Change of winter crops sown area in the zone of the special military operation of Russia (February 2022-present), as revealed by satellite data

Savin Igor' ORCID: 0000-0002-8739-5441 Doctor of Agriculture Academician of the Russian Academy of Sciences, Doctor of Agricultural Sciences, Chief Scientific Associate 119017, Russia, Moscow, lane. Pyzhevsky, 7, p. 2, of. 25 savigory@gmail.com

Introduction. On February 24, 2022, the President of Russia, in response to the appeal of the leaders of the republics of Donbass, decided to conduct a special military operation in Ukraine (SVO). There are numerous discussions about the consequences of ITS. Their manifestation is noted both at the global level ^[1], and at the level of individual countries ^[2], Russia and its regions ^[3], and, of course, at the local level in the area of its implementation. At the local level, the consequences are most obvious for the entire socio-economic sphere and people's lives. Many enterprises have stopped their activities, most of the population has left their permanent place of residence. But, part of the economic activity in the SVO zone has not stopped. This also applies to agriculture. Individual landowners continue to cultivate crops, albeit in a reduced form. The scale of active agricultural activity in the SVO zone is not exactly known, despite the fact that such information is important for planning support to existing agricultural producers and for assessing the possibilities of self-sufficiency of the population with food.

In recent decades, active scientific research has been conducted in the field of developing operational and accurate methods for monitoring crops based on satellite technologies ^[4,5]. It is shown that despite many still unresolved problems, satellite data currently allow us to obtain fairly accurate data on the areas of individual crops ^[6,7]. Satellite methods of monitoring the areas of winter crops have been most developed and tested in different countries ^[8,9]. To carry out such assessments, there are currently quite long and accessible satellite data archives ^[10-12]. Therefore, the purpose of these studies was to analyze the changes in the area of winter crops in the zone of the SVO and in the adjacent territories in the current year compared to the previous five seasons.

Object and methods. The territory of the SVO zone is a flat or hilly lowland with a temperate climate, fertile chernozem soils and mainly steppe vegetation, which is mostly replaced by agricultural land. The main agricultural specialization of the territory is grain production. Of the grain crops, winter crops occupy the predominant areas. Rapeseed is also cultivated as a winter crop ^[13]. Thus, the areas of winter crops were used by us as an indicator of agricultural activity in the research area.

The VEGA Internet service was used as the main source of satellite data for research ^[12]. The service allows the user to access the archive of the most frequently used Landsat, Sentinel-2 and MODIS data for solving practical problems in the field of agriculture. Archives of satellite images obtained from the first two platforms have been available for the last few years, and archives of MODIS data for more than 20 years.

In addition to the original satellite data, presented both as separate survey channels and as different color composites, the VEGA website stores some results of applied analysis of the original satellite data.

In particular, we used masks of winter crops for analysis, which were built by the ICI RAS using a specially developed technology ^[14]. The masks are based on MODIS satellite data and are available for the research area for all years from 2001 to 2023.

We used masks of winter crops for the research area for the seasons 2017/2018, 2018/2019, 2019/2020, 2020/2021, 2021/2022 and 2022/2023.

Masks were applied to administrative allotments at the oblast (republic) level for the SVO zone and adjacent regions of Ukraine and for each region the areas under winter crops shown on the masks were calculated.

The results of the analysis were visualized as graphs in Excel and analyzed for the fall or growth of the area in the current growing season compared to previous seasons.

According to the color composites of Landsat or Sentinel-2 images, close to the natural colors selected for late autumn and early spring time, the area with the absence of fields with winter crops in the 2022/2023 season was visually deciphered by the color of the image. Fields with winter crops in these images are clearly recognized by their characteristic green color (Fig. 1).

Fig.1. An example of an image of fields with winter crops in the central part of the Zaporozhye region on the Landsat-8 color composite in colors close to natural, obtained on January 26, 2023 (according to the VEGA Internet service)

Results and discussion.

Figure 2 shows the masks of winter crops for the last 6 seasons in the research area. In general, the masks are quite similar to each other, but the placement of crops varies from season to season, as well as their area. Attention is drawn to the smaller area of winter crops in the LPR and DPR in comparison with neighboring regions of Ukraine. In the territory of the DPR controlled by Ukraine, there were also more crops in each season than in the rest of the territory. But with the beginning of its sowing areas throughout the territory of the DPR and the LPR became noticeably less than it was before. This can be clearly seen in the graphs of the dynamics of the area of crops in the context of the regions shown in Figure 3. From the figure it follows that of all the analyzed regions, only in the Republic of Crimea, the area of winter crops has grown significantly after the start of its own (by at least 8% of the area of the entire region, or by more than 40% relative to the area of crops of the previous season). In the Kherson, Mykolaiv and Zaporizhia regions, the areas in the 2022/2023 season remained almost at the same level as in the previous season. But, according to Figure 2, the areas in the Kherson and Zaporozhye regions were distributed more unevenly than before. There are more of them in some places, and less in the SVO zone itself. The drop in areas in the 2022/2023 season was recorded quite strongly in the DPR and LPR (the area of winter crops decreased by almost 30% relative to the previous season), that is, it is in the regions of the SVO zone itself. In the Dnipropetrovsk region, the area of winter crops also decreased by 20% relative to the area of last season's crops, but this drop turned out to be distributed throughout the region. However, the areas of winter crops fell the most in the Kharkiv region (by 8% of the area of the entire region, or by more than 50% of the area of winter crops relative to last season). In other regions, the fall did not exceed 3-4% of the area of the region (about 20% of the area of winter crops last season).

Fig.2. Masks of winter crops sown using MODIS satellite data for the last growing seasons (according to the VEGA Internet service)

Fig.2. Masks of winter crops sown using MODIS satellite data for the last growing seasons (according to the VEGA Internet service)

Consequently, the total fall in each region did not exceed several percent of the total area of the region, which is about 20-30% of the area of winter crops last season. But, in the immediate vicinity of the zone of active hostilities, the sowing of winter crops has completely stopped. On average, in a strip of 15-25 km from the entire line of hostilities on each side, the sowing of winter crops in the 2022/2023 season was almost completely stopped (Fig.4). It is interesting to note that the sowing of winter crops was stopped in places on the right bank of the Dnieper in the Kherson region, from where the Russian troops withdrew after the dates of their sowing. This indicates that the curtailment of winter sowing is determined not so much by direct military actions, but by the outflow of the rural population from the area of its implementation.

Fig.4. The zone of absence of winter crops in the 2022/2023 season (shown in red)

Conclusion. The use of the VEGA satellite data archives made it possible to estimate the scale of losses in the areas of winter crops in the area of Russia's special military operation in Ukraine.

It was found that the total fall in each region (republic) of the SVO zone did not exceed several percent of the area of the region or about 20-30% of the area of winter crops in the previous season.

The most severe fall in the area of winter crops in the 2022/2023 season was recorded in the DPR, LPR, Kharkiv and Dnipropetrovsk regions. Of these, the areas of winter crops fell the most in the Kharkiv region (by 8% of the area of the entire region, or by more than 50% of the area of winter crops relative to last season).

On average, in a strip of 15-25 km from the entire line of hostilities on each side, the sowing of winter crops in the 2022/2023 season was almost completely stopped.

The study was carried out with the support of the Ministry of Education and Science of Russia NCMU "Agrotechnologies of the Future" (Agreement No. 075-15-2022-321).