DARCOF · Research > Darcof I > Soil fauna, nitrogen dynamics and plant growth

Soil fauna, nitrogen dynamics and plant growth

In organic agriculture, relationships on the farm are critical to the stability of the system as a whole, the ability to produce, and the impact on the environment. The effect of some of these relationships is first seen after many years, and can be difficult to elucidate in experimental studies and investigations. There is thus a need to build up simulation models that throw light on relevant biological and environmental aspects of organic farming at the farm level.

The interactions between fauna, microflora, and physical / chemical factors in the soil is, in the short term, critical to the survival and growth of crops, and in the long term crucial for maintaining good soil quality. In organic farming (which is based on the greatest possible utilisation of natural ecological processes), the role of organisms in soil processes is thought to be more significant than is normally accepted for conventional agriculture. The number of organisms has also been shown to be much higher in organic than in conventionally tilled fields.

Nitrogen mineralised from such organic matter as dead plant residues and animal manure is usually rapidly assimilated by the soil microflora, bacteria and fungi. Most of the soil fauna get their nutrition by consuming fungi and bacteria. Animals can therefore support the mobilisation of nitrogen, making it available to plant roots and for microbial regrowth.

Against this background this project has four main objectives:

  • To identify interactions between soil organisms, and estimate the impact of these on nitrogen dynamics in organic farming

  • To estimate the role of the microfauna in supplying nitrogen for plant growth in ecological rotations with cereals, cover crops and clover grass.

  • To adapt an existing rotation simulation model for use with organic farming

  • To evaluate the abundance of the most important species of Collembola and surface dwelling predators in organic farming with the assistance of a simulation model

Summary
Publications


Project title
I.7 Interactions between soil fauna, nitrogen dynamics and plant growth - research and simulation models

Project leaders
Jørgen Aagaard Axelsen,
National Environmental Research Institute, Department of Terrestrial Ecology,
Vejlsøvej 25, P.O. Box 314, DK 8600 Silkeborg
Tel: +45 8920 1400. Fax: +45 8920 1413.
E-mail: jaa@dmu.dk

Jørgen E. Olesen,
Danish Institute of Agricultural Science, Research Centre Foulum

Henning Petersen, Natural History Museum, Aarhus

Project participants
Poul Henning Krogh, Martin Holmstrup and Hanne Lakkenborg Kristensen, National Environmental Research Institute
Peter Gjelstrup, National History Museum, Aarhus
Ole M. Christensen and Janice G. Mather, University of Aarhus
Søren Christensen, University of Copenhagen