Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free:

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site:, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Google Analytics

Targeted advertising cookies


The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at or by post at:

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

Dernière mise à jour : Mai 2018

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

Home page

Prediction of P concentrations in soil leachates: Results from 6 long term field trials on soils with a high P load

T. Vanden Nest (a), B. Vandecasteele (a), G. Ruysschaert (a), R. Merckx (b)

Nest & al., 2017
Agriculture, Ecosystems & Environment Volume 237, 16 January 2017, Pages 55-65

Decennia of imbalance between P fertilization and P uptake by crops in regions with intensive agriculture in Europa and North America have resulted in an increase in soil P content above those required for optimum plant growth [1]. In order to control the P losses, P fertilization has been legally restricted. In several EU28 countries, the ammonium lactate extraction method (P-AL) is used as a soil test for P fertilizer advice, but sometimes also to determine the allowed P fertilizer dose to reduce leaching losses. The objective of this study is to select a soil P test or a combination of soil P tests, which is also useful to predict the risk for P leaching.

Main results

We tested if a single soil P capacity test allows for a reliable forecast of P leaching from agricultural soils with a high P load. We hypothesized that P-AL is well adapted to identify agricultural soils with excessive soil P stocks, but that within the category of soils with elevated P-AL levels (i.e., soils with a P-AL level > 180 mg P kg-1), the soil P availability parameters P-CaCl2 and hot water extractable P (HWP) are better suited to predict P leaching losses.

Six long term field trials with a high P load (P-AL: 123 to 375 mg P kg-1) on silt loam soils with a specific history of organic and inorganic fertilizer application were sampled for soil analysis and to conduct leaching experiments in the laboratory (figure 1).

Fig.1 Nest 2017

Figure 1: Diagram of the equipment for leaching experiment

P concentrations in the leachates served as a proxy for P leaching. Five field trials were used for model calibration and a sixth one for model validation. Two models, either with P-CaCl2 or with HWP as independent variables, have proven to be suited to distinguish soils with low and high risk for P leaching. In the range of P-AL in this study, P-AL proved to be a non-significant factor and was therefore not retained in either of the models. We conclude that for soils with large soil P stocks (high P-AL concentrations), both P-CaCl2 and HWP are suitable to detect the ones with a higher risk of P leaching losses. We suggest a threshold value for P-CaCl2 and HWP to be used in combination with P-AL (figure 2), to select those soils where further P fertilization restrictions or other measures to reduce P leaching losses are needed most urgently. This threshold value however depends on what is considered as an acceptable P concentration in the leaching water of the tillage layer.

Fig.2 Nest 2017.TIF

Figure 2 : (left) Scatter plots of the relation between P-CaCl2, HWP and P-AL (mg P kg-1) and the TP concentrations (mg P L-1) in column leachates of the leaching experiments. PCaCl2, HWP and P-AL are calculated on dry soil basis. The dashed lines illustrate the medians of TP, P-CaCl2, HWP and P-AL. (right) Risk to exceed a TP concentration of 0.5, 1, 2 or 4 mg P L-1 in function of P-CaCl2, HWP and P-AL. The Y-value is calculated as the percentage of data points with respectively a P-CaCl2, HWP and P-AL level equal or below the X-value, that exceed the predefined TP concentration limit. (HWP: hot water extractable P, P-CaCl2: 0.01 M CaCl2 extractable P, P-AL: ammonium lactate extractable P, TP: total P concentration in leachates).


Jordan-Meille, L., Rubæk, G.H., Ehlert, P.A.I., Genot, V., Hofman, G., Goulding, K., Recknagel, J., Provolo, G., Barraclough, P., 2012. An overview of fertilizer-P recommandations in Europe: soil testing: calibration and fertilizer recommandations. Soil Use Manage. 28, 419–435.


a Institute for Agricultural and Fisheries Research (ILVO), Plant Sciences Unit, Crop Husbandry and Environment, Burg. Van Gansberghelaan 109, 9820 Merelbeke, Belgium
b Katholieke Universiteit Leuven, Department of Earth and Environmental Sciences, Division of Soil and Water Management, Kasteelpark Arenberg 20, 3001 Heverlee, Belgium