Statistical processing

Source data

Data for the statistics are collected from several sources, each covering different types of crops. In general, area information comes from the Danish Agency for Green Land Conversion and Aquatic Environment.

Harvest of cereals, rapeseed and legumes

Questionnaire-based survey with a gross sample of approximately 2,800 farms (approximately 8 percent of all farms) and a net sample of approximately 2,700 farms. The selection is random and stratified.

Forecast for winter cereals

Prepared by DAKOFO and the Association of Danish Variety Owners. DAKOFO is a trade association for the grain and feed trade in Denmark. The Association of Danish Variety Owners represents plant breeders. The forecasts up to 2015 have been prepared by Statistics Denmark, also based on data from the Danish Agency for Agriculture and Fisheries and estimates from SEGES regarding winter rapeseed. Seed information also came from the Danish Agriculture and Fisheries Agency and SEGES. Revised area information came from 'Harvest of grain, rapeseed and peas and straw'.

Harvest of roughage

The statement includes the following crops: seed potatoes, potatoes for flour production, table potatoes, sugar beet, fodder beet, lucerne, maize for feed, grain for ensilage, grass in rotation, grass outside rotation and arrears after grain and whole grain.

Yield per ha is based on various sources:

• Potatoes: yield estimate from SEGES • Sugar beet: information from Nordic Sugar • Arrears after grain and whole grain: the area is assumed to constitute 2.6 per cent. of the area with grain to maturity and 90 per cent. of the area with whole grain (expert estimate from 2017, together with the alfalfa calculation 1.38 × whole grain) • Other crops: information from the accounting statistics for agriculture, which contains both areas and production

Since the accounting statistics are available with a one-year delay, the yields per ha are projected based on related crops, where the correlation is high:

• Fodder beet is projected with the development for sugar beet • Maize for feed is projected with the development for maize to maturity • Whole grain and arrears after grain, alfalfa and whole grain are projected with the development for spring barley • Grass is projected with the development for grain in total.

Example: Maize to maturity has a yield of 60 hkg per ha in 2018 and 75 in 2019. From the accounting statistics for agriculture, we know that corn for feed in 2018 has a yield of 320 hkg per ha. For 2019, the yield is therefore calculated as 320*(75/60)=400.

Seeds for sowing

Information comes from the Danish Agency for Green Land Redevelopment and Aquatic Environment.

Frequency of data collection

Annual.

Data collection

Data for the Harvest of Grain, Rapeseed, Peas and Legumes is collected annually from farmers via a web questionnaire. The sample is selected randomly and stratified.

• Questionnaire and guidance for the Harvest of Grain, Rapeseed and Legumes

Harvest of roughage, Forecast for winter seed and Seed for sowing are obtained from external experts and organisations (SEGES, Danish Sugar Beet Growers, DAKOFO, Association of Danish Variety Owners) as well as from the accounting statistics for agriculture and administrative registers from the Danish Agricultural Agency. Primarily existing data and expert estimates are used, and separate questionnaires are not sent to these groups.

Data validation

The collected data is debugged based on consistency rules and yield limits. Suspicious values ​​are compared with previous years' results and with comparable farms.

For the harvest of grain, rapeseed and peas as well as straw, the reports are checked against average yields and against previous years' harvest data.

The forecast for winter grain is based on data and expert assessments from Dakofo. Since the forecast is based on estimates, the final results may deviate slightly from the forecast.

Data compilation

Estimation of average yields in the Harvest of cereals, rapeseed and legumes

Average yields are estimated at different levels (agricultural sector, size, ecology). In each stratum, the first estimate is used, which is calculated on at least 5 observations. Small groups can therefore share average yields for safety reasons. In practice, this means that at the regional level, many average yields will be the same, namely the national level.

Water percentage

The production of crops and straw is calculated according to standardized water percentages. These are based on optimal, average values ​​for the individual crops at harvest, estimated by SEGES and other experts. In the study of the harvest of cereals, rapeseed and legumes, the individual farm indicates the water percentage if it deviates from the standard, and production/yield is converted proportionally. For other crops, agricultural consultants indicate if the year's harvest deviates from the standard percentage.

Standard water percentages used:

• Grains, field peas and other legumes: 15 percent ·
• Rapeseed: 9 percent
• Grass and clover in rotation: 50 percent
• Lucerne: 40 percent
• Maize for ensiling etc.: 45 percent
• Grains for ensiling etc.: 17 percent.

No correction to standard water percentage for roughage.

Straw

The total harvest yield in weight is converted to straw yield using standard factors. Straw includes standard water content (see percentages above).

Conversion factors from grain yield (kg) to straw yield (kg):

-Winter wheat: 0.55 - Spring wheat: 0.50 - Rye: 0.80 - Triticale: 0.80 - Winter barley: 0.55

Calculation of arrears after grain and whole grain

The area with arrears after grain and whole grain is calculated as 90 percent of the area with whole grain plus 2.6 percent of the area with grain to maturity. The average yield for arrears after grain and whole grain is calculated at 54.7 hkg per hectare (2024). This figure is projected annually with the development in yield per hectare for spring barley. Production is calculated based on the area and the average yield.

Roughage and root vegetables

Current yields are not available for several roughage crops, as the Agricultural Accounts Statistics are published with a one-year delay. The yields are therefore projected with the development in related crops, where there is a stable historical relationship:

• Fodder beet: last year's yield per ha
• Maize for feed: projected based on information from SEGES Sortinfo (e.g. 490/545 = 0.90 for a drop in yield from 542 to 490 hkg)
• Cereals for whole grain: projected with the development for spring barley to maturity
• Grass in rotation: last year's yield per ha
• Grass outside rotation: projected with the development for total grain to maturity

Expert estimates from 2017 are used for alfalfa (1.38 × whole grain) and for arrears after cereals and whole grain, where the yield is projected annually with the development for spring barley.

Adjustment

No further corrections of data in addition to what has already been described in 'Data validation' and 'Data processing'.