Askov Long-Term Experiments on Animal Manure and Mineral Fertilizers - Lermarken

This experiment has been added by the GLTEN Curators using existing published sources.
Local identifier
Askov-LTE Lermarken
Years operational
Originally established to to compare the effect of nutrients added in manure with that of N, P, and K added in mineral fertilizers. The experiment has been used to study nutrient balances, changes in soil organic matter, and accumulation in soil of nutrients, soil microbiological properties and the development of new protocols for testing availability of plant nutrients retained in soil.
Established in 1894, the Askov-LTE is among the very few agricultural experiments with treatments continued beyond 125 years. It remains the only known experiment maintained for more than a century that allows a direct comparison of incremental and corresponding rates of N, P, and K in animal manure and mineral fertilizers. Another unique feature is the field layout as in contrast to other experiments of similar age, the Askov-LTE includes four replicate blocks (fields) with abundant treatment replicates within each block. This allows the significance of treatment effects be tested thoroughly by statistical analyses. Records of crop yields stretch back to the start of the experiments in 1894, while systematic sampling and archiving of soil at 4 years intervals began in 1923. Archiving of crop samples began in 1949. Encompassing results from routine soil and plant analyses, archived soil and plant samples, a detailed documentation of changes in treatments and general field management, recordings of climate parameters, and an extensive backlog of results obtained in specific projects, the Askov-LTE provides a unique research platform for studies in very diverse scientific disciplines.
Data Access Statement
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Data license
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Data policy
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Askov Research Station
experimental research station
Aarhus University
research organisation
DCA - Danish Centre for Food and Agriculture
research organisation
Bent Christensen
DCA - Danish Centre for Food and Agriculture
Department of Agroecology - Organic Matter

Site: Lermarken

research station field
Askov Research Station
Geographic location
55.47163, 9.114015
© OpenStreetMap contributors
63 Metres
Visits permitted?
Cultivation of the Lermarken site began around year 1800 when the farm “Øster Havgaard” was first established. According to Land Register maps, dated 1793, the site was at that time still covered in open, mixed heath- and grassland with scattered deciduous scrubs and most likely used for free-range grazing of sheep, cattle and pigs. Lermarken was first tile-drained in the 1860’ies and with occasional addition of marl. Re-draining at greater depth took place following 1885, when F. Hansen acquired the farm “Øster Havgaard” that then became Askov Experimental Station.
Tillage and drilling implements and operations, weed control and crop protection measures against fungi and insects, choice of crop cultivars and liming practice follow the general trends in agriculture. One notable exception is the composition of the grass-clover mixture kept unchanged since 1949. Therefore, the history of field operations adopted in the experiments reflects the general development in agriculture and accordingly field operations have experienced a continuous change in time. Tillage: All tillage operations are parallel to plot borders. Ploughing occurs with a standard, tractor pulled mouldboard plough in March/April for spring-sown crops, and in September for autumn sown crops. Ploughing depth is adapted to the depth of the Ap-horizon which typically 18 - 20 cm. Crop planting: Planting of cereals is with 12.5 cm inter-row distance. Winter wheat is sown medio September while spring sown cereals is sown in March/April. Planting of maize occurs early May when soil temperatures have reached ~10 oC. For silage maize, the row-distance is 75 cm with a target plant density of 110,000 plants ha-1. Crop protection: The use of herbicides, fungicides and insecticides at recommended rates occurs when observations in the field indicate that significant attacks are expected. Liming: Application of Mg-enriched lime at a rate of 3 to 5 t ha-1 takes place every four-to-fifth year to maintain pH (CaCl2) between 5.5 and 6.5 in the plough layer. Nutrient addition: Application of mineral fertilizers and animal manure (for winter wheat) occurs when crop growth commences in March/April. Crop harvest: Experimental harvest for yield determination occurs in the net plots (see Table 4). The grass-clover crop is cut twice in the production year, the first cut in June and last in late August depending on crop development. The grass-clover is harvested with a plot forage harvester and the biomass removed from the plots immediately after cutting. Cereals are harvested with an experimental plot combiner allowing yields of grain and straw to be determined separately, leaving 5-10 cm stubbles. Removal of cereal straw occurs shortly after harvest. The maize is whole crop harvested in early to mid-October, when the crop becomes senescent due to adverse climatic conditions. At that stage, the crop dry matter content typically ranges from 25 to 35% depending on nutrient treatment. The whole-crop plot harvester leaves approximately 15 cm stubbles. Following harvest of crops, the field (and stubbles) remains undisturbed until ploughing. The grass-clover sward left after the second cut in the production year is allowed a short re-growth period before being sprayed with a full spectra herbicide. After the herbicide effect has been achieved, the field is ploughed, rolled and the seedbed prepared for winter wheat.
Soil description
USDA Classification is Typical Hapludalf, coarse loamy to fine loamy, mixed mesic
Soil properties
VariableDepthValue (range)UnitsRef yearEstimated?Baseline?
clay content0 – 20 Centimetres11 Percent
silt content0 – 20 Centimetres13 percent
find sand content0 – 20 Centimetres43 Percent
course sand content0 – 20 Centimetres37 Percent
clay content20 – 35 Centimetres11 Percent
silt content20 – 35 Centimetres12 Percent
find sand content20 – 35 Centimetres40 percent
course sand content20 – 35 Centimetres31 Percent
soil pH0 – 20 Centimetres (5.5 – 6.5)
soil total carbon0 – 20 Centimetres1.5 Percent
soil density0 – 20 Centimetres1.5 gram per cubic centimetre
soil total carbon20 – 35 Centimetres0.8 Percent
soil density20 – 35 Centimetres1.55 gram per cubic centimetre
Climate properties
VariableTime periodValue (range)Units
precipitation 1999 – 2018 953 mm
air temperature 1999 – 2018 8.8 degree Celsius

Design period: (1894—)

The Askov-LTE at the Lermarken site has four fields (blocks), designated the B2-, B3-, B4-, and B5-field. the experiment grows a classical 4-course rotation of winter cereals, row crops, spring cereals and grass-clover mixture.
Design description
No rigid statistically design applies to the distribution of treatment replicates, however, when the experiments were established, it was recognized that to obtain reliable quantifications of treatment effects, a given treatment had to be repeated in different parts of the field to alleviate effects of spatial heterogeneity in soil properties. Not all treatments are present in all four fields, and the number of replicates varies among fields. The use of four fields (blocks) allows all rotation elements to be grown every year in separate fields.
CropYears grown
winter wheat
grass clover leys
Crop Rotations
winter cereals
  • 1
  • 2
row crop
  • 1
    mangolds and potatoes
  • 2
  • 3
    mangolds and turnips
  • 4
    beet roots or turnips/swedes
  • 5
    beet roots
  • 6
    silage maize
spring cereals
  • 1
  • 2
  • 1
    grass clover leys
    grass-clover mixture
Factor name
Factor levels
farmyard manure exposure
Animal manure supplied as farmyard manure 1894-1922; farmyard manure+liquid slurry 1923-1972; cattle slurry since 1973
1/2 AM
Manure at half rate
1 AM
Manure at standard rate
1 1/2 AM
Manure at 1 1/2 times normal rate
2 AM
Manure at 2 times normal rate
NPK fertilizer exposure
Fertilizer rates differ between crops. See
1/2 NPK
NPK at 1/2 rate
NPK at standard rate
1.5 NPK
NPK at 1.5 times standard rate
NPK at 2 times standard rate
1.5 N3PK
N at 1.5 times standard rate, PK at three times standard rate (check)
Nitrogen and phosphorous at standard rate, no potassium
Nitrogen and potassium at standard rate, no phosphorous
Phosphorous and potassium at standard rate, no nitrogen
N at standard rate only
P at standard rate only
K at standard rate only
grain yield traitNot specified
soil CNot specified
plant analysesNot specified

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