EDINA agcensus

Frequently Asked Questions

agcensus frequently asked questions




Q. What is the Agricultural Census?

A. The Agricultural Census is conducted in June each year by the government departments dealing with Agriculture and Rural Affairs i.e. for England, Wales and Scotland. Each farmer declares the agricultural activity on the land via a postal questionnaire. The respective government departments collect the over 150 items of data and publish information relating to farm holdings for recognised geographies.

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Q. How can I gain access to Agricultural Census data?

A. There are a number of routes into the data. UK Access Management Federation access can be gained through an academic institutional subscription (prices are based on Jisc-banding scheme). Monthly pro-rata adjustments apply to UK Academic Institutions that subscribe part-way through a subscription year. Policy/Commercial/Research organisations can subscribe to the EDINA agcensus service. Individuals from academic institutions without a subscription, or individuals from Policy/Commercial/Research organisations can also gain access to the service on a per-project basis: please contact edina@ed.ac.uk for further information.

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Q. Is there trial access to the agcensus service?

A. No. A free visualisation of all census items at 10km level of aggregation for the most recent census year held is available to enable potential users to preview distribution maps of chosen census items. In addition, there is an anonymised subset of downloadable data at 5 km.

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Q. What is the difference between Major and Minor holdings?

A. Farm holdings above a certain economic or physical threshold are regarded as Major Holdings. Holdings below these thresholds are regarded as Minor holdings. The data provided from the respective government departments and converted by Edinburgh University Data Library correspond to Major holdings only. A subset of data for Scotland for both Major and Minor holdings exist for 1989 - 1996. This data will be made available in due course.

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Q. Once my organisation has subscribed is there a limit to the amount of data I can download?

A. An academic or Policy/Research/Commercial subscription allows unlimited access to the Agricultural Census data held in the database for the period of the subscription.

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Q. Which subject areas/disciplines have made use of Agricultural Census data in the past?

A. Epidemiology, Public and Community Health; Market Research; GIS Modelling; Environmental and Resource Management, Ecology, Agriculture and Rural Studies.

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Q. Can the service be used for class teaching purposes?

A. The full agcensus service can be used for demonstrating or teaching purposes on the understanding that each student has their own personal university account and the academic institution has valid subscription to access the service. Alternatively academic or non-academic institutions wishing to demonstrate the service can use the free visualisation demo.

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Q. Is there data for Northern Ireland?

A. No. Although the geography of Northern Ireland is based on the Irish National Grid, inclusion of Agricultural Census data from Northern Ireland will be investigated as the service develops.

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Q. What are the Academic and Non-academic terms of use?

A. Please refer to the EDINA agcensus Terms and Conditions.

An Academic or Policy/Research/Commercial subscription allows unlimited access to the Agricultural Census data held in the database for the period of the subscription. The data itself can be used for academic study or research conducted within the subscription period. Should the duration of the research project extend beyond the period of the subscription a new subscription will be required.

In certain circumstances (e.g. for teaching purposes) the use of the data beyond the duration of the academic study or research may still permitted; however, written permission is required from EDINA.

EDINA reserves the right to monitor usage of the service.

The data may not be transferred to any other person or body without the prior written permission from EDINA. Any publication relating to the data must include acknowledgement to EDINA at Edinburgh University Data Library and the Department of Environment, Food and Rural Affairs (DEFRA) for England, The Welsh Assembly Government, or The Scottish Government (formerly SEERAD). EDINA reserve the right to monitor usage of the service.

A. Please refer to the EDINA agcensus Terms and Conditions.

Q. I’m not from an academic institution, can I still get access?

A. Yes, you can apply for a subscription. Please complete the relevant application form available - here and return this to EDINA or e-mail the Helpdesk at: edina@ed.ac.uk for more information about a subscription.

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Q. Are usage statistics available for agcensus?

A. Yes. Usage statistics can be obtained by the site representative or service support colleague within an academic institution. They can complete a web statistics registration by going to - https://edina.ac.uk/edinastats/. Others subscribers should contact the EDINA helpdesk edina@ed.ac.uk for more information about a subscription.

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Q. How is the Agricultural Census data held at EDINA generated?

A. Edinburgh University Data Library has developed algorithms which convert the data for recognised geographies, obtained from the government departments, into grid square estimates. The key to transforming the raw data into grid square data is the definition of each geography (e.g. parish, in the case of Scotland) in terms of 1km squares. This Framework is used in conjunction with a 7-fold classification of the land-use of the same 1km grid squares called the Landuse Framework. Agricultural Census items are distributed over 1km grid squares of suitable land use. For example, crops are distributed over agricultural land but sheep can also be distributed over hill land but all agriculture is excluded from urban and inland water.

For further information please refer to the ESRC RRL working paper (No. 11, November 1988): Land Use and agricultural activity: an areal approach to harnessing the Agricultural census in Scotland

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Q. Why convert to grid square data?

A. The input data is converted to grid square estimates for a number of reasons, namely:

  1. the format of data obtained from the government departments is potentially disclosive;
  2. the geographies (e.g. Scottish parishes, Welsh communities) vary in size and shape, the land use capabilities also vary across these geographies; (iii) farmers may under- or over-report agriculture activity e.g. by combining small holdings to produce one return or farm may be on the boundary of 2 geographies; (iv) livestock may be elsewhere; (v) the census returns are a 'snapshot' of activity on 1 June.

(for further information see: http://edina.ac.uk/agcensus/support/agcen2.pdf). Grid square data containing British National Grid easting and northing co-ordinates also facilitates analysis within desktop GIS such as ArcGIS, MapInfo.

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Q. To which part of the grid square do the easting and northing co-ordinates refer?

A. The south west corner (i.e. the bottom left) of the grid square.

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Q. What are the landuse categories?

A. Information about landuse types.

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Q. In what format are the data downloaded?

A. The data are downloaded as WinZipped ASCII delimited Comma Separated Values.

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Q. What dataset resolutions are available?

A. The data are available at 2km, 5km and 10 km levels of aggregation. Customised aggregations can be made for specific purposes on request.

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Q. I have chosen a small area of the country to visualise, however the distribution patterns aren't clear. What can I do?

A. When focussing on a small area, remember to choose a small grid square resolution. Note that there are twenty-five 2km x 2km grid squares in a 10km x 10km grid square. In some cases, it may be inappropriate to analyse a small area using the 10km x 10km grid square resolution.

Alternatively, you can use the Zoom tool to focus to a smaller scale.

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Q. How often are the data updated?

A. It is intended that the data for each territory be updated as regularly as possible. This is dependant upon the respective government departments collating and publishing the census data prior to supplying us with the data for the recognised geographies required for our algorithms. Data for more recent years are awaiting processing.

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Q. Are the Agricultural Censuses for each territory 100% samples?

A. In Scotland the annual June census covers the 50,000 agricultural holdings with sampling of smaller holdings. The smallest spatial unit for which data are made available are parishes (subject to disclosure restrictions). Note however that the EDINA agcensus service does not distribute data at the parish level.

Since the late 1990s the agricultural census in England and in Wales has been conducted as a sample survey (postal questionnaire or via internet), in which data is only sought from a proportion of holdings in each year.

For England a completely random sample of the 200,000 agricultural holdings would be inefficient due to the large number of small holdings thus a stratified random sampling approach was been employed in which holdings are divided into groups on the basis of theoretical labour requirement with higher sampling rates being used in the larger strata. Simply stratifying on labour requirements would however lead to low precision for some crops thus DEFRA employ a separate strata with higher sampling rates for horticultural holdings. The sample size has varied from between 25%-33% since the inception of stratified random sampling in the late 1990s. The imputation of values for the June survey for England is done by the separate ratio approach. In brief, this method ascertains the ratio between the current number of e.g. sheep and the previous year's number of sheep for the holdings which responded to the current year's survey. The ratio is then applied to the total number of e.g. sheep from last year to get a new estimate for the number of sheep in England. These calculations are applied on each stratum and on each census item. The estimated totals of which are summed to give a national figure.

As of 2004 DEFRA are no longer distribute the small area data on an annual basis. They now conduct a decennial Agricultural Census (as demanded by EU regulations), the most recent of which was 2010. See the methodology used to create the 1km gridded data prior to aggregating to 5km (for non-disclosive items) and 20km (for disclosive items) and prior to treatment by the EDINA land-use framework and conversion algorithm.

The Statistical Directorate of the Welsh Assembly Government commenced with an agricultural survey (to replace the agricultural census) in 2006.

It should be noted that in the case of the Welsh Agricultural Survey whilst the accuracy of the sample survey data and its conversion to grid square estimated values remains consistent with those of earlier census years the spatial granularity offered by the survey and subsequent data imputation could potentially diminish the geographical variation across the territories.

Further information on the sampling strategy and statistical analysis (PDF file).

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Q. Some values for census items measured in hectares are greater than the total grid square area, why?

A. There are anomalies in the collection of Agricultural Census data that distort the grid square estimates. For example, a farmer is only required to return one census form, even if he owns several holdings, some of which may be in other parishes or even quite remote from the main holding.

Certain items, especially rough grazing etc., may be either grossly over- or under-represented in any particular area.

For example, data on rough grazing and woodland are not available for many years for Scotland. The anomalies in the way these items are reported at parish level are too great to make conversion to grid square estimates sensible. A farmer can report all his holdings on one census form and these 2 items in particular may include land in other areas well away from the main holding.

Other area items, e.g. total area, are similarly problematic.

Grid square estimates are derived from parish summaries or DEFRA estimates, taking account of potential land-use capability at 1km level. In the conversion algorithm the data are distributed to all suitable 1km squares for that item in the area of reporting, but no agricultural data are allocated to unsuitable squares, e.g. urban, inland water, non-agricultural land. There may be too few suitable land-use squares in a reporting area and this can lead to an area greater than the size of the square.

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Q. How far back does the data go?

A. The Data held at EDINA goes as far back as 1969 for Scotland, England and Wales. Note that data for certain years are not available.

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Q. Are the data comparable for each country over time?

A. Prior to 1998 data for England and Wales was provided by DEFRA. Farmers from both territories completed the same questionnaire. Since 1998 Welsh farmers complete a questionnaire supplied by the Welsh Assembly Agriculture and Rural Affairs Department. Farmers in Scotland complete a questionnaire as supplied by The Scottish Government. Due to each government department having responsibility for their respective questionnaire there is not complete comparability over the three territories with regard to questions asked. Similarly, due to changes in agricultural policy the content of the questionnaires within the three territories changes over time. For example certain census items have been aggregated over time for confidentiality purposes

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Q. What are the units of measurement?

A. The units of measurement of census items from the Agricultural Census data are in metric units: areas are expressed in hectares, with the exception of 'glasshouse' areas which are expressed in square metres; weights are expressed in tonnes. Data from the census prior to 1976 have been converted from imperial units given on the census form to metric units. For further information please refer to the questionnaire for the census year of interest.

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Q. Why are some census items not present on the relevant questionnaire?

A. Certain groups of census items were received from the respective government departments as additional items and were not part of the original questionnaire sent out to each farmer. The census groups in question are: Analyses, Farm Type, Standard Man Days for England and Wales (for certain years); Change, Frequency, Parish Frequencies for Scotland (for certain years). For further information please contact: edina@ed.ac.uk

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Q. How are the 'geographic image maps' generated?

A. The 'geographic image maps' are created by the Minnesota MapServer. Minnesota MapServer is an OpenSource development environment for building spatially enabled Internet applications. The software builds upon other popular OpenSource or freeware systems like Shapelib, FreeType, Proj.4, libTIFF, Perl and others. MapServer is not a full-featured GIS system however it does allow you to browse GIS data and create 'geographic image maps'. (Copyright © 1996-2003 Regents of the University of Minnesota)

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Q. What are the Scottish Summaries? Is there a comparable set of data for other UK territories?

A. The Scottish Summary statistics are Agricultural Census statistics for Scotland for the period 1912-1978 (with some summary statistics for the other territories of the United Kingdom). The statistics are downloadable as Adobe PDF.

The statistics are available at country, district and county level and topics covered include: cropping acreages, livestock numbers, production of crops, market prices, wholesale prices, labour, machinery, in addition to a range of other statistics.

DEFRA provide access to a range of Agricultural Census data including county profiles from 1900-1980.

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Q. agcensus data can be downloaded in KML format. What is KML?

KML (Keyhole Markup Language) is a file format that uses XML-based language to manage geographic information. Originally, KML was used to display data in Google Earth and Google Maps but with its adoption by the Open Geospatial Consortium, KML files are becoming a standard for managing spatial data across a variety of mapping applications.

EDINA agcensus terms and conditions apply. Data should not be published nor made available in a public web space.

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