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28. International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Organic Horticulture: Productivity and Sustainability Lisbon, Portugal, 2012/03/31; Plant architecture governs living conditions of herbivores. In fruit trees, the perennial structure is modulated by training and pruning which may affect pests. The effect of tree architecture manipulation on the development of the rosy apple aphid Dysaphis plantaginea (RAA) was investigated from 2002 to 2009 in apple orchards. The first step (2002-2005) consisted in comparing the Centrifugal Training system (CT) with extinction pruning (i.e., selective removal of spurs at bud-burst to favour light penetration and spur fruiting) to the Solaxe system (OS) with no extinction pruning. RAA infestation was significantly lower in CT trees 2 years out of 4. The hypothesis of a within-tree structural effect on RAA development was proposed beside possible microclimatic and mechanical (i.e., infested shoot removal) effects. In a second step (2007-2008) we investigated the relationships between the branch structure and RAA development in both training systems. In CT trees, branches displayed higher shoot orders compared to OS. Infestation dynamics presented similar patterns in both systems, but RAA spreading rate was lower in CT trees. These results suggested that the complexity of the aerial system due to higher branching orders affected insect movement within its habitat. In 2009 a glasshouse experiment with oneyear- old potted apple trees was carried out to test the combined effect of simplified architectures (1 vs. 2 extension shoots per tree) and of three nitrogen regimes on the development of RAA artificially set on the trees. There was no significant difference in aphid numbers at peak infestation between architectural treatments although RAA migration was earlier with 1 extension shoot. Moreover, a higher aphid population was shown for intermediate nitrogen regimes highlighting the pest response to trophic parameters. These experiments confirm the importance of tree training strategies in the management of orchard pests. They provide avenues to design sustainable orchard systems based on cultural methods giving partial control of pests.

Several isoflavones, such as genistein, daidzein, and their glucosyl and malonyl forms were detected by HPLC–UV in cotyledons, together with glycitein forms in the hypocotyl of two 1-maturity class contrasting soybean varieties (Ales with high isoflavone and low protein concentrations vs. Nikir, showing opposite behaviour). Cultivation involved drip irrigation and rainfed conditions, factorially combined with two levels of nitrogen supply (0 and 100 kg ha−1 at R1–R3 stages) at Legnaro (NE Italy) for two years (2006–2007). Yield components and hypocotyl and cotyledon isoflavone concentrations were measured in stems and branches separately. Ales was confirmed as having a higher total cotyledon isoflavone concentration (TCIC) than Nikir, with higher fractions of total daidzein in cotyledons and total glycitein in hypocotyl. In 2007, a 40% decline in total hypocotyl isoflavone concentration (THIC) was observed compared with 2006, due to a higher daily range temperature regime during seed filling. Irrigation increased seed yield and protein, but its effect on TCIC was negligible. Irrigation reduced THIC (∼8%) in the drier year (2007), perhaps due to greater hypocotyl weight (dilution effect) and lower fungal disease attack. TCIC and THIC were generally increased by the unusual nitrogen fertilisation practice (TCIC in year 2: 1.85 vs. 1.58 mg g−1), especially in Nikir. The most important finding was a 24.4% cotyledon (1.54 vs. 1.96 mg g−1) and 4.2% hypocotyl (14.9 vs. 14.3 mg g−1) greater isoflavone concentration in seeds of branches compared with those of the main stem, and this may have a practical application in sowing density. It is currently concluded that nitrogen fertilisation improves the nutraceutical properties of soybean, although its effect depends on the activity of the isoflavone biosynthetic pathway and the concurrent extent of seed bulging.

The experiment compared reductions in the level of N fertilisation of corn crop ( i.e. , no N fertilisation; 0-N, or 150 kg of N/ha; 150-N) with those currently adopted in the Po valley of North Italy ( i.e. , 300 kg of N/ha; 300-N) on chemical and nutritional characteristics of grain, stalks and leaves in corn hybrids selected for whole plant silage production ( i.e. , FAO 700 maturity). Grain composition and starch availability for digestion was examined at three stages of maturity of the kernels ( i.e. , ½ milk line, ¾ milk line and black layer). One hybrid had a lower grain yield (15.2 versus 16.0–16.8 tonnes DM/ha; P i.e. , 150-N and 0-N versus 300-N) lowered (P versus 0.412) and leaves (0.604 and 0.620 versus 0.622). Stage of maturity of grain did not interact with the N level of fertilization, and advanced maturity was associated with a marked increase (P i.e. , 0-N) reduced the zein contents and increased rumen fermentability.

La méthode est basée sur les contributions respectives de 5 types fonctionnels de graminées (TFG : A, B, b, C, D) à la végétation prairiale, et plus particulièrement sur la proportion des types A+B qui s’avère être un indicateur synthétique de la productivité des prairies. Ce mode de caractérisation des prairies a été mis en œuvre dans 8 élevages de l’Aubrac. L’analyse de la proportion de TFG A+B aux échelles de la parcelle et du système fourrager permet de mesurer le degré de spécialisation des végétations au sein d’une prairie (et selon son usage) et entre prairies, puis d’identifier et d’analyser les facteurs qui conditionnent cette diversité. Certains élevages présentent un faible contraste entre parcelles affectées à des usages différents mais une forte diversité intraparcellaire ; à l’opposé, d’autres élevages présentent de forts contrastes entre parcelles d’usages différents mais une faible diversité intraparcellaire., The method below helps analyze the function of perennial grassland in grass-based livestock farming systems by studying the relationship between environmental factors, farming practices and use value of grassland within the forage system. This method, based on the functional analysis of grassland, evaluates the individual contribution of 5 types of grasses (GFTs). Types A+B ratio appears to be a synthetic indicator of grassland productivity. Implementation in 8 livestock farms in the area of Aubrac showed that GFT A+B ratio, whether considered on a local (parcel of land) or global scale (forage system) made it possible to determine plant specialization levels within a single grassland field and among different grassland fields, as well as help identify and analyze the factors responsible for stimulating diversity. Different results were observed: on the one hand, minor differences between the different parcels (intended for different uses) but with a significant diversity within the parcels themselves, and on the other hand significant differences between the parcels but with only a low diversity within the parcels themselves.

International audience; The method below helps analyze the function of perennial grassland in grass-based livestock farming systems by studying the relationship between environmental factors, farming practices and use value of grassland within the forage system. This method, based on the functional analysis of grassland, evaluates the individual contribution of 5 types of grasses (GFTs). Types A+B ratio appears to be a synthetic indicator of grassland productivity. Implementation in 8 livestock farms in the area of Aubrac showed that GFT A+B ratio, whether considered on a local (parcel of land) or global scale (forage system) made it possible to determine plant specialization levels within a single grassland field and among different grassland fields, as well as help identify and analyze the factors responsible for stimulating diversity. Different results were observed: on the one hand, minor differences between the different parcels (intended for different uses) but with a significant diversity within the parcels themselves, and on the other hand significant differences between the parcels but with only a low diversity within the parcels themselves.; La méthode est basée sur les contributions respectives de 5 types fonctionnels de graminées (TFG : A, B, b, C, D) à la végétation prairiale, et plus particulièrement sur la proportion des types A+B qui s’avère être un indicateur synthétique de la productivité des prairies. Ce mode de caractérisation des prairies a été mis en œuvre dans 8 élevages de l’Aubrac. L’analyse de la proportion de TFG A+B aux échelles de la parcelle et du système fourrager permet de mesurer le degré de spécialisation des végétations au sein d’une prairie (et selon son usage) et entre prairies, puis d’identifier et d’analyser les facteurs qui conditionnent cette diversité. Certains élevages présentent un faible contraste entre parcelles affectées à des usages différents mais une forte diversité intraparcellaire ; à l’opposé, d’autres élevages présentent de forts contrastes entre parcelles d’usages différents mais une faible diversité intraparcellaire.

International audience; The method below helps analyze the function of perennial grassland in grass-based livestock farming systems by studying the relationship between environmental factors, farming practices and use value of grassland within the forage system. This method, based on the functional analysis of grassland, evaluates the individual contribution of 5 types of grasses (GFTs). Types A+B ratio appears to be a synthetic indicator of grassland productivity. Implementation in 8 livestock farms in the area of Aubrac showed that GFT A+B ratio, whether considered on a local (parcel of land) or global scale (forage system) made it possible to determine plant specialization levels within a single grassland field and among different grassland fields, as well as help identify and analyze the factors responsible for stimulating diversity. Different results were observed: on the one hand, minor differences between the different parcels (intended for different uses) but with a significant diversity within the parcels themselves, and on the other hand significant differences between the parcels but with only a low diversity within the parcels themselves.; La méthode est basée sur les contributions respectives de 5 types fonctionnels de graminées (TFG : A, B, b, C, D) à la végétation prairiale, et plus particulièrement sur la proportion des types A+B qui s’avère être un indicateur synthétique de la productivité des prairies. Ce mode de caractérisation des prairies a été mis en œuvre dans 8 élevages de l’Aubrac. L’analyse de la proportion de TFG A+B aux échelles de la parcelle et du système fourrager permet de mesurer le degré de spécialisation des végétations au sein d’une prairie (et selon son usage) et entre prairies, puis d’identifier et d’analyser les facteurs qui conditionnent cette diversité. Certains élevages présentent un faible contraste entre parcelles affectées à des usages différents mais une forte diversité intraparcellaire ; à l’opposé, d’autres élevages présentent de forts contrastes entre parcelles d’usages différents mais une faible diversité intraparcellaire.

The nitrogen (N) requirement of dedicated crops for bioenergy production is a particularly significant issue, since N fertilisers are energy-intensive to make and have environmental impacts on the local level (NO 3 leaching) and global level (N 2 O gas emissions). Nitrogen nutrition of Miscanthus × giganteus aboveground organs is assumed to be dependent on N stocks in belowground organs, but the precise quantities involved are unknown. A kinetic study was carried out on the effect of harvest date (early harvest in October or late harvest in February) and nitrogen fertilisation (0 or 120 kg N ha −1 ) on aboveground and belowground biomass production and N accumulation in established crops. Apparent N fluxes within the crop and their variability were also studied. Aboveground biomass varied between 24 and 28 t DM ha −1 in early harvest treatments, and between 19 and 21 t DM ha −1 in late harvest treatments. Nitrogen fertilisation had no effect on crop yield in late harvest treatments, but enhanced crop yield in early harvest treatments due to lower belowground biomass nitrogen content. Spring remobilisation, i.e. nitrogen flux from belowground to aboveground biomass, varied between 36 and 175 kg N ha −1 , due to the variability of initial belowground nitrogen stocks in the different treatments. Autumn remobilisation, i.e. nitrogen flux from aboveground to belowground organs, varied between 107 and 145 kg N ha −1 in late harvest treatments, and between 39 and 93 kg N ha −1 in early harvest treatments. Autumn remobilisation for a given harvest date was linked to aboveground nitrogen accumulation in the different treatments. Nitrogen accumulation in aboveground biomass was shown to be dependent firstly on initial belowground biomass nitrogen stocks and secondly on nitrogen uptake by the whole crop. The study demonstrated the key role of belowground nitrogen stocks on aboveground biomass nitrogen requirements. Early harvest depletes belowground nitrogen stocks and thus increases the need for nitrogen fertiliser.

Meadows continue to be the most important source of pasture and hay for beef cattle production in the hill and upland areas in the NE region of Portugal. The aim of this study was to evaluate CP contents and IVOMD values during the year, in three harvests (spring, hay cut and autumn) under the effect of three rates of N fertilisation in seven mountain meadows. The results showed that the highest CP and IVOMD occurred in the beginning of spring when meadows are in active vegetative growth. Effects of N fertilisation on CP and IVOMD occurred only in oligotrophic meadows, but in an irregular way, and mainly on IVOMD.

Alanine aminotransferase (AlaAT) catalyses the reversible conversion of pyruvate and glutamate into alanine and oxoglutarate. In soybean, two subclasses were identified, each represented by two highly similar members. To investigate the role of AlaAT during hypoxic stress in soybean, changes in transcript level of both subclasses were analysed together with the enzyme activity and alanine content of the tissue. Moreover, the dependency of AlaAT activity and gene expression was investigated in relation to the source of nitrogen supplied to the plants. Using semi-quantitative PCR, GmAlaAT genes were determined to be highest expressed in roots and nodules. Under normal growth conditions, enzyme activity of AlaAT was detected in all organs tested, with lowest activity in the roots. Upon waterlogging-induced hypoxia, AlaAT activity increased strongly. Concomitantly, alanine accumulated. During re-oxygenation, AlaAT activity remained high, but the transcript level and the alanine content decreased. Our results show a role for AlaAT in the catabolism of alanine during the initial period of re-oxygenation following hypoxia. GmAlaAT also responded to nitrogen availability in the solution during waterlogging. Ammonium as nitrogen source induced both gene expression and enzyme activity of AlaAT more than when nitrate was supplied in the nutrient solution. The work presented here indicates that AlaAT might not only be important during hypoxia, but also during the recovery phase after waterlogging, when oxygen is available to the tissue again.

Agricultural crops can be either a source or a sink of ammonia (NH3). Most NH3 exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed compensation points. We present here a leaf-scale simplified NH3 stomatal compensation point model related to the plants N and carbon (C) metabolisms, for C3 plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH4+), NH3 and nitrate (NO3−) between the different compartments, NH4+ production through photorespiration and NO3− reduction, NH4+ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH3. The simulated compensation point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH4+ flux to the leaf. Atmospheric NH3 concentration seem to have very little effect on the compensation point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH3 compensation point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH4+ may be required.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Modelling can be a powerful tool to help us understand and evaluate farmers’ practices. It can provide us with references that can then be compared to farmers’ practices. We applied this type of modelling approach in order to understand and to evaluate N fertilisation in apple orchards. We used Epistics, an agronomic model that simulates the N and water dynamics in apple orchards and that generates N fertilisation schedules by using a supply demand approach over fixed planning horizons. A schedule is characterised by a total N amount and an application timing. These types of model-generated schedules were evaluated on nitrate leaching and fulfilment of crop N requirements. Schedule generation was performed with different weightings of these two objectives. Farmers’ practices were compared to fertilisation schedules generated by Epistics, either with user-defined or with optimised parameters of schedule generation. Model analysis showed that not taking environmental risks into account led to considerable over-fertilisation (e.g., mean of 141 kg N/ha/yr for year 2003 for all plots) with high leaching. With limited consideration of environmental risks, a sharp decrease of the model-generated total N amount to be applied per ha and per year was observed (e.g., mean of 57 kg N/ha/yr for year 2003 for all plots) without restricting fulfilment of N requirements. Farmers’ fertilisation practices were similar to those generated by the model that took limited environmental risks into account. They corresponded, on average, to a moderate over-fertilisation, aimed at fulfilling about twice the crop N requirements. For a given total N amount to be applied per ha and per year, the farmers’ different fertilisation timing did not influence N leaching or the fulfilment of crop N requirements. Although the variability of total N amounts applied by farmers is partly unexplained, this approach, which combines the analysis and evaluation of farmers’ practices, contributed to understanding and improving farmers’ fertilisation practices

Several studies have shown that when the diversity of species increases in pasture swards, the forage production is larger and the weeds less abundant. This hypothesis was tested in a trial with 25 micro-plots comprising mixtures of grasses or grass-legume associations, where the initial diversity varied from 1 to 8 species. These micro-plots were subjected to 2 different cutting rates and to 2 different levels of nitrogen fertilisation. The results show that the number of species sown had no effect on the dry matter production nor on the distribution of this production within a year or among years; neither was there any effect on the weeds. On the other hand, the choice of species, especially in the case of tall fescue and cocksfoot, had an important effect on the dry matter production per hectare. The specific diversity of the associations decreased sharply with time, and after 5 years; the associations with the most complex initial diversities had only 2 or 3 species left., Comme l'annoncent plusieurs études, l'augmentation de la diversité spécifique des couverts prairiaux permet-elle une augmentation de la production fourragère et un moindre salissement par les adventices ? Un dispositif mis en place à Lusignan fournit des éléments de réponse. Ce dispositif en microparcelles est composé de 25 couverts avec une diversité spécifique initiale de 1 à 8 espèces (mélanges de graminées ou associations graminées - légumineuses), conduits sous 2 rythmes de défoliation et 2 niveaux de fertilisation azotée. Le nombre d'espèces semées dans les couverts n'a pas d'incidence sur la production de matière sèche, sur sa répartition intra ou interannuelle ni sur le salissement des couverts. En revanche, le choix des espèces, et en particulier la fétuque élevée et le dactyle, a un impact fort sur la production. La diversité spécifique des associations diminue au cours du temps et, après 5 ans, les associations les plus complexes ne comptent plus que 2 ou 3 espèces.

L'augmentation des teneurs en nitrate de l'eau dans la plupart des territoires d'élevage intensif et les réglementations européennes mises en place depuis 5 ans dans le cadre de la directive Nitrate puis de la directive cadre sur l'eau ont suscité de nombreux travaux pour évaluer et prédire les risques de pertes d'azote sous les principaux systèmes de culture, notamment sous prairies des systèmes fourragers laiters intensifs d'Europe du Nord et de l'Ouest. Le cycle de l'azote est particulièrement complexe dans les exploitations laitières, à cause de la multiplicité des compartiments, de la diversité et de l'importance des flux mis en jeu, des phénomènes de recyclage, et des interactions entre facteurs eux aussi très divers et variables : pratiques de fertilisation et d'utilisation, type de couvert végétal, caractéristiques des sols et des climats, impacts des animaux au pâturage, etc. Les travaux menés en stations expérimentales en France et en Europe ont permis d'évaluer les pertes de nitrate par lixiviation ainsi que leur variabilité, de dégager les facteurs clés explicatifs et de proposer des indicateurs et des outils d'aide à la décision pour améliorer l'efficacité d'utilisation de l'azote et minimiser les pertes par lixiviation. Ils ont également permis de progresser dans la modélisation des processus impliqués dans le cycle de l'azote en prairie. Les études menées à l'échelle parcellaire intègrent peu à peu une approche pluri-annuelle, permettant à la fois d'intégrer la pérennité du couvert herbacé et l'effet des rotations prairies-cultures sur ces risques de pertes., The increases in the nitrate contents of water in most regions with intensive animal rearing, together with the European regulations which have now been running for five years, and which are part of the 'Nitrate' direction and later of the general direction on water, have given rise to many studies for the evaluation and forecast of the risks of nitrogen losses, especially in the case of pastures of intensive dairy systems. A synthesis of these studies is proposed here. The nitrogen cycle is particularly complex on dairy farms, due to the multiplicity of the parts, the diversity and importance of the flows involved, the effects of re-cycling, and the interactions among many factors, themselves diverse and variable : fertilisation and management practices, sward type, special features of the soil and the climate, impacts of the grazing animals, etc. Thanks to studies made in experimental stations in France and elsewhere in Europe, it has been possible to evaluate the amounts and variability of the nitrogen losses through leaching, and to define the crucial explanatory factors, and also to propose some indicators and decision - making aids for an improved efficiency of nitrogen use and for minimizing the leaching losses. The modelling of the processes involved in the nitrogen cycle of the pastures has thus made progress. Studies at the field level are integrating little by little a multi-annual approach, so as to be comprehensive of the perenniality of the sward and of the effect of cash crop - ley successions on the risks of losses.

A three-year study was conducted for winter wheat after soybean on humogley soil in North- eastern Croatia to evaluate the effects of five tillage systems (CT- conventional tillage with mouldboard ploughing ; DH-disk harrowing ; MT- multitiller ; RT-rotosem ; PR-mouldboard ploughing+rotosem) and four nitrogen levels (N0, N140, N170, N200 kg N/ha) on weed species composition, plant density, and plant dry weight in the absence of herbicide. Annual species of Ambrosia artemisiifolia L., Chenopodium album L., Galium aparine L., Polygonum lapathifolium L. and Stellaria media L. were dominated in all three years. The density of total weeds was significantly affected by tillage and it ranged across from 9.6 plants after RT to 28.2 plants per m2 after PR tillage. No significant differences in total dry weight were found between CT and RT, which had the lowest dry weight from 17.4 g and 19.6 g.m-2, respectively. An increased level of applied nitrogen tended to significantly decrease total weed density from 21.0 plants at N0 to 13.6 plants per m2 at N200 (Table 4). In a three-year average, no significant differences in weed dry weight were observed between N170 and N200 levels which gave approximately 21% and 16% higher dry biomass compared to N140 level, respectively. No significant differences in dry weight of G. aparine populations were found between all three nitrogen levels after CT and RT tillage treatments. Total weed density and weed dry weight were poorly correlated within all tillage x nitrogen combinations (r2 values of 0.10 to 0.48). That suggests that tillage and N fertilisation levels can be utilized as a strategy in weed control management for winter wheat on humogley soil.

A three-year study was conducted for winter wheat after soybean on humogley soil in North- eastern Croatia to evaluate the effects of five tillage systems (CT- conventional tillage with mouldboard ploughing ; DH-disk harrowing ; MT- multitiller ; RT-rotosem ; PR-mouldboard ploughing+rotosem) and four nitrogen (N) levels (0, 140, 170, 200 kg N.ha-1) on weed species composition, plant density, and plant dry weight in the absence of herbicide. Annual species of Ambrosia artemisiifolia L., Chenopodium album L., Galium aparine L., Polygonum lapathifolium L. and Stellaria media L. were dominated in all three years. The density of total weeds was significantly affected by tillage and it ranged across from 9.6 plants after RT to 28.2 plants.m-2 after PR tillage. No significant differences in total dry weight were found between CT and RT, which had the lowest dry weight from 17.4 g and 19.6 g.m-2, respectively. An increased level of applied nitrogen tended to significantly decrease total weed density from 21.0 plants at N0 to 13.6 plants.m-2 at N200. In a three-year average, no significant differences in weed dry weight were observed between N170 and N200 levels which gave approximately 21% and 16% higher dry weight compared to N140 level, respectively. No significant differences in dry weight of G. aparine populations were found between all three nitrogen levels after CT and RT tillage treatments. Total weed density and weed dry weight were poorly correlated within all tillage x nitrogen combinations (r2 values of 0.10 to 0.48). That suggests that tillage and N fertilisation levels can be utilized as a strategy in weed control management for winter wheat on humogley soil.

Surface and groundwaters must regain good chemical and biological quality before 2015 according to European Directives. Good Agricultural Practices (GAPs) establish a compromise between the risks of pollution and the loss of revenue. The minimum result expected is conformity with the drinking water standard of 50 mgNO3.L-1 in the collected water and the avoidance of transfer of pollution from the hydrosphere into the atmosphere. However their implementation does not guarantee that these objectives will be reached ; that requires a means of quantifying the impact of effective agricultural practices on nitrate pollution. We have tested different methods of quantification by using data from a collaborative experiment on pollution prevention, carried out on the site of Bruyères (02). The question targeted was « what is the impact of GAP, applied regularly, on the scale of a catchment area ? » The research question was « can nitrate pollution be modelled, in a farming situation, on the scale of a catchment area ? » The study site is a plateau of 187 ha which supplies a groundwater aquifer located in the Lutetian geological layer. This aquifer feeds five main springs which have suffered increasing pollution since 1970. The 21 cultivated fields on the plateau were subjected to regular implementation of GAPs by the three farmers since 1990. The farming practices and the hydrogeology of the site were characterised. The flow rates of the springs respond to effective rainfall after a delay of a week. The mean residence time of the tritium molecule in the aquifer is 25 years, because of the thickness of the unsaturated zone. In view of this delay, an intermediate level of evaluation is necessary : the losses under the root zone. The methods of quantification differ according to their degree of dependence on the experimental data : i) the LIXIM mathematical model, associated with all the observed data ; ii) a stochastic model of crop response to the nitrogen rate, initialised each year, iii) the functional dynamic model STICS, which can simulate the losses of the soil/plant/atmosphere system continuously over several years. The predictions of the variables of economic and environmental interest are compared with the observed data on the scale of the station and of the basin. The environmental and economic impacts for different scenarios of pollution prevention are simulated. The mineral nitrogen residues at harvest and at the beginning of winter are similar and stable over time at 41 et 57 kgN.ha-1 respectively. The averaging of the losses, calculated with LIXIM, over the crop rotation, smooths out the crop factor and makes the soil type the principal determinant of the concentration. The mean weighted nitrate concentration in the percolating water is 46 mgNO3.L-1 for the cultivated zone and 37 mgNO3.L-1 for the whole basin. This good result is confirmed qualitatively by the fall observed in the contents at several collection points since the year 2000. The response time of the aquifer would be equal to half of its renewal time. The reduction in the nitrate content of the percolation water permitted by GAPs, compared with a conventional scenario, is between 27 and 39%, depending on the simulation method. The cost of the GAPs is 0.07, Les eaux superficielles et souterraines doivent recouvrer une bonne qualité chimique et biologique avant 2015, d'après la Directive Cadre Européenne. Les Bonnes Pratiques Agricoles (BPA) établissent un compromis entre les risques de pollution et de perte de revenu. Le résultat minimal escompté est de respecter la norme de potabilité de 50 mgNO3.L-1 dans les eaux de captage et d'éviter les transferts de pollution de l'hydrosphère vers l'atmosphère. Cependant leur mise en oeuvre ne garantit pas d'atteindre ces objectifs ; cela nécessite des moyens de quantifier l'impact des pratiques agricoles effectives sur la pollution nitrique. Nous avons testé différentes méthodes de quantification, en nous appuyant sur les données issues d'une expérimentation partenariale de prévention de la pollution, menée sur le site de Bruyères (02). La question finalisée est "quel est l'impact des BPA, appliquées de façon systématique, à l'échelle d'un bassin"? La question de recherche est "peut-on modéliser la pollution nitrique, en situation agricole, à l'échelle du bassin hydrologique"? Le site d'étude est un plateau de 187 ha qui alimente une nappe d'eau souterraine, sise dans le Lutétien. Cette nappe alimente 5 sources principales qui connaissent une pollution croissante depuis 1970. Les 21 parcelles cultivées du plateau ont fait l'objet d'une mise en oeuvre systématique des BPA, par les 3 agriculteurs, depuis 1990. Les pratiques agricoles et l'hydrogéologie du site ont été caractérisées. Les débits des sources répondent aux pluies efficaces dans un délai d'une semaine. Le temps moyen de séjour de la molécule de Tritium dans l'aquifère est de 25 ans, à cause de l'épaisseur de la zone non saturée. Compte tenu de ce délai, un niveau intermédiaire d'évaluation est nécessaire : les pertes sous la zone racinaire. Les méthodes de quantification diffèrent selon leur degré de dépendance aux données expérimentales : i) le modèle de calcul LIXIM, associé avec toutes les données observées; ii) un modèle stochastique de réponse des cultures à la dose d'azote, initialisé annuellement; iii) le modèle fonctionnel dynamique STICS, qui peut simuler les pertes du système sol- plante- atmosphère de façon continue pendant plusieurs années. Les prédictions des variables d'intérêt économique et environnemental sont confrontées, aux données observées, aux échelles de la station et du bassin. Les impacts environnementaux et économiques, de différents scénarios de prévention de la pollution, sont simulés. Les reliquats d'azote minéral à la récolte et en entrée d'hiver sont proches et stables dans le temps avec respectivement 41 et 57 kgN.ha-1. L'intégration des flux calculés avec LIXIM, à l'échelle de la rotation culturale, conduit à lisser le facteur culture et à faire du type de sol le principal déterminant de la concentration. La teneur en nitrate moyenne pondérée, de l'eau de percolation, est de 46 mgNO3.L-1 pour la zone cultivée et de 37 mgNO3.L-1 pour l'ensemble du bassin. Ce bon résultat est confirmé qualitativement par la baisse constatée des teneurs de plusieurs captages depuis l'an 2000. Le temps de réponse de l'aquifère serait égal à la moitié de son temps de renouvellement. L'abattement de la teneur en nitrate de l'eau de percolation permis par les BPA, relativement à un scénario conventionnel, est compris entre 27 et 39 %, suivant la méthode de simulation. Le coût des BPA est de 0.07

Diplôme : Dr. Ing.; Surface and groundwaters must regain good chemical and biological quality before 2015 according to European Directives. Good Agricultural Practices (GAPs) establish a compromise between the risks of pollution and the loss of revenue. The minimum result expected is conformity with the drinking water standard of 50 mgNO3.L-1 in the collected water and the avoidance of transfer of pollution from the hydrosphere into the atmosphere. However their implementation does not guarantee that these objectives will be reached ; that requires a means of quantifying the impact of effective agricultural practices on nitrate pollution. We have tested different methods of quantification by using data from a collaborative experiment on pollution prevention, carried out on the site of Bruyères (02). The question targeted was « what is the impact of GAP, applied regularly, on the scale of a catchment area ? » The research question was « can nitrate pollution be modelled, in a farming situation, on the scale of a catchment area ? » The study site is a plateau of 187 ha which supplies a groundwater aquifer located in the Lutetian geological layer. This aquifer feeds five main springs which have suffered increasing pollution since 1970. The 21 cultivated fields on the plateau were subjected to regular implementation of GAPs by the three farmers since 1990. The farming practices and the hydrogeology of the site were characterised. The flow rates of the springs respond to effective rainfall after a delay of a week. The mean residence time of the tritium molecule in the aquifer is 25 years, because of the thickness of the unsaturated zone. In view of this delay, an intermediate level of evaluation is necessary : the losses under the root zone. The methods of quantification differ according to their degree of dependence on the experimental data : i) the LIXIM mathematical model, associated with all the observed data ; ii) a stochastic model of crop response to the nitrogen rate, initialised each year, iii) the functional dynamic model STICS, which can simulate the losses of the soil/plant/atmosphere system continuously over several years. The predictions of the variables of economic and environmental interest are compared with the observed data on the scale of the station and of the basin. The environmental and economic impacts for different scenarios of pollution prevention are simulated. The mineral nitrogen residues at harvest and at the beginning of winter are similar and stable over time at 41 et 57 kgN.ha-1 respectively. The averaging of the losses, calculated with LIXIM, over the crop rotation, smooths out the crop factor and makes the soil type the principal determinant of the concentration. The mean weighted nitrate concentration in the percolating water is 46 mgNO3.L-1 for the cultivated zone and 37 mgNO3.L-1 for the whole basin. This good result is confirmed qualitatively by the fall observed in the contents at several collection points since the year 2000. The response time of the aquifer would be equal to half of its renewal time. The reduction in the nitrate content of the percolation water permitted by GAPs, compared with a conventional scenario, is between 27 and 39%, depending on the simulation method. The cost of the GAPs is 0.07 €.m-3 of drinked water, making prevention competitive with water treatment at the Bruyères site. Dynamic modelling with STICS appears to be effective in the agricultural situation, but its reliability depends on the availability and relevance of the databases used to calibrate it. It can take account of a large number of technical inputs and their long-term interactions. Coupling STICS with a geographical information system (GIS) enables the spatial variability of the physical and cultural features of the environment to be integrated. However it is not possible to guarantee the reliability of the predictions for both any time and any place. Access to the precise value of parameters like the crop’s maximum rooting depth or the stock of organic nitrogen is simply not feasible. According to the STICS model, the nitrogen losses simulated in gaseous form are equal to those in solution. This result needs to be verified. Bearing in mind these limitations, modelling based on experimentation can become a management tool for nitrogen in cropping systems on a regional scale. The problem of limiting nitrate leaching is shifted towards the conception of sustainable cropping systems.; Les eaux superficielles et souterraines doivent recouvrer une bonne qualité chimique et biologique avant 2015, d'après la Directive Cadre Européenne. Les Bonnes Pratiques Agricoles (BPA) établissent un compromis entre les risques de pollution et de perte de revenu. Le résultat minimal escompté est de respecter la norme de potabilité de 50 mgNO3.L-1 dans les eaux de captage et d'éviter les transferts de pollution de l'hydrosphère vers l'atmosphère. Cependant leur mise en oeuvre ne garantit pas d'atteindre ces objectifs ; cela nécessite des moyens de quantifier l'impact des pratiques agricoles effectives sur la pollution nitrique. Nous avons testé différentes méthodes de quantification, en nous appuyant sur les données issues d'une expérimentation partenariale de prévention de la pollution, menée sur le site de Bruyères (02). La question finalisée est "quel est l'impact des BPA, appliquées de façon systématique, à l'échelle d'un bassin"? La question de recherche est "peut-on modéliser la pollution nitrique, en situation agricole, à l'échelle du bassin hydrologique"? Le site d'étude est un plateau de 187 ha qui alimente une nappe d'eau souterraine, sise dans le Lutétien. Cette nappe alimente 5 sources principales qui connaissent une pollution croissante depuis 1970. Les 21 parcelles cultivées du plateau ont fait l'objet d'une mise en oeuvre systématique des BPA, par les 3 agriculteurs, depuis 1990. Les pratiques agricoles et l'hydrogéologie du site ont été caractérisées. Les débits des sources répondent aux pluies efficaces dans un délai d'une semaine. Le temps moyen de séjour de la molécule de Tritium dans l'aquifère est de 25 ans, à cause de l'épaisseur de la zone non saturée. Compte tenu de ce délai, un niveau intermédiaire d'évaluation est nécessaire : les pertes sous la zone racinaire. Les méthodes de quantification diffèrent selon leur degré de dépendance aux données expérimentales : i) le modèle de calcul LIXIM, associé avec toutes les données observées; ii) un modèle stochastique de réponse des cultures à la dose d'azote, initialisé annuellement; iii) le modèle fonctionnel dynamique STICS, qui peut simuler les pertes du système sol- plante- atmosphère de façon continue pendant plusieurs années. Les prédictions des variables d'intérêt économique et environnemental sont confrontées, aux données observées, aux échelles de la station et du bassin. Les impacts environnementaux et économiques, de différents scénarios de prévention de la pollution, sont simulés. Les reliquats d'azote minéral à la récolte et en entrée d'hiver sont proches et stables dans le temps avec respectivement 41 et 57 kgN.ha-1. L'intégration des flux calculés avec LIXIM, à l'échelle de la rotation culturale, conduit à lisser le facteur culture et à faire du type de sol le principal déterminant de la concentration. La teneur en nitrate moyenne pondérée, de l'eau de percolation, est de 46 mgNO3.L-1 pour la zone cultivée et de 37 mgNO3.L-1 pour l'ensemble du bassin. Ce bon résultat est confirmé qualitativement par la baisse constatée des teneurs de plusieurs captages depuis l'an 2000. Le temps de réponse de l'aquifère serait égal à la moitié de son temps de renouvellement. L'abattement de la teneur en nitrate de l'eau de percolation permis par les BPA, relativement à un scénario conventionnel, est compris entre 27 et 39 %, suivant la méthode de simulation. Le coût des BPA est de 0.07

The effects of enriched CO 2 atmosphere on partitioning of recently assimilated carbon were investigated in a plant-soil-microorganism system in which Lolium perenne seedlings were planted into cores inserted into the resident soil within a sward that had been treated with elevated CO 2 for 9 consecutive years, under two N fertilisation levels (Swiss FACE experiment). The planted cores were excavated from the ambient (35 Pa pCO 2 ) and enriched (60 Pa pCO 2 ) rings at two dates, in spring and autumn, during the growing season. The cores were brought back to the laboratory for 14 C labelling of shoots in order to trace the transfer of recently assimilated C both within the plant and to the soil and microbial biomass. At the spring sampling, high N supply stimulated shoot and total dry matter production. Consistently, high N enhanced the allocation of recently fixed C to shoots, and reduced it to belowground compartments. Elevated CO 2 had no consequences for DM or the pattern of C allocation. At the autumn sampling, at high N plot, yield of L. perenne was stimulated by elevated CO 2 . Consistently, 14 C was preferentially allocated aboveground and, consequently belowground recent C allocation was depressed and rhizodeposition reduced. At both experimental periods, total soil C content was similar in all treatments, providing no evidence for soil carbon sequestration in the Swiss Free Air CO 2 Enrichment experiment (FACE) after 9 years of enrichment. Recently assimilated C and soil C were mineralised faster in soils from enriched rings, suggesting a CO 2 -induced shift in the microbial biomass characteristics (structure, diversity, activity) and/or in the quality of the root-released organic compounds.

Stimulated by perception that plants do not adopt nutritive elements from their environment at the same proportional rate they are contained in the environment but at the rates specific to a plant species as well as by the fact that physiological and biochemical processes in plants and, consequently, the adoption of ions are affected by environmental factors the purpose of our study was to determine how different nitrogen feedings affect the protein, calcium and phosphorus content in the wheat, as one of the major cereals, and to what extent are the concentrations of protein and Ca and P related. The investigation was carried out on five replicates of various wheat corn genotypes grown under the same topographical and different agrotechnical conditions in the course of two years. The protein content (N x 5.7) of the samples were assessed according to Kjeldahl method (Büchi-Kjeldahl System ). After microwave digestion calcium concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and total phosphorus by spectrophotometric molybdenum blue method. Depending on genotypes, nitrogen feeding and year of grown the mean values of protein content, expressed on dry matter, ranged from 9.29 – 15.22 g/100g. The concentrations of Ca and P depending on investigated sample ranged from 0.035 to 0.053 g/100g dry matter and from 0.219 to 0.531 g/100 g dry matter, respectively. Taking into account confidence limits there are significant differences (P=0.01) in protein, calcium and phosphorus content between some of investigated cultivars, cultivar for each vegetation years and due to nitrogen feeding applied. Analysis of the results reveals positive correlation between proteins and investigated macroelements contents in examined wheat grains.

International audience; The use of crop models for nitrogen fertiliser management raises several issues. A first problem is to define suitable criteria for optimising nitrogen fertilisation in function of economic, quality and environmental objectives. A second issue is to assess the capacity of the crop model to predict the variables involved in the calculation of the criteria such as grain yield, grain protein content, residual soil mineral nitrogen or nitrogen balance. A third issue is to evaluate the results obtained by applying the decision rules selected by the crop model. The three problems are considered in this paper in the case of winter wheat and the STICS model. Fourteen field experiments with various N fertilisation strategies were used for evaluating the model. STICS predicted grain yield and nitrogen balance more accurately than protein content and soil mineral N at harvest. Among the eight criteria tested for optimising N fertilisation, those using a maximal threshold on nitrogen balance seem to be the most valuable for satisfying agricultural and environmental objectives. Under conditions of environmental constraint, STICS was more efficient than the reference method (AZOBIL) at selecting the optimal nitrogen fertilisation scenario.

Soil micro-arthropods play an important role in the nutrient cycle of agro-ecosystems and are considered to have a strong impact on microbial activity. The occurance of soil microarthropods was investigated in the International Organic Long-Term Field Experiment (IOSDV). The investigation took place in the experimental fields of Berlin/Germany, Madrid/Spain and Tartu/Estonia. Field plots "without organic fertisation", "farmyard manure" and "straw-beet-leaves-green manure" without mineral N-fertilisation and with 120kg/ha mineral N-fertilisation respectively have been investigated. Data shows that the effects of organic manure and mineral N-fertilisation are considerably influenced by specific site characteristics. The highest abundances were found in the experimental field of Madrid. In the two nothern sites soil microarthropods were found only in very low quantities. Data indicates that not only organic manure but also mineral N-fertilisation may influence the abundance of soil micro-arthropods positively.

Soil CH4 flux rates were determined on 28 occasions between June 1996 and July 1997 in a temperate deciduous woodland in south-west England. The effects of environmental and edaphic factors on flux rates and the effects of chronic deposition of sulphuric acid, nitric acid and ammonium sulphate were investigated. The soil was a consistent net CH4 oxidiser, with mean (n = 10) oxidation rates for plots exposed to ambient throughfall ranging from 44.3 to 110.6 μg CH4 m-2 h-1 between samplings; net CH4 production was not observed. The annual mean uptake rate differed by only 6% from the annual mean flux calculated from the literature for other studies of >364 d duration in temperate and boreal deciduous woodlands. The CH4 uptake rates were correlated with soil water potential (square-root transformed), temperature and depth of organic horizon (r2 = 0.78, 0.30 and 0.41, respectively). Soil water potential was the best predictor of net CH4 oxidation rates and when temperature was added to the regression model no improvement in the r2 was observed. The chronic deposition of sulphuric acid stimulated net methane oxidation (P

The investigations were carried out at the experimental plot of the Faculty of Agriculture Osijek and Production unit in Vinkovci during 1993 and 1994. Hybrid Bc 592 was used for the investigation. Stands were arranged with space within rows (for S1-48 000 plants ha-1=29.7 cm, S2-60 000 plants ha-1=23.8 cm and S3-80 000 plants ha-1=17.9 cm) and between rows 70 cm.Three nitrogen fertilisations were applied (N1=90, N2=180 and N3=270 kg ha-1) with 100 kg ha-1 P2O5 and 150 kg ha-1 K2O. Foliar treatments by mixture INA-Fertina K1 in 3% concentration was carried out twice each year in intensive corn growth phase on one part of the experiment. On the basis of corn grain chemical analysis (concentration of main nutritives and water) carried out in 1993 and 1994 it is shown that increased nitrogen fertilisation in the second and third group had positive influence on protein share increase.The highest energy value was achieved in the third group by conversion of different corn yield of some groups into energy value expressed in FU. Namely it was by 723 FU higher than the first group and by 422 FU higher than the second one. This different corn energy value in groups was conversed into amount of one finished animal product-milk as well as its market realisation and the following values were obtained: more milk (by 654 kg i.e.1.572 kg) was produced in the second and third group than in the first group which financially means 1.635 kn i.e.3.929 kn more than the first one. Similar results as with corn in 1993 were achieved by corn conversion of some groups (1994) into energy value.

The adoption of precision agriculture techniques for N management has the potential for improving agronomic, economic and environmental efficiency in the use of such input. The present work was aimed at testing a simplified N balance method for the prescription of N fertilisation in uniform management zones defined from information on measured soil properties on grain maize in central Italy. The results of this preliminary experience show that the application of the N balance prescription map did not bring to significant differences, from a uniform N fertilisation, in terms of grain yield, economic return above N cost and nitrate content in the soil profile at the end of the growing season. However, the adoption of the prescribed N fertilisation strategy for the whole field would have caused a limited saving in the amount of fertiliser employed, quantified at about 10 kg N ha–1.

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake). This project was made possible through several funding sources: a Collaborative Research and Development NSERC grant for a project titled: Soil fertility and productivity of poplar plantations in southern Quebec (awarded to Dr. James Fyles of McGill and co-researchers including Dr. Christian Messier), a Canada Research Chair in Forest Productivity (awarded to Dr. Frank Berninger), an internal UQÀM subsidy (PARFAC awarded to Dr. Frank Berninger) and a FARE bursary awarded to Susy Domenicano (UQÀM). LC was supported by a Ramon y Cajal contract (RYC-2009-04985) from the Ministerio de Ciencia e Innovación of Spain.