Search results for "040103 agronomy & agriculture"
showing 10 items of 794 documents
Shifts in diversity and microscale distribution of the adapted bacterial phenotypes due to Hg(II) spiking in soil.
2003
In a previous experiment [Ranjard et al. (2000) FEMS Microbiol Ecol 31:107–115], the spatial heterogeneity of a mercury impact on soil bacterial community was revealed by an increase of mercury-resistant (HgR) bacterial numbers in the outer fraction and the sand fractions when compared to those in the silt fractions. The objectives of the present study were (i) to investigate whether mercury exposure affects the diversity and the distribution within the various fractions of the HgR populations and (ii) to evaluate the contribution of the HgR populations to the overall community adaptation. A total of 236 strains isolated before (104 isolates) and 30 days (132 isolates) after spiking were ch…
A decision support system based on multisensor data fusion for sustainable greenhouse management
2018
The sustainable exploitation of natural resources is nowadays an important challenge for governments and institutions, considering the expected increase of the world population. In order to respond to this emergent criticality, the principles of green economy have been introduced in the European policy discussion to achieve a good compromise between the sustainability and the profitability of productions by increasing the efficiency of farming operations. Such approach poses some technical and financial challenges for small-sized enterprises because they generally do not possess adequate internal knowledge, nor they can acquire external expertise due to their budget restrictions. Decision S…
N2O emission in maize-crops fertilized with pig slurry, matured pig manure or ammonium nitrate in Brittany
2008
International audience; N2O is a potent greenhouse gas and solutions have to be sought to reduce its emission from agriculture. This work evaluates N2O emission from maize-crop (Zea mays) fields submitted to different organic or mineral fertilizers (pig slurry, matured pig manure or ammonium nitrate) in Brittany (France). N2O emission was evaluated along a year in two experimental sites receiving 110 or 180 kg N ha−1 as ammonium nitrate or pig slurry and 180 or 132 kg N ha−1 as ammonium nitrate or matured pig manure at Champ Noel and Le Rheu experimental plots, respectively. N2O emission was evaluated by interpolation method of periodic fluxes on the field scale and by simulation with NOE a…
Soil environmental conditions rather than denitrifier abundance and diversity drive potential denitrification after changes in land uses
2010
Land-use practices aiming at increasing agro-ecosystem sustainability, e.g. no-till systems and use of temporary grasslands, have been developed in cropping areas, but their environmental benefits could be counterbalanced by increased N2O emissions produced, in particular during denitrification. Modelling denitrification in this context is thus of major importance. However, to what extent can changes in denitrification be predicted by representing the denitrifying community as a black box, i.e. without an adequate representation of the biological characteristics (abundance and composition) of this community, remains unclear. We analysed the effect of changes in land uses on denitrifiers for…
Modelling denitrification including the dynamics of denitrifiers and their progressive ability to reduce nitrous oxide: comparison with batch experim…
2005
Nitrous oxide contributes to the global greenhouse effect and affects the chemistry of O 3 in the upper troposphere and lower stratosphere. To define a relevant model for microbial NO 3 - and N 2 O reductions in soil and estimate the parameters involved, we propose a method combining measurements of anaerobic soil slurry and simulations of NO 3 - and N 2 O reductions, including non-enzymatic competition between NO 3 - and N 2 O as electron acceptors and the microbial dynamics of two denitrifier groups that are either able or unable to reduce N 2 O. Three models varying in the description of soil capability to reduce N 2 O through denitrification were assessed. The procedure was applied on a…
Testing a theoretical resistance law for overland flow under simulated rainfall with different types of vegetation
2020
Abstract In this paper a recently theoretically deduced flow resistance equation, based on a power-velocity profile, was tested using data collected for overland flow under simulated rainfall carried out in plots with vegetation. The available data were obtained exploring a wide range of rainfall intensities (from 60 to 181 mm h−1) and slopes (from 3.6 to 39.6%), and with four different types of vegetation. The database, including measurements of flow velocity, water depth, cross sectional flow area, wetted perimeter and bed slope, was divided in four datasets (one for each vegetation type), which allowed the calibration of the relationship between the velocity profile parameter Γ, the slop…
Evaluating the Effects of Sediment Transport on Pipe Flow Resistance
2021
In this paper, the applicability of a theoretical flow resistance law to sediment-laden flow in pipes is tested. At first, the incomplete self-similarity (ISS) theory is applied to deduce the velocity profile and the corresponding flow resistance law. Then the available database of measurements carried out by clear water and sediment-laden flows with sediments having a quasi-uniform sediment size and three different values of the mean particle diameter Dm (0.88 mm, 0.41 mm and 0.30 mm) are used to calibrate the Γ parameter of the power-velocity profile. The fitting of the measured local velocity to the power distribution demonstrates that (i) for clear flow the exponent δ can be estimated b…
Simulated raindrop's characteristic measurements. A new approach of image processing tested under laboratory rainfall simulation
2018
Abstract The size of the drops determines soil erosion and runoff rates, and then the fate of ecosystems. Various raindrop measurement techniques and tools have been developed to determine natural and simulated raindrop size distributions and mean drop size. There is a need to improve the procedure to determine the raindrop properties, and this is why we develop a new technique to analyze drop size distribution and fall velocity. For this purpose a rainfall simulator with two oscillating Veejet 80100 nozzles in laboratory condition, and high speed imaging technique and edge detection approach in image processing was applied to identify and measure drop size and calculate drop velocity. The …
Vegetation Types Mapping Using Multi-Temporal Landsat Images in the Google Earth Engine Platform
2021
Vegetation Types (VTs) are important managerial units, and their identification serves as essential tools for the conservation of land covers. Despite a long history of Earth observation applications to assess and monitor land covers, the quantitative detection of sparse VTs remains problematic, especially in arid and semiarid areas. This research aimed to identify appropriate multi-temporal datasets to improve the accuracy of VTs classification in a heterogeneous landscape in Central Zagros, Iran. To do so, first the Normalized Difference Vegetation Index (NDVI) temporal profile of each VT was identified in the study area for the period of 2018, 2019, and 2020. This data revealed strong se…
Effect of cobalt and silver nanoparticles and ions on Lumbricus rubellus health and on microbial community of earthworm faeces and soil
2016
The aim of this study was to investigate the impact of silver and cobalt, supplied both as ions and nanoparticles (Ag+, Co2+, AgNPs, CoNPs) through contaminated food to earthworms (Lumbricus rubellus), on their health as well as on microbial community of both soil and earthworm faeces. Earthworms and microbes were exposed to the contaminants in laboratory microcosms with artificial soil. Contaminants were supplied once a week for 5 weeks by spiking them on horse manure. The accumulation of CoNPs and Co2+ in earthworm tissues was two and three times greater than AgNPs and Ag+, respectively. Except for AgNPs, contaminants significantly affected microbial community structure of earthworm faece…