Statistical processing

Source data

In general areas are obtained from the Integrated Administration and Control System (IACS) by the Danish Veterinary and Food Administration, supplemented by Statistics Denmark's Agricultural and horticultural survey.

The harvest of cereals, rape and peas and straw

• Questionnaire Based.
• Gross sample of about 2,800 farms (about 8 per cent of all farms). Net Sample: about 2,700 farms.
• Random, stratified sampling.

Harvest of roughage

For areas the source is IACS whereas for yields per hectare source are SEGES, Danish association of sugar beets farmers and the accounts statistics for agriculture. The accounts statistics for agriculture are available with a delay of one year, and for this reason the yields per hectare are updated with the development in crops where recent figures are available where for each fodder crop a crop is selected with a high correlation.

Fodder beets are updated with the development for sugar beets Maize for fodder is updated with the development for grain maize Green harvested cereals, luzerne and aftermath for cereals are updated with the development for spring barley Grass is updated with the development for cereals, total

Example: Grain maize has a yield of 60 hkg per ha in 2018 and 75 in 2019. From the accounts statistics on agriculture we know that maize for fodder has a yield of 320 hkg per ha. For 2019 the yield is thus estimated to 320*(75/60)=400.

The forecast for winter crops

Seed information from the Danish Veterinary and Food Administration and from the Knowledge Centre for Agriculture.

Seed

Information from the Danish Veterinary and Food Administration.

Frequency of data collection

Annual.

Data collection

The survey of harvest of cereals etc. is collected annually from farmers using a web questionnaire. Sampling: random, stratified selection.

• Questionnaire and instructions for the Harvest of grain, rapeseed and leguminous seed

Harvest of forage, the forecast for winter seed and seeds are collected annually from SEGES, Danish Sugar Beet Growers and the accounting statistics for agriculture and experts.

Data validation

The submitted forms to the 'Harvest of cereals etc.' are validated against deviation from average yields.

Data compilation

Estimation of average yields on grain, rapeseed and leguminous seed

Average yield is estimated at different levels (composed of agricultural share, size, ecology). In each "stratum" the first estimate calculated on at least 5 observations is used. This means in some cases that smaller groups must "share" the average yield for safety reasons. In practice, this means that at regional level, many average yields will be the same, namely the national level.

Humitidy degree

The production of crops and straw is calculated according to standardized humitidy degree. 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 grain, rapeseed and leguminous seed, the individual farm indicates the humitidy degree if it deviates from the standard, and production/yield is converted proportionally. For other crops, agricultural consultants state if the year's harvest deviates from the standard percentage.

Standard humitidy degree used

• Cereals, field peas and other pulses: 15 per cent.
• Rapeseed: 9 per cent.
• Grass and clover in the rotation: 50 per cent.
• Lucerne: 40 per cent.
• Maize for silage etc.: 45 per cent
• Grain for silage etc.: 17 per cent.

No corrections are made to humidity percentages for roughage.

Straw

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

Conversion factors from kernel yield (kg) to straw yield (kg)

• Winter wheat: 0.55
• Spring wheat: 0.50
• Rye: 0.80
• Triticale: 0.80
• Winter barley: 0.55
• Spring barley: 0.55
• Oats: 0.60
• Mixed semen: 0.60
• Winter rape incl. non-food: 0.90
• Spring rape rape incl. non-food: 0.90
• Field peas: 0.50
• Leguminous seed in total: 0.50

Source: "Håndbog for driftsplanlægning" (Handbook for operational planning).

Water percentage is not calculated for straw.

Adjustment

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