FOULUM (Cropsys)

Long term experimental facility


Open-air Platform

Parent institution: Aarhus University, Department of Agroecology
Active since 1997
Active through 1997-now

Fields of study

  • Climatology, Climate Change
  • Environmental sciences, Pollution
  • Other
  • Agricultural science

Contact Information

Rasmussen, Jim

The experiment compares different fertility building practices in conventional and organic farming arable practices with focus on cereal production. These practices include crop rotations with and without a whole-year grass-clover, use of cover crops (with and without, and with legume-based cover crops in organic farmed plots versus non-legume cover crops in conventional treatments), and with and without manure applied as slurry. There is also a comparison of organic versus conventional management, where the conventional crops are fertilized with mineral fertilizers and the organic with pig manure applied as slurry.

The experiment was started in 1997 as a replicated (2 blocks) experiment with 4-course crop rotations with all crops in the rotation represented every year. Eight different fertility building treatments combinations are compared, which makes a total of 64 plots. The measurements include crop dry matter and N yield, total above-ground biomass and N of crops and cover crops, soil nitrate concentration in soil solution using suction cups, biomass and density of weeds, phenology, soil carbon, nitrogen etc. at 4 year intervals, and in addition a number of measurements of soil and plant carbon and nitrogen stocks and flows, e.g. nitrous oxide emissions.

The Location

Country: Denmark

Latitude: 56.49394167

Longitude: 9.563028

Nearest town: Viborg

Distance from neaerst town: 15 km

Relevant Research Questions

The experiment addresses the carbon and nitrogen cycling in arable cropping systems under a wide range of management conditions (organic and conventional). The focus is on productivity of the cropping systems in terms of dry matter and nitrogen yields and the associated emissions of greenhouse gases and losses of nitrogen to the environment (e.g. nitrate leaching). The experiment this provides estimates of how short and long-term fertility building measures affects crop productivity and environmental impacts of mostly cereal-based agricultural cropping systems.


The experiment is one of the very few long-term experiments globally that compares a range of soil fertility management measures in organic arable farming and which has a good record of data on vegetation and soil data covering both carbon and nitrogen fluxes as well as effects on biodiversity. Differences in fertility levels has been developed which is reflected in plant growth and nitrogen losses from the system.


The major limitation is the size of the plots and thus the restrictions in space available for additional treatments and measurements. Some of the treatments also put limitations on what additional treatments can be added, e.g. use of pesticides in the organic farming treatments are subject to restrictions. However, current limitations in terms of addressing the C and N fluxes related to management and climatic influences are determined by the lack of instrumentation to quantify C flower, in particular NEE and soil respiration. For the N fluxes there is need for automated measurements of N2O emissions. Also to investigate effects of climate manipulations there is need for equipment that allows manipulation of temperature and precipitation in subplots.

Experimental Capabilities

Experimental Facilities

At the site there are also semifield and growth chamber facilities for more controlled experimentation

Experiments duration: Years;

Experimental Aerea

Total area: 11328 m²

177 m2 in each of 64 plots

Available area: 11328 m²

Experimental Unit Size

unit size: 454 m²

The area available for new experimentation depends on the type of experimentation.


Replicates number: 2

2 in principle, but over a 4 year rotation it is 8.

Temporary storage

  • Dark room
  • Drying oven
  • Freeze drier
  • Freezer
  • Liquid N
  • Refrigerator

Available Instruments

  • TDR
  • Line quantum
  • SPAD
  • Spectral reflectance measurements
  • Suction cups for soil water sampling permanently installed
  • Static chambers for gas emission measurements
  • LI-COR soil respiration
  • Leaf area measurements
  • Respirometer

Electricity available on site.

Distance from Laboratory facilities


Years measured: 1987-2019


Mean Temperature: 8.1 (20 year average: 1999-2019) °C

February Mean Temperature: 1.2 (20 year average: 1999-2019) °C

July Mean Temperature: 16.1 (20 year average: 1999-2019) °C


Mean Annual Speed: 3.6 (20 year average: 1999-2019) m/s

Max. Annual Speed: m/s

Dominant Direction: 191


Precipitation type: Both;

Total annual precipitation: 754 (20 year average: 1999-2019) mm

Mean snow cover duration: days

Soil Types

State Variables

Continuously Measured

  • Air humidity
  • Air temperature
  • Atmospheric pressure
  • Incident PAR
  • Incident shortwave radiation

Spot Measured

  • Phenology
  • Population densities
  • Soil water content
  • Species richness

Environmental Pressures

Variable Ecosystem Status
Warming Agrosystem Planned
Precip Agrosystem Planned
Management - Nutrients (levels or nutrient type) Agrosystem Active
Management - conventional vs. organic or other eco-friendly practice Agrosystem Active
Management - rotation practice Agrosystem Active
Management - species and/or ecotype combinations Agrosystem Active

On site Staff and Accomodation

Peak season staff

Up to 12 people

Off season staff

Up to 8 people

Visiting personnel

No visitors allowed.

No beds on site

Showers on site

Showers on site

No laundry on site