Nutrients/Data uncertainties limitations: Difference between revisions

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{{ComponentDataUncertaintyAndLimitationsTemplate
{{ComponentDataUncertaintyAndLimitationsTemplate
|Reference=OECD, 2012; FAO, 2012a; Beusen et al., 2008;
|Description=<h2>Data,  uncertainties and limitations</h2>
===Data===
The data stem from various parts of IMAGE, such as land cover, biomes, crop production and allocation, livestock, fertiliser use and nutrient excretion rates. Environmental data include temperature and precipitation, runoff, and soil properties (see Input/output Table [[Nutrients|Introduction part]]).
External data are used in determining historical N excretion rates, manure spreading and fertiliser use efficiency, but their development in the future is a scenario assumption. Additional information used only in this section includes lithology, relief and slope of the terrain. Additional data used in the nutrient budget model include subnational data as used for the United States, India, Brazil and China.
===Uncertainties===
With regard to uncertainties, the budget calculations and individual input terms for 2000 have been found to be in close agreement ([[Bouwman et al., 2009]]) with detailed country estimates for the member countries of the Organisation for Economic Co-operation and Development ([[OECD, 2012]]).


|Reference=Bouwman et al., 2009; OECD, 2012; FAO, 2012; Beusen et al., 2008;
However, uncertainty is larger for some budget terms than for others. Data on fertiliser use are more reliable than on N and P animal excretions, which are calculated from livestock data ([[FAO, 2012b]]) and excretion rates per animal category. Data on crop nutrient withdrawal are less certain than on crop production, because the withdrawal is calculated with fixed global nutrient contents of the harvested proportions of marketed crops. In addition to uncertainty in nutrient contents, major uncertainties arise from insufficient data, for instance, on crops that are not marketed and on the use of crop residues. This leads to major uncertainties about nutrient withdrawal.
|Description=<h2>Data,  uncertainties and limitations</h2>
The data used in this chapter stem from various parts of IMAGE, such as those on land cover, biomes, crop production and allocation, livestock, fertiliser use and nutrient excretion rates;  environmental data include those on temperature and precipitation, runoff, and soil properties. External data are used for determining historical N excretion rates, manure spreading and fertiliser use efficiency, whereas their development in the future is a scenario assumption. Additional information only used in this chapter includes lithology, relief and slope of the terrain. The uncertainty of the model parameters are discussed in the various chapters of this book. Additional data used in the nutrient budget model include subnational data as used for the United States and China.
Regarding uncertainties, the budget calculations and individual input terms for the year 2000 were found to be in good agreement ([[Bouwman et al., 2009]]) with detailed country estimates for the member countries of the Organisation for Economic Co-operation and Development ([[OECD]]) ([[OECD, 2012]]). However, it is clear that the uncertainty in some of the budget terms is larger than for others. Data on fertiliser use are more reliable than on N and P animal excretions, which is calculated from livestock data ([[FAO, 2012]]) and excretion rates by animal category. Data on crop nutrient withdrawal are less certain than on crop production, because the withdrawal is calculated with fixed global nutrient contents of the harvested shares of marketed crops. Apart from the uncertainty in nutrient contents, major uncertainties arise from lack of data; data on crops that are not marketed and the use of crop residues are not available, and this causes major uncertainties about nutrient withdrawal.
Sensitivity analysis ([[Beusen et al., 2008]]) showed that the most important determinants of the uncertainty of the nutrient model comprise:
# N excretion rates
# NH3 emission rates from manure in animal housing and storage systems,
# the fraction of the time that ruminants graze
# the fraction of non-agricultural use of manure) specific to mixed and industrial systems
# animal stocks.


Sensitivity analysis ([[Beusen et al., 2015]]) of global nutriënt transport model with data for the year 2000 showed that:
* runoff is a major factor for N and P delivery, retention and river export.
* Uptake velocity and all factors used to compute the subgrid in-stream retention are important for total in-stream retention and river export of both N and P
* Soil N budgets, wastewater and all factors determining litterfall in floodplains are important for N delivery to surface water.
* For P the factors that determine the P content of the soil (soil P content and bulk density) are important factors for P delivery and river export.


Sensitivities for the years 1900 and 1950 ([[Beusen et al., 2016]]) show that inputs from vegetation in floodplains (for N and P) and weathering (for P) are important in the first half of the 20th century, when human activites were not yet overshadowing natural sources of nutrients.
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Latest revision as of 15:24, 2 November 2016

link to framework components overview

Parts of Nutrients/Data uncertainties limitations

  1. Introduction page
  2. Model description
  3. Policy issues
  4. Data, uncertainty and limitations
  5. Overview of references
Component is implemented in:
Components:
Related IMAGE components
Projects/Applications
Key publications
References
Nutrient module of IMAGE 3.0
Flowchart Nutrients. See also the Input/Output Table on the introduction page.
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