DOI: 10.23637/rothamsted.00033662
title: Rothamsted Fertiliser Emissions Scenarios Tool (R-FEST)

description: A simple and interactive tool developed for the quantification of emissions associated with the applications of different chemical nitrogen fertiliser products, at water management catchment (WMC) scale for England.


Fertiliser application in agricultural fields is an integral part of modern intensive farming to help provide food security but also contributes significantly to damaging changing climate and excess energy use at both national and global scales. To meet these challenges, fertiliser production technologies and on-farm and in-field management and applications are going through progressive changes across the world. Increased spatial variabilities are expected in the emissions associated with fertiliser production with the potential deployment of distributed production systems; e.g., modularized green ammonia production units. More spatially explicit evidence on the emissions associated with fertiliser use are in demand for supporting spatial targeting, scenario development and strategic planning. A simple and interactive tool has therefore been developed for the quantification of emissions associated with the applications of different chemical nitrogen fertiliser products, at water management catchment (WMC) scale for England. For a Business-As-Usual (BAU) scenario, the tool was populated with recent spatially disaggregated data on land use and cropping, current survey data on crop and farm type-specific fertiliser practices, and existing knowledge about in-field emissions. Customized fertiliser production technologies, application practices (types, rates, coverage) and management impacts can be specified to generate different scenarios and their emissions can be evaluated at WMC and national scales, including both emissions to air - nitrous oxide (N2O), carbon dioxide (CO2) and ammonia (NH3), plus emissions to water - nitrate (NO3).
description: The tool is a macro-enabled multi-sheet Excel workbook. Because of the use of user defined functions and procedures in the VBA programming language for the modelling, it is necessary to enable macro for the tool to work in advance. The following procedure can be used to achieve this: 


1)Start Excel and open a blank workbook. 


2)Click the following buttons in sequence: ‘File, Options, Trust Center, Trust Center Settings, Macro Settings’ 


3) Please select option 2 (‘Disable VBA Macros with notification’) or 4 (‘Enable VBA Macros …’). 


4) Open the Excel workbook for the tool. Please enable the macro if prompted. 

 

The template has been set up for interactive modelling, wherein the following key inputs / factors can be changed: 

1) major crops and land use distributions 

2) fertiliser application rates and coverages 

3) embedded emissions with different fertiliser products wherein different types of fertilisers can be represented; e.g., conventional fertilisers, fertilisers based on green ammonia, etc. Location-specific emission intensities can be specified to represent the potential contribution from distributed production systems in specific WMCs 

4) proportional usages of fertiliser products by different crops and grass 

5) nitrate, nitrous oxide and ammonia emissions coefficients (i.e., emission factors) for crops and grass for different farm types. 

 

For fertiliser rates and coverages, changes can be made by modifying the actual values or specifying a relative change. More detailed instruction can be seen in the relevant section of the worksheets. Functions are available for targeted scenario modelling, wherein a selection of farm types, crops and geographic areas can be specified. Default values for all inputs have been assembled using an updated recent national dataset and information, as well as modelled outputs. Key data sources are provided in the 'Data sources' worksheet for reference purposes and in support of further updates in the future. National totals of fertiliser usages and emissions by different products are tabulated at the top of the output worksheets. It is worth noting not all farm types and catchments in England were considered. The land use and cropping data for different WMCs are based on the aggregated data for different WFD surface waterbodies; i.e., not individual holding level data. Because of these discrepancies, the direct comparison against reported GHG inventories for England at national level are not recommended. 

 

A typical modelling run will involve reviewing various inputs and parameters, making necessary changes, specifying modelling domains (specific farm types, crops, government regions, WMCs), confirming changes made and obtaining refreshed results via embedded buttons in the 'Control' worksheet. These procedures are shown as clickable buttons in the ‘Control’ worksheet. The result sheets will become visible when valid outputs are available. 

 

The underpinning code has been locked for viewing to prevent unintentional changes ('green'). Some rows / columns are hidden for clarity. Generally speaking, cells shaded in green can be changed by users and cell areas shaded in other colours are for display only and should not be changed. There is no 'Undo' function implemented so users are strongly advised to save a copy of the tool before any scenario simulations.