Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie


Shelf life

CAS and PHP session cookies

Login credentials, session security



Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie


Shelf life


Trace the visitor's route in order to establish visit statistics.

13 months


Store the anonymous ID of the visitor who starts the first time he visits the site

13 months


Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at or by post at :


24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021

Menu Logo Principal logo SOERE PRO Logo CIRAD Logo AnaEE Logo IRD Logo Ouagadougou university

Home page

0-20 µm aggregate typology based on the nature of aggregative organic materials in a cultivated silty topsoil

F. Watteau, G. Villemin, F. Bartoli, C. Schwartz, J.L. Morel

Watteau & al., 2011
Watteau & al., Soil Biology & Biochemistry 46 (2012) 103-114

Soil structure describes the arrangement of the solid parts of the soil and of the pore space located between them [1] but also describes the manner in which soil particles are aggregated. This multi-scale geometry is among others governed by parent material-dependent soil texture and aggregation processes due to the combined physical, chemical and biological interactions occurring between soil constituents [2]. These interactions are themselves functions of the environmental conditions under which the soil was formed and continues to evolve and vary according to recent management history. Water/nutrient storage and habitat for soil organisms are vital soil characteristics related to soil structure and leading to sustained biological productivity. Thus, soil structure appears to be a key characteristic of soil biofunctioning. Here, transmission electronic microscopy (TEM) was used to test the sensitivity of micro-aggregates to land use and cultivation practices. The aims of this study were therefore to use TEM to characterize the water-stable 0-20 µm micro-aggregates of a cultivated topsoil and to highlight any impact of cultivation practices and of inter-annual variation on soil structure dynamics.

Main results

The study was conducted on a Calcic Cambisol (pH of 7.1, organic matter content of 33 g kg-1, C-to-N ratio around 10), developed in Eastern France and sampled two consecutive years before and after the exceptional dry period occurring in 2003. It was cropped under maize following moderate tillage and fertilization within an experimental station. Digested sewage sludge has been applied since 1996 according to regulations for environmental controls at the rate of 10 Mg ha-1 year-1 for 4 years. Granulometric soil fractionations involving water or sodic resin, of samples from plots with or without sewage sludge addition were performed (figure 1).

Fig.1 Watteau 2011

Figure 1: Differential size distributions in 2002 and 2003 of the topsoils of the control (Fig. 1a) and the amended soil (Fig. 1b). dW (%) = substraction of the weight percentages of water-stable fractions from sodic resin-stable fractions

Then morphological and analytical characterization by TEM of the water-stable <20 µm micro-aggregates were carried out to specify their aggregative organic matter (figure 2).

Fig.2 Watteau 2011

Figure 2: Ultrastructural examination of the (2–20 µm) fractions of the amended topsoil. 4.1 – Global view of the fraction in 2002. 4.2 – Global view of the fraction in 2003. 4.3 – Specific micro-aggregate. Spectrum 1 : EDX analysis of the organic matter of the micro-aggregate. Spectrum 2 : EDX analysis of the mineral of the micro-aggregate Caption – agI, agII, agIII: micro-aggregate of type I, II or III; b: bacteria; c: clay; cw: cell wall residue; ex: exopolymers; h: hole in the resin due to the micro-quartz; m: mineral; om: organic matter; q: quartz grains;  *1 and *2: localization of EDX analysis 1 and 2.

0-20 µm water-stable fraction contained more than 60% of the soil carbon. A typology of <20 µm micro-aggregates was established according the nature of aggregative organic matter. It appeared that among 0-2 µm and 2-20 µm micro-aggregates, those containing young organic matter of plant and microbial origin were involved in the most stable associations. The impact of the dry period on soil microstructure between 2002 and 2003 corresponded to both an increase in the 0-2 µm water-dispersibility and a decrease in the mean size of the 2-20 µm water-stable aggregates. Sewage sludge addition slightly increased the proportion of the 50-200 µm water-stable macro-aggregates and induced the formation of micro-aggregates containing sludge flocs, which could be considered as specific sewage sludge fingerprints. Descriptors of 0-20 µm stable micro-aggregates, i.e. size, stability and typology, appeared as a promising tool to specify the dynamics of the organo-mineral associations in soils subjected to environmental changes or cultivation practices. 


1. Marshall, T.J., Holmes, J.W., 1979. Soil Physics. Cambridge University Press.

2. Gobat, J.-M., Aragno, M., Matthey, W., 1998. Le sol vivant, bases de pédologie, Biologie des sols. Presses Polytechniques et Universitaires Romandes, Lausanne.


Laboratoire Sols et Environnement, Nancy Université, INRA, 2 avenue de la Forêt de Haye, BP 172, F-54505 Vandoeuvre-lès-Nancy Cedex, France