How to calculate nitrogen balance
Managing nitrogen to exploit your OSR's potential.
Nitrogen is an important input that can be used to influence Canopy Structure and Green Area Index (GAI) to provide an efficient balance between light interception and standing ability. This Nitrogen Calculator has been designed to calculate how much nitrogen you should apply to your oilseed rape crop and, importantly, the latest date that it should be applied in order to optimise GAI and maximise yield.
Using the figures that you enter, it will calculate how much additional N your crop needs and the latest application timings that will make best use of the N that you apply. This ensures that you are using N efficiently and effectively, and don't waste time and money by applying more nitrogen than the crop needs or by applying it when it is too late for the crop to take full advantage of it.
Simply complete the fields in the calculator (below), and it will display how much nitrogen should be applied and when it should be applied. All fields marked with an asterisk must be completed (a step-by-step guide to using the calculator is provided at the bottom of this page).
This calculator has been created from information provided to Syngenta with grateful thanks by ADAS Rosemaund.
This calculator has been developed as a tool to help inform nitrogen application decisions, and Syngenta Seeds Ltd cannot accept any liability arising out of or in connection with the use of this tool. Any recommendation is given as a guide only. You should work with your agronomist when calculating N rates and timings, taking into consideration the fertility of the field. All applications should be carried out following best practice and working within any relevant legislation/regulations that may apply.
1. Measure the amount of nitrogen in the crop
Measure and calculate canopy size in terms of Green Area Index (GAI). GAI is the ratio of green tissue to ground area, and it can be measured by visual assessment (reference photos can be found on the HGCA website )
Multiply the GAI by 50kg nitrogen per hectare, and enter this
figure as the amount of crop canopy nitrogen. For example, if the crop has a GAI of 1.5, enter 75 as the amount of crop canopy nitrogen (1.5 x 50 = 75)
2. Measure the amount of nitrogen in the soil
Soil mineral nitrogen is best measured directly using systems such as the GrowHow N-Min analysis. An estimate can also be made based on a combination of previous cropping, soil type and overwinter rainfall using RB209 or PLANET software.
3. Decide on your target yield
This will affect the amount of nitrogen that is required.
4. Tick if you are using manufactured fertiliser
The uptake of manufactured nitrogen is 60%, so this needs to be taken into account.
GrowHow's unique N-Min & N-Calc service has been used within the Syngenta OSR Sigma Team to calculate growers' nutrient requirements: follow this link to find out more .
5. Enter your crop's anticipated mid-flowering date
This will affect the timing and number of nitrogen applications.
6. Enter the number of applications
The calculator will work out the timing for your applications based on the crop's ability to take up and use the nitrogen you apply.
7. Click the 'Calculate' button
You will be provided with a recommendation (that you can print) based on the information you have entered.
If you wish to change any of the information that you provided, simply enter the new details and click 'Calculate' to get a new recommendation.
This calculator is intended as a tool for managing canopy development and no consideration is included of what management might be used to extend canopy duration.
This calculator has been developed as a tool to help inform nitrogen application decisions, and Syngenta Seeds Ltd cannot accept any liability arising out of or in connection with the use of this tool. Any recommendation is given as a guide only. You should work with your agronomist when calculating N rates and timings, taking into consideration the fertility of the field. All applications should be carried out following best practice and working within any relevant legislation/regulations that may apply.Source: www3.syngenta.com