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It is generally known that soil organic carbon (SOC) stocks tend to increase with an increase in C input, whereas the C sequestration efficiency (CSE), i.e., the conversion ratio of C input to SOC, differs depending on the amount and type of C input. However, there is still a need to better understand the impact of various fertilization practices on CSE. We studied the data from eight long-term experiments located in the main dryland region of China in order to comprehensively assess the key drivers of CSE in the plow layer considering nearly four decades of various fertilizer treatments, i.e., no fertilizer (CK); chemical nitrogen, phosphorus, and potassium (NPK/NP); chemical fertilizers plus manure (NPKM/NPM/NM); and straw (NPKS/NPS/NS). Our results showed that manure amendment had the most significant fertilization effect on SOC sequestration with an average CSE of 14.9%, which was significantly higher than that of chemical fertilization (9.0%) and straw return treatments (7.9%). In addition, manure amendment also had the highest average SOC increase rate of 684 kg C ha-1 yr-1. Variance partitioning analysis (VPA) illustrated that the CSE of the main dryland region of China was mostly controlled by edaphic characteristics (32.2%), especially the soil C/N ratio and clay content. VPA and structural equation modeling revealed that the magnitude and influencing factors driving CSE varied among different fertilizer treatments. Soil total N was the limiting factor for CSE in the CK treatment, whereas the soil C/N ratio and pH were the main explanatory factors for CSE in the long-term chemical NPK fertilizer treatment. The negative impact of C input from straw was the main driver of CSE under straw return treatments, though C input had a positive effect on the improvement of soil physical properties. However, when considering manure amendments, the improvement of soil nutrients and clay content controlled CSE, underlining the main positive direct effect of soil chemical properties. In a nutshell, our results recommend manure plus chemical fertilizers as a sustainable practice for improving the C sequestration rate and efficiency in dryland cropping systems.

Enhancing soil organic carbon (SOC) stocks through fertilization and crop rotation will contribute to sustaining crop productivity and mitigating global warming. In this study, we analyzed the differences in total SOC stocks and their driving factors in the topsoil (0–20 cm) with various fertilization measures in two puddled lowland rice-based cropping systems (i.e., rice-wheat rotation and double rice rotation systems) over the last four decades from seven long-term experiments in the Yangtze River catchment. The soil types include Cambisol, Luvisol, and Anthrosol. The treatments include no fertilizer application (CK), application of chemical nitrogen, phosphorus and potassium fertilizers (NPK) and a combination of NPK and manure applications (NPKM). Every year, field was ploughed to a depth of 15–20 cm before wheat sowing and rice transplanting. Residue was removed after plant harvesting. Results showed that during the last four decades, the average crop grain yield ranged from 1,151 ± 504 kg ha−1 yr−1 under CK treatment to 7,553 ± 1,373 kg ha−1 yr−1 under NPKM treatment. The topsoil SOC stock significantly increased by 8.6 t ha−1 on average under NPKM treatment in rice-wheat system and by 2.5–6.4 t ha−1 on average under NPK and NPKM treatments in double rice system as compared with CK. A higher SOC sequestration rate and a longer SOC sequestration duration were found in NPKM treatment than that in NPK treatment in both cropping systems. The highest SOC stock ratio (SOC stock in fertilizer treatments to CK) was observed under the NPKM treatment in both cropping systems, though no significant difference was found between these two cropping systems. However, the fertilization-induced relative increase of the SOC stock was 109.5% and 45.8% under the NPK and NPKM treatments, respectively in the rice-wheat system than that in the double rice system. This indicates that the rice-wheat system is more conducive for SOC sequestration. RF and SEM analyses revealed that the magnitude and influencing factors driving SOC sequestration varied between two systems. In the double rice system, continuous flooding weakens the influence of precipitation on SOC sequestration and highlights the importance of soil properties and C input. In contrast, soil properties, C input and climate factors all have important impacts on SOC sequestration in rice-wheat system. This study reveals that the rice-wheat system is more favorable for SOC sequestration despite its lower C input compared to the double rice system in China’s paddies.

Description of the subject. Given the current low price of milk, a lot of producers have decided to process their milk into products with a higher added-value, including butter. However, all milks are not suitable to be transformed into butter. It would thus be useful to be able to predict milk processing properties. Objectives. The aim of this paper was to study the ability of milk to be processed into butter using infrared spectrophotometry. Method. A normalized protocol for the production of butter was developed. Milk samples (n = 110) collected between 2013 and 2016 were analyzed by near and medium infrared spectrometry (315 spectra). Butter samples were also analyzed by visible-near infrared spectrometry (220 spectra). Composition of the products was subsequently assessed using validated prediction equations. Principal components analyses were performed to discriminate samples. Results. Butter properties seemed to be influenced by seasons and feedings. Water content and color parameters could be predicted on the basis of butter infrared spectra. Conclusions. It was possible to correlate butter characteristics with milk properties. However, it was not possible to predict butter characteristics on the basis of milk near infrared spectra. It could be interesting to try predictions from milk medium infrared spectra.

Introduction. For dairy producers who want to transform their milk, the ability of milk to coagulate is an important parameter. It makes it possible to transform milk into cheese. Therefore, it is necessary to understand the coagulation process and the techniques to measure it in order to achieve the best transformation performance. The objective of this review is to describe the milk coagulation process, the factors influencing it and the methods for measuring the coagulation of milk at lab level. Literature. The processing of milk into cheese involves three steps: coagulation, dewatering and refining. Coagulation is a key step which involves the use of rennet and depends on several parameters (pH, calcium content, temperature, etc.). Some milks never coagulate. To measure the coagulation ability of milk and identify different parameters in milk coagulation properties, the Formagraph, the computerized renneting meter and the Optigraph have been developed (reference methods). Equations have been developed using infrared spectrometry to predict the parameters obtained by the reference methods. Conclusions. The milk coagulation mechanism is known. However, the issue of non-coagulating milk persists and represents a real challenge in terms of yield. The use of infrared is a faster alternative to reference methods that measure the coagulation properties of milk, but still requires an improvement in prediction equations.

The management of soil organic matter, an important issue in reducing nitrate leaching to groundwater. Description of the subject. The nitrate concentration in half of the groundwater bodies of the Walloon Region (Belgium) has justified their classification as vulnerable zones under the Nitrates Directive (ND). This vulnerable area has a relatively high diversity of agro-soil environments. Thus, the nitrogen content of agricultural soils can vary locally by a factor 4. Objectives. This study aimed to establish whether the carbon content of a soil is a significant risk factor in nitrate leaching to groundwater. Method. The article is based on measurements of nitrate nitrogen residue (APL) and soil total organic carbon (TOC) at the beginning of the leaching period. The measurements were made in 2012 in 1,500 plots, during inspections organized by the Wallonia Public Service. This was as part of the application of the Program for the Sustainable Management of Nitrogen in Agriculture, the scheme for implementing the ND within the Walloon region. Results. Examination of the results showed both that the APL was positively correlated to the TOC and that plots with "noncompliant" APL results had a significantly higher average TOC than the other plots. Conclusions. Since APL is an environmental indicator of the risk of nitrate leaching, it appears that the TOC may constitute a risk of groundwater contamination by nitrate. It is therefore advisable to improve the inclusion of this parameter in advice regarding nitrogen fertilization and secondly, in the case of summer harvest, to better manage the sowing of catch crops.

Introduction. Interacting soil organisms support biological processes that participate in soil functions, organic matter decomposition, and nutrient cycling. Earthworms and microorganisms play a range of beneficial roles in agricultural systems, including increased organic matter mineralization, nutrient cycling, and soil structure stabilization. Literature. The following aspects of crop residue management effects are examined in this paper: (i) earthworm composition and structure; (ii) soil microbial communities; and (iii) phosphorus (P) and nitrogen (N) element availability and distribution in the soil profile. Conventional tillage (ploughing) is often reported to generate decreased soil organism abundance and diversity, primarily earthworms and microorganisms, as well as a uniform distribution of the nutrients P and N within the ploughed soil horizon. Soil residue incorporation of mineral particles can maintain P and N levels, however returning soil also increases aeration and the activation of microbial activity. Hence, comparisons of tillage effects on soil biological functioning and nutrient cycling remain unclear. Conclusions. This review highlights the challenges in establishing definitive evidence regarding the effects of crop residue management on soil organisms and nutrient dynamics. The studies examined reported variability in soil and climate, and the complexity of soil processes contributed to the absence of clear findings. Further research is required under temperate climate conditions.

Introduction. Phosphorus (P) is an essential element for plant growth. Therefore, it is essential to accurately evaluate its content in the soil. This requires reliable indicators of soil P status. Literature. This paper reviews literature regarding the indicators of P status in soils. Many indicators can be found, including single extractions (soluble, available, or total P), which are the most common indicators used worldwide. Over time, increasingly complex P indicators have been developed as sequential extractions which characterize the various forms of P, degree of P saturation, diffusive gradients in thin films, biological extractions, isotopic methods, or more complex models. To make a choice among them, different criteria should be applied, including relevance, cost and time, ease of interpretation, and, most importantly, the objective of the analysis. It is also necessary to analyze the appropriateness to soil and climate. Firstly, this paper describes the various types of indicators present in the literature, and proposes a classification system. Secondly, all cited indicators are evaluated and compared. Finally, the P indicators met in Wallonia, southern Belgium are discussed. Conclusions. Each P indicator presents advantages and disadvantages. This review highlights the importance of careful consideration of indicator choice, and the establishment of interpretation thresholds.

Introduction. Residues of previous crops provide a valuable amount of organic matter that can be used either to restore soil fertility or for external use. A better understanding of the impact of crop residue management on the soil-water-plant system is needed in order to manage agricultural land sustainably. This review focuses on soil physical aspects related to crop residue management, and specifically on the link between soil structure and hydraulic properties and its impact on crop production. Literature. Conservation practices, including crop residue retention and non-conventional tillage, can enhance soil health by improving aggregate stability. In this case, water infiltration is facilitated, resulting in an increase in plant water availability. Conservation practices, however, do not systematically lead to higher water availability for the plant. The influence of crop residue management on crop production is still unclear; in some cases, crop production is enhanced by residue retention, but in others crop residues can reduce crop yield. Conclusions. In this review we discuss the diverse and contrasting effects of crop residue management on soil physical properties and crop production under a temperate climate. The review highlights the importance of environmental factors such as soil type and local climatic conditions, highlighting the need to perform field studies on crop residue management and relate them to specific pedo-climatic contexts.

Do manures spread before the sowing of a catch crop (CIPAN) present an excessive risk of nitrate leaching?. Description of the subject. The implementation of the Nitrates Directives in the Walloon region (in the south of Belgium) allows the summer spreading of any kind of manure on soils in preparation for the sowing of a catch crop. Objectives. This paper aims to assess whether the spreading of a manure before sowing a catch crop is more risky for groundwater quality than planting a cereal followed by another crop without any action being implemented between the harvesting of the cereal and the sowing (winter or spring) of the next crop. Method. This study is based on measurements of the nitrate nitrogen content of soils, at the beginning of the leaching period, performed on reference parcels and on controlled parcels. Results. Three thousand six hundred soil analyses performed in relation to controlled parcels between 2008 and 2013 showed that the presence of a catch crop (information about the possible application of a manure was not known) led to a nitrate nitrogen content (median) lower (with a very highly significant difference) than in a situation where no action was implemented between the two main crops. For the same period, the analysis of 600 results in reference parcels led to the same conclusion. Moreover, no significant difference was found between the two kinds of manure ("fast action", such as pig slurry or "low action", such as bovine manure). Conclusions. After the harvesting of a cereal, the spreading of a manure before sowing a catch crop creates no higher risk for water quality than the succession of a cereal by a crop sowed in the autumn.

The limitations of conventional agriculture have accelerated the need for a transition to an environmentally and economically sustainable agricultural model. In this regard, the role played by soil organic matter (SOM) is key. Here, we aimed to study the impact of permaculture and biointensive micro-gardening practices, characterized by intensive cultivation, the use of large and localized organic inputs and the non-use of mineral fertilizers and pesticides, on soil physicochemical properties and SOM distribution in aggregate-size fractions. The physicochemical properties of soils in permaculture farming implemented for 7 years were compared with a soil under pasture. A soil experiencing conventional agriculture practices in similar geopedoclimatic conditions was simultaneously studied. Soils were separated into four aggregate-size fractions, into which organic carbon (OC) concentrations have been measured. The major soil physicochemical properties were measured on the bulk soils. The concentrations of total OC and nitrogen (N) in bulk soils were higher under permaculture practices, due to significant inputs of manure and compost, resulting in higher concentrations of the bioavailable nutrients Ca, Mg, K, and P. The permaculture practices sustained a level of macroaggregation similar to that of the pasture, and well above that of conventional practices. OC concentrations increased in the 250–2,000, 50–250 μm and occluded 50–250 μm fractions, but not in the

Characterization of soil-plant systems in the hills of the copper belt in Katanga. A review. Introduction. The Copper belt of Katanga presents huge resources of Cu and Co-ore. On the copper hills of the area, mineralized rock outcrops and a specific flora have developed as a response to the high levels of Cu and Co in the soil. Soil-vegetation relationships need to be understood in order to develop biodiversity conservation programs prior to industrial mining of the copper hills. Literature. This paper reviews the current knowledge regarding soil characterization in the copper hills of Katanga and makes proposals for further research on the influence of the very specific chemical conditions of contaminated soils on the vegetation there. The focus is on the geochemical background and the bioavailability of Cu and Co. Much progress has been made recently regarding the identification of soil-vegetation relationships. Conclusions. Despite advances in this area, the issue of Cu and Co mobility within soil-plant systems is not yet entirely resolved.

Introduction. This article reviews soil and crop production information from Bukidnon, Northern Mindanao, the Philippines. It focuses on the parent materials involved in forming Bukidnon soils, clay forming minerals, soil classification, types and location distribution, physico-chemical characteristics, soil potentialities and constraints, and the yields of the major crops. Literature. The information discussed was gathered from on-line journals, a compilation of agricultural research reports published in Northern Mindanao, published theses, government data and reports, and books. Bukidnon has existing soil information that could be useful for assessing and monitoring soil fertility and in establishing a regional Land Information System (LandIS). Soils in the Province are classified according to Soil Order, Great Group and soil type under the USDA Soil Taxonomic Classification. Data on crop production yields are also available. Soil information is intended more for crop fertilization planning at the broader scale. Studies on geomorphopedology and the interactions of elements within the soil are scarce. The relationship between soil formation and its characteristics and plant responses is not discussed here. Conclusion. The recommendations arising from this study are: (1) to conduct in-depth geomorphopedological studies in marginal areas of undifferentiated soils, (2) to study the relationship between soil characteristics and crop responses including nutrient assimilation by plants, focusing on phosphorus (P), and (3) to develop a generic protocol and establish a LandIS for mountain areas that can be replicated in other areas in Mindanao, the Philippines.

Effects of carbonate and organic amendments on two vegetable crops in contaminated soil in Lubumbashi (DR Congo). The risk of contamination of vegetables grown in gardens in the city of Lubumbashi due to soil pollution is high. The present study describes experiments involving the use of agronomic solutions aimed at reducing these risks. The choice of appropriate amendments (type and quantity) and the selection of plant varieties able to restrict the transfer of trace metals (TM) from the soil to plant edible organs represent some of the most conventional remediation techniques. Here, amaranth and spinach beet were cultivated in pot trials using randomized complete blocks with four replications on a contaminated soil. The pots received different doses of liming and/or organic products. Along with an effect on soil chemistry, the amendments were found to be effective in reducing the transfer of trace metals from soil to plant. The lime-based treatments were found to be more effective than compost. However TM levels in plants remained high whatever the application of amendments and the problem of food chain contamination remains.

Impacts of earthworms on soil components and dynamics. A review. Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil fertility by participating to important processes in soil such as soil structure regulation and organic matter dynamics. Earthworms also modify the microbial communities through digestion, stimulation and dispersion in casts. Consequently, changes in the activities of earthworm communities, as a result of soil management practices, can also be used as indicators of soil fertility and quality. It is therefore important to understand how earthworm communities affect soil dynamics. This review adresses the current state of knowledge on earthworm's impacts on soil structure and soil organic matter (carbon, nitrogen, and phosphorus) dynamics, with special emphasis on the effects of land management practices on earthworm communities.

Review of the mobility of trace elements in soils and of the use of physico-chemical stabilization as an in situ management strategy for contaminated sites. Industrial activities have greatly impacted the quality of the biophysical environment in some areas. This review focuses on the consequences of soil contamination by metallic trace elements: what factors determine the mobility of contaminants in soils and what remediation practices based upon physico-chemical stabilization can be used in response? Physico-chemical stabilization is an in situ remediation technique, which aims at limiting the dispersion of metals in the environment through the use of soil conditioners and amendments in contaminated sites. In this article, we firstly review the concepts involved in the mobility of trace elements and their indicators. We then provide an overview of the current information regarding the different kinds of amendments that may be applied to stabilize contaminants in soils and the processes involved.

Forest cover representation in hydrological modeling: a comparison of ten models. A review. There are many hydrological models, some of which can be used for forested environments. This review aims to compare ten of these models (BILJOU, EPIC, BROOK90, SWAT, RHESSys, MIKE SHE, SHETRAN, WaSiM ETH, DHSVM and Hydrus) in order to provide guidance in the choice of model. The comparison of the models focuses on the following forest fluxes: interception, transpiration and root water uptake, root distribution, the understory effect, tree growth and model validation. The review underlines the fact that each model deals with forest fluxes in a different way. Most of the models deal with interception in a similar way, and root distribution is used in the process of root water uptake. Understory and growth are seldom considered.

Use of near-infrared reflectance spectroscopy in soil analysis. A review. This paper presents a literature review on the development of near infrared reflectance spectroscopy for soil analysis and the contribution of this technique to the evaluation of soil fertility analysis. This technique is used to estimate the chemical composition of soil samples on the basis of their absorption properties. It is therefore an indirect method of measurement, which requires a calibration phase for the prediction of these properties. NIR spectroscopy offers many advantages compared to reference analysis: it is known to be a physical, non-destructive, rapid, reproducible and low cost method. Often employed in other analytical domains, such as agro-food, NIR spectroscopy has, however, seldom been used in soil characterization, due to the complexity of the soil matrix. Thanks to the development of chemometric methods, numerous studies have recently been conducted to evaluate the feasibility of the application of the technique in soil analysis. Most authors conclude that NIR spectroscopy is promising; however, to date, use of the technique has not spread to routine laboratories. The paper is organized as follows. Firstly, we provide an overview of the NIR spectroscopy technique and related chemometric methods. Secondly, we describe the soil characteristics that can be predicted using this technique. Finally, we detail examples of results that have been obtained through the use of the technique, mainly in the determination of clay and organic carbon content, and of cation exchange capacity.

Soil mapping in Belgium: historical overview and presentation of the current work on valorisation and revision of the Digital Soil Map of Wallonia. Over the past few years, there has been growing concern about soils and their properties, thanks to greater environmental awareness. Consequently, existing documents on soil are valuable in risk assessment and for the research of well-adapted solutions. In this context, this paper reviews the main stages of soil mapping in Belgium and presents current works to valorize the Digital Soil Map of Wallonia and update associated databases. Belgium is among the first countries to be completely covered by a detailed soil map (1:20,000). The origin of the Soil Map of Belgium, its realisation between 1947 and 1991, the principles and characteristics as well as the related products are described. But since its publication, due to the increasing need of soil information and thanks to the development of geographical information systems the Walloon part of the map was digitalised between 2000 and 2003 by the Digital Soil Map of Wallonia (DSMW) Project. From this early action at regional level, a selection of immediately derived products is presented and briefly commented. However, if these products go beyond the initial objective of agricultural production increase, they do not always meet the environmental challenges nor the future legislation at European, national and regional levels. To fill this gap, the recent tasks carried out by the DMSW team are presented through a description of their methodological and technical framework. The long-term objective is to build Regional Soil Information Systems based on the use of the Digital Soil Map of Wallonia as a tool of integration, structuring and referencing of pedological information.

Interest of soil maps to elaborate a sampling strategy in soils contaminated by atmospheric fallouts: application to the study of soil effect on the fate of metallic trace elements. As a result of pollution from atmospheric dusts, some sites of Wallonia (Belgium) are contaminated by metallic trace elements (MTE) such as cadmium, lead and zinc. These metalliferous soils are called 'calaminary sites'. The major aim of this study concerns the multi-scalar characterization of MTE distribution in these contaminated soils and landscapes. The strategy of sampling described in this paper is based on the influence of soil type and its land use on the fate of MTE. After analysis of collected samples, it will be possible to have an idea of the distribution of MTE among soil components, and therefore, to evaluate the risks caused by environmental changes such as an agricultural use of afforested areas.

Making use of the Digital Soil Map of Wallonia and of an available soil analysis database for assessing the risk of pesticide leaching to groundwater. This study shows how the Digital Soil Map of Wallonia and the associated soil database Aardewerk can be combined with the MetaPEARL model to assess the sensitivity of agricultural soils to pesticide transfer into underground water tables in Wallonia (Southern Belgium). MetaPEARL is based on an analytical expression which describes the concentration of leached pesticides at the soil profile bottom depending on available data on soil characteristics, climate and pesticide properties. The results show an important soil sensitivity to pesticide transfer with a coefficient of retention on organic matter (Kom) very weak (about 10 dm3.kg-1) or with a relatively high half-life time (DT50 about 60 days). In this case, the pesticide is weakly retained by soil organic matter or slowly degraded and then stays available in the soil and can be quickly leached during rainfalls. In other respects, the pesticide sensitivity to leaching is strongly correlated with soil texture and its organic matter content. It is also observed that the concentration of leached pesticide is strongly depending of the rainfall surplus (water flux into the soil or hydrous balance). A sensitivity analysis has shown that the model is very sensitive to soil thickness, to organic matter content, to the bulk density of the mineral fraction by textural classes and of the organic matter. Therefore, these pedological variables have to be assessed with the highest precision to avoid adding further uncertainty to the predictions obtained. On the basis of the most sensitive soil variables, the analysis of "spatial" uncertainty related to the results delivered by MetaPEARL, due to the consideration of an unique representative value by soil type and by region (deterministic approach), shows that this approach tends to under-estimate the concentration of pesticide leached in the soil, compared to the use of a stochastic simulation (probabilistic approach) which takes into account the soil characteristic variability within a given soil type. This stochastic approach allows also the calculation of a more relevant threshold of risk probability (percentile) which can be compared to an imposed standard in view to enhance a sustainable management of natural resources.

A methodology for site selection and soil sampling in relation with main parent materials in Wallonia (Southern Belgium). Despite the small size of its territory, Wallonia shows a geological context singularly varied and contrasted. From main geostructures to lithostratigraphical formations, this diversity has greatly influenced soil types. Rock weathering represents one of the main processes in soil forming. Throughout its nature and its composition, the parent material is identified as one of the main factor influencing pedogenesis and soil properties. Understanding the spatial determinism of these properties requires a better characterisation of the parent materials as well as of their spatial distribution. The Soil Science Unit of Gembloux Agro-Bio Tech has therefore initiated the collect of topsoil and subsoil samples representative of the diversity of Walloon agricultural soils, in relation with their parent materials and presenting a wide range of physico-chemical properties. The sampling strategy relies on the stratification of the territory in physical units and on the identification of the dominant parent materials and soils. The 1:20,000 Numerical Soil Map of Wallonia, the 1:250,000 Map of the Main Soil Types of Wallonia and the Map of Rural Space Units helped largely to fulfill these tasks. The very wide panel of feasible analyses on these samples opens interesting prospects on valorization of the data in a regional soil information system. Indeed, considering the importance of samples representativity in the approach, the pedotheque and analytical database should become reference tools in Wallonia, serving needs of numerous research projects.

To a sampling and personal fertility advice, the tools for decision support. Environmental and agronomic issues require always more well thought and suited farmer management of agricultural inputs; soil analysis is therefore an essential tool to support decision. However, for a soil analysis to provide valuable information, it is essential for the sample to be representative of the studied field. Without this representativeness, an analytical result, as accurate as it could be, would not be of interest if it could mislead the farmer. In practice, the main difficulty for the sampler is the recognition of soil criteria which are essential to provide a fertility advice, especially in Wallonia (Belgium) where soil variability is very important. With the Digital Soil Map of Wallonia (DSMW), drowned at the scale 1/5,000, it seems appropriate to give these information to the samplers in an useful form for routine works. That is why a mapping tool for decision support, named REQUACARTO, was designed to be used for soil analysis by provincial laboratories, members of the REQUASUD laboratories network. This tool responds to a real requirement in Wallonia: achieving a quality sampling for the development of personalized soil fertility advice.

Foreword. /.

Fertility state of agricultural and forest soils in Walloon region. Feeding on plants and animals, the human societies are broadly dependent on soils because these, beyond their role as support of plant production, produce, contain, and collect the most part of the nutriments necessary to life. The sustainable management of the agricultural and forest soils implicates an uninterrupted assessment of their state by the measure of fertility indicators. This last is perceptible as the soil suitability to assume the plant biomass production. The soil suitability results from environmental physical, chemical and biological factors such as parental material, climate, etc. The human activities, particularly the agricultural and forest practices, also play a major role in the soil suitability. To avoid losses towards aquatic environment, these practices have to aim at satisfying the vegetables needs, while watching not to exceed the capacity of soil to keep the nutriments. Several tools exist in Walloon region to estimate the fertility state of soils, mainly at (physico-)chemical levels. This article introduces an outline of the agricultural, and forest soils state in various mineral and organic elements, and specify as well as possible involvements in other environmental problems.

Pertinence of pedological stratification of regional-scale reference systems about metallic trace elements content in soils.Walloon case studies. The natural background levels of metallic trace elements (ETM) in soils should be known in order (i) to understand the processes in which they are involved and (ii) to settle reference systems dedicated to the appraisal of agricultural or forest management practices, to the detection of contaminations, or to the time-course follow-up of regional values. A methodological framework has thus been set up to evaluate the importance of natural driving factors, also-called the pedogeochemical background, of the spatial distribution of ETM in soils. The methodology also aims at defining indicator values of the current degree of ETM contamination in agricultural soils. The spatial distributions of both ETM content and soil forming factors constitute the basement parameters of regional reference soil systems (RSS) about ETM content. The stratification of these regional reference soil systems on a pedological base, which means that soil volumes are clearly identified, appears to be valuable to refine predictions. This is shown through some case studies in the Walloon Region from Belgium. The more the regional reference systems will consider ancillary soil information as well as the geographic specificities of small natural regions, the more they will be relevant to detect local contaminations. For that reason, the digital soil map of Belgium can be considered as a potential powerfull tool for geochemical mapping, after an adaptation of its legend.