Soil organic carbon stock retrieval from Sentinel-2A using a hybrid approach

Digital soil maps find application in numerous fields, making their accuracy a crucial factor. Mapping soil properties in homogeneous landscapes where the soil surface is concealed, as in forests, presents a complex challenge. In this study, we evaluated the spatial distribution of soil organic carbon stocks (SOCstock) under forest vegetation using three methods: regression kriging (RK), random forest (RF), and RF combined with ordinary kriging of residuals (RFOK) in combination with Sentinel-2A satellite data. We also compared their accuracies and identified key influencing factors. We determined that SOCstock ranged from 0.6 to 10.9 kg/m2 with an average value of 4.9 kg/m2. Among the modelling approaches, we found that the RFOK exhibited the highest accuracy (RMSE = 1.58 kg/m2, NSE = 0.33), while the RK demonstrated a lack of spatial correlation of residuals, rendering this method inapplicable. An analysis of variable importance revealed that the SWIR B12 band of the Sentinel-2A satellite contributed the most to RFOK predictions. We concluded that the RFOK hybrid approach outperformed the others, potentially serving as a foundation for digital soil mapping under similar environmental conditions. Therefore, it is essential to consider spatial correlations when mapping soil properties in ecosystems that are inaccessible for capturing the spectral response of the soil surface.

Navigating Agricultural Expansion in Harsh Conditions in Russia: Balancing Development with Insect Protection in the Era of Pesticides

As the world's population continues to increase, ensuring food security becomes a major problem. This often leads to the expansion of agricultural production, even in harsh conditions and becomes a key problem for many countries, including Russia. However, such expansion may entail certain costs, including the potential loss of insect populations, which are vital for ecological balance and agricultural productivity. The development of fallow lands in these regions is necessary to increase food production and increase food security; it is important to balance this with protection from harmful insects and sustainable farming methods. Research into the effects of insecticides on insects is an ongoing challenge, and new, sustainable farming methods are needed to ensure that protection from harmful insects and sustainable development can coexist. This article discusses the use of pesticides to protect the well-being of mankind, the problems of studying the effects of pesticides on insects and the vulnerability of insects to pesticides in regions with harsh conditions. It also discusses successful methods of sustainable agriculture and the importance of the legal framework governing the use of pesticides. The article emphasises the importance of balanced development with insect protection to ensure the sustainability of agricultural expansion in harsh conditions.

Influence of Mineralized Water Sources on the Properties of Calcisol and Yield of Wheat (Triticum aestivum L.)

The use of conservation agriculture (SWC-soil and water conservation) technologies is now becoming more and more necessary. For the soils in arid ecosystems, the problem of irrigation deficiencies has always been relevant, and clean fresh water is always insufficient to irrigate these agricultural lands. This paper provides a brief historical overview of the use of mineralized water sources in agriculture and their impacts on soils and plants (Triticum aestivum L.). The experiment involving wheat cultivation in saline soils irrigated with mineralized water was set for 3 years. The main chemical and physical-chemical properties of the agro-transformed solonchaks and mineralized water sources were investigated. According to the contents of mobile forms of N, P, and K, the soils were poorly supplied; after a series of irrigation phases, they remained the same. There were signs of the growth of mobile phosphorus in the variants where mineralized water sources were applied. Our results showed that under conditions of irrigation with water sources with mineralization rates of up to 2.8-3.5 g/L, the wheat yield increased by 1.5 c/ha compared to the control. The use of mineralized water for irrigation purposes will reduce the use of clean river water.

Soils and olericultural practices in circumpolar region of Russia at present and in the past

Circumpolar regions are often associated with activities such as reindeer herding, hunting, fishing, and gathering wild foods, but few know that locals have practiced olericulture since ancient times. Under a changing climate, the agricultural frontier will inevitably shift northward, so it is important to understand the current and past patterns of local soil functioning. Olericultural practices in the Arctic region seem difficult due to the harsh climate; however, it is being implemented. In this paper, we report the agricultural practices used by local residents to increase the yield of crops grown in the Yamal region. We also studied the chemical properties and fertility of soils under private gardens (both active and abandoned). At present, the yields of private olericulture in Yamal even exceed those of industrial vegetable-growing farms. It is revealed that private vegetable growers can achieve an increase in soil fertility by increasing the content of nutrients (P2O5 over 1,500 mg kg−1, K2O up to 500 mg kg−1) and organic carbon up to 17%, as well as the regulation of the acid-alkaline regime. It is also found that soil fertility indicators in private vegetable gardens are higher compared to industrial fields. Such soils are not typical for the cryolithozone and can be classified as Anthrosols. Soils of abandoned vegetable gardens can retain a high level of fertility for a long time due to the specific climatic conditions of the Arctic. As a result, the research showed that it is possible to grow vegetables beyond the Arctic Circle by adapting local soils and applying specific practices typical for cryolithozone.

Cryoconites as biogeochemical markers of anthropogenic impact in high mountain regions: analysis of polyaromatic pollutants in soil-like bodies

The globalisation and omnidirectional character of anthropogenic processes has challenged scientists around the world to estimate the harmful effects of these processes on ecosystems and human health. Polycyclic aromatic hydrocarbons (PAHs) is one the most infamous group of contaminants, originated both from natural and anthropogenic processes. They could transport to high latitudes and altitudes through atmospheric long-distance transfer and further enter ecosystems of these vulnerable regions by deposition on terrestrial surfaces. An interesting object for tracking transboundary contamination processes in high mountain ecosystems is called cryoconite. Cryoconite, a dark-coloured supraglacial sediment which is abundant in polar and mountain environments, is considered as a storage of various pollutants, including PAHs. Thus, it may pose a risk for local human health and ecosystem through short-distance transfer. Studied cryoconite sediments were collected at the surface of Skhelda and Garabashi glaciers, Central Caucasus high-mountain region, as well as mudflow, moraine material and local soils at the Baksan Gorge in order to examine levels of their contamination. We analysed the content of 15 priority polyaromatic compounds from the US EPA list and used the method of calculation of PAHs isomer ratios with the purpose of identifying their source. To estimate their potential toxicity, Benzo[a]pyrene (BaP) equivalents were calculated. Maximum concentration was defined for NAP (84 ng×g-1), PHE (40 ng×g-1) and PYR (47 ng×g-1), with the minimum concentration for ANT (about 1 ng×g-1). The most polluted material is a cryoconite from Garabashi glacier because of local anthropogenic activities and long-distance transfer. High-molecular weight PAHs are dominated in PAHs composition of almost all samples. The most common sources of PAHs in studied materials are combustion processes and mixed pyrolytic/petrogenic origin. Toxicity levels of separate PAHs did not exceed the maximum permissible threshold concentrations values in most cases. However, the sum of PAHs in BaP equivalents exceed the threshold values in all samples, in some of them more than twice.

Morphological features, productivity and pollution state of abandoned agricultural soils in the Russian Arctic (Yamal Region)

Recently, questions about the return of the concept of Arctic agriculture in order to promote sustainable development of the northern regions and ensure food security have been raised more often. The re-involvement of previously-used and abandoned soils into agricultural usage can provide an essential contribution for the development of the Arctic regions. We conducted a comprehensive research of soils with different levels of abandonment in the central part of the Yamal Region (Russia) and compared their morphological features, chemical and physical properties, fertile qualities and the level of contamination with heavy and trace metals to background soils of the region. It has been noted that there are no evident features of cryoturbation processes in the profiles of abandoned agricultucal soils and regular changes in the redox regime, as a consequence of the presence of reductimorphic spots in the soil profiles, have been recorded. Soil organic matter (SOM) stock in the topsoil of abandoned soils is estimated as medium and has a similar level to the stocks of total organic matter in the agricultural soils of the Arctic circumpolar region (Norway, Sweden, and Finland). Statistically significant differences in the content of nutrients between abandoned and background soils were recorded which indicates stability of the soil nutritional state during different abandoned states. Particularly notable are the differences between the content of available forms of phosphorus. The results of the study revealed significant differences between soils of various periods of abandonment and the background soils of the Yamal Region. Abandoned soils can be used for ground and greenhouse agriculture, these soils having a high level of fertility and are not limited for use in agriculture by the level of contamination with heavy and trace metals. According to the character of trace metal contamination, abandoned and background soils are evaluated as uncontaminated on the base of Zc and Igeo indices values. Reuse of the previously abandoned soils can undoubtedly become the basis for increasing agricultural production and ensuring food security in the Yamal Region.