The impact of the war in Ukraine on wheat production

Ahmad Al Bit­ar.  We cal­cu­lated wheat crop yields using satel­lite data in two regions: Poltava, an area far from the front; and Kher­son, which was invaded by the Rus­si­an army. In 2022 (the year of Rus­si­a’s inva­sion of Ukraine), wheat yields in the Kher­son region fell by 20% com­pared to pre­vi­ous years: the amount of dry bio­mass (the amount of organ­ic mat­ter) decreased from 9.7 tons per hec­tare (t/ha) in 2020 and 2021 to 7.8 t/ha. In the Poltava region, on the oth­er hand, yields remain stable: this demon­strates the neg­at­ive impacts in areas invaded by the Rus­si­an army. This affects the food secur­ity of many coun­tries, since Ukraine was the world’s 5th largest wheat export­er in 2021. 

There are two dis­tinct ways in which it has had an effect. Firstly, access to plots of land is lim­ited due to the pres­ence of Rus­si­an troops. This hinders agri­cul­tur­al prac­tices such as tilling the soil, fer­til­ising and irrig­a­tion. The oth­er impact con­cerns human and mater­i­al resources. Farm­ers may fall vic­tim to the war or be recruited to the front. And mater­i­al resources such as fer­til­isers or means of trans­port­ing wheat are affected by the war. 

Our work does not allow us to dis­en­tangle the dif­fer­ent causes; fur­ther stud­ies com­bined with val­id­a­tion data will be neces­sary. Here we demon­strate that it is pos­sible to quanti­fy the impact of war with­in agri­cul­tur­al plots, at a res­ol­u­tion of 10 meters and over large areas. This work is car­ried out using satel­lite obser­va­tions and mod­el­ling, and there­fore without going into the field: this is unprecedented. 

Agri­cul­tur­al prac­tices homo­gen­ise crops to optim­ise yields. Here, on the con­trary, we observe het­ero­gen­eity of bio­mass with­in the plots. They look like plots left in their nat­ur­al state. We assume that the lack of agri­cul­tur­al prac­tices explains this drop in yield in the Kher­son region. 

We mainly used data from Sentinel‑2, satel­lites launched as part of the European Earth obser­va­tion and mon­it­or­ing pro­gramme, Coper­ni­cus. These satel­lites carry optic­al instru­ments, which provide high-res­ol­u­tion images of the Earth in the vis­ible spec­trum (the equi­val­ent of pho­to­graphs) and near-infrared. They make a com­plete cir­cum­nav­ig­a­tion of the plan­et every five days. 

One of the cru­cial fea­tures of the Coper­ni­cus pro­gramme is its com­mit­ment to the con­tinu­ity of long-term obser­va­tions. The oth­er cru­cial point is that the data is free of charge for sci­ent­ists and private applic­a­tions. This makes it pos­sible to cap­it­al­ise on the know­ledge acquired in order to trans­fer these new meth­od­o­lo­gies to oth­er regions of the world. 

It is of course very dif­fi­cult to carry out field stud­ies in war zones. Pre­vi­ous stud­ies have iden­ti­fied sig­ni­fic­ant dis­rup­tions in the wheat dis­tri­bu­tion chain, but it is dif­fi­cult to determ­ine the cause because mul­tiple factors may be involved, such as the destruc­tion of trans­port infra­struc­ture, increased fer­til­iser prices and pop­u­la­tion dis­place­ment. Our study makes it pos­sible to assess the dir­ect impact of the Rus­si­an inva­sion on crop growth. 

In gen­er­al, satel­lites are the tools of choice in dis­aster situ­ations. There is an inter­na­tion­al Charter on Space and Major Dis­asters that coordin­ates the space response to dis­asters. Space agen­cies, gov­ern­ments and private com­pan­ies can mobil­ise their satel­lites to focus on the affected areas and provide data to emer­gency ser­vices and decision-makers. 

Two pre­lim­in­ary steps are neces­sary. The first con­sists of cor­rect­ing the satel­lite images for the effects of the atmo­sphere and clouds using the MAJA tool from the French space agency CNES. The second step aims to identi­fy the wheat plots. It is car­ried out by the com­pany Kermap using arti­fi­cial intelligence. 

The Agri­Car­bon-EO pro­cessing chain is then applied. It integ­rates remote sens­ing data and agro­nom­ic mod­el­ling to provide wheat pro­duc­tion maps with a res­ol­u­tion of 10 metres. Agri­Car­bon-EO is the res­ult of ten years of research and devel­op­ment at CESBIO. All the tools were val­id­ated in vari­ous European con­texts before being trans­ferred to Ukraine. 

Ver­onika Ant­onen­ko. From the start of the study, we iden­ti­fied the import­ance of veri­fy­ing the impact of the weath­er. By com­par­ing the weath­er in 2020, 2021 and 2022 with the cli­ma­to­logy of the last forty years, we found that the con­di­tions were with­in the norm in our two study areas. This allowed us to exclude the weath­er as an explan­at­ory factor for this drop in yield. 

Interview by Anaïs Marechal