DNDC

Criterion

Explanation

Carbon and nitrogen biogeochemical model for agricultural ecosystems. Important ecological drivers of the model include climate, soil, vegetation and human activities. Model can be used to predict crop growth, soil temperature and moisture regimes, soil carbon dynamics, nitrogen leaching, and gas emissions. Model bridges carbon and nitrogen biogeochemical cycles with primary ecological drivers.

Model Domain

General

Developer

University of New Hampshire: Professor Changsheng Li.

Hardware computing requirements

PC operating Windows with 64M memory are minimum requirements, additional recommended requirements include 350MHz processor or higher and graphics adapter of SVGA or higher.

Code language

Visual C++ 6.0

Original application

Original model developed to simulate rain-event driven N₂O, N₂ and CO₂ evolution from agricultural soils using three sub-models (thermal-hydraulic, decomposition, denitrification) (Li et al., 1992; Gilhespy et al., 2014).

Public/proprietary and cost

Model publicly available. No associated cost for use.

Physically or empirically based

Physically based model on carbon and nitrogen biogeochemical processes. Empirically based on equations produced from laboratory studies.

Mathematical methods used

Model incorporates classical laws of physics, chemistry and biology and empirical equations generated from laboratory studies, to parameterize geochemical or biochemical reaction for decomposition, urea hydrolysis, ammonia volatilization, nitrification, denitrification and methane dynamics processes. Model specific equations and procedures are provided in UNH, 2017. Model consists of various sub-models: Soil-climate, crop growth, decomposition, nitrification, denitrification and fermentation.

Input data requirements

Model can be operated using site or regional mode.

Input consist of ecological drivers: climate parameters (temperature, precipitation, humidity, wind speed, solar radiation, humidity), soil parameters (temperature, pH, texture, clay content, bulk density, porosity, field capacity, soil organic carbon, salinity, soil slope, microbial activity index, land use) and cropping management (crop type, tillage, fertilization, amendments, irrigation, flooding, physical structures, grazing, cutting, number of cropping systems applied, duration of cropping).

Meteorological, soil, cropping management and microbial data can be obtained through public databases. Detailed land and cropping management information can often be obtained from land managers.

Outputs

Soil properties (temperature, moisture, pH, oxidation-reduction potential, substrate concentration profiles (nitrate, dissolved organic carbon, ammonium, etc.), daily and annual crop biomass, carbon and nitrogen pools/fluxes/budgets, water budget). Plant-soil system gas emissions (carbon dioxide–CO₂, methane–CH₄, ammonia–NH₃, nitric oxide–NO, nitrous oxide–N₂O and dinitrogen–N₂). Output is on timescale of days, years to centuries. Output files are in plain text format, quick viewing of results also provided in model program.

Pre-processing and post-processing tools

Model application file, database files.

Representation of uncertainty

Uncertainty in data input can be specified by user. Uncertainty in model simulations can be calculated in program using Monte Carlo approach (site mode) or Most Sensitive Factor method (regional mode).

Prevalence

Very commonly applied model, used by academic and government entities. Applications vary widely (forested wetlands, livestock farms, pasture lands, etc.) and have led to the development of many specialized versions of DNDC for various locales. Limited in used for modeling in the Bay-Delta regions, DNDC model validations performed for the Bay-Delta (Deng and Salas, 2017; Li et al., 2014; Merrill et al., 2010).

Ease of use for public entities

Easy to moderate, no special training required, user guide available. No specialized hardware or software necessary.

Ease of obtaining information and availability of technical support

No commercial help desk available. User support available upon request from contact at http://www.dndc.sr.unh.edu/ or from individual modelers.

Source code availability

Model available at http://www.dndc.sr.unh.edu/. Source code available upon request.

Status of model development

Development and expansion of model is on-going with contributions from various researchers, modelers and agencies.

Challenges for integration

Integration challenges not clear. Model able to simulate output from various timesteps and spatial resolutions.