scholarly journals Agriculture Model Comparison Framework and MyGeoHub Hosting: Case of Soil Nitrogen

Inventions ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 25
Author(s):  
Anupam Bhar ◽  
Benjamin Feddersen ◽  
Robert Malone ◽  
Ratnesh Kumar
Keyword(s):  
Soil Nitrogen ◽  
Field Data ◽  
Model Comparison ◽  
Test Model ◽  
Soil N ◽  
N Dynamics ◽  
Benchmark Model ◽  
C Dynamics ◽  
Comparison Results ◽  
Speed Up

To be able to compare many agricultural models, a general framework for model comparison when field data may limit direct comparison of models is proposed, developed, and also demonstrated. The framework first calibrates the benchmark model against the field data, and next it calibrates the test model against the data generated by the calibrated benchmark model. The framework is validated for the modeling of the soil nutrient nitrogen (N), a critical component in the overall agriculture system modeling effort. The nitrogen dynamics and related carbon (C) dynamics, as captured in advanced agricultural modeling such as RZWQM, are highly complex, involving numerous states (pools) and parameters. Calibrating many parameters requires more time and data to avoid underfitting. The execution time of a complex model is higher as well. A study of tradeoff among modeling complexities vs. speed-up, and the corresponding impact on modeling accuracy, is desirable. This paper surveys soil nitrogen models and lists those by their complexity in terms of the number of parameters, and C-N pools. This paper also examines a lean soil N and C dynamics model and compares it with an advanced model, RZWQM. Since nitrate and ammonia are not directly measured in this study, we first calibrate RZWQM using the available data from an experimental field in Greeley, CO, and next use the daily nitrate and ammonia data generated from RZWQM as ground truth, against which the lean model’s N dynamics parameters are calibrated. In both cases, the crop growth was removed to zero out the plant uptake, to compare only the soil N-dynamics. The comparison results showed good accuracy with a coefficient of determination (R2) match of 0.99 and 0.62 for nitrate and ammonia, respectively, while affording significant speed-up in simulation time. The lean model is also hosted in MyGeoHub cyberinfrastructure for universal online access.

EFFECTS OF GRAZING ON MICROBIAL FUNCTIONAL GROUPS INVOLVED IN SOIL N DYNAMICS

2005 ◽  
Vol 75 (1) ◽  
pp. 65-80 ◽  
Author(s):  
A. K. Patra ◽  
L. Abbadie ◽  
A. Clays-Josserand ◽  
V. Degrange ◽  
S. J. Grayston ◽  
...  
Keyword(s):  
Functional Groups ◽  
Soil N ◽  
N Dynamics ◽  
Microbial Functional Groups ◽  
Soil N Dynamics

scholarly journals Plant and soil nitrogen in oligotrophic boreal forest habitats with varying moss depths: does exclusion of large grazers matter?

Oecologia ◽  
2021 ◽  
Author(s):  
Maria Väisänen ◽  
Maria Tuomi ◽  
Hannah Bailey ◽  
Jeffrey M. Welker
Keyword(s):  
Boreal Forest ◽  
Vascular Plant ◽  
Soil N ◽  
Inorganic N ◽  
N Dynamics ◽  
N Content ◽  
Feather Moss ◽  
Foliar N ◽  
Plant Soil ◽  
Plant Soil Interactions

AbstractThe boreal forest consists of drier sunlit and moister-shaded habitats with varying moss abundance. Mosses control vascular plant–soil interactions, yet they all can also be altered by grazers. We determined how 2 decades of reindeer (Rangifer tarandus) exclusion affect feather moss (Pleurozium schreberi) depth, and the accompanying soil N dynamics (total and dissolvable inorganic N, δ15N), plant foliar N, and stable isotopes (δ15N, δ13C) in two contrasting habitats of an oligotrophic Scots pine forest. The study species were pine seedling (Pinus sylvestris L.), bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.), and feather moss. Moss carpet was deeper in shaded than sunlit habitats and increased with grazer exclusion. Humus N content increased in the shade as did humus δ15N, which also increased due to exclusion in the sunlit habitats. Exclusion increased inorganic N concentration in the mineral soil. These soil responses were correlated with moss depth. Foliar chemistry varied due to habitat depending on species identity. Pine seedlings showed higher foliar N content and lower foliar δ15N in the shaded than in the sunlit habitats, while bilberry had both higher foliar N and δ15N in the shade. Thus, foliar δ15N values of co-existing species diverged in the shade indicating enhanced N partitioning. We conclude that despite strong grazing-induced shifts in mosses and subtler shifts in soil N, the N dynamics of vascular vegetation remain unchanged. These indicate that plant–soil interactions are resistant to shifts in grazing intensity, a pattern that appears to be common across boreal oligotrophic forests.

scholarly journals The seven sisters DANCe

2018 ◽  
Vol 612 ◽  
pp. A70 ◽  
Author(s):  
J. Olivares ◽  
E. Moraux ◽  
L. M. Sarro ◽  
H. Bouy ◽  
A. Berihuete ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Model Comparison ◽  
Precise Determination ◽  
Model Parameters ◽  
Data Sets ◽  
Adequate Model ◽  
Comparison Results ◽  
Bayesian Evidence ◽  
Mass Segregation

Context. Membership analyses of the DANCe and Tycho + DANCe data sets provide the largest and least contaminated sample of Pleiades candidate members to date. Aims. We aim at reassessing the different proposals for the number surface density of the Pleiades in the light of the new and most complete list of candidate members, and inferring the parameters of the most adequate model. Methods. We compute the Bayesian evidence and Bayes Factors for variations of the classical radial models. These include elliptical symmetry, and luminosity segregation. As a by-product of the model comparison, we obtain posterior distributions for each set of model parameters. Results. We find that the model comparison results depend on the spatial extent of the region used for the analysis. For a circle of 11.5 parsecs around the cluster centre (the most homogeneous and complete region), we find no compelling reason to abandon King’s model, although the Generalised King model introduced here has slightly better fitting properties. Furthermore, we find strong evidence against radially symmetric models when compared to the elliptic extensions. Finally, we find that including mass segregation in the form of luminosity segregation in the J band is strongly supported in all our models. Conclusions. We have put the question of the projected spatial distribution of the Pleiades cluster on a solid probabilistic framework, and inferred its properties using the most exhaustive and least contaminated list of Pleiades candidate members available to date. Our results suggest however that this sample may still lack about 20% of the expected number of cluster members. Therefore, this study should be revised when the completeness and homogeneity of the data can be extended beyond the 11.5 parsecs limit. Such a study will allow for more precise determination of the Pleiades spatial distribution, its tidal radius, ellipticity, number of objects and total mass.

Soil N dynamics in a natural calcareous grassland under a changing climate

1998 ◽  
Vol 27 (3) ◽  
pp. 267-273 ◽  
Author(s):  
N. Jamieson ◽  
D. Barraclough ◽  
M. Unkovich ◽  
R. Monaghan
Keyword(s):  
Calcareous Grassland ◽  
Soil N ◽  
N Dynamics ◽  
Changing Climate ◽  
Soil N Dynamics

Effects of transition season management on soil N dynamics and system N balances in rice–wheat rotations of Nepal

2007 ◽  
Vol 103 (2) ◽  
pp. 98-108 ◽  
Author(s):  
M. Becker ◽  
F. Asch ◽  
S.L. Maskey ◽  
K.R. Pande ◽  
S.C. Shah ◽  
...  
Keyword(s):  
Soil N ◽  
N Dynamics ◽  
Transition Season ◽  
Soil N Dynamics

scholarly journals Soil nitrogen cycle unresponsive to decadal long climate change in a Tasmanian grassland

2019 ◽  
Vol 147 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Tobias Rütting ◽  
Mark J. Hovenden
Keyword(s):  
Climate Change ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Sink ◽  
Vegetation Type ◽  
Terrestrial Ecosystems ◽  
Soil N ◽  
Mineral N ◽  
N Dynamics ◽  
Terrestrial Carbon Sink ◽  
Soil Nitrogen Cycle

AbstractIncreases in atmospheric carbon dioxide (CO2) and global air temperature affect all terrestrial ecosystems and often lead to enhanced ecosystem productivity, which in turn dampens the rise in atmospheric CO2 by removing CO2 from the atmosphere. As most terrestrial ecosystems are limited in their productivity by the availability of nitrogen (N), there is concern about the persistence of this terrestrial carbon sink, as these ecosystems might develop a progressive N limitation (PNL). An increase in the gross soil N turnover may alleviate PNL, as more mineral N is made available for plant uptake. So far, climate change experiments have mainly manipulated one climatic factor only, but there is evidence that single-factor experiments usually overestimate the effects of climate change on terrestrial ecosystems. In this study, we investigated how simultaneous, decadal-long increases in CO2 and temperature affect the soil gross N dynamics in a native Tasmanian grassland under C3 and C4 vegetation. Our laboratory 15N labeling experiment showed that average gross N mineralization ranged from 4.9 to 11.3 µg N g−1 day−1 across the treatment combinations, while gross nitrification was about ten-times lower. Considering all treatment combinations, no significant effect of climatic treatments or vegetation type (C3 versus C4 grasses) on soil N cycling was observed.

Relationship of the Illinois soil nitrogen test to spring wheat yield and response to fertilizer nitrogen

2008 ◽  
Vol 88 (5) ◽  
pp. 837-848 ◽  
Author(s):  
S J Steckler ◽  
D J Pennock ◽  
F L Walley
Keyword(s):  
Soil Nitrogen ◽  
Crop Yields ◽  
Wheat Yield ◽  
N Fertilizer ◽  
Yield Response ◽  
Regression Equations ◽  
Soil N ◽  
Fertilizer N ◽  
Available N ◽  
Nitrate N

The Illinois soil N test (ISNT) has been used to distinguish between soils that are responsive and non-responsive to fertilizer N in Illinois. We examined the suitability of this test, together with more traditional measures of soil fertility, including spring nitrate-N and soil organic carbon (SOC), for predicting yield and N fertilizer response of wheat (Triticum aestivum) on hummocky landscapes in Saskatchewan. The relationship between ISNT-N and wheat yield and fertilizer N response was assessed using data and soils previously collected for a variable-rate fertilizer study. Soils were re-analyzed for ISNT-N. Our goal was to determine if ISNT-N could be used to improve the prediction of crop yields. Although ISNT-N was correlated with both unfertilized wheat yield (r = 0.467, P = 0.01) and fertilizer N response (r = -0.671, P = 0.01) when data from all study sites were combined, correlations varied according to landscape position and site. Stronger correlations between nitrate-N and both unfertilized wheat yield (r = 0.721, P = 0.01) and fertilizer N response (r = -0.690, P = 0.01) indicated that ISNT-N offered no advantage over nitrate-N. Although both tests broadly discriminated between sites with high or low N fertility, few relationships were detected on a point-by-point basis within a field. Stepwise regression equations predicting yield and yield response did not include ISNT-N, due in part to the high degree of collinearity between ISNT-N and other variables such as SOC, suggesting that ISNT-N alone was not a key indicator of soil N supply. Key words: Illinois soil nitrogen test, potentially available N, soil N, fertilizer N recommendations

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