Rothamsted Research

where knowledge grows

Agri-Modelling

NWFP Modellers:

Lianhai Wu

Anita Shepherd

Kate Gongadze

The North Wyke Farm Platform provides a response to the needs of modellers who have long required more agri-environmental data for simulations regarding sustainable agriculture, providing data for agri-model input and calibration data to compare with simulated output.

This website provides a guide to using the Farm Platform Data Portal for data, splitting it into input data and calibration data. We provide some examples of results produced using the models we have used.

Please let us know if you have used the Farm Platform data for your modelling, we would appreciate your feedback on how easy or difficult you found the Data Portal.

The aim is that the Data Portal supplies data on temperate high rainfall grassland livestock systems internationally for models to use the Farm Platform in their simulations.

 

Rothamsted North Wyke has a long history of modelling experimental data, for example the SIMSDairy model. Models currently being used with data from the farm platform include:

How to use the Data Portal and Guides for modelling
   

When using the Farm Platform Data Portal for the first time, a good familiarisation to the North Wyke Farm Platform and the data is to:

  • Read the background information on the Farm Platform provided in Data Portal User Guide Establishment and Development of the NWFP.

  • A description of the site, its soils and set-up of the hydrologically isolated fields can be found in Data Portal User Guides 2 – Soils of North Wyke and 3 – Hydrological Assessment.

  • Learn about the range of parameters measured, experimental design and data collection methods in Data Portal User Guides 6 – User Guide to the 15 Minute Data and 7 - User Guide to Field Survey Data.

  • First look at the datasets (both downloaded datasets and metadata) and assess if they would be relevant for input to your model.

  • Input to your model one dataset at a time from the data portal (information on datasets are supplied on this website).

  • Explore changing dataset years or parameters and see what difference it makes. This helps the user become familiar with the data format and values.

  • Check Data Portal User Guides & Information, Known Issues section for known problems with using the data portal .

  • When you are more familiar with the data and its format, if you have any questions, consult the more detailed explanatory information provided in the data portal user guides, including data conversion methods, sensor sensitivity, and potential limitations of data. If you still have questions email the data query contact address, but please remember the Farm Platform team can answer questions relating to data, not modelling.

Reading the explanatory guides are a very important step, and not to be bypassed but the explanatory information may be absorbed and understood better when you have familiarised yourself with the datasets available.

   
Datasets suitable for process model input
 

Soils information can be gained from:

  • Data Portal User Guides - 2 – Soils of North Wyke which contains % sand, silt, clay for available water capacity determination

  • Data Portal - Field Surveys - Soil Survey contains pH and bulk density

Weather data can be obtained from:

  • Data Portal – Time Series data - MET Station for whole of Farm Platform.

Field management data including fertilizer applications and silage cutting operations can be gained from:

  • Data Portal – Livestock, Field Event & Survey data - Field Events datasets*.

  • These should be used with Data Portal User Guides Technical case study 2: Field spreading area calculations, to calculate the rate of application.

Stock numbers per field can be gained from:

  • Data Portal - Livestock datasets

*The field events files are described in farming operations terms, hence the Defra RB209 Fertilizer Manual is useful for conversion. Ready- converted fertilizer to elemental amounts are included here for the fertilizer types used on the Farm Platform.

   
Datasets suitable for process model calibration and validation
 

Crop Production

  • Data Portal – Field Surveys – Silage Cut Survey gives dry matter yield from the herbage cut for silage production

Soil moisture sensor

  • Data Portal - Time Series data – Soil moisture & Precipitation for each catchment

Flume runoff flow & nutrients in runoff water

  • Data Portal - Time Series data – Water Flow and Properties for each catchment

Above-ground herbage nitrogen & carbon

  • Data Portal – Livestock, Field Event & Survey data – herbage survey
 

Extra data which may be useful in modelling is to be found in Data Portal User Guides & Information, in the File Downloads section. This supplementary file store is very useful for models using a daily time-step since it contains statistical summaries of the 15-minute datasets, including daily weather data, flume measurements and soil moisture, temperature and field precipitation. The file store also contains GIS shape files for the farm platform fields.

Links to further sources of data, including datasets from the same North Wyke site as well as other sites, are given in Data Portal User Guides & Information, in the Useful External Data Sources section.

   

Process modelling has been carried out using the data of the Farm Platform, here are some results which could be used in comparison to your modelled output:

   
   

The SPACSYS model (Wu et al., 2007) is a field scale, weather-driven and daily-time-step dynamic simulation model. The current version includes a plant growth and development component, a nitrogen cycling component, a carbon cycling component, a phosphorus cycling component, plus a soil water component that includes representation of water flow to field drains as well as downwards through the soil layers, together with a heat transfer component. The model has a capability to simulate the interaction of C, N, P, soil water and temperature in the soil-plant-atmosphere continuum system.

The main processes concerning plant growth in the model are plant development, assimilation, respiration, and partition of photosynthate and nitrogen from uptake estimated with various mechanisms implemented in the model, plus N fixation for legume plants, and root growth and development that is described in 3D root system by the following processes: branching, extension, architecture, mortality, water uptake and nutrient uptake. An alternative 1D root system is implemented to simplify processes involved in root growth and development. The functionality on water and nitrogen uptake by roots is also quantified.

The model has been used to investigate a number of issues including nitrate leaching, resource use efficiency by crops, root systems, GHG emissions and and the responses of cropping/grassland systems on environmental changes. The model can address the questions, such as, how to increase N and water use efficiency through manipulating genetic traits of plant root architecture; what field managements to mitigate GHG emissions and diffuse pollution; how response of plants/cropping systems to climate change and carbon sequestered into soils with land use change.

Wu, L., McGechan, M. B., McRoberts, N., Baddeley, J. A., Watson, C. A., 2007. SPACSYS: integration of a 3D root architecture component to carbon, nitrogen and water cycling - model description. Ecol. Model. 200, 343-359.

   

DAYCENT is the daily time-step version of the CENTURY biogeochemical model (Parton et al., 1994). DAYCENT simulates fluxes of C and N among the atmosphere, vegetation, and soil (Parton et al., 1998). Submodels include soil water content and temperature by layer, plant production and allocation of net primary production (NPP), decomposition of litter and soil organic matter, mineralization of nutrients, N gas emissions from nitrification and denitrification, and CH4 oxidation in non-saturated soils.

Operators create a schedule file which calls in modules for field management and makes it possible to manage operations on a daily basis. Model outputs include: daily N-gas flux (N2O, NOx, N2), CO2 flux from heterotrophic soil respiration, soil organic C and N, NPP, H2O and NO3 leaching, and other ecosystem parameters.

Parton, W.J. and Rasmussen, P.E. 1994. Long term effects of crop management in wheat/fallow: II. CENTURY model simulations. Soil Science Society of America Journal 58: 530-536.

Parton, W.J., Hartman, M., Ojima, D., Schimel, D. 1998. DAYCENT and its land surface submodel: description and testing. Global Planetary Change, 19, 35-48.

   

SH2O-NW is a simple but effective soil water model to predict the soil moisture stored in the root zone and determine field runoff from soil (Shepherd et al., 2002). The model has been validated for the North Wyke Farm Platform (Shepherd et al., 2016), and is parsimonious requiring available water capacity and soil runoff curve number plus meteorological data.

Water availability in the root zone involves a water balance in which effective rainfall, runoff and evapo-transpiration are the main factors. The model assumes that in the absence of a water table, effective rainfall is the only source of water. The effective rainfall is calculated from rainfall minus surface runoff. If the available water is below a critical threshold, the crop demand cannot be met. The relative reduction in water use is related to the ratio of the available water and the water holding capacity.

A. Shepherd, S.M. McGinn, G.C.L. Wyseure. 2002. Simulation of the effect of water shortage on the yields of winter wheat in North-East England. Ecological Modelling, 147(1), 41-52.

Anita Shepherd, Wellen Atuhaire, Lianhai Wu, David Hogan, Robert Dunn and Laura Cardenas. 2015. Historic record of pasture soil water and the influence of the North Atlantic Oscillation in south-west England. Hydrology Research, accepted.