How much greenhouse gases are emitted by agriculture?

In a rap­idly chan­ging world, the pri­or­ity for the agri­cul­tur­al sec­tor is to feed more people. At the same time, the sec­tor is trans­form­ing itself by adapt­ing to cli­mate change, or even mit­ig­at­ing it, through a vari­ety of dif­fer­ent meas­ures: the reduc­tion of green­house gas (GHG) emis­sions, the stor­age of car­bon in soil and energy pro­duc­tion. In France, the imple­ment­a­tion of all these meas­ures – pro­moted by the Nation­al Low Car­bon Strategy – would lead to a 46% reduc­tion in green­house gas emis­sions linked to agri­cul­ture by 2050¹.

On a glob­al level the “agri­cul­ture, forestry and oth­er land use” sec­tor is respons­ible for 23% of anthro­po­gen­ic GHG emis­sions, i.e. 12 GtCO₂ equivalent/year². Most of these emis­sions are due to either agri­cul­tur­al emis­sions of meth­ane (CH₄) (4 GtCO₂ equivalent/year) and nitrous oxide (N₂O) from nitro­gen fer­til­isa­tion (2.2 GtCO₂ equivalent/year), or to land use changes and defor­est­a­tion, which release 5.2 Gt of car­bon diox­ide (CO₂) per year.

Accord­ing to a European Com­mis­sion report³, pre­ci­sion farm­ing could reduce GHG emis­sions from European agri­cul­ture by 1.5 to 2%. This is mainly based on vari­able rate applic­a­tion sys­tems, which deliv­er a dose of fer­til­iser adap­ted to the needs of the plants, thus redu­cing the asso­ci­ated N₂O emis­sions. Oth­er tools that can reduce GHG emis­sions are self-guid­ance devices for agri­cul­tur­al machinery, through improved driv­ing that reduces fuel consumption.

Pre­ci­sion farm­ing allows for indi­vidu­al­ised inputs to a plant or anim­al accord­ing to its needs. It is based on an “observation/diagnosis/prediction/action” cycle that relies on inform­a­tion and com­mu­nic­a­tion tech­no­lo­gies. Satel­lite data, increas­ingly sup­ple­men­ted by on-board sensors, are used to meas­ure plant defi­cien­cies, par­tic­u­larly in field crops. This data is then integ­rated into agro­nom­ic mod­els that provide recom­mend­a­tions for fer­til­iser applic­a­tions at vari­able rates, depend­ing on the pos­i­tion with­in the plot. Sim­il­ar decision sup­port tools are also used in live­stock farm­ing to avoid over­feed­ing cattle, lim­it­ing manure and thus CH₄ emis­sions.

Digit­al tech­no­logy suf­fers from a sig­ni­fic­ant lack of use. In Europe, as little as 22% of farms use vari­able rate fer­til­iser applic­a­tion tools. In France, only 10% of cer­eal farms have adop­ted them.

Sev­er­al factors explain this. Firstly, the return on invest­ment is not always clearly eval­u­ated. These tech­no­lo­gies and ser­vices are costly, and farm­ers need to know the bene­fits – wheth­er eco­nom­ic, envir­on­ment­al, or related to per­ceived use­ful­ness. In the Occit­an­ie region, we have set up the Occit­an­um Liv­ing Lab to test these tools on dif­fer­ent farms and eval­u­ate the bene­fits and costs they entail.

The use­ful­ness of this tool depends on how it is integ­rated into the work­ing envir­on­ment. This is why it is import­ant to encour­age co-design that brings togeth­er man­u­fac­tur­ers and farm­ers to pro­duce tools that are adap­ted to farm­ers’ needs. They can thus be sim­pler to use and adap­ted to the work car­ried out in the field. How­ever, there are still a num­ber of obstacles: lack of train­ing in the agri­cul­tur­al sec­tor in gen­er­al, ideo­lo­gic­al oppos­i­tion, ques­tions about data secur­ity, etc.

No, tech­no­logy is not the solu­tion, but it is a part of it. Rather, it is the changes in agri­cul­tur­al prac­tices, which tech­no­logy will facil­it­ate, that reduce the impact on the envir­on­ment. Tech­no­logy accom­pan­ies these changes, to help them devel­op on a lar­ger scale, for example.

I am talk­ing about agroe­co­logy. This approach con­sists of pro­mot­ing a bal­ance in the sys­tem with the help of eco­lo­gic­al pro­cesses, without chem­ic­al inputs, unlike con­ven­tion­al agri­cul­ture. For example, mono­cul­tures can be replaced by a mix­ture of spe­cies, which reduces the need for inputs.

But agroe­co­logy is a more com­plex farm­ing sys­tem. On the one hand, it requires close atten­tion to plant and anim­al health to anti­cip­ate and treat the prob­lem quickly. Tech­no­lo­gic­al tools can help to detect prob­lems early: optic­al sensors for plant health, con­nec­ted insect traps to detect pests, or anim­al move­ment sensors to mon­it­or their health. On the oth­er hand, mix­ing plant spe­cies requires pre­ci­sion sow­ing, even in the middle of a pre­vi­ous crop. Pre­ci­sion seed­ers make it easi­er to do this, while avoid­ing turn­ing over the soil and releas­ing CO₂ into the atmosphere.

This is a ques­tion that the sci­entif­ic com­munity is begin­ning to address, but an assess­ment of their envir­on­ment­al foot­print through life cycle ana­lys­is has not yet been made. Even so, the GHG sav­ings from digit­al tools are expec­ted to be much high­er than their actu­al eco­lo­gic­al foot­print.  Nev­er­the­less, we must con­tin­ue to take meas­ure­ments in order to get an accur­ate pic­ture of the envir­on­ment­al benefits.

The cent­ral issue is data flow. We are not yet at the stage of big data in agri­cul­ture, but the ques­tion needs to be asked before the data explodes. We will need to con­sider the choice of data to be kept, the form of data stor­age, devel­op­ment of frugal algorithms…

While until now digit­al tech­no­lo­gies have mainly been con­cerned with eco­nom­ic gains and com­fort, which are the main con­cerns of oper­at­ors, their con­tri­bu­tion to and impact on cli­mate change are now becom­ing increas­ingly important.