REPORT COST action 832
Small Organizing Meeting Working group 2, Topic 1: Soil Processes
Square de Meeûs 8, Brussels, Belgium. Thursday, 19 November 1998








Gil Sotres


Destain (WG1)







United Kingdom




United Kingdom





The aim of this meeting was the organization of a meeting of WG2 on 13-15 May 1999, in Cordoba, Spain. During all discussions, mentioned below, topics for this meeting were discussed. Part of the Cordoba meeting will be combined with WG1, which also meets in Cordoba in that period. For this reason, the coordinator of WG1, Destain, was also present.

Agenda (adapted time schedule).

9.00 - 9.10

Welcome to the participants. Adoption of the agenda

9.10 - 9.30

Outcome of the results of the technical committee of WG1
(Gembloux, Belgium, 23-24 October)

9.30 - 10.15

Role of Soil processes within the overall WG2 framework
(P losses at field scale)
Discussion on conceptual models, based on the integration of soil and hydrological aspects

10.30 - 12.00

State of the art of soil processes at field scale:
- review; definitions, concepts
- determination of the omissions and lack of knowledge

13.00 - 14.00

Soil testing for environmental risk
- comparing methods; review of data sets; options for additional comparison within this COST action; possibilities to relate soil fertility parameters to environmental risk parameters
- organization of sample exchange between participants of COST 832 (objectives, methodology, logistics)

14.00 - 15.00

Clarify the role of organic P for P losses
definition of organic P losses/terminology, methods to measure organic P losses as a fraction of total P losses; interaction with soil organic P pool; factors which influence organic P losses.

15.30 - 17.00

General discussion and proposal for joint meeting WG2 and WG1


A first draft of the minutes of WG1 (Gembloux, Belgium, Oct. 1998) was handed out. J.P. Destain gave an overview of the discussions in Gembloux and a tentative program of WG1 in Cordoba. Soil testing for environmental risk is a point in overlap with the goals of WG2, which will be discussed later. The final minutes will be presented on the web site.

Maarten Hens and Oscar Schoumans wrote a discussion paper for this meeting. The document was adapted based on the discussions and will be distributed with these minutes: click on: paper. Some very interesting discussion points have been made on terminology and soil testing methods.

During the discussion on terminology, it appeared that current use of terms sometimes deviates from their linguistic meaning. E.g., leaching means originally: "removal of soluble compounds from a matrix", thus, both in horizontal and in vertical direction. In soil science however, only vertical transport is thought of when the term leaching is used.

As was already proposed by Haygarth for the Antrim meeting, it was decided that the release and transport process should be separated in terminology used. Thus, it was proposed to make a distinction between:

1. The process of P coming into the mobile (liquid) phase by:
- solubilization (desorption of adsorbed P, dissolution of precipitated P, etceteras)
- erosion (detachment from the soil matrix of soil particles, containing P)

2. The transport of soluble P or particle bound P, by:
- surface flow (surface runoff)
- subsurface flow (mostly called leaching)

Within erosion, no distinction should be made between particle bound P of different size (e.g. < or > 0.45 Ám), since the boundary is arbitrary. Also, it was found that particles in soil solutions form a continuum as far as their size is concerned. Thus, erosion deals with the release and subsequent transport of particles of any size.

 Existing data sets on a (possible) relationship between different soil tests, both for agronomic and environmental purposes, will be collected and summarized by Vanderdeelen (see address at the end). Members from all countries are invited to send in this kind of information. Results of this exercise will be presented in Cordoba. Maarten Hens will set up a small experiment in order to measure from different Belgium topsoils some relevant environmental and agronomic soil data. In WG1 a literature study will be done in order to make an inventory of available environmental soil P test methods. In WG2 data will be collected, summarized and, if necessary, interpreted.

 It was decided to present the following topics at the meeting in Cordoba; names of persons who will prepare a presentation on the topic are given between brackets:

1. Concepts and definitions [Hens, Schoumans]

2. Solubilization, transport of soluble particles:
- Review of field experiments and laboratory studies; influence of soil type and land use [Turner, Sinaj, Hens]
- Review of concepts, process descriptions, and forms of P [(physico-) chemical processes: Chardon; biological processes: Gil-Sotres, Turner]
- Environmental soil P tests [Vanderdeelen]

 3. Erosion, transport of particle bound P:
- Review of experimental data, with special attention to particle size of transported material; influence of land use and soil type [Barberis, Withers]
- Review of concepts, process descriptions, and forms of P [Withers]
- Environmental soil P tests of particle transport [Withers, Hartikainen]. Paul Withers will ask Anita Folly to help with this topic. At the MC-meeting it appeared that Istvan Sisak is also working on this field. Oscar Schoumans has asked him to send information and to take part in this discussion.

An important point is that in Cordoba the key word will be soil processes. This means that with respect to e.g. soil erosion the influence of soil characteristics (fysico-chemical; e.g. distribution size) will be discussed and not the influence of hydrology or weather conditions on erosion. This has also been discussed at the MC-meeting with Peter Strauss, who will coordinate the discussions and workshop on the topic erosion next autumn in Austria.


 Wageningen, Nov. 30th 1998, W.J.Chardon & O.F.Schoumans


Data relating environmental and agronomic field test should be sent to:

Prof. Dr. J. Vanderdeelen
Dep. Toegepaste Anal. & Fysische Chemie
Fac. Landbouwk. Toegepaste Biol. Wetensch.
Universiteit Gent
Coupure Links 653
B - 9000 Gent