SOIL SCIENCE AND PLANT NUTRIENT MANAGEMENT WORKING GROUP
(RAPPORTEUR: P. VON FRAGSTEIN AND H. KLOEN)
There were ten participants from eight countries: Panohkov, P.P. (Bulgaria); Holberg, N. (Denmark); Gautronneau, Y. (France); Fragstein, P. von (Germany); Kloen, H. (The Netherlands); Hansen, S. (Norway); Brunner, T., Mäder, P. and Sharp, D. (Switzerland) and Philipps, L. (United Kingdom).
The overall task of the Working Group was put into a very wide frame. Before starting discussions about the specific points, questions of general importance in the context of agricultural research were tried to be clarified:
Agricultural research:
|
For whom?
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- For improving the farming systems (for farmers)
- For the scientific community
- For policy makers and administrative authorities
|
Definition of terms:
|
|
- Approach
- Methodology
- Methods
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Typology of methods:
|
|
- Destructive vs. non-destructive
- Descriptive vs. non descriptive
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Aim of methods:
|
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- For analysis
- For assessment
- For diagnosis
- For prognosis
- For evaluation
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As a result of the introductory discussion, the group decided to slightly reorient the task of the Session. There was general agreement among the participants that research methods should be aimed at:
- improvement and maintenance of soil fertility; and
- efficient use of nutrients (maximum recycling).
A first step which is discussed below is the development of indicators for soil fertility and nutrient efficiency. This results in a list of indicators and a very provisional list of priorities.
Improvement and maintenance of soil fertility |
Priority |
Physical approach |
|
Cultivated soil profile (macroscopic method)
- Qualitative approach
- Bulk density
- Compaction
- Earthworm channels
- Root growth
- Rhizobium nodules
|
(1) |
| Micromorphological investigations
|
(3) |
Chemical approach |
|
| Standard soil analysis, but better would be the integration of two to three extractants of increasing activity for a better understanding of the potential of nutrient release of the soil |
(1) |
| Nutrient balancing
|
(1) |
| Organic matter |
(1) |
| C/N-ratio
|
(1) |
| Humus balance
|
(1) |
| Measurements of mineralization capacity |
(2) |
| Salinity (of regional relevance)
|
(3) |
Biological approach |
|
| Microbial analysis
|
|
|
Biomass |
(1) |
|
Nmic |
(1) |
|
Cmic |
(1) |
|
FDA |
(1) |
| Mycorrihizae measurements |
(3) |
Efficient use of nutrients |
Priority |
| Yield, yield components |
(1) |
| Nutrient balances, including nutrient losses |
(1) |
| Nutrient availability (isotopes) |
(1) |
| Plant analysis, product quality parameters |
(2) |
| Efficiency ratio |
(2) |
| Limitation of nutrients (law of minimum) |
(3) |
Measurement of rooting system
- Physical issues
- Morphological issues
- Biochemical issues
|
(3) |
Next steps to be taken could be:
- Comparison of parameters in terms of easy/low cost assessment, variation in time, suitability for different climates, soil types and land use. Based on such an overview, one or more sets of indicators could be formulated for general use.
- Listing and comparing research methods aimed at improving/maintaining soil fertility and nutrient use in terms of:
- aggregation level (field/crop/farm/region);
- scope: one or more nutrients, designing farming systems or only manuring strategy, plant/animal production, one or more years, including yields, quality, economics.
Way of interaction with farming practice (see 'On-farm Research' Working Group).
A SWOT table was prepared for the cultivated soil profile (Gautronneau, et al., www.isara.fr/profilcultural)
