Science Links
Mission of Rothamsted Research
Origins of Rothamsted Research
Company Information
Contact Us
Statements and Policies
Annual Reports
Press Office
Location And Map of Harpenden Campus
Ownership and Funding
Lawes Agricultural Trust
The Next Decade 2002-2012
Strategic Plan 2005-2010
Senior Management
Rothamsted International
Resources at Rothamsted Research
Controlled Environment and Glasshouse Facilities (PDF)
Rothamsted Multimedia (photographs, video and audio)
Long Term Experiments
Classical Experiments
Guide to the Classical and other Long-term Experiments, Datasets and Sample Archive
Electronic Rothamsted Archive
Rothamsted Archive
Rothamsted Library
Conference Facilities
Rothamsted Manor
Rothamsted Farms
Environmental Change Network and Local Weather
Trustees Only (Strictly Confidential)
Research Centres
Research Overview
Conferences and Meetings
Publications
Research Departments:
Applied Crop Sciences (Broom's Barn)
Biological Chemistry
Biomathematics and Bioinformatics
Grassland Systems Science (North Wyke)
Plant and Invertebrate Ecology
Plant Pathology and Microbiology
Plant Science
Sustainable Soils and Grassland Systems
Associated Companies
Climate Change and Land Management
The economic value of research carried out by RRes (PDF)
Growing Energy - Biomass crops as a substitute for fossil fuels (PDF)
DESSAC - DEcision Support System for Arable Crops
Impact Over the Past 30 Years
Leafspot Forecast
RothLime (Rothamsted Lime Requirement Model)
Rothamsted Insect Survey Aphid Bulletin
Rothamsted Research Association (formerly ARIA)
Sugar Beet Research at Broom's Barn
SUNDIAL (SimUlation of Nitrogen Dynamics In Arable Land)
Weeds or Wild Plants?
Public Events
Resources for Schools
Science Snapshots
Open Weekend 2010
DeBug - Interactive Insects
Science Stories - Comic Books
Zones of Inhibition - Art and Science
BERTIE the BEET
Rothamsted Radio - Grove School Podcasts
Molecular Biology Notebook (teaching resource)
Vacancies
Why Choose Rothamsted?
About Rothamsted
Sites and facilities
Staff Support, Sports and Social Activities
Accommodation
University Links
PhD Information
Postgraduate Prospectus
Available studentships
Eligibility criteria
Studentship types
How to apply
Soil Science home page
General information: introduction, the nitrate issue, development of SUNDIAL
Model description
SUNDIAL The Research Tool
SUNDIAL-FRS (Fertiliser Recommendation System)
Whole farm modelling using SUNDIAL
Related publications
References and Further ReadingThe model has 15 compartments, as shown below. There are four input compartments, allowing nitrogen (N) to be added to the soil/crop system: atmospheric N, inorganic fertiliser N and organic manure N. There are seven transformation compartments, into and out of which N flows. Nitrogen may leave the system by one of four output compartments: denitrification, leaching, volatilisation and harvested N. The N content of each compartment is updated according to the flows of N into and out of that compartment each week. Further details of each compartment can be obtained by clicking on the relevant box in the diagram below.
|
Atmosphere Fertiliser Seed Organic Manure Biomass Ammonium Humus Nitrate Crop Debris Stubble & Straw Crop Denitrification Leaching Harvest Volatilisation |
Inputs of nitrogen to the soil from the atmosphere include those in the rain, from dry deposition of gases such as ammonia and oxides of nitrogen, and from symbiotic and non-symbiotic nitrogen fixation. Inputs in the UK typically range from 20 - 60 kg N/ha year, depending on location and crop. Atmospheric inputs are assumed to be distributed evenly throughout the year. Back to diagram.
Inorganic nitrogen fertiliser can be applied as single or split applications. Each application is described by the amount, application date and fertiliser composition (percentage nitrate-N, urea N and ammonium-N as (NH4)2SO4 or other NH4 salt). The fertiliser may be labelled so that the progress of a particular application may be traced throughout the simulation. Back to diagram.
This compartment comprises the nitrogen contained in the seed. This is assumed to be 4 kg N/ha for small grain cereals, and more or less for other crops depending on the size and spacing of the seed. Back to diagram.
Nitrogen may be added to the soil as organic manure - FYM, poultry manure, etc. Each application is described by the amount, application date and composition. The organic manure may be labelled so that the progress of a particular application may be traced throughout the simulation. Back to diagram.
The biomass compartment comprises the N in the soil microbial biomass, consisting of soil microfauna and microflora. The biomass controls the mineralisation of complex organic forms of N (humus and crop debris nitrogen) into ammonium, and the immobilisation of simple inorganic forms of N (nitrate and ammonium) into organic forms. Back to diagram.
Nitrogen enters the nitrate pool from nitrate fertilisers, inputs from the atmosphere and from the nitrification of ammonium. The priorities for nitrate transformations are: immobilisation>denitrification>plant uptake>leaching. Back to diagram.
Nitrogen enters the ammonium pool by the mineralisation of soil organic nitrogen (organic manure, humus, soil microbial biomass and crop debris), from any applied organic manure and from ammonium fertilisers. The priorities for ammonium transformations are: immobilisation>nitrification>plant uptake. Back to diagram.
This compartment contains all the N taken up by the crop, including that in the roots. Afixed amount of N is added in the seed, depending on the specified crop type. This could be considered as a separate compartment. Nitrogen can be taken up as nitrate or ammonium. Part of the crop N is returned to the soil in the crop debris and stubble and straw compartments. The remainder is removed as harvest N. This includes crop product (grain, tubers, seed, etc) and any crop residue which is removed or burnt (straw, sugar beet tops, etc). Nitrogen may also be lost from the senescing crop by volatilisation of ammonia. Back to diagram.
This compartment contains all the N in the soil humus. Nitrogen enters this pool from crop debris, the soil microbial biomass and from any applied organic manure. Back to diagram.
This compartment contains all the crop N returned to the soil during the growth of the crop. This includes N in dead roots, root exudates, fallen leaves and other plant debris shed during the growing season. Upon decomposition the N in the crop debris compartment will enter the humus and biomass compartments. Crop residues which are returned to the soil at harvest (straw, chaff, stubble, lost tubers, etc) are passed into this compartment from the stubble and straw compartment. Back to diagram.
This compartment contains all the crop residue N which is returned at harvest. This will include stubble, chaff, lost tubers, etc, and may also include straw, sugar beet tops, etc. Crop residues which are returned to the soil during the growth of the crop, such as fallen leaves and roots exudates, are included in the crop debris compartment. If part of the crop residue is removed or destroyed at harvest, e.g. cereal straw may be baled and carted or burnt, then this becomes an output from the system and is included in the harvest N compartment. Back to diagram.
Nitrate can be lost from the soil/crop system by denitrification, i.e. the reduction of nitrate to nitrite (NO2-), nitrous oxide (N2O) and nitrogen gas (N2), usually by soil bacteria. Denitrification is assumed to occur only in the top 0-25cm layer of soil. Back to diagram.
Nitrate can be lost from the soil/crop system by leaching, i.e. the process by which nitrate is carried through and out of the soil by water draining through it. Nitrate is assumed to be infinitely soluble in water and to move downwards at the same rate as the water in which it is dissolved. Ammonium N is not leached, nor is any form of organic N. Back to diagram.
This compartment contains all the crop N removed at harvest, i.e. in the product (grain, seed, tubers, etc), and in any straw or other cartable residue removed or burnt (cereal straw, oilseed rape straw, sugar beet tops, etc). Back to diagram.
This compartment contains all the N lost by the volatilisation of ammonia (NH3). Ammonia can be lost from the soil after the application of inorganic fertiliser or organic manure, and also from the senescing plant. In the model losses during senescence can only occur after anthesis. Back to diagram.