014 | 0.13 | 0.42 | 0.26 | 0.03 | 0.13 | 0.97 |
2016 | 0.15 | 0.42 | 0.30 | 0.02 | 0.12 | 1.00 |
2018 | 0.15 | 0.40 | 0.32 | 0.02 | 0.12 | 1.00 |
2020 | 0.14 | 0.39 | 0.28 | 0.01 | 0.10 | 0.91 |
Source: Pesticide Usage Survey
Notes:
- All pesticides include seed treatments.
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In recent years cereals accounted for the majority of both treated area and the weight of pesticides applied to arable crops in the United Kingdom. The majority of UK cereals (more than 80%) are grown in England. Figure 11.3 shows the application rates for different types of pesticides used on cereal crops in Great Britain and how these have fluctuated over time.
Further information can be found on the pesticide usage webpage.
Water use
Figure 11.4 Water abstraction, England (million cubic metres)
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Year | Spray irrigation | Other Agriculture | Total |
---|---|---|---|
2010 | 102 | 24 | 126 |
2011 | 117 | 25 | 142 |
2012 | 50 | 25 | 75 |
2013 | 97 | 25 | 122 |
2014 | 88 | 26 | 114 |
2015 | 94 | 25 | 119 |
2016 | 84 | 26 | 110 |
2017 | 87 | 22 | 109 |
Source: Environment Agency
Notes:
- Based on most recent data available.
- Spray irrigation includes small amounts of non-agricultural irrigation.
- 2015 figure has a break in the series where information concerning abstractions in the country of England and the Dee/Wye regional charge areas (formally the Wales regional charge area) has been amalgamated into the North West and Midlands regional charge areas respectively.
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Water abstraction from groundwater and surface water sources may be needed for irrigation purposes to maintain high yields and good crop quality, particularly in areas with low rainfall and for certain crop types. Over abstraction can be detrimental to aquatic ecosystems and limit resource for other industries. In 2017 around 1% of the total water abstracted in England was attributed to agriculture, most of which took place in the south and east of the country.
Volumes of water abstracted for agricultural purposes is highly variable from year to year and greatly influenced by rainfall amounts, especially during the growing season. As demonstrated in Figure 11.4, in 2017, the recorded abstraction rate in England was 109 million cubic litres which was a slight decrease from 110 million cubic litres in 2016.
Further information on the water abstraction webpage.
Fertiliser uses
Nitrogen and phosphorous are key nutrients needed for crop growth. A deficit in either or both of these nutrients can have a negative impact on crop yields and levels of production. The main source of these nutrients are mineral fertilisers and organic fertilisers such as manures and slurries from livestock. Various factors can have an adverse impact on the environment such as application method, over-application and natural losses from soils and manures. These impacts include water quality (nitrogen and phosphorous levels in waterbodies), air quality (ammonia emissions) and climate change (nitrous oxide emissions).
Most agricultural soils do not contain enough naturally occurring plant-available nitrogen to meet the needs of a crop throughout the growing season so supplementary nitrogen applications are needed each year. Nitrogen usually has a large immediate effect on crop growth, yield and quality. Correct rate and timing of applications is important to ensure crop growth requirements are met.
Annual levels of use of nitrogen and phosphate application are influenced by fertiliser prices, crop prices, crop type and weather-related issues during the growing season, for example the fall in phosphorus application rates in 2009 was related to high fertiliser prices and the changes in nitrogen use seen in 2019/20 reflect exceptional changes in the balance of the winter and spring cropping seasons (see Figures 11.5 and 11.6).
Figure 11.5 Nitrogen (N) use (kg/ha) on all crops and grass, Great Britain
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Source: British Survey of Fertiliser Practice
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In Great Britain between 1990 and 2019 the overall mineral nitrogen application rate on tillage crops was largely in the range of 140 -150 kg/ha, but the rate in 2020 fell below this level. The rate of nitrogen application fell by 16 kg/ha to 121 kg/ha in 2020 compared to 2019. For grassland, nutrient application rates have always been lower than for cropped land. Between 1990 and 2020 there has been a downward trend in the overall mineral nitrogen application rate on grassland and in 2020 the rate was 53 kg/ha (see Figure 11.5). A reduction in total cattle numbers is thought to have contributed to this, possibly in conjunction with some improvements in manure use efficiency.
Phosphate is applied in fertilisers and manures, particularly to replace the quantities removed in harvested crops. Most British soils can hold large quantities of phosphate in forms that are available for crop uptake over several years. Therefore, managing the supply of phosphate is based on maintaining appropriate levels in the soil with the timing of applications less critical.
Figure 11.6 Phosphate P2O5 use (kg/ha) on all crops and grass, Great Britain
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Source: British Survey of Fertiliser Practice
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From 1990 to 2020 total mineral phosphate application rates have more than halved to a rate of 15 kg/ha in 2020 (see Figure 11.6). More recently the decline has levelled off with a similar rate seen since 2012. For grassland, rates applied have always been less than on cropped land. Both rates on grassland and cropped land have shown an overall downward trend between 1990 and 2020, with rates applied on grassland remaining at 8kg/ha for the last few years.
Further information found in the British Survey of Fertiliser Practice annual report.
Soil nutrient balances
Soil nutrient balances provide an indication of the overall environmental pressure from nitrogen and phosphorus in agricultural soils. They measure the difference between nutrients applied to soils (largely as fertilisers and manures) and those removed from soils by the growth of crops, including grass for fodder and grazing. An increase in the balance per hectare indicates a greater environmental risk from nutrient losses and their associated emissions whereas a decrease in the balance per hectare broadly indicates a reduced environmental risk. However, there is a risk that nutrient deficits lead to poor soil fertility and subsequent loss of yields.
Figure 11.7 Nitrogen (N) soil nutrient balance (kg/ha)
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Source: Defra, Soil Nutrient Balances
Notes:
- The series break in 2009 is due to changes in farm survey data collection.
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Provisional estimates for 2020 show that the nitrogen balance for the UK was a surplus of 92 kg/ha on managed agricultural land (see Figure 11.7).
This is an increase of 6.1 kg/ha (7%) to the nitrogen balance surplus compared to 2019. The increase was driven by a decrease in offtake of 13.5kg/ha (12%) while inputs decreased by 7.4kg/ha (3.8%) over the same period. The decrease in offtake was attributed to significantly higher cereal crop yields and production in 2019.
The longer-term trend (compared to 2000) shows an overall reduction to the nitrogen balance surplus of 19 kg/ha (17%). The main drivers for this fall have been reductions in the application of inorganic (manufactured) fertilisers and manure production due to lower livestock numbers, although this has been partially offset by a reduction in the nitrogen offtake (particularly forage) over the same period.
Figure 11.8 Phosphorus (P) soil nutrient balance (kg/ha)
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Source: Defra, Soil Nutrient Balances
Notes:
- The series break in 2009 is due to changes in farm survey data collection.
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Provisional estimates for 2020 show that the phosphorus balance for the UK was a surplus of 7.3kg/ha on managed agricultural land (see Figure 11.8).
This is an increase of 1.9 kg/ha (34%) to the phosphorus balance surplus compared to 2019. This is the largest surplus for over 10 years and has been driven by a 2.2kg/ha (12%) decrease in offtake while inputs decreased by 1.9kg/ha (1.5%) when compared to 2019. As with nitrogen, the decreased production in harvested cereal crops significantly impacted the phosphorus balance.
The longer-term trend (compared to 2000) shows an overall reduction of 2.7 kg/ha (27%) with the main drivers being similar to those for nitrogen.
Further information found on the soil nutrient balances publication can be found here
Water quality
Agriculture contributes to the pollution of water bodies through the leaching of fertilisers, pesticides, and manure (nutrients and faecal bacteria)as well as an increase in sediments. Rainfall may wash a proportion of fertiliser off fields into local water bodies or cause soluble nutrients to filter into groundwater. Pesticides can be washed into water bodies by rainwater or may enter them directly if they are sprayed close to water. Pesticides can also enter groundwater via soil infiltration. In addition, erosion can wash topsoil into water bodies and these soils can carry large amounts of phosphates and agri-chemicals bonded to clay particles.
High nutrient concentrations, particularly phosphorus, can cause nutrient enrichment (eutrophication) resulting in excessive growth of macrophytes and algae which can deplete dissolved oxygen levels. Excessive levels of nutrients must be removed from water bodies used for drinking water to meet legal limits, with water companies incurring significant costs. It has been estimated that agriculture accounts for around 61% of the total nitrogen in river water in England and Wales [footnote 1] and around 28% of the total phosphorus load in river water in Great Britain [footnote 2], although this estimate may also include phosphorus from septic tanks [footnote 3].
Due to the implementation of the Water Framework Directive (WFD) a revised approach to monitoring water quality across the UK was introduced in 2009. The WFD assesses water quality using three categories (ecological quality, chemical quality and hydrological quality). For each site each category is assigned a grade which are then combined to provide an overall classification. The combined score is based on ‘one out, all out’, e.g., if one category is ranked as ‘poor’ the water body will be classified as ‘poor’.
As in 2019, 36% of surface water bodies assessed under WFD in the UK were in ‘high’ or ‘good’ status in 2020. Diffuse water pollution from agriculture and rural land use has been directly attributed to 28% of failures to meet the WFD standards in England [footnote 4].
Further information on the status of water bodies in the United Kingdom
Greenhouse gas emissions
Agriculture accounts for approximately 10% of total greenhouse gas emissions in the UK. Three greenhouse gasses emitted by agriculture are nitrous oxide, methane and carbon dioxide.
Agriculture is the major source of both nitrous oxide and methane emissions in the UK, accounting for 69% of total nitrous oxide emissions and 48% of all methane emissions in 2020. In contrast, agriculture only accounted for about 1.7% of total carbon dioxide emissions in the UK.
Figure 11.9 Nitrous oxide emissions (million tonnes carbon dioxide equivalent)
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Year | Non-agriculture | Agriculture | UK total |
---|---|---|---|
2010 | 7.9 | 15.1 | 22.9 |
2011 | 7.0 | 15.1 | 22.0 |
2012 | 6.9 | 14.9 | 21.8 |
2013 | 6.8 | 15.0 | 21.8 |
2014 | 6.8 | 15.6 | 22.3 |
2015 | 6.8 | 15.2 | 22.0 |
2016 | 6.6 | 15.0 | 21.7 |
2017 | 6.7 | 15.5 | 22.2 |
2018 | 6.7 | 15.3 | 22.0 |
2019 | 6.7 | 15.3 | 22.0 |
2020 | 6.4 | 14.5 | 20.9 |
Source: Department for Business, Energy and Industrial Strategy (BEIS, formerly DECC)
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The majority of agricultural nitrous oxide emissions come from soils, particularly as a result of nitrogen fertiliser application, manure (both applied and excreted on pasture) and leaching/run-off. In 2020 nitrous oxide emissions from agriculture are estimated to have fallen by just under 20% since 1990 and just under 16% since 2000. This is consistent with trends in fertiliser usage over the same period.
Figure 11.10 Methane emissions (million tonnes carbon dioxide equivalent)
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Year | Non-agriculture | Agriculture | UK total |
---|---|---|---|
2010 | 41.7 | 25.1 | 66.8 |
2011 | 39.2 | 25.0 | 64.2 |
2012 | 37.7 | 24.9 | 62.6 |
2013 | 33.6 | 24.8 | 58.4 |
2014 | 31.0 | 25.4 | 56.4 |
2015 | 29.9 | 25.5 | 55.4 |
2016 | 28.2 | 25.4 | 53.7 |
2017 | 28.5 | 25.5 | 54.1 |
2018 | 28.6 | 25.1 | 53.6 |
2019 | 28.2 | 25.1 | 53.4 |
2020 | 26.5 | 24.8 | 51.3 |
Source: Department for Business, Energy and Industrial Strategy (BEIS, formerly DECC)
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The majority of methane emissions from agriculture arise from enteric fermentation (digestive processes) in ruminating animals, with manure management practices accounting for the remainder. In 2020, methane emissions from agriculture are estimated to have fallen by 15% since 1990 and 12% since 2000, mainly as a result of decreasing livestock numbers, particularly in cattle. However, since 2009 the long-term fall has stalled and in recent years methane emissions have remained largely similar to 2009 values.
Further information on greenhouse gas emissions from agriculture
Air quality
Ammonia emissions impact on air quality and subsequently human and animal health. In addition, deposition of ammonia can damage sensitive habitats due to eutrophication and the acidification of soils. In 2020 agriculture accounted for 87 % of the UK’s ammonia emissions.
Figure 11.11 Ammonia Emissions (thousand tonnes)
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Year | Non-agriculture | Agriculture | UK total |
---|---|---|---|
2010 | 37.1 | 222.6 | 259.7 |
2011 | 37.0 | 221.2 | 258.1 |
2012 | 36.0 | 219.3 | 255.2 |
2013 | 34.6 | 218.2 | 252.8 |
2014 | 33.3 | 228.3 | 261.6 |
2015 | 31.9 | 231.2 | 263.1 |
2016 | 32.2 | 235.1 | 267.3 |
2017 | 33.0 | 238.1 | 271.1 |
2018 | 32.0 | 237.8 | 269.8 |
2019 | 32.0 | 234.6 | 266.6 |
2020 | 33.3 | 225.9 | 259.2 |
Source: National Atmospheric Emissions Inventory
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The main sources of ammonia emissions in the UK are agricultural soils and livestock, in particular cattle. In 2020 ammonia emissions from agriculture are estimated to have fallen by 22% since 1990 and 10% since 2000 due to long-term reductions in cattle numbers and more efficient fertiliser use. However, this represents a slight increase since emissions from agriculture reached their lowest point in 2013. This recent increase is largely due to an increase in ammonia emission from agricultural soils.
Further information and a detailed breakdown found on the Defra emissions of air pollutants webpage.
Soils
The success of UK agriculture depends upon healthy soils; they are arguably a farmer’s most valuable asset. Soil degradation costs England and Wales an estimated £0.9bn - £1.4bn per year [footnote 5]. In the face of a changing climate and increase in food demand, it is important to mitigate the risks to long-term productive capacity and encourage famers to manage their soils in a sustainable way. While rates of soil erosion in England are not excessively high, it is estimated to affect around 17% of land in England and Wales with impacts in the form of loss of productive capacity and nutrients, but also off-site costs to the environment [footnote 5]. Around 3.9 million hectares of our soils are at risk of soil compaction which could lead to a total yield penalty of around £163 million per year [footnote 5].
Actions to improve soil organic matter can be mutually beneficial for soil and production. For example, early establishment of crops in the autumn reduces soil erosion risk during the late autumn and winter months [footnote 6] and can also increase winter cereal yields [footnote 7].
Biodiversity
Bird populations are considered to be a good indicator of the general state of wildlife as they have a wide habitat distribution, are near the top of the food chain and long-term datasets are available on them for the UK. Agriculture provides valuable resources in terms of winter food, spring forage and nesting habitats for farmland bird populations. The largest declines in farmland bird populations occurred between the late 1970s and early 1990s due to the impact of rapid changes in farmland management. Whilst agri-environment schemes offer specific measures designed to help stabilise and recover farmland bird populations, the situation is complex with other pressures such as weather effects and disease pressures adversely impacting some species.
Figure 11.12 Farmland Bird Index (1970 = 100)
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Source: BTO/RSPB
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The farmland bird index comprises 19 species of bird. The long-term decline of farmland birds in the UK has been mainly driven by the decline of the 12 species known as the ‘specialists’ that are restricted to, or highly dependent on, farmland habitats (see Figure 11.12). Between 1970 and 2019, populations of farmland specialists declined by about 70% whereas farmland generalists have declined by about 13%. The 2019 index for all farmland bird species was at 44.6, less than half of its level in 1970.
Further information on the farmland bird index.
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Hunt, D.T.E., et al, 2004, Updating an estimate of the sources of nitrogen to waters in England and Wales. Defra project WT03016. ↩
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White, P.J. and Hammond, J.P., 2006, Updating the estimate of the sources of phosphorus in UK waters. Defra project WT0701CSF. ↩
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May, L., et al, 2011, The impact of phosphorus inputs from small discharges on designated freshwater sites. Report to Natural England and Broads Authority, SWR/CONTRACTS/08-09/112. ↩
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POSTnote 478 October 2014 Diffuse Pollution of Water by Agriculture, ↩
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SP1606 Total costs of soil degradation project 2011 Defra. ↩ ↩2 ↩3
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(Chambers et al. 2000; Evans 1990) ↩
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Green et al. (1985) found a 0.35% reduction in wheat yield and a 0.43% reduction in barley yield for every day of sowing later than mid-September. ↩