Building factorial regression models to explain and predict nitrate concentrations in groundwater under agricultural land

2008 ◽  
Vol 357 (1-2) ◽  
pp. 42-56 ◽  
Author(s):  
T.Y. Stigter ◽  
L. Ribeiro ◽  
A.M.M. Carvalho Dill
Keyword(s):  
Regression Models ◽  
Agricultural Land ◽  
Factorial Regression ◽  
Nitrate Concentrations

scholarly journals THE SUITABILITY OF SEAWATER ON CONCRETING IN THE NIGER – DELTA ZONE

2019 ◽  
pp. 39-48
Keyword(s):  
Compressive Strength ◽  
Niger Delta ◽  
Mathematical Theory ◽  
Regression Models ◽  
Cement Content ◽  
Suitable Condition ◽  
Maximum Level ◽  
Minimum Level ◽  
Concrete Compressive Strength ◽  
Factorial Regression

This study was carried out in order to determine the suitability or otherwise of seawater for concreting. The study was carried out using the Box-Wilson symmetric composite plan B3, comprising 15 experimental points with 3 levels of treatment each. In accordance with the principle of the mathematical theory of experiment, multi-factorial regression models were evolved. The cement content at maximum level[x1 (+), water content at the minimum level [x2 (-)] and retarding admixture at minimum level of treatment [x3(-)] proved to be the most suitable condition for concreting. The result as follows were; Concrete slump: 60mm, Concrete density: 2450g/cm3, Concrete compressive strength: 22.56N/mm2, 26.65N/mm2 and 30.09N/mm2 for 7days, 14days and 28 days, respectively.

Assessing Nitrogen Legacies in Western Europe

2021 ◽  
Author(s):  
Andreas Musolff ◽  
Sophie Ehrhardt ◽  
Rémi Dupas ◽  
Rohini Kumar ◽  
Pia Ebeling ◽  
...  
Keyword(s):  
Time Series ◽  
Agricultural Land ◽  
Time Lags ◽  
Water Safety ◽  
Biological Fixation ◽  
Nitrogen Inputs ◽  
Wide Range ◽  
N Input ◽  
Nitrate Concentrations ◽  
Input Time

<p>Intensive agricultural land use have introduced vast quantities of nutrients such as reactive nitrogen (N) to soils and subsequently to groundwater and surface waters. High nitrate concentrations are still a pressing issue for drinking water safety and aquatic ecosystem health e.g. in Europe, although fertilizer inputs have been significantly lowered in the last decades. This is partly due to a slow response of riverine nitrate concentrations to changes in nitrogen inputs attributed to N legacies in catchments. N can be stored organically bound as a biogeochemical legacy in soils or can be slowly transported as nitrate in groundwater forming a hydrologic legacy. Legacy can thus lead to a net retention of N in catchments and to substantial time lags in the response to input changes. Here, we systematically explore legacy effects over a wide range of catchment in the Western European countries France and Germany. We are making use of long observational time series of nitrate concentration in 238 catchments covering 40% of the total area of France and Germany. We apply a Weighted Regression on Time, Discharge, and Season (WRTDS) to derive continuous daily flow-normalized concentrations and loads. The temporal pattern of concentration and loads at the catchment outlet is compared to the N input time series evolving from agricultural N surplus, atmospheric deposition and biological fixation. We found that on long-term catchments retain on average 72% of the N input. Time lags between input and output were successfully explained by a lognormal transport time distribution. The modes of these distributions were found to be rather short with a median mode of 5.4 years across all catchments. Based on this data-driven assessment only the fate of N in the catchments is hard to assess as denitrification in soil and groundwater can lead to similar observations as the storage of N in legacies. Focusing on the mobile part of N that is exported by catchments, we estimate that a substantial amount of N is still stored in the subsurface that will be released in the coming years. We therefore analyzed how catchment nitrate export will evolve under the scenario of a total cut down, reduced or constant future N inputs. We report the expected timescale of reaction to implemented measures to help tackling this pressing water quality problem.</p>

scholarly journals Nitrate leaching from short-hydroperiod floodplain soils

2012 ◽  
Vol 9 (5) ◽  
pp. 5659-5694 ◽  
Author(s):  
B. Huber ◽  
J. Luster ◽  
S. M. Bernasconi ◽  
J. Shrestha ◽  
E. Graf Pannatier
Keyword(s):  
Nitrate Leaching ◽  
Agricultural Land ◽  
Field Capacity ◽  
N Transformations ◽  
Total N ◽  
N Input ◽  
Nitrate Concentrations ◽  
Gravel Bars ◽  
One Year ◽  
Alluvial Forest

Abstract. Numerous studies have shown the importance of riparian zones to reduce nitrate (NO3–) contamination coming from adjacent agricultural land. Much less is known about nitrogen (N) transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation) and there is no study that could show whether these soils are a N sink or source. Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm) over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation) and N output (leaching) to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater. Overall, the main factor explaining the differences in nitrate concentrations was the variability in soil texture and volumetric water content (VWC) at field capacity (FC). In subsoils with high VWC at FC and VWC near 100 % FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol l−1, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha−1 yr−1 in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO3– ha−1 yr−1 were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11 % to the total nitrate load in groundwater.

scholarly journals Nitrate leaching from short-hydroperiod floodplain soils

2012 ◽  
Vol 9 (11) ◽  
pp. 4385-4397 ◽  
Author(s):  
B. Huber ◽  
J. Luster ◽  
S. M. Bernasconi ◽  
J. Shrestha ◽  
E. Graf Pannatier
Keyword(s):  
Nitrate Leaching ◽  
Agricultural Land ◽  
Field Capacity ◽  
N Transformations ◽  
Total N ◽  
N Input ◽  
Nitrate Concentrations ◽  
Gravel Bars ◽  
One Year ◽  
Alluvial Forest

Abstract. Numerous studies have shown the importance of riparian zones to reduce nitrate (NO3−) contamination coming from adjacent agricultural land. Much less is known about nitrogen (N) transformations and nitrate fluxes in riparian soils with short hydroperiods (1–3 days of inundation) and there is no study that could show whether these soils are a N sink or source. Within a restored section of the Thur River in NE Switzerland, we measured nitrate concentrations in soil solutions as an indicator of the net nitrate production. Samples were collected along a quasi-successional gradient from frequently inundated gravel bars to an alluvial forest, at three different depths (10, 50 and 100 cm) over a one-year period. Along this gradient we quantified N input (atmospheric deposition and sedimentation) and N output (leaching) to create a nitrogen balance and assess the risk of nitrate leaching from the unsaturated soil to the groundwater. Overall, the main factor explaining the differences in nitrate concentrations was the field capacity (FC). In subsoils with high FCs and VWC near FC, high nitrate concentrations were observed, often exceeding the Swiss and EU groundwater quality criterions of 400 and 800 μmol L−1, respectively. High sedimentation rates of river-derived nitrogen led to apparent N retention up to 200 kg N ha−1 yr−1 in the frequently inundated zones. By contrast, in the mature alluvial forest, nitrate leaching exceeded total N input most of the time. As a result of the large soil N pools, high amounts of nitrate were produced by nitrification and up to 94 kg N-NO3− ha−1 yr−1 were leached into the groundwater. Thus, during flooding when water fluxes are high, nitrate from soils can contribute up to 11% to the total nitrate load in groundwater.

scholarly journals Nitrate Relationships between Stream Baseflow, Well Water, and Land Use in the Tomorrow-Waupaca Watershed

2001 ◽  
Vol 1 ◽  
pp. 187-193 ◽  
Author(s):  
Henry Lin ◽  
Rebecca Cook ◽  
Byron Shaw
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Ground Water ◽  
Agricultural Land ◽  
Sampling Site ◽  
Agricultural Land Use ◽  
Strong Positive Correlation ◽  
Ground Water Quality ◽  
Stream Monitoring ◽  
Nitrate Concentrations

We examined the use of stream baseflow water quality as a representative measure of mean ground water quality in the Tomorrow-Waupaca Watershed in central Wisconsin and the relationship between agricultural land use and watershed water quality. From 1997 to 1999, 38 stream sites were sampled for nitrate during winter and summer baseflow conditions. Some sites have been sampled during winter baseflow conditions since 1994. The land area contributing ground water to each stream sampling site was delineated, resulting in 38 sub-basins. In addition, over 3500 test results from private wells in the watershed were compiled and mapped using a Geographic Information System (GIS). Nitrate concentrations in stream baseflow and well waters were found to have strong positive correlation in the sub-basins of second order or higher. This indicates that stream baseflow may be valid for monitoring mean ground water quality in watersheds predominantly fed by ground water, where much of the stream nitrate is believed to originate from ground water. Analysis of seasonal variation in the stream data showed that winter nitrate concentrations were higher than summer concentrations, implying that winter stream monitoring may be more critical for the assessment of overall ground water quality in the watershed. We also found that, as the amount of agricultural land increased in each sub-basin, average nitrate concentrations in the well and stream waters also increased, suggesting a connection between agricultural land use and nitrate contamination of water resources in the watershed.

Environmental effects of manure policy options in The Netherlands

2004 ◽  
Vol 49 (3) ◽  
pp. 101-108 ◽  
Author(s):  
O. Oenema ◽  
L. van Liere ◽  
S. Plette ◽  
T. Prins ◽  
H. van Zeijts ◽  
...  
Keyword(s):  
Land Use ◽  
The Netherlands ◽  
Surface Waters ◽  
Agricultural Land ◽  
Sandy Soils ◽  
Nitrous Oxide Emissions ◽  
Ecological State ◽  
Policy Options ◽  
Nitrate Concentrations ◽  
Farm Gate Balance

This study explores the effects of manure policy options for agricultural land in The Netherlands on nitrate leaching to groundwater, ammonia and nitrous oxide emissions to the atmosphere and on eutrophication of surface waters. The implementation of the farm gate balance MINAS at farm level, with levy-free N surpluses in the range of 300 to 40 kg per ha per year, and levy-free P surpluses in the range of 17.5 to 0.4 kg of P per ha per year, have been examined. Results indicate that nitrate concentrations in the upper groundwater are related to N surplus, land use, soil type and groundwater level. On dry sandy soils, the N surplus has to be below 60 to 140 kg of N per ha per year, depending on land use, to decrease the nitrate concentrations in the upper groundwater to below 50 mg nitrate per litre. Decreases of N and P concentrations in surface waters, upon lowering levy-free surpluses appear relatively small. For improving the ecological state of surface waters, we recommend a combination of low levy-free N and P surpluses with dredging P rich sediments, flushing of ditches, and decreasing discharges from other sources.

Statistical models for genotype by environment data: from conventional ANOVA models to eco-physiological QTL models

2005 ◽  
Vol 56 (9) ◽  
pp. 883 ◽  
Author(s):  
Fred A. van Eeuwijk ◽  
Marcos Malosetti ◽  
Xinyou Yin ◽  
Paul C. Struik ◽  
Piet Stam
Keyword(s):  
Statistical Models ◽  
Regression Models ◽  
Physiological Model ◽  
Environment Interaction ◽  
Response Curves ◽  
Physiological Models ◽  
Factorial Regression ◽  
Multiple Quantitative Trait Locus ◽  
Bilinear Models ◽  
Genotype Environment Interaction

To study the performance of genotypes under different growing conditions, plant breeders evaluate their germplasm in multi-environment trials. These trials produce genotype × environment data. We present statistical models for the analysis of such data that differ in the extent to which additional genetic, physiological, and environmental information is incorporated into the model formulation. The simplest model in our exposition is the additive 2-way analysis of variance model, without genotype × environment interaction, and with parameters whose interpretation depends strongly on the set of included genotypes and environments. The most complicated model is a synthesis of a multiple quantitative trait locus (QTL) model and an eco-physiological model to describe a collection of genotypic response curves. Between those extremes, we discuss linear-bilinear models, whose parameters can only indirectly be related to genetic and physiological information, and factorial regression models that allow direct incorporation of explicit genetic, physiological, and environmental covariables on the levels of the genotypic and environmental factors. Factorial regression models are also very suitable for the modelling of QTL main effects and QTL × environment interaction. Our conclusion is that statistical and physiological models can be fruitfully combined for the study of genotype × environment interaction.

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