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  • Authors: Vasilyeva, Nadezda A.; Chenu, Claire;

    Fate of char particles and reasons of char C stabilization in soils is not well understood especially due to difficulties of its quantification. In this study we showed how char C content could be estimated from elemental analysis along with its size redistribution and co-stabilization with non-char C in long-term. We studied C dynamics in the size and density fractons of soil samples from a historical collection of 80 years bare fallow (no plant input plus tillage) experiment in Versailles, France (1929, 1939, 1949, 1962, 1972, 1991, 2008 years). Coarse char particles were observed in the soil substantially contributing to total organic C. Thus, char C study in this soil was carried out as a nessessary step for estimation of non-char C dynamics. Physical fraction allowed us to follow separately the dynamics of mineral-associated and free C. We analyzed bulk soils, fractions and picked out char particles for C, N and 13C contents. Total organic carbon concentrations in fractions pointed to char C input during 1939-1949 years. After that patterns of C and C/N and _ 13C changes in all fractions suggested redistribution of char C from coarse to finer fractions. Evolution of C/N and _ 13C suggested that all free C fractions, although enriched in char, still contained non-char C in the end of the 80 years C depletion chronosequence. Especially high proportion of non-char C was observed in the silt-size free C fraction. Linear combinations of contrasting char and non-char C C/N values allowed estimation of their proportions from the C/N evolution in the fractions. No substantial admixture of char C was observed for mineral-associated C fractions. Stable C pool in 2008 comprised of 4.6 g C kg-1 soil and was composed of mineral-associated C (3.5 g C kg-1 soil) and char-associated C (1.1 g C kg-1 soil). In both cases organic matter could be stabilized through adsorption and/or occlusion with solid particles (mineral or char). Stabilization capacities of different size class minerals reflected in C concentrations of fractions were 1.2 g C kg-1 for silt-size minerals and 19.4 g C kg-1 for clay-size minerals, contrastingly three orders of magnitude more C was associated with char particles or about 1.2 kg non-char C kg-1 sand-size char and about 1.4 to 3.5 kg non-char C kg-1 silt-size char. Such a high capacity of stabilization by char particles could not be explained by adorbtion alone. In conclusion, combination of C/N and _13C signature allowed estimation of char content in this soil. Total char C content (sum up of redistributed char C in free fractions) remained not significantly different in the C depletion experiment during five decades after char input. Century scale char and non-char C co-stabilization in this soil could be explained by combination of adsorption and physical protection in microaggregates constructed of mineral and char particles.

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  • Authors: Vasilyeva, Nadezda A.; Chenu, Claire;

    Fate of char particles and reasons of char C stabilization in soils is not well understood especially due to difficulties of its quantification. In this study we showed how char C content could be estimated from elemental analysis along with its size redistribution and co-stabilization with non-char C in long-term. We studied C dynamics in the size and density fractons of soil samples from a historical collection of 80 years bare fallow (no plant input plus tillage) experiment in Versailles, France (1929, 1939, 1949, 1962, 1972, 1991, 2008 years). Coarse char particles were observed in the soil substantially contributing to total organic C. Thus, char C study in this soil was carried out as a nessessary step for estimation of non-char C dynamics. Physical fraction allowed us to follow separately the dynamics of mineral-associated and free C. We analyzed bulk soils, fractions and picked out char particles for C, N and 13C contents. Total organic carbon concentrations in fractions pointed to char C input during 1939-1949 years. After that patterns of C and C/N and _ 13C changes in all fractions suggested redistribution of char C from coarse to finer fractions. Evolution of C/N and _ 13C suggested that all free C fractions, although enriched in char, still contained non-char C in the end of the 80 years C depletion chronosequence. Especially high proportion of non-char C was observed in the silt-size free C fraction. Linear combinations of contrasting char and non-char C C/N values allowed estimation of their proportions from the C/N evolution in the fractions. No substantial admixture of char C was observed for mineral-associated C fractions. Stable C pool in 2008 comprised of 4.6 g C kg-1 soil and was composed of mineral-associated C (3.5 g C kg-1 soil) and char-associated C (1.1 g C kg-1 soil). In both cases organic matter could be stabilized through adsorption and/or occlusion with solid particles (mineral or char). Stabilization capacities of different size class minerals reflected in C concentrations of fractions were 1.2 g C kg-1 for silt-size minerals and 19.4 g C kg-1 for clay-size minerals, contrastingly three orders of magnitude more C was associated with char particles or about 1.2 kg non-char C kg-1 sand-size char and about 1.4 to 3.5 kg non-char C kg-1 silt-size char. Such a high capacity of stabilization by char particles could not be explained by adorbtion alone. In conclusion, combination of C/N and _13C signature allowed estimation of char content in this soil. Total char C content (sum up of redistributed char C in free fractions) remained not significantly different in the C depletion experiment during five decades after char input. Century scale char and non-char C co-stabilization in this soil could be explained by combination of adsorption and physical protection in microaggregates constructed of mineral and char particles.

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  • Authors: Larrieu, Laurent; Jabiol, Bernard;

    National audience; It is more and more common for forest managers and forestry advisors to make use of soil or site analyses. But they are often at a loss concerning trophic analyses because “field” criteria are lacking and because a comprehensive diagnosis requires soil samples and chemical analyses that they are unfamiliar with. Although these chemical analyses are sometimes irrelevant to the diagnosis, at others they are critical. This article provides advice on sampling methods on the choice of tests requested from laboratories on the basis of the site and of the objectives. It also describes a software application for computer-aided interpretation of analyses; Le diagnostic pédologique ou stationnel fait de plus en plus partie de la démarche du gestionnaire ou du conseiller forestier. Mais ceux-ci sont le plus souvent démunis face au besoin de diagnostic trophique, car les critères "de terrain" sont peu nombreux et qu'un diagnostic complet nécessite des prélèvements de terre et des analyses chimiques avec lesquelles ils sont peu familiarisés. Or, ces analyses chimiques, si elles sont parfois inutiles au diagnostic, deviennent d'autres fois fondamentales. Cet article donne des conseils de prélèvement d'échantillon, des conseils pour le choix des analyses à demander au laboratoire en fonction du contexte stationnel et des objectifs, et présente un outil informatique d'aide à l'interprétation des résultats d'analyse

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Parent, Leon-Étienne; +1 Authors

    Actual phosphorus models are created in conventional tillage system. In addition, most simulation models are process-based, which need mathematical descriptions of fundamental physio-chemical mechanisms. The small time-step e.g. daily might not fit long-term simulation. In this study, a P model based on measured data was created to simulate the evolution of soil P status along soil profile in long-term. In P model, a soil zone was divided into 30 grids according to vertical (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and lateral (0-10, 10-20 and 20-30 cm for two sides into inter-row) coordinates. For each grid, P stock was defined as total amount of phosphate ions in solid and liquid phases. The P inputs and P outputs of each grid such as fertilizer, uptake, runoff and leaching were estimated with measured data in every time-step (yearly). The P status (phosphate ion concentration in soil solution) was calculated from P stock and P budget in each time step. The simulation was conducted with two tillage systems [moldboard plough (MP) and no-till (NT)].The P model managed to simulate the evolution of P status along soil profile in MP and NT during 25 years; while it was a homogenous distribution of soil P within 0-20 cm in MP. The simulated results indicated that higher accumulation of soil P in upper layers might lead to a lower use of soil P stocked in sub-soil by crop uptake. However, the model still needs validation and adjustment of parameters to form more accurate results.

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  • Authors: Carazas Aedo, Wilfredo; Douline, Alexandre;

    This manual was designed for the builders, technicians, professionals involved in rural housing development programmes in humid tropical climates where :- rainfalls are important, - clay content of the soil is very high,- existing building techniques are based on the use of adobe blocks as in-fill material (wooden structure filled with adobe for rural housing / concrete structure filled adobe or burnt bricks for public buildings).The adobe technique is not considered as a specific technology with its own characteristics, and both the production cycle and the building details are not well masterd.

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  • Authors: Paradelo, Remigio; Villada, Antía; Barral, María Teresa;

    An agricultural acid soil developed on amphibolites was amended with 5% of five commercial composts (produced mainly from municipal solid wastes) and incubated in the laboratory during 90 days, with the objective of studying the fate of trace elements in soil after compost addition by means of chemical analyses based on BCR fractionation schemes. In general, the addition of the composts had little effect on the distribution of trace elements, because of their high previous contents in the soil. Compost addition increased the oxidizable (organic matter) and reducible (iron oxides) fractions of soil Cu, and the soluble and reducible fractions of soil Zn. None of the composts modified Pb distribution, which was mostly found in the reducible fraction, nor that for Cr or Ni, present in more than 80% in the residual non-extractable fraction. Among the elements studied, Zn was that of most concern, since the addition of some composts increased the soluble forms of this element.

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Parent, Leon-Étienne; +1 Authors

    In context of conservation agriculture, various soil properties modifications including phosphorus (P) stratification along soil profile induced by no-till practice (NT) might affect crop root development. This study aimed to investigate tillage and P fertilization effects on root distribution and morphology of corn and soybean. A field corn-soybean rotation experiment established in 1992 at l’Acadie is a split-plot design (4 replicates) with tillage (moldboard plough (MP) and NT) and P fertilization (0 (0P), 17.5 (0.5P) and 35 (1P) kg P·ha-1 every two years) as main and sub-plot factors. Soils and corn roots were sampled in 2014 at silking stage by collecting soil cores to 60-cm depth (0-5, 5-10, and every 10 cm) at 5, 15 and 25 cm perpendicularly to the row. Soybean roots were sampled in 2015 at flowering stage. Root length (RL) was determined with WinRHIZO. Corn root length density (RLD) was higher in MP (1.48 cm·cm-3) than in NT (1.28 cm·cm-3). 0P and 0.5P treatments (1.29 and 1.23 cm·cm-3, respectively) significantly reduced RLD compared to 1P (1.62 cm·cm-3). Corn roots mostly accumulated at 0-5 and 5-10 cm. Tillage and P fertilization had no effect on corn root vertical distribution. However, tillage had significant effects on soybean root vertical partition. Soybean in NT had a RLD of 1.95 cm·cm-3 on average; and roots mostly accumulated at 0-10 cm with 44% of total RL. MP had lower RLD (1.55 cm·cm-3), with the highest RL proportion (36%) at 10-20 cm. Additionally, soybean had relatively higher RLDs in 0P and 0.5P than 1P.Compared to corn, the higher proportion of soybean roots in top layers in NT might indicate a higher sensibility of soybean roots to the soil P stratification. While the reduction of corn roots in NT could be more related to a higher weed competition.

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  • Authors: Eveillard, Philippe; Saby, Nicolas; Gouny, Laëtitia; Denoroy, Pascal; +1 Authors

    Amounts of nutrients phosphorus and potassium applied as mineral fertilisers have decreased by 70% in France in the last twenty-five years, without any compensation by more organic fertilisers. UNIFA, the French fertiliser industry association, produces official delivery statistics on mineral fertilisers and estimates for organic inputs. UNIFA has calculated nutrient balances in 21 regions of France to show the trend in the phosphorus and potassium balance since 1988/1989.The nutrient balance has been calculated from the difference between the total input to soils and the total nutrient removal in crops and grass, calculated according to the annual statistics of the Ministry of Agriculture.The difference between the total input and output has reduced considerably since 1988 in all regions. This is the logical result of reduced nutrient inputs during this period. Although the recycling of urban and industrial bio waste and the importation of organic fertilisers has increased since 2005, this does not compensate for the decrease in both mineral fertilisers and of animal excreta, due to reduced numbers of livestock.The balance has been negative for phosphorus for the last ten years, especially in the cereal producing northern and central part of France. The consequence of this is a decrease of extractable Olsen phosphorus in soil analyses, which can be assessed from a large database of more than two million soil analyses covering the 25 years since 1990.The trend for exchangeable potassium is less significant in the data from both intensive cattle rearing regions and cereal growing regions. This French National Soil Test FNST database (BDAT in French) is operated by the National Agronomic Research Institute INRA under the auspices of the French Soils Scientific Interest Group (Gis Sol).

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Morel, Christian;

    Actual phosphorus models are created in conventional tillage system. In addition, most simulation models are process-based, which need mathematical descriptions of fundamental physio-chemical mechanisms. The small time-step e.g. daily might not fit long-term simulation. In this study, a P model based on measured data was created to simulate the evolution of soil P status along soil profile in long-term. In P model, a soil zone was divided into 30 grids according to vertical (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and lateral (0-10, 10-20 and 20-30 cm for two sides into inter-row) coordinates. For each grid, P stock was defined as total amount of phosphate ions in solid and liquid phases. The P inputs and P outputs of each grid such as fertilizer, uptake, runoff and leaching were estimated with measured data in every time-step (yearly). The P status (phosphate ion concentration in soil solution) was calculated from P stock and P budget in each time step. The simulation was conducted with two tillage systems [moldboard plough (MP) and no-till (NT)].The P model managed to simulate the evolution of P status along soil profile in MP and NT during 25 years; while it was a homogenous distribution of soil P within 0-20 cm in MP. The simulated results indicated that higher accumulation of soil P in upper layers might lead to a lower use of soil P stocked in sub-soil by crop uptake. However, the model still needs validation and adjustment of parameters to form more accurate results.

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  • Authors: Nys, Claude; Legout, Arnaud; Jambois, Anne; Département EFPA, .; +1 Authors

    Révisé en juillet 2014 Révisé en juillet 2014; This case study shows how INRA, thanks to its expertise and knowledge acquired through a wide network ofexperimental test sites, today provides an accurate overview of the issues to be considered when nutritiondysfunctions or forest decline are detected in forest ecosystems (yellowing needles or leaves, diminishedleafing, drying shoots, etc.).; Les amendements calcaires permettent de restaurer une croissance satisfaisante des arbres. Les amendements calcaires permettent de restaurer une croissance satisfaisante des arbres (+20% à 30% de rendement sur des forêts en déficit nutritionnel sévère), et d’éviter les dommages posés par l’acidification des sols à la biodiversité et au caractère récréatif de la forêt. Le cas illustre l’utilisation de données collectées depuis 37 ans sur des dispositifs expérimentaux, pour la remédiation du dépérissement forestier constaté dans le massif des Vosges. Les analyses de sols conduites avec l’expertise de l’institut ont concerné 30 000 hectares de forêt du domaine public, pour lesquels un amendement a été recommandé dans 50% des cas.

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  • Authors: Vasilyeva, Nadezda A.; Chenu, Claire;

    Fate of char particles and reasons of char C stabilization in soils is not well understood especially due to difficulties of its quantification. In this study we showed how char C content could be estimated from elemental analysis along with its size redistribution and co-stabilization with non-char C in long-term. We studied C dynamics in the size and density fractons of soil samples from a historical collection of 80 years bare fallow (no plant input plus tillage) experiment in Versailles, France (1929, 1939, 1949, 1962, 1972, 1991, 2008 years). Coarse char particles were observed in the soil substantially contributing to total organic C. Thus, char C study in this soil was carried out as a nessessary step for estimation of non-char C dynamics. Physical fraction allowed us to follow separately the dynamics of mineral-associated and free C. We analyzed bulk soils, fractions and picked out char particles for C, N and 13C contents. Total organic carbon concentrations in fractions pointed to char C input during 1939-1949 years. After that patterns of C and C/N and _ 13C changes in all fractions suggested redistribution of char C from coarse to finer fractions. Evolution of C/N and _ 13C suggested that all free C fractions, although enriched in char, still contained non-char C in the end of the 80 years C depletion chronosequence. Especially high proportion of non-char C was observed in the silt-size free C fraction. Linear combinations of contrasting char and non-char C C/N values allowed estimation of their proportions from the C/N evolution in the fractions. No substantial admixture of char C was observed for mineral-associated C fractions. Stable C pool in 2008 comprised of 4.6 g C kg-1 soil and was composed of mineral-associated C (3.5 g C kg-1 soil) and char-associated C (1.1 g C kg-1 soil). In both cases organic matter could be stabilized through adsorption and/or occlusion with solid particles (mineral or char). Stabilization capacities of different size class minerals reflected in C concentrations of fractions were 1.2 g C kg-1 for silt-size minerals and 19.4 g C kg-1 for clay-size minerals, contrastingly three orders of magnitude more C was associated with char particles or about 1.2 kg non-char C kg-1 sand-size char and about 1.4 to 3.5 kg non-char C kg-1 silt-size char. Such a high capacity of stabilization by char particles could not be explained by adorbtion alone. In conclusion, combination of C/N and _13C signature allowed estimation of char content in this soil. Total char C content (sum up of redistributed char C in free fractions) remained not significantly different in the C depletion experiment during five decades after char input. Century scale char and non-char C co-stabilization in this soil could be explained by combination of adsorption and physical protection in microaggregates constructed of mineral and char particles.

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  • Authors: Vasilyeva, Nadezda A.; Chenu, Claire;

    Fate of char particles and reasons of char C stabilization in soils is not well understood especially due to difficulties of its quantification. In this study we showed how char C content could be estimated from elemental analysis along with its size redistribution and co-stabilization with non-char C in long-term. We studied C dynamics in the size and density fractons of soil samples from a historical collection of 80 years bare fallow (no plant input plus tillage) experiment in Versailles, France (1929, 1939, 1949, 1962, 1972, 1991, 2008 years). Coarse char particles were observed in the soil substantially contributing to total organic C. Thus, char C study in this soil was carried out as a nessessary step for estimation of non-char C dynamics. Physical fraction allowed us to follow separately the dynamics of mineral-associated and free C. We analyzed bulk soils, fractions and picked out char particles for C, N and 13C contents. Total organic carbon concentrations in fractions pointed to char C input during 1939-1949 years. After that patterns of C and C/N and _ 13C changes in all fractions suggested redistribution of char C from coarse to finer fractions. Evolution of C/N and _ 13C suggested that all free C fractions, although enriched in char, still contained non-char C in the end of the 80 years C depletion chronosequence. Especially high proportion of non-char C was observed in the silt-size free C fraction. Linear combinations of contrasting char and non-char C C/N values allowed estimation of their proportions from the C/N evolution in the fractions. No substantial admixture of char C was observed for mineral-associated C fractions. Stable C pool in 2008 comprised of 4.6 g C kg-1 soil and was composed of mineral-associated C (3.5 g C kg-1 soil) and char-associated C (1.1 g C kg-1 soil). In both cases organic matter could be stabilized through adsorption and/or occlusion with solid particles (mineral or char). Stabilization capacities of different size class minerals reflected in C concentrations of fractions were 1.2 g C kg-1 for silt-size minerals and 19.4 g C kg-1 for clay-size minerals, contrastingly three orders of magnitude more C was associated with char particles or about 1.2 kg non-char C kg-1 sand-size char and about 1.4 to 3.5 kg non-char C kg-1 silt-size char. Such a high capacity of stabilization by char particles could not be explained by adorbtion alone. In conclusion, combination of C/N and _13C signature allowed estimation of char content in this soil. Total char C content (sum up of redistributed char C in free fractions) remained not significantly different in the C depletion experiment during five decades after char input. Century scale char and non-char C co-stabilization in this soil could be explained by combination of adsorption and physical protection in microaggregates constructed of mineral and char particles.

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  • Authors: Larrieu, Laurent; Jabiol, Bernard;

    National audience; It is more and more common for forest managers and forestry advisors to make use of soil or site analyses. But they are often at a loss concerning trophic analyses because “field” criteria are lacking and because a comprehensive diagnosis requires soil samples and chemical analyses that they are unfamiliar with. Although these chemical analyses are sometimes irrelevant to the diagnosis, at others they are critical. This article provides advice on sampling methods on the choice of tests requested from laboratories on the basis of the site and of the objectives. It also describes a software application for computer-aided interpretation of analyses; Le diagnostic pédologique ou stationnel fait de plus en plus partie de la démarche du gestionnaire ou du conseiller forestier. Mais ceux-ci sont le plus souvent démunis face au besoin de diagnostic trophique, car les critères "de terrain" sont peu nombreux et qu'un diagnostic complet nécessite des prélèvements de terre et des analyses chimiques avec lesquelles ils sont peu familiarisés. Or, ces analyses chimiques, si elles sont parfois inutiles au diagnostic, deviennent d'autres fois fondamentales. Cet article donne des conseils de prélèvement d'échantillon, des conseils pour le choix des analyses à demander au laboratoire en fonction du contexte stationnel et des objectifs, et présente un outil informatique d'aide à l'interprétation des résultats d'analyse

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Parent, Leon-Étienne; +1 Authors

    Actual phosphorus models are created in conventional tillage system. In addition, most simulation models are process-based, which need mathematical descriptions of fundamental physio-chemical mechanisms. The small time-step e.g. daily might not fit long-term simulation. In this study, a P model based on measured data was created to simulate the evolution of soil P status along soil profile in long-term. In P model, a soil zone was divided into 30 grids according to vertical (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and lateral (0-10, 10-20 and 20-30 cm for two sides into inter-row) coordinates. For each grid, P stock was defined as total amount of phosphate ions in solid and liquid phases. The P inputs and P outputs of each grid such as fertilizer, uptake, runoff and leaching were estimated with measured data in every time-step (yearly). The P status (phosphate ion concentration in soil solution) was calculated from P stock and P budget in each time step. The simulation was conducted with two tillage systems [moldboard plough (MP) and no-till (NT)].The P model managed to simulate the evolution of P status along soil profile in MP and NT during 25 years; while it was a homogenous distribution of soil P within 0-20 cm in MP. The simulated results indicated that higher accumulation of soil P in upper layers might lead to a lower use of soil P stocked in sub-soil by crop uptake. However, the model still needs validation and adjustment of parameters to form more accurate results.

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  • Authors: Carazas Aedo, Wilfredo; Douline, Alexandre;

    This manual was designed for the builders, technicians, professionals involved in rural housing development programmes in humid tropical climates where :- rainfalls are important, - clay content of the soil is very high,- existing building techniques are based on the use of adobe blocks as in-fill material (wooden structure filled with adobe for rural housing / concrete structure filled adobe or burnt bricks for public buildings).The adobe technique is not considered as a specific technology with its own characteristics, and both the production cycle and the building details are not well masterd.

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  • Authors: Paradelo, Remigio; Villada, Antía; Barral, María Teresa;

    An agricultural acid soil developed on amphibolites was amended with 5% of five commercial composts (produced mainly from municipal solid wastes) and incubated in the laboratory during 90 days, with the objective of studying the fate of trace elements in soil after compost addition by means of chemical analyses based on BCR fractionation schemes. In general, the addition of the composts had little effect on the distribution of trace elements, because of their high previous contents in the soil. Compost addition increased the oxidizable (organic matter) and reducible (iron oxides) fractions of soil Cu, and the soluble and reducible fractions of soil Zn. None of the composts modified Pb distribution, which was mostly found in the reducible fraction, nor that for Cr or Ni, present in more than 80% in the residual non-extractable fraction. Among the elements studied, Zn was that of most concern, since the addition of some composts increased the soluble forms of this element.

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Parent, Leon-Étienne; +1 Authors

    In context of conservation agriculture, various soil properties modifications including phosphorus (P) stratification along soil profile induced by no-till practice (NT) might affect crop root development. This study aimed to investigate tillage and P fertilization effects on root distribution and morphology of corn and soybean. A field corn-soybean rotation experiment established in 1992 at l’Acadie is a split-plot design (4 replicates) with tillage (moldboard plough (MP) and NT) and P fertilization (0 (0P), 17.5 (0.5P) and 35 (1P) kg P·ha-1 every two years) as main and sub-plot factors. Soils and corn roots were sampled in 2014 at silking stage by collecting soil cores to 60-cm depth (0-5, 5-10, and every 10 cm) at 5, 15 and 25 cm perpendicularly to the row. Soybean roots were sampled in 2015 at flowering stage. Root length (RL) was determined with WinRHIZO. Corn root length density (RLD) was higher in MP (1.48 cm·cm-3) than in NT (1.28 cm·cm-3). 0P and 0.5P treatments (1.29 and 1.23 cm·cm-3, respectively) significantly reduced RLD compared to 1P (1.62 cm·cm-3). Corn roots mostly accumulated at 0-5 and 5-10 cm. Tillage and P fertilization had no effect on corn root vertical distribution. However, tillage had significant effects on soybean root vertical partition. Soybean in NT had a RLD of 1.95 cm·cm-3 on average; and roots mostly accumulated at 0-10 cm with 44% of total RL. MP had lower RLD (1.55 cm·cm-3), with the highest RL proportion (36%) at 10-20 cm. Additionally, soybean had relatively higher RLDs in 0P and 0.5P than 1P.Compared to corn, the higher proportion of soybean roots in top layers in NT might indicate a higher sensibility of soybean roots to the soil P stratification. While the reduction of corn roots in NT could be more related to a higher weed competition.

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  • Authors: Eveillard, Philippe; Saby, Nicolas; Gouny, Laëtitia; Denoroy, Pascal; +1 Authors

    Amounts of nutrients phosphorus and potassium applied as mineral fertilisers have decreased by 70% in France in the last twenty-five years, without any compensation by more organic fertilisers. UNIFA, the French fertiliser industry association, produces official delivery statistics on mineral fertilisers and estimates for organic inputs. UNIFA has calculated nutrient balances in 21 regions of France to show the trend in the phosphorus and potassium balance since 1988/1989.The nutrient balance has been calculated from the difference between the total input to soils and the total nutrient removal in crops and grass, calculated according to the annual statistics of the Ministry of Agriculture.The difference between the total input and output has reduced considerably since 1988 in all regions. This is the logical result of reduced nutrient inputs during this period. Although the recycling of urban and industrial bio waste and the importation of organic fertilisers has increased since 2005, this does not compensate for the decrease in both mineral fertilisers and of animal excreta, due to reduced numbers of livestock.The balance has been negative for phosphorus for the last ten years, especially in the cereal producing northern and central part of France. The consequence of this is a decrease of extractable Olsen phosphorus in soil analyses, which can be assessed from a large database of more than two million soil analyses covering the 25 years since 1990.The trend for exchangeable potassium is less significant in the data from both intensive cattle rearing regions and cereal growing regions. This French National Soil Test FNST database (BDAT in French) is operated by the National Agronomic Research Institute INRA under the auspices of the French Soils Scientific Interest Group (Gis Sol).

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  • Authors: Mollier, Alain; Li, Haixiao; Ziadi, Noura; Morel, Christian;

    Actual phosphorus models are created in conventional tillage system. In addition, most simulation models are process-based, which need mathematical descriptions of fundamental physio-chemical mechanisms. The small time-step e.g. daily might not fit long-term simulation. In this study, a P model based on measured data was created to simulate the evolution of soil P status along soil profile in long-term. In P model, a soil zone was divided into 30 grids according to vertical (0-5, 5-10, 10-20, 20-30 and 30-40 cm) and lateral (0-10, 10-20 and 20-30 cm for two sides into inter-row) coordinates. For each grid, P stock was defined as total amount of phosphate ions in solid and liquid phases. The P inputs and P outputs of each grid such as fertilizer, uptake, runoff and leaching were estimated with measured data in every time-step (yearly). The P status (phosphate ion concentration in soil solution) was calculated from P stock and P budget in each time step. The simulation was conducted with two tillage systems [moldboard plough (MP) and no-till (NT)].The P model managed to simulate the evolution of P status along soil profile in MP and NT during 25 years; while it was a homogenous distribution of soil P within 0-20 cm in MP. The simulated results indicated that higher accumulation of soil P in upper layers might lead to a lower use of soil P stocked in sub-soil by crop uptake. However, the model still needs validation and adjustment of parameters to form more accurate results.

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  • Authors: Nys, Claude; Legout, Arnaud; Jambois, Anne; Département EFPA, .; +1 Authors

    Révisé en juillet 2014 Révisé en juillet 2014; This case study shows how INRA, thanks to its expertise and knowledge acquired through a wide network ofexperimental test sites, today provides an accurate overview of the issues to be considered when nutritiondysfunctions or forest decline are detected in forest ecosystems (yellowing needles or leaves, diminishedleafing, drying shoots, etc.).; Les amendements calcaires permettent de restaurer une croissance satisfaisante des arbres. Les amendements calcaires permettent de restaurer une croissance satisfaisante des arbres (+20% à 30% de rendement sur des forêts en déficit nutritionnel sévère), et d’éviter les dommages posés par l’acidification des sols à la biodiversité et au caractère récréatif de la forêt. Le cas illustre l’utilisation de données collectées depuis 37 ans sur des dispositifs expérimentaux, pour la remédiation du dépérissement forestier constaté dans le massif des Vosges. Les analyses de sols conduites avec l’expertise de l’institut ont concerné 30 000 hectares de forêt du domaine public, pour lesquels un amendement a été recommandé dans 50% des cas.

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