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