Assessment of the state of vegetation cover of recultivated dumps of uranium deposits in Northern Kazakhstan

The purpose of this study was to assess the processes of plant community formation on recultivated dumps of spent uranium-containing industrial waste from uranium deposit mines, as well as to identify the degree of impact of agro-climatic factors, agrochemical indicators of soils of recultivated dumps, and the level of residual ionizing radiation on the productivity of the emerging vegetation cover. Studies of plant colonization of recultivated Grachevsky and Shantobinsky uranium mine dumps located in Northern Kazakhstan were carried out. The mining and technical stage of reclamation consisted of planning a dump with slopes of 15° and covering it with a 1 m layer of chestnut soil. In total, 30-35 plant species are present in the dumps, the projective coverage is approximately the same (56.6-70.0%), and the herbage density is 15-16.6 plants/100 m2. As a result of the measures taken to recultivate the dumps, the intensity of the background ionizing radiation at the Grachevsky mine dump was in the range of 25-35 µR/hr and at the Shantobinsky mine dump 10-25 µR/hr, which indicates compliance with safety standards. The plant species which can be used for artificial plant colonization of uranium-containing waste dumps, were identified.

Quantitative assessment of soil condition, basic environmental factors and productivity of Linum usitatissimum in the steppe zone of Kazakhstan using the remote sensing method

The influence of environmental factors, such as lack of water and uneven rainfall, depletion of nutrients in the soil and reduced soil fertility, planting patterns and plant density, uneven growth stages, are the main limiting factors that hinder the growth of agricultural production in arid regions. The aim of the study was to assess the potential of Sentinel-2 to quantify soil conditions, which can improve the understanding of spatiotemporal dynamics in organic agriculture in the steppe zone of Kazakhstan and improve productivity management of Linum usitatissimum. In the course of the research, the influence of individual factors of the general environmental impact, such as the influence of humidity, meteorological conditions, the content of individual nutrient components of the soil on the yield, was studied. The meteorological conditions in this region in 2021 and the data of agrochemical analysis of the soil on which the oilseed crop was grown were evaluated. Sentinel-2 satellite images were used to determine the NDVI and GNDVI indices. A high content of nitrate nitrogen (12.3-16.2 mg/kg), a very low level of available phosphorus (3-10 mg/kg), and a high content of potassium (289-420 mg/kg) were found in the soil. A low content of humus (2.68-3.31%) and sulfur (1.1-4.9 mg/kg) was found. A study of the NDVI growth index showed that the highest value was reached by the period of July 20, 2021. After this period, a decrease in the vegetation index was observed. In conditions of severe drought, this change occurred earlier than under favorable conditions, and correlated with low flax yield (1.6-6.9 c/ha). This study demonstrates the potential of Sentinel-2 for quantifying soil conditions, which not only improves our understanding of spatial-temporal dynamics and environmental components in organic agriculture in the steppe zone of Kazakhstan, but also improves the management of Linum usitatissimum productivity.