scholarly journals Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ligang Xu ◽  
Hailin Niu ◽  
Jin Xu ◽  
Xiaolong Wang
Keyword(s):  
Nitrate Leaching ◽  
Soil Profile ◽  
Nitrate Nitrogen ◽  
Initial Conditions ◽  
Simulated Data ◽  
Intensive Agriculture ◽  
Health Concern ◽  
N Leaching ◽  
And Migration ◽  
Leachm Model

Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities.

scholarly journals Limitations of Improved Nitrogen Management to Reduce Nitrate Leaching and Increase Use Efficiency

2001 ◽  
Vol 1 ◽  
pp. 10-16 ◽  
Author(s):  
James L. Baker
Keyword(s):  
Water Quality ◽  
Nitrate Leaching ◽  
Management Practices ◽  
Nitrate Nitrogen ◽  
Nitrogen Management ◽  
N Leaching ◽  
N Loss ◽  
Use Efficiency ◽  
Rate Method ◽  
N Management

The primary mode of nitrogen (N) loss from tile-drained row-cropped land is generally nitrate-nitrogen (NO3-N) leaching. Although cropping, tillage, and N management practices can be altered to reduce the amount of leaching, there are limits as to how much can be done. Data are given to illustrate the potential reductions for individual practices such as rate, method, and timing of N applications. However, most effects are multiplicative and not additive; thus it is probably not realistic to hope to get overall reductions greater than 25 to 30% with in-field practices alone. If this level of reduction is insufficient to meet water quality goals, additional off-site landscape modifications may be necessary.

scholarly journals Onion Irrigation and Nitrogen Leaching in the Arkansas Valley of Colorado 1990-1991

1993 ◽  
Vol 3 (2) ◽  
pp. 184-187 ◽  
Author(s):  
J.E. Ells ◽  
A.E. McSay ◽  
P.N. Soltanpour ◽  
F.C. Schweissing ◽  
M.E. Bartolo ◽  
...  
Keyword(s):  
Water Quality ◽  
Nitrate Leaching ◽  
Irrigation Water ◽  
Soil Profile ◽  
Management Practices ◽  
Nitrate Nitrogen ◽  
N Fertilizer ◽  
Irrigation Requirement ◽  
Previous Season ◽  
N Management

Water and nitrogen (N) are major inputs in the production of onions in the Arkansas Valley of Colorado. Because nitrates move with irrigation water, the effect of different rates of application of both N fertilizer and water on nitrate leaching were studied simultaneously. After a 2-year field study (1990-1991), it was concluded that >50 t·ha-1 of onions could be obtained without any N fertilizer when >42 ppm of nitrate nitrogen (NO3-N) were initially present in the top 33 cm of soil and up to 112 cm of irrigation water was applied. Total onion yield was not improved by applying more than the calculated irrigation requirement. The 2-m profile of soil under these experiments was found to contain >1400 kg·ha-1 of residual NO3-N prior to fertilizer treatments. When twice the estimated irrigation requirement was applied, >1000 kg·ha-1 of NO3-N was unaccounted for and presumed to have been mostly leached below the 2-m profile and partly denitrified. In both years, the onions were planted on land that had been fallowed the previous season, which does not help explain the presence of the high levels of nitrates found in the soil profile. It was concluded that sound water and N management practices in onion fields are crucial for preservation of water quality.

NLEAP Computer Model and Multiple Linear Regression Prediction of Nitrate Leaching in Vegetable Systems

2002 ◽  
Vol 12 (2) ◽  
pp. 250-256 ◽  
Author(s):  
Hudson Minshew ◽  
John Selker ◽  
Delbert Hemphill ◽  
Richard P. Dick
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Nitrate Leaching ◽  
Cover Crops ◽  
N Uptake ◽  
N Leaching ◽  
Residual Soil ◽  
Vegetable Crops ◽  
Crop N Uptake ◽  
Mlr Model

Predicting leaching of residual soil nitrate-nitrogen (NO3-N) in wet climates is important for reducing risks of groundwater contamination and conserving soil N. The goal of this research was to determine the potential to use easily measurable or readily available soilclimatic-plant data that could be put into simple computer models and used to predict NO3 leaching under various management systems. Two computer programs were compared for their potential to predict monthly NO3-N leaching losses in western Oregon vegetable systems with or without cover crops. The models were a statistical multiple linear regression (MLR) model and the commercially available Nitrate Leaching and Economical Analysis Package model (NLEAP 1.13). The best MLR model found using stepwise regression to predict annual leachate NO3-N had four independent variables (log transformed fall soil NO3-N, leachate volume, summer crop N uptake, and N fertilizer rate) (P < 0.001, R2 = 0.57). Comparisons were made between NLEAP and field data for mass of NO3-N leached between the months of September and May from 1992 to 1997. Predictions with NLEAP showed greater correlation to observed data during high-rainfall years compared to dry or averagerainfall years. The model was found to be sensitive to yield estimates, but vegetation management choices were limiting for vegetable crops and for systems that included a cover crop.

scholarly journals Numerical Analysis of the Transport and Fate of Nitrate in the Soil and Nitrate Leaching to Drains

2001 ◽  
Vol 1 ◽  
pp. 170-180 ◽  
Author(s):  
Alaa El-Sadek ◽  
Mona Radwan ◽  
Jan Feyen
Keyword(s):  
Nitrate Leaching ◽  
Initial Conditions ◽  
Continuous Cropping ◽  
Nitrogen Transport ◽  
State Variables ◽  
Nitrogen Application ◽  
Transport And Transformation ◽  
Bottom Boundary Condition ◽  
Rainfall Depth ◽  
Simulation Results

In this study, the transport and fate of nitrate within the soil profile and nitrate leaching to drains were analyzed by comparing historic field data with the simulation results of the DRAINMOD model. The nitrogen version of DRAINMOD was used to simulate the performance of the nitrogen transport and transformation of the Hooibeekhoeve experiment, situated in the sandy region of the Kempen (Belgium) and conducted for a 30-year (1969–1998) period. In the analysis, a continuous cropping with maize was assumed. Comparisons between experimentally measured and simulated state variables indicate that the nitrate concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions, and the rainfall depth and distribution. Furthermore, the study reveals that the model used gives a fair description of the nitrogen dynamics in the soil and subsurface drainage at field scale. From the comparative analysis between experimental data and simulation results it can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting in an acceptable level of nitrate leaching for the environment.

scholarly journals Modelling of dust generation, transport and remobilization in full-metal fusion reactors

2022 ◽  
Author(s):  
Svetlana Ratynskaia ◽  
Ladislas Vignitchouk ◽  
Panagiotis Tolias
Keyword(s):  
Initial Conditions ◽  
External Input ◽  
Dust Particles ◽  
Fusion Reactors ◽  
Dust Production ◽  
Dust Transport ◽  
Dust Generation ◽  
Wall Interaction ◽  
And Migration ◽  
Generation Mechanisms

Abstract The design, licensing and operation of magnetic confinement fusion reactors impose various limitations on the amount of metallic dust particles residing inside the plasma chamber. In this context, predictive studies of dust production and migration constitute one of the main sources of relevant data. These are mainly conducted using dust transport codes, which rely on coupled dust-plasma and dust-wall interaction models, and require external input on the dust and droplet initial conditions. Some particularities of dust modelling in reactor-relevant conditions are analyzed with an emphasis on dust generation mechanisms relevant for disruption scenarios and on dust remobilization mechanisms relevant for ramp-up scenarios. Emerging topics such as dust production by runaway electron impact and pre-plasma remobilization of magnetic dust are also discussed.

Parameter investigation for decentralised dewatering and solar thermic drying of sludge

2005 ◽  
Vol 51 (10) ◽  
pp. 65-73 ◽  
Author(s):  
B. Wett ◽  
M. Demattio ◽  
W. Becker
Keyword(s):  
Sewage Sludge ◽  
Initial Conditions ◽  
Simulated Data ◽  
Field Tests ◽  
High Water ◽  
High Water Content ◽  
Secondary Importance ◽  
Initial Height ◽  
Sludge Cake ◽  
Slurry Layer

The purpose of this paper is an experimental and model assisted investigation of the capabilities of a dewatering system for sewage sludge for decentralised sites. Laboratory and field tests are performed with different initial conditions and the influences of filter medium, initial height, initial total suspended solids, temperature and relative humidity are discussed. The experimental work shows the feasibility of geotextile media for dewatering high water content sewage sludge and that the textile structure is of secondary importance. The specific filter resistance of the sludge cake is found to be the most significant factor in dewatering applications. The mathematical description of the dewatering process is based on the superposition of two models, the Conventional Filtration Theory for the filtration phase and the BT-model for the drying phase. Feasibility and limits of the theoretical approach are evaluated by means of a comparison between measurements and simulated data of cyclic reloading tests. It is found that a better filtration efficiency is achieved at higher TSS and at lower initial height of the slurry layer. Due to the viscosity decrease, a higher temperature enhances not only evaporation, but also filtration rate.

scholarly journals Diet-induced Generalized Periodontitis in Lewis Rats

2019 ◽  
Vol 69 (5) ◽  
pp. 384-400
Author(s):  
Jonathan G Messer ◽  
Stephanie La ◽  
Deborah E Kipp ◽  
Evelyn J Castillo ◽  
Joshua F Yarrow ◽  
...  
Keyword(s):  
Gene Expression ◽  
Inflammatory Cytokines ◽  
Alveolar Bone ◽  
Health Concern ◽  
Lewis Rats ◽  
Periodontal Tissues ◽  
Baseline Group ◽  
Gingival Epithelium ◽  
And Migration ◽  
Mechanical Intervention

Periodontitis is an important public health concern worldwide. Because rodents from the genus Rattus are resistant to spontaneous periodontitis, experimental periodontitis must be initiated by mechanical procedures and interventions. Due to their exacerbated Th1 response and imbalanced Th17 regulatory T-cell responses, Lewis rats are highly susceptible to inducible inflammatory and autoimmune diseases. We hypothesized that feeding Lewis rats a diet high in sucrose and casein (HSC) would alter the oral microenvironment and induce inflammation and the development of periodontitis lesions without mechanical intervention. A baseline group (BSL, n = 8) was euthanized at age 6 wk. Beginning at 6 wk of age, 2 groups of Lewis rats were fed standard (STD, n = 12) or HSC (n = 20) chow and euthanized at 29 wk of age. We evaluated the degree of periodontitis through histology and μCT of maxillae and mandibles. The HSC-induced inflammatory response of periodontal tissues was assessed by using immunohistochemistry. Gene expression analysis of inflammatory cytokines associated with Th1 and Th17 responses, innate immunity cytokines, and tissue damage in response to bacteria were assessed also. The potential systemic effects of HSC diet were evaluated by assessing body composition and bone densitometry endpoints; serum leptin and insulin concentrations; and gene expression of inflammatory cytokines in the liver. Placing Lewis rats on HSC diet for 24 wk induced a host Th1-immune response in periodontal tissues and mild to moderate, generalized periodontitis characterized by inflammatory cell infiltration (predominantly T cells and macrophages), osteoclast resorption of alveolar bone, and hyperplasia and migration of the gingival epithelium. HSC-fed Lewis rats developed periodontitis without mechanical intervention in the oral cavity and in the absence of any noteworthy metabolic abnormalities. Consequently, the rat model we described here may be a promising approach for modeling mild to moderate periodontitis that is similar in presentation to the human disease.

Sample Volume Effect on the Determination of Nitrate-Nitrogen in the Soil Profile

1989 ◽  
Vol 32 (3) ◽  
pp. 0934-0938 ◽  
Author(s):  
D. G. Baker ◽  
R. S. Kanwar ◽  
J. L. Baker
Keyword(s):  
Soil Profile ◽  
Nitrate Nitrogen ◽  
Volume Effect ◽  
Sample Volume

scholarly journals Selecting among Alternative Scenarios of Human Evolution by Simulated Genetic Gradients

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 506 ◽  
Author(s):  
Catarina Branco ◽  
Miguel Arenas
Keyword(s):  
Human Evolution ◽  
Simulated Data ◽  
Real Data ◽  
Population Admixture ◽  
Evolutionary Processes ◽  
Long Distance ◽  
History Of ◽  
Pros And Cons ◽  
Alternative Scenarios ◽  
And Migration

Selecting among alternative scenarios of human evolution is nowadays a common methodology to investigate the history of our species. This strategy is usually based on computer simulations of genetic data under different evolutionary scenarios, followed by a fitting of the simulated data with the real data. A recent trend in the investigation of ancestral evolutionary processes of modern humans is the application of genetic gradients as a measure of fitting, since evolutionary processes such as range expansions, range contractions, and population admixture (among others) can lead to different genetic gradients. In addition, this strategy allows the analysis of the genetic causes of the observed genetic gradients. Here, we review recent findings on the selection among alternative scenarios of human evolution based on simulated genetic gradients, including pros and cons. First, we describe common methodologies to simulate genetic gradients and apply them to select among alternative scenarios of human evolution. Next, we review previous studies on the influence of range expansions, population admixture, last glacial period, and migration with long-distance dispersal on genetic gradients for some regions of the world. Finally, we discuss this analytical approach, including technical limitations, required improvements, and advice. Although here we focus on human evolution, this approach could be extended to study other species.

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