GHG - Crops
It takes just 10 -15 minutes to get a rough estimate of your carbon footprint by entering information off the top of your head. To refine this estimate using information from farm records can take longer, about 30-60 minutes, but this will become easier and more efficient with each new assessment. Often the most time consuming part is looking up and estimating the exact kWh and fuel for the given crop from all your electricity and fuel bills. After completion, you may also wish to spend some time exploring options for reducing GHG emissions and making a plan.
Not yet. We recognise how valuable this would be and are collecting the data necessary to provide this. We need to ensure we have sufficient good quality data before building this into the tool and are setting up a data ethics framework to also assure the responsible use of data. This is on our members’ ‘wish list’ for the future. We suggest to look for available regional or national GHG analysis published by the government or institutions of your country.
The crop affects your carbon footprint via residues, below-ground biomass, and nitrous oxide emissions from nitrogen application. If you don’t see your crop listed, choose from the “other” crops at the bottom of the drop-down list. The main impact of not finding a direct match is that you will have to provide your own estimate of crop residue. This figure is to be entered in dry weight.
New annual crops may be added to the Cool Farm Tool when the following information can be provided: dry matter fraction, above-ground nitrogen fraction, the ratio of above and below-ground biomass, below-ground nitrogen fraction, as well as an estimate of residue amounts based on gross yield. Please contact the Cool Farm Alliance for further information.
Crop residues are to be entered in terms of DRY MATTER.
The Cool Farm Tool uses IPCC guidelines to estimate residues. These values are only estimates but have quite an impact on field emissions. Furthermore, the amount of residues is greatly dependent on the management at the field level. If you/the user has more accurate data available, please overwrite the default values.
Crop residues that are left on the field/incorporated/mulched increase emissions, but not soil carbon. Does this part of the tool take into account the effects of both humification and mineralization?
This section only considers the nitrogen emissions from the mineralization of the residues (emissions). In the past, the Cool Farm Tool also estimated the potential soil carbon increase from leaving the residues in the field (carbon storage. However, this increase would only happen if this is a management that has been changed recently (past 20 years). For all other cases, the soil carbon would be in equilibrium and no additional carbon is stored (see answers on soil carbon change).
There are two options: choose the one closest to it (evt. only indicate the active element under ‘fertilizer,weight or units’), or define your custom NPK blend by indicating the percentage for all elements. Also, specify the percentage of N applied as ammonium, nitrate, or urea.
Why do I get an error message when I use “compose your own” fertilizer saying “Total N entered does not match calculated total”?
The % of total N entered in the top row must be the sum of %N entered for nitrate, ammonium, and urea (e.g. if 30% N comes equally from ammonium & urea, it’s 15/0/15% ). Please correct the values.
If I use legumes and do not apply any additional fertilizers, why are soil/fertilizer emissions positive?
Soil emissions include background emissions as well as nitrogen application- related emissions. Background emission always occurs also if no nitrogen is added, due to mineralization of soil organic matter. Also, the below-ground biomass of your crop adds nitrogen to the soil, which is mineralized and triggers emissions. The highest nitrogen fraction for below-ground biomass can be found for nitrogen-fixing forage and is lowest for crops such as rice, sorghum or millet. The soil-related emissions are assessed using not the IPCC guidelines, but the widely accepted Bowman model.
Yes, the carbon footprints of Cool Farm Tool include fertilizer production emissions and considers different regions of production.
These emissions are allocated to the production of milk or meat in the Cool Farm Tool and therefore there are no production emissions allocated to the crop carbon footprint.
Because of the high number of agro-chemicals available to farmers, it is beyond the scope of this model to incorporate a detailed emissions sub-model for this aspect. The coefficient used for pesticides is 20.5 kg CO2e per application per hectare, which represents the best average available. We conducted a review of this issue in 2010 and concluded that refining this factor was unimportant because of the relatively small portion of the overall footprint represented by pesticides combined with the number of formulations available and the potential difficulties in obtaining information about product manufacture.
No, this is currently not supported by the Cool Farm Tool. However, if you know the average fuel consumption per hour and the total motor hours you can use the fuel use section to provide a more accurate estimate.
The different emission factors refer to the fact that CHP heat, electricity or biogas may be used for own consumption (on-site), made available for other users (export) or retrieved from a CHP that does not belong to your farm (import). The emission factors are as follows:
When using CHP please be aware of double counting. If your CHP runs on natural gas and you have entered the consumption already under energy use, do not enter anything here. You may, however, receive a discount for exported electricity or heat!
How does the Cool Farm Tool estimate soil carbon change due to management interventions? What parameters are taken into account?
Change in soil carbon (release or sequestration of emissions) is estimated based on differences in the management of tillage and cover crops. Also, the transformation from grassland to arable land and vice versa is considered. The method is based on Ogle et al. 2005 and is suggested by the IPCC 2006 guidelines for land use, management and change.
The approach simulates the increase or decrease of soil carbon in a soil layer of up to 30 cm over a time period of 20 years by considering the types of changes compared to current use, management, and soil carbon. The kind of intervention (e.g. from till to no-till, from forests to arable land) and soil carbon stock determine the magnitude of change. This change is then equally attributed over a 20-years period (linear attribution).
After the 20-year period, the soil carbon has reached a new equilibrium and will no longer change. Therefore, data entries of practices that have been introduced more than 20 years ago wont impact emission results.
Why is carbon sequestration potential bigger for soils with a high Soil Organic Matter than for soils with a low SOM?
The IPCC Tier 1 method, which the Cool Farm Tool uses as the basis of its soil carbon module, observes that soil carbon under annual production is a fixed fraction of the native (pre-agriculture) carbon stock. It also says that management practices such as changing tillage or organic inputs to the soil change the carbon stock by a fixed fraction relative to current stock (the fraction being the amount of carbon stored or released).
This means that soils with a higher native stock tend to still have more carbon under agricultural production than soils which have lower native stocks. And this in turn means that if, after long term agricultural production, soil carbon stocks and thus soil organic matter are higher on Field X than Field Y, then Field X also has more potential gain (as a fraction of a higher carbon stock is bigger than a fraction of a low carbon stock). This is reflected in higher sequestration rates for soils with higher soil organic matter in the tool.
Also, please note that the Cool Farm Tool is only build for soils with soil organic matter (SOM) up to 10%.
How do I reflect carbon sequestration in a farming system that uses different tillage for different crops within a rotation?
The IPCC defines tillage categories as below. As there are many tillage options available to farmers, anything which isn’t clearly at one end or the other can get classified as “reduced till.”
When you consider ticking the box for tilling under the “carbon” tab in the CFT, think of “no-till”, “reduced-till”, and “conventional till” as terms that apply to a rotation rather than to crops in a rotation. “No-till” means the land is never tilled, “conventional till” means annual or more than annual tillage, “reduced-till” is anything in between.
Although the tool can be used in many ways to try to predict subtle effects of annual difference in management, these give the illusion of a precision the tool really doesn’t have. The effects of soil management changes on soil carbon are highly unpredictable in the 3-5 years after a practice change. Farmers should tick the box on tillage changes only if/when they are confident that the transition to a different tillage system is of longer term (>5 years).
If on a growing area farmers manage crops in rotation with different tilling practices, they should always choose the most conservative option, e.g. if the management switches between no-till & reduced till, choose reduced till for any crop in the rotation.
Conventional tillage: Substantial soil disturbance with full inversion and/or frequent (within year) tillage operations. At planting time, little (e.g., <30%) of the surface is covered by residues.
Reduced tillage: Primary and/or secondary tillage but with reduced soil disturbance (usually shallow and without full soil inversion). Normally leaves surface with >30% coverage by residues at planting.
No-till: Direct seeding without primary tillage, with only minimal soil disturbance in the seeding zone. Herbicides are typically used for weed control.
- (a) The farmer does not own the field, they cannot make long term decisions for tillage on that field. If the field is not owned or if the farmer is not confident about their tillage plans in the future, assume that the tillage system they have used in the recent past will continue and assign the tillage class as the most intensive tillage system used in the cropping rotation during the past 4 years.
- (b) If the field is owned by the farmer, if possible, add a question for the Specialist to ask the farmer about his/her tillage plans specific to the field, moving forward. The farmer can select from among our current tillage classes.
- In the case where the farmer anticipates applying different tillage options to different crops (e.g. no-till for soy and 1-pass for corn) select the most intensive tillage class to apply to the field in the CFT.
- If the farmer does not know what he/she plans for tillage or isn’t decided, use the previous data and select the most intensive tillage class that they have historically used.
Does the cover crop component of the tool address only carbon sequestration? How are the effects of fertilization accounted for?
Currently, only the effect on soil carbon has been accounted for. The nitrogen added in plant residues through N fixation leading to higher nitrous oxide emissions and ammonia emissions is not considered at the moment. If the cover crop is fertilized, you can include that additional N in your total N additions. This way you can see the benefits on emissions when reducing nitrogen inputs.
How do I indicate that I grow cover crops if they are only grown ahead of the main crop in a crop rotation?
There are two ways to reflect this in the tool. You can indicate cover crops in the assessment of the crop that is preceded by a cover crop. Nothing should be indicated in the assessment of crops for which you don’t grow cover crops.
Alternatively, you can distribute the carbon sink benefits across all crops in the rotation, e.g. if you grow cover crops in 4 out of 5 years on the whole field in rotation, you can indicate 80% cover crops in all crop assessments. The latter is safer as it is a more accurate reflection of reality.
What if the cover crop that precedes the main crop (e.g. grass cover) is used as cash crop? Do both get carbon credits from cover cropping?
Both the main crop and the cover crop (e.g. grass cover) are sold or used (e.g. as feed) and thus need to be modelled in separate assessments. As the cover crop is added prior to the main crop and provides roots in the ground that would otherwise be bare, tick the cover crop box for the main crop, but not in the assessment of the cover crop to ensure that you are not double counting.
The model uses different allometric equations that determine biomass based on very few parameters, which are easy to measure (e.g. diameter at breast height). The selection is based on the allometric equations included in the IPCC 2006 report. Unfortunately, we do not have any European hardwood included yet. This is a drawback communicated by different users and is currently being developed as part of the new perennial crop module.
The Cool Farm Tool is in the process of including additional tree species to the tool. In general, what is needed is an allometric equation that determines above ground biomass based on 1 or 2 easily observed parameters. The Cool Farm Alliance is always open to discuss further improvements of the methods. However, all improvements require not only the methods itself but also the funding for the IT implementation. At the same time, we want to keep the tool simple and uncluttered. Please contact the Alliance via email@example.com to discuss any potential inclusion of new tree species.
The Cool Farm Tool covers seed emissions only for potato, but not for the remaining field crops. In general, these emissions are quite low, compared to the other sources of emission. However, there has also been increasing demand for including this source of emission and may be included in the future.
This depends on the scope you have defined for your assessments. Do you want to determine the emissions till the farm gate or e.g. till processor? Livestock feed, compost or other heavy inputs transported to the farm and used in production should be included.
For fertilizers, the tool does not automatically include transport emissions, as the location of production is often not known. Good practice, however, may be to also include the transport from your direct supplier. For feed items, the data includes transport from point of production to the Netherlands using a global average. You may want to include the transport from your direct supplier to your farm, which would provide a good estimate for feed items.
If I use manure from my livestock for fertilisation, is it sufficient to enter the management type “daily spread” or should I enter the manure as a fertiliser?
In the beef and dairy module, the “manure” tab accounts for the emissions from management and storage of manure collected from animals in-house (emissions from manure left on field during grazing is already calculated by the tool). Select the applicable manure management type. If you do not have any storage and apply your manure daily, use “daily spread”.
In any case, you also need to account for the emissions through fertiliser application. Therefore, please also indicate the applied manure either in the section “grazing – grassland fertilisation” or in the crop module under “inputs”.
When making an assessment in the tool, it is an annual footprint of a crop, but also of a specific growing area. When you grow different crops in a rotation, the different crops that follow each other need to be assessed individually and separately. You should indicate all related practices, soil characteristics etc. for a specific crop as well as the growing area on which it is cultivated.
If you grow different crops on the same field, you can use the function “save as” to duplicate the assessment of one crop, and consequently change the entries to the new crop that is on this field (make sure e.g. to indicate the used area for crop, reset the residue amount and represent the cultivation practices for the new crop). Finally, the most interesting part is the land management: if you use cover crops or tilling in your rotation, this is the only thing that needs special care. Please see the relevant questions in this FAQ. Once you assessed the different crops, you can combine the footprints offline to get a picture of the emissions of this rotation.
Even if we do not include any methodology of the positive effect of rotation in the tool, you will be able to record e.g. changes in the SOM due to rotational practices, and thus indirectly monitor the positive effects of your practices on your soil.
You can account for this in the “carbon” tab of a crop assessment. If you converted a field that was previously under crop production to an orchard, select a land use change from arable -> grassland. Then indicate the planted trees and their growth under the section 6.1 out of crop biomass changes. If you change a grassland to an orchard, do not indicate any land use change (orchard can be considered same as grassland), and add again the planted trees as biomass in the “carbon” tab section 6.1.