CARBONCLOUD'S AGRICULTURAL MODEL
Calculating GHG emissions at farm-gate
Measuring the climate footprint of a crop at farm gate is a complex, multi-parameter calculation that involves data from several biological activities and multiple greenhouse gases. These activities and greenhouse gas emissions vary significantly from crop to crop, e.g., deforestation may be the largest contributing factor to the climate footprint of Brazilian cocoa at farm but completely insignificant for Spanish tomatoes at farm. Conversely, energy used for farm machinery may be the largest contributing factor for Spanish tomatoes at farm, contributing 37% of the total footprint while for Brazilian cocoa at farm, energy comprises 5% of the total climate footprint.
Most LCA studies of individual crops at farm account for this per-crop significance and may omit calculating activities that are insignificant to the total climate footprint – rightfully for the purpose of the study. However, this makes many available individual climate footprint studies of different crops and different countries incomparable since they don’t account for the same activities.
Large non-profit organizations such as FAO and UNFCCC account for and update some of the parameters that contribute to the climate footprint of crops at farm, e.g., fertilizer use per country, yields per crop per country, emissions factors for nitrogen, but these global organizations have not synthesized these parameters towards the calculation of farm-gate climate footprints at a crop and country level.
This is why CarbonCloud developed its agricultural dataset: To synthesize credible activity and parameter information into usable farm-gate climate footprints for every crop in the world and incorporate them into climate footprint calculations downstream from the farm – in a comparable manner, within the same system boundaries, and with a high level of automation that resolves the calculation complexity and data updates.
Below you can read CarbonCloud’s modeling of the agricultural dataset, including:
- The GHG emissions mechanisms
- The activities inputted in each mechanism
- The data input sources for every activity
- The emission factors and sources applied to the mechanisms
Emissions mechanisms
Mechanisms
The mechanisms contributing to the climate footprint of a crop are the following:
Fertilizers & Increased efficiency
Pesticide production
(CO2)
Much like fertilizer production below, these are emissions caused by the energy used to produce pesticides and the emissions leaked during the production process. These emissions do not occur at an activity at farm but account for upstream activity.
Fertilizer production
(N2O, CO2)
The energy used to produce synthetic fertilizers and the emissions leaked during the production process. These emissions do not occur at an activity at farm but account for upstream activity.
Direct N2O emissions (Field bacteria)
(N2O)
Organic or synthetic fertilizers and crop residues get digested by farm soil bacteria and emit nitrous oxide (N2O), a powerful greenhouse gas, during the process.
Indirect N2O emissions (Off-field bacteria)
(N2O)
Some of the nitrogen from fertilizers and crop residues leaks beyond the farm through leeching into groundwater or through run-off into nearby bodies of water. It is then digested by bacteria and produces N2O in processes similar to those for field bacteria, but with somewhat different emission factors. Indirect N2O emissions are important as they account for 1/3 of the total global agricultural N2O source [1].
Limestone & Urea
(CO2)
Limestone and Urea are both used to increase yield efficiency: Pulverized limestone – Calcitic limestone (CaCO3) and Dolomite (CaMG(CO3)2) – decreases soil acidity and promotes plant growth. Urea is a concentrated solid nitrogen fertilizer used that comprises over 50% of total nitrogen fertilizer application. Limestone and urea contain carbon oxides which after application are released to the atmosphere as CO2.
Pesticide production
(CO2)
Much like fertilizer production below, these are emissions caused by the energy used to produce pesticides and the emissions leaked during the production process. These emissions do not occur at an activity at farm but account for upstream activity.
Land Use & Land Use Change (LULUC)
Deforestation
(CO2)
Standing forests bind large amounts of carbon. When forests are cut down to make room for cropland and pasture, a large part of the bound carbon is emitted as CO2. Deforestation is Land Use Change that today occurs mostly in tropical areas. Agriculture is a primary cause of tropical deforestation.
Farming on drained wetlands
(N2O, CO2)
Much like forests, swamps have organic material sinks that bind large amounts of carbon over the years. When these wetlands are drained to be used as agricultural land, the stored carbon is released into the atmosphere as CO2 for years to come. Farming on drained wetlands is Land Use Change that occurs mostly in boreal forest areas, such as North Asia, Europe, and North America [2], and in some tropical areas, where Indonesia contributes 40% of the world’s total emissions from organic soils [3]. Organic soils represent up to 30% of the total soil carbon, playing an important role in maintaining the earth’s carbon balance [4].
Flooded rice fields
(CH4)
This mechanism applies only to rice crops. Rice is often grown in flooded fields to improve growth and yield by reducing pests, weeds, and reliance on natural rainfall. Bacteria digestion of remaining stubbles and straws in this low-oxygen environment produces methane, a short-lived but potent greenhouse gas.
Machine-driven interventions
Farm machinery
(CO2)
Much of the human interventions in agriculture, such as tillage, fertilizer & pesticide application, and harvesting, are carried out through heavy machinery that is powered by fossil fuels. The upstream production and transportation of the fossil fuels as well as the combustion in the machine engine during these activities emits carbon dioxide.
Irrigation
(CO2)
Watering agricultural land on demand is done with irrigation pumps that operate either with electricity or diesel whose production and use (for diesel) emit carbon dioxide. For diesel pumps, the upstream production and transportation of fossil fuels as well as the combustion in the machine engine during these activities emits carbon dioxide.
Drying
(CO2)
Drying of certain crops, such as cereal and pulses, is often carried out at farm to reduce humidity and improve storage. Drying at farm is done with machinery that uses either electricity or diesel whose production and use (for diesel) emit carbon dioxide. For diesel pumps, the upstream production and transportation of fossil fuels as well as the combustion in the machine engine during these activities emits carbon dioxide.
Activities
Activities
Each GHG-emitting mechanism listed above is related to one or more of the activities listed below. Relevant emissions factors are applied to the final metric of each of these activities to provide the emissions in CO2e for each mechanism.
According to the IPCC, the activities from agriculture that have a climate impact on the agricultural products and that CarbonCloud accounts for at every crop-country combination are:
Product mass
Applies to: All mechanisms
Product mass determines the allotment of the climate footprint per kg of product at farm gate. It distributes the synthesized climate footprint per country, and per crop to the activity. The following metrics are necessary for the calculation of the final climate footprint for every crop and country regardless of the activities, which is why the units of the subsequent activities are in the respective metric per hectare per year.
Harvest yield
Measured in: Tonnes per hectare per year
The amount of the crop harvested in a year in the country of search.
Water removed per kg of dried product
Measured in: Kilograms of water per kilogram of crop in the country
Input: Data synthesized from IPCC or harmonized data from peer-reviewed studies on a national level.
The amount of water removed from crops that have been dried per kg of dry product.
Machine-driven interventions
Total diesel use for machinery
Measured in: Liter per hectare per year
Input: Peer-reviewed studies on a per-crop level.
Applies to mechanisms: Farm machinery
The emissions from the extraction, transportation, and combustion of diesel used in farm machinery engines and applied to different crops per their agricultural practice needs.
Electricity use for irrigation / Diesel use for irrigation
Measured in: Kilowatt hours (for electric pumps) per hectare per year / liters of diesel (for diesel pumps) per hectare per year
Input: AQUASTAT, peer-reviewed studies
Applies to mechanisms: Irrigation
The amount of water each crop requires determines the electricity or fuel used for irrigation. The water use per crop with distribution to groundwater and freshwater is synthesized from AQUASTAT (FAO) and harmonized data from peer-reviewed studies.
Fertilizer and other applied compounds
Total nitrogen use
Measured in: Kilograms of nitrogen per hectare per year
Input: IFA, Peer-reviewed studies
Applies to mechanisms: Fertilizer production, Direct 2O emissions, Indirect N2O emissions
The total of nitrogen use from all fertilizers applied is distributed per country based on a synthesis of data from the International Fertilizer Association (IFA) or harmonized data from peer-reviewed studies on a national or crop level. Distribution per crop is then done based on the nitrogen needs of each crop based on a synthesis of harmonized data from peer-reviewed studies.
Synthetic nitrogen use
Measured in: Kilograms of nitrogen per hectare per year
Input: IFA, FAOSTAT, UNFCCC, peer-reviewed studies
Applies to mechanisms: Fertilizer production, Direct N2O emissions, Indirect N2O emissions
The total of nitrogen use from all applied fertilizers is appropriately allotted to the synthetic fertilizers according to use. The synthesis is based on data from IFA, FAOSTAT or UNFCCC for the countries available. The distribution per crop is then done based on the nitrogen needs of each crop based on a synthesis of harmonized data from peer-reviewed studies.
Organic nitrogen use
Measured in: Kilograms of nitrogen per hectare per year
Input: FAOSTAT, UNFCCC, peer-reviewed studies
Applies to mechanisms: Fertilizer production, Direct 2O emissions, Indirect N2O emissions
The total of nitrogen use from all applied fertilizers distributed per organic fertilizers is based on data from FAOSTAT or UNFCCC for the countries available. Distribution per crop is then done based on the nitrogen needs of each crop based on a synthesis of harmonized data from peer-reviewed studies.
Nitrogen in crop residues returned to soil
Measured in: Kilograms of nitrogen per hectare per year
Input: IPCC, peer-reviewed studies
Applies to mechanisms: Direct 2O emissions, Indirect N2O emissions
This activity measures the nitrogen in parts of the crop that remain at farm and function similarly to fertilizers due to their nitrogen content. It is based on nitrogen estimates in crops from the IPCC combined with nitrogen content in crops based on calculations from the IPCC or more localized metrics from peer-reviewed studies.
Annual amount for phosphate fertilizer applied to soils
Measured in: Kilograms of P2O5 per hectare per year
Input: IFA
Applies to mechanisms: Fertilizer production
The data is synthesized from the International Fertilizer Association (IFA) and distributed per country and per crop.
Annual amount for K2O fertilizer applied to soils
Measured in: Kilograms of K2O per hectare per year
Input: IFA
Applies to mechanisms: Fertilizer production
The data is synthesized from the International Fertilizer Association (IFA) and distributed per country and per crop.
Calcitic limestone applied (CaCO3) fertilizer applied to soils
Measured in: Kilograms of CaCO3 per hectare per year
Input: UNFCCC
Applies to mechanisms: Limestone & Urea
The data is synthesized from UNFCCC for the countries available and distributed per area cropland.
Dolomite (CaMg(CO3)2) fertilizer applied to soils
Measured in: Kilograms of CaMg(CO3)2 per hectare per year
Input: UNFCCC
Applies to mechanisms: Limestone & Urea
The data is synthesized from UNFCCC for the countries available and distributed per area cropland.
Urea fertilization applied to soils
Measured in: Kilograms of urea per hectare per year
Input: FAOSTAT
Applies to mechanisms: Limestone & Urea
The data is calculated as a fraction of the estimated synthetic fertilizer used from FAOSTAT data.
Land Use and Land Use Change (LULUC)
Managed/drained organic soils out of total area
Measured in: Hectare of drained organic soil per hectare of land
Input: UNFCCC, FAOSTAT
Applies to mechanisms: Organic soils/drained wetlands
Data is synthesized from UNFCCC for the available countries and FAOSTAT for the remaining countries and distributed per crop according to farmland area used for each crop.
Deforestation
CarbonCloud incorporates the state-of-the-art model and database of Pendrill et al. (2022) to calculate and allocate deforestation emissions to the relevant crops and countries. The Pendrill model synthesizes remote-sensing data as well as FAOSTAT data on carbon emissions from forest cover loss by commodity. Read the detailed explanation of our deforestation model here.
Emission factors
CarbonCloud uses emission factor values from the IPCC, UNFCCC when national emission factors are available, peer-reviewed studies. For example, for nitrous oxide emissions, the emissions factor values CarbonCloud uses come from UNFCCC when national emission factors are available, and IPCC when they are not. CarbonCloud applies these emission factors:N2O emissions from N inputs
Applies to mechanisms: Direct N2O emissionskg volatilized N per kg synthetic N
Applies to mechanisms: Indirect N2O emissionskg volatilized N per kg organic N
Applies to mechanisms: Indirect N2O emissionsN2O emissions from atmospheric deposition of N
Applies to mechanisms: Indirect N2O emissionsFraction of N lost through leaching and runoff
Applies to mechanisms: Indirect N2O emissionsN2O emissions from N leaching and runoff
Applies to mechanisms: Indirect N2O emissionsN2O emissions from drained/managed organic soils
Applies to mechanisms: Farming on drained wetlandsCO2 emissions from drained/managed organic soils
Applies to mechanisms: Farming on drained wetlandsEmission factor for calcitic limestone (CaCO3) application
Applies to mechanisms: Limestone & UreaEmission factor for dolomite (CaMg(CO3)2 application
Applies to mechanisms: Limestone & UreaEmission factor for urea application
Applies to mechanisms: Limestone & UreaCO2 and N2O emissions from nitrous fertilizer production (by continent)
Applies to mechanisms: Fertilizer productionCO2 emissions from phosphorous production
Applies to mechanisms: Fertilizer productionCO2 emissions from potassium production
Applies to mechanisms: Fertilizer productionCO2 emissions from lime production
Applies to mechanisms: Fertilizer productionCO2 emissions from the production of pesticides
Applies to mechanisms: Fertilizer productionElectricity
Applies to mechanisms: IrrigationEmission factor for diesel including upstream emissions
Applies to mechanisms: Farm machinery, irrigation, dryingEnergy required to dry 1kg of H2O
Applies to mechanisms: DryingCH4 emissions from rice cultivation
Applies to mechanisms: Flooded rice fieldsOther emission factors for flooded rice fields
(Including scaling factors for water regimes and organic amendments)
Applies to mechanisms: Flooded rice fieldsCO2 emissions from deforestation
Applies to mechanisms: DeforestationReferences
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