Christian Walter

Institut Agro Rennes Angers

Understanding spatial and temporal variability in soil organic carbon (SOC) content helps simultaneously assess soil fertility and several parameters that are strongly associated with it, such as structural stability, nutrient cycling, biological activity, and soil aeration. Therefore, it appears necessary to monitor SOC regularly and investigate r...

Monitoring changes in soil properties is essential to ensure ecosystem function and agricultural productivity. This study evaluated the ability of visible near infrared (Vis-NIR) spectroscopy to detect the temporal trend in soil organic carbon (SOC) content after 5 years in a 12 km ² agricultural catchment in western France. Partial least squares r...

A group of researchers participating in the SERENA project of the EJP Soil program conducted a meta-analysis to study the methods used in existing prospective studies focusing on six soil ES (e.g. biomass production, habitat for biodiversity, hydrological control, environmental pollution control, greenhouse gas and climate regulation, pest and dise...

Soils provide services that can increase food security and mitigate global warming. Simulation modelling of biophysical processes is one approach used to estimate values of soil ecosystem services (SES) based on soil properties and climate conditions. The SES are usually investigated using statistical approaches that assume that values of SES are n...

Soil organic carbon (SOC) storage and redistribution across the landscape (through erosion and deposition) are linked to soil physicochemical properties and can affect soil quality. However, the spatial and temporal variability of soil erosion and SOC remains uncertain. Whether soil redistribution leads to SOC gains or losses continues to be hotly...

The work was undertaken in a farm of a thousand hectares located in the plain of Sisseb-Plain of Kairouan. Saline clay soil, P=300 mm/year, ETP=1500 mm/year. Irrigation with borehole water, EC= 3 dS/m. Various soil samples and geophysical measurements by EM38 and EM31 were taken at several space and time scales. Discussion and Conclusions The monit...

Soil available water capacity (AWC) and Bulk Density (BD) are key properties for understanding water flows in soils, land‐use planning and irrigation management. As measuring these properties is costly and time‐consuming, pedotransfer functions (PTFs) are commonly used to predict BD and soil moisture at a specific matric potential, and then estimat...

http://www.pedometrics.org/Pedometron/Pedometron46.pdf

Radar remote sensing has shown a high potential for soil surface parameters estimation in different pedo-climatic context. In the present study, we investigated Sentinel-1 radar signal in order to analyze its behavior as function of soil moisture and soil roughness. In addition, we evaluated the approach combining the modified Integral Equation Mod...

Soils are essential for supporting food production and providing ecosystem services but are under pressure due to population growth, higher food demand, and land use competition. Because of the effort to ensure the sustainable use of soil resources, demand for current, updatable soil information capable of supporting decisions across scales is incr...

Soil salinization is a major problem affecting soils and threatening agricultural sustainability in arid and semi-arid regions, which makes it necessary to establish an efficient strategy to manage soil salinity and confront economic challenges that arise from it. Saline soil recovery involving drainage of shallow saline groundwater and the removal...

Soil salinity due to irrigation is a major constraint to agriculture, particularly in arid and semi-arid zones, due to water scarcity and high evaporation rates. Reducing salinity is a fundamental objective for protecting the soil and supporting agricultural production. The present study aimed to empirically measure and simulate with a model, the r...

Alors que les sols occupent une place centrale dans les différents enjeux globaux que sont la sécurité alimentaire, l’accès à l’eau potable, la régulation du climat, le développement des énergies renouvelables et la préservation de la biodiversité, ils peuvent être soumis à des dégradations liées à une mauvaise gestion, comme l’érosion, la perte de...

Soil organic carbon (SOC) has a significant effect on the carbon cycle, playing a vital role in environmental services and crop production. Increasing SOC stock is identified as an effective way to improve carbon dioxide sequestration, soil health, and plant productivity. Knowing soil water is one of the primary SOC decomposition driver, periods in...

Spatial quantification of soil attributes is needed to assess and monitor soil resources. Our objective was to map soil total carbon (TC) over 580 ha bare soils, in Djerid arid area (SW Tunisia). One hundred and forty-four soil samples were collected in nodes of 200 m square grid and their spectra acquired in the laboratory at 400–2500 nm have serv...

Soil is a reservoir of natural capital that provides several ecosystem services, ensuring human well-being and sustainable socioeconomic development. Many researchers nevertheless argue that there is no consensus on practical indicators to assess soil ecosystem services (SES). As many policy decisions rely on metrics and indicators to communicate c...

All across the world, and particularly in arid and semi-arid zones, the negative effects of agricultural productivity and unsustainable development have led to soil salinization, which is one of the critical environmental issues. Since the problem of salinization evolves at the scale of space and time, it is necessary to develop a comprehensive str...

Salinization is a major soil degradation threat in irrigated systems worldwide. Irrigated systems in the Niger River basin are also affected by salinity, but its spatial distribution and intensity are not currently known. The aim of this study was to develop a method to detect salt-affected soils in irrigated systems. Two complementary approaches w...

Digital Soil Mapping (DSM) is increasingly needed to improve existing soil information and derive soil property maps at the suitable spatial resolution for sustainable soil landscape management. However, predicting several soil properties while preserving specific pedological process is a great challenge, particularly when only coarse soil informat...

Enhancing the spatial resolution of pedological information is a great challenge in the field of digital soil mapping (DSM). Several techniques have emerged to disaggregate conventional soil maps initially and are available at a coarser spatial resolution than required for solving environmental and agricultural issues. At the regional level, polygo...

Many factors could influence simultaneously soil spectra. We aimed to study the single effect of organic carbon and total iron in soil visible and short-wave near-infrared spectra and to quantify their contents. Two datasets of soil mixture samples were prepared by mixing, in various fractions, an organic carbon-rich material with a total iron-rich...

The soil organic carbon (SOC) pool is the largest terrestrial carbon (C) pool and is two to three times larger than the C stored in vegetation and the atmosphere. SOC is a crucial component within the C cycle, and an accurate baseline of SOC is required, especially for biogeochemical and earth system modelling. This baseline will allow better monit...

As a critical interface in the environment, soils can provide a wide range of ecosystem services (ES). However, while there is growing demand to assess soil ES from agricultural systems, considering them in land management strategies remains a challenge. Indeed, because of the difficulty in relating soil properties to ES, soil ES are still not full...

Color is an important soil property and often used to infer soil properties and delineate soil horizons. We in- vestigated the effect of soil texture, carbon, total elements, and particle-size fractions on the color of sandy soils using five color models. In total, 915 soil samples were collected to a maximum depth of 220 cm at 400 locations in the...

Soil organic carbon (SOC) is important for its contributions to agricultural production, food security, and ecosystem services. Increasing SOC stocks can contribute to mitigate climate change by transferring atmospheric CO2 into long-lived soil carbon pools. The launch of the 4 per 1000 initiative has resulted in an increased interest in developing...

We present two ways to assess SOC storage and sequestration potentials in France, using the French soil monitoring network data. We first estimate SOC saturation using the Hassink equation and calculate the additional SOC sequestration potential (SOCseqp) by the difference between SOC saturation and fine fraction C. We map the geographical distribu...

Soil thickness (ST) is a crucial factor in earth surface modelling and soil storage capacity calculations (e.g., available water capacity and carbon stocks). However, the observed depths recorded in soil information systems for some profiles are often less than the actual ST (i.e., right censored data). The use of such data will negatively affect m...

Enhancing the spatial resolution of pedological information is a great challenge in the field of Digital Soil Mapping (DSM). Several techniques have emerged to disaggregate conventional soil maps initially available at coarser spatial resolution than required for solving environmental and agricultural issues. At the regional level, polygon maps rep...

Water impoundments have major impacts on biogeochemical cycles at the local and global scales. However, although reservoirs flood soils, their biogeochemical evolution below water and its ecological consequences are very poorly documented. We took advantage of the complete emptying of the Guerlédan Reservoir (Brittany, France) to compare the compos...

The root system and its architecture play an essential role in the plants physiology, from stability for aboveground structure to water and nutrient transport and storage. However, due to the opaque characteristic of the soil or other growing media and the fragility of some of the root system structure, non-destructive temporal observation remains...

Aim This study tested the capacity of the semi-aquatic grass Echinochloa stagnina to grow on highly salt-affected soil to improve soil structure and decrease salinity of saline Vertisols. Methods The experimental study, conducted over 11 months on soil columns in laboratory conditions, tested three treatments: i) ponded bare soil without crops (CT...

Soil is a natural capital that provides several ecosystem services ensuring human well-being and sustainable socioeconomic development. The scarcity of soil information is the main shortcoming to assess soil ecosystem services (SESs). At regional level, soil information is available at coarse spatial resolution (1:250,0000 in Brittany, France) and...

Soils have critical relevance to global issues, such as food and water security, climate regulation, sustainable energy, desertification and biodiversity protec-tion. As a consequence, soil is becoming one of the top priorities for the global environmental policy agenda. Conventional soil maps suffer from large limita-tions, i.e. most of them are s...

Core Ideas AgrHyS is a long‐term observatory of the agroecosystem. AgrHyS supports strongly interdisciplinary environmental research. AgrHyS offers an original experimental setup to explore the soil–groundwater–water–plants–atmosphere continuum. AgrHyS supports original and innovative techniques for environmental monitoring. The AgrHyS is a long‐t...

Soil organic carbon (SOC) sequestration and soil redistribution (through erosion and deposition) are linked to soil physical, chemical and biological properties and, consequently, affect soil and environmental quality. In a global-change context, the changes in spatial distribution and temporal dynamics of both SOC and soil erosion remain uncertain...

Increasing soil organic carbon (SOC) stocks via land management has been proposed as a temporary climate change mitigation measure. An upper limit of soil stable SOC storage, which refers to the concepts of SOC saturation has been proposed. Using systematic grid sampling of topsoil in mainland France and an equation that predicts this SOC saturatio...

Visible-near infrared diffuse reflectance spectroscopy (vis-NIR DRS) is recognized as a promising tool for predicting various soil physico-chemical and biological properties. However, models’ applicability, transferability, and scaling are still questionable. Our objective was to study, for total carbon, these aspects in arid context. QuickBird sat...

This chapter highlights the conditions for sustainable management of agricultural soils, mobilizing the concepts of agroecology. The relationship between agriculture and soil has evolved over the last century. In order to define the agricultural capability of a soil, the following two groups of properties must be considered. The first group deals w...

Although soils have a high potential to offset CO2 emissions through its conversion into soil organic carbon (SOC) with long turnover time, it is widely accepted that there is an upper limit of soil stable C storage, which is referred to SOC saturation. In this study we estimate SOC saturation in French topsoil (0–30 cm) and subsoil (30–50 cm), usi...

The creation of an environmental tool diagnosis from existing modules in other models in order to contribute to improve the nitrogen management. Did the simplification of soil description, in terms of horizons number and of the shape’s curve of root profile in the French model of culture STICS, allows us to simulate correctly the quantity of leachi...

ISI Document Delivery No.: BK4DMTimes Cited: 0Cited Reference Count: 5Zoghlami, Rahma Ines Parnaudeau, Virginie Walter, ChristianProceedings Paper1st Euro-Mediterranean Conference for Environmental Integration (EMCEI)Nov 22-25, 2017Sousse, TUNISIAGewerbestrasse 11, cham, ch-6330, switzerland2522-8714

Spatial disaggregation of soil map units involves the downscaling of information to produce new information at a finer scale than the original source. Currently, it is becoming a powerful tool to address the spatial distribution of soil information over large areas, where legacy soil polygon maps are the only source of soil information. Because of...

In life cycle assessment (LCA), simple models are currently used to estimate cropping system nitrogen (N) emissions on farms. At large spatial scales (e.g., countries), these models are valid. At a smaller spatial scale (e.g., territories), these models may be less accurate, since they completely or partially ignore local conditions such as managem...

Soil pH is one of the most common and important measurements used to assess soil quality and manage soil fertility. Soil acidification is a slow process that can have large consequences. Therefore, it is important to detect soil changes early. Using a French soil test database, we show that the soil pH increased in 36% of arable soils monitored fro...

Les méthodes de comptabilisation et de vérification du stockage additionnel de carbone

Phytodesalinization by salt-tolerant plants or halophytes has been developed as an alternative way to reclaim salt-affected soils. This study tested the use of Echinochloa stagnina Retz. Beauv. to increase salt removal from saline Vertisols and compared the desalinization potential of two cropping techniques of this fodder crop to those of two othe...

Sensitivity Analysis in Earth Observation Modeling highlights the state-of-the-art in ongoing research investigations and new applications of sensitivity analysis in earth observation modeling. In this framework, original works concerned with the development or exploitation of diverse methods applied to different types of earth observation data or...

About 500 dams creating large water reservoirs have been built in France since 100 years. Compared to natural lakes, the ecology and carbon budget of these water bodies are influenced by the submerged soils and vegetation, as well as by the artificial management of the water level. The fate of soil carbon 80 years after dam establishment has been s...

Digital soil mapping is becoming a powerful tool to increase the spatial detail of soil information over large areas, which is essential to address agronomic and environmental issues. When it exists, information about soil is often sparse or available at a coarser resolution than required. The spatial distribution of soil at the regional scale is u...

The French soil-test database (Base de Données d'Analyses de Terre: BDAT) is populated with analytical results of agricultural topsoil samples requested by farmers for fertilization planning. The coordinates of the farms are unknown due to data confidentiality policies, and the best available georeference is at level of municipality. We compared fo...

Soil provides ecosystem services, supports human health and habitation, stores carbon and regulates emissions of greenhouse gases. Unprecedented pressures on soil from degradation and urbanization are threatening agro- ecological balances and food security. It is important that we learn more about soil to sustainably manage and preserve it for futu...

Soil provides ecosystem services, supports human health and habitation, stores carbon and regulates emissions of greenhouse gases. Unprecedented pressures on soil from degradation and urbanization are threatening agro-ecological balances and food security. It is important that we learn more about soil to sustainably manage and preserve it for futur...

Agroforestry systems are promoted for providing a number of ecosystem services and environmental benefits, including soil protection and carbon sequestration. This study proposes a modelling approach to quantify the impact of soil redistribution on soil organic carbon (SOC) storage in a temperate hedgerow landscape. Evolution of SOC stocks at the l...

Indonesian food production depends highly on Java Island, which holds the most fertile soils in the country but had limited area. The objective of the research was to analyse the availability of suitable land for agriculture in Tuban Regency, an agricultural regency in Java Island. Land suitability was evaluated with spatial multicriteria analysis,...

This book chapter describes the main features of the Landsoil erosion model then investigates the sensitivity of its key parameters by local (one-at-a-time) methods. A virtual catchment is used to represented numerous characteristic distributions of site properties with respect to water and sediment fluxes.

Global food security entails fertile soils capable of providing food for a growing population and moreover contributing to other needs such as energy, clothing, etc. However, soils also play a major role in flow regulation within the biosphere and host an important biodiversity underlying biological processes and contributing to overall ecosystem e...

Clay content (fraction < 2 µm) is one of the most important soil properties. It controls soil hydraulic properties like wilting point, field capacity and saturated hydraulic conductivity, which in turn control the various fluxes of water in the unsaturated zone. In our study site, the Kairouan plain in central Tunisia, existing soil maps are neithe...

Clay content (fraction < 2 µm) is one of the most important soil properties. It controls soil hydraulic properties like wilting point, field capacity and saturated hydraulic conductivity, which in turn control the various fluxes of water in the unsaturated zone. In our study site, the Kairouan plain in central Tunisia, existing soil maps are neithe...

Les descriptions de 12 profils pédologiques effectuées en 1992 sur le bassin versant du Coet-Dan sont présentées avec les analyses correspondantes.

Soil organic carbon (SOC) sequestration and soil redistribution are linked to soil properties, land use, farming system and climate. In a global-change context, landscape and climate changes are expected and will most probably have impacts on changes in the soil. Soil change was simulated from 2010 to 2100 in an 86-ha hedgerow landscape under diffe...

In poorly‐drained mineral soils, little interest has been shown on the effects of the duration and frequency of water saturation periods on carbon ( C ) and nitrogen ( N ) mineralization. This study investigates C and N mineralization rates in a poorly‐drained mineral soil in response to transient and permanent waterlogged conditions. Soil samples...

Aims In agroforestry systems, root activity of trees may either reduce nutrient leaching beneath neighboring crops or compete with them. A previous study reveals high chloride (Cl) accumulation in the soil under a bottomland oak hedgerow in western France. Our study tests whether Cl can be used as an indicator of the spatial extent of tree root act...

Agriculture et Foncier - Concurrences entre usages des sols et entre usagers des sols agricoles : la question foncière renouvelée http://www.clubdemeter.com/pdf/cahier/presentation/presentation_cahier_15.pdf

Composting wastes permits the reuse of organic matter (OM) as agricultural amendments. The fate of OM during composting and the subsequent degradation of composts in soils largely depend on waste OM quality. The proposed study aimed at developing a model to predict the evolution in organic matter quality during the aerobic degradation of organic wa...

Monitoring soil salinity over time is a crucial issue in Saharan oases to anticipate salinisation related to insufficient irrigation management. This project tested the ability of electromagnetic conductivity surveys to describe, by means of regression-tree inference models, spatiotemporal changes in soil salinity at different depths within a compl...

Inappropriate agricultural land management practices cause irreversible soil losses in many parts of Europe. Soil degradation is predicted to increase in the next future as an effect of climate and cropping system changes. The most concerned areas are expected to be those already severely affected by erosion, as is the whole of the Mediterranean. M...

Soil organic carbon (SOC) has a crucial impact on global carbon storage at world scale. SOC spatial variability iscontrolled by the landscape patterns resulting from the continuous interactions between the physical environmentand the society. Natural and anthropogenic processes occurring and interplaying at the landscape scale, such as soilredistri...