Assessment of phytotoxicity of arable soils of Valkivska community according to different methodological approaches

Abstract

The article substantiates the relevance of biotesting in assessing the ecological state of the soil, in particular by determining its phytotoxicity, as one of the most sensitive and informative integrated indicators of the presence of toxic components in the soil environment. Due to its indicator function, the soil phytotoxicity index is used both to identify local sources of pollution and for a comprehensive assessment of the overall level of anthropogenic load on the studied area. The study was conducted on two types of soil — typical chernozems (Haplic Chernozems) and podzolized chernozems (Chernic Phaeozems). To determine the level of phytotoxicity of arable soils in the territory of the Valkivska community of the Kharkiv region, two methodological approaches used: (i) determining the degree of soil contamination according to the Kraynyukov–Kryvytska method and (ii) integrated phytotesting methodology according to Miroshnychenko. Soil samples for testing taken from the arable layer (0–30 cm). Seeds of dicotyledonous and monocotyledonous plants used for biotesting. Seeds germinated for 72 hours in water extracts from the studied soils, and the control variant — in distilled water. Bioindicative parameters were determined by morphometric indicators of seedlings — the length of shoots and roots. After that, the difference between the length in the studied and control variants, the growth inhibition index (I) and the values of complex integrated indicators predicted by both methodological approaches were calculated.By comparing the effectiveness of two methods that differ in the principles of interpretation of bioindication parameters, it was determined that both approaches are similar in terms of soil condition characteristics. As a result, it was noted that the combination of the two methods allows for a more complete and multi-component ecological assessment. The method of Krainyukov and Kryvytska is suitable for rapid express analysis and operational identification of potentially dangerous areas. The integrated phytotesting method according to Miroshnychenko, due to a wider range of indicators, provides a deeper and more detailed characterization of soil phytotoxicity. Together, the data indicate a generally satisfactory condition of the soils of the Valkivska community with individual manifestations of moderate phytotoxicity, which requires regular monitoring and further analysis of possible sources of influence. According to the classification of the degree of toxicity in the Krainyukov-Kryvytska method, most soils assessed as having a low or moderate level of toxicity, which indicates the absence of pronounced local technogenic loads. According to the Miroshnychenko method, a wider range of variations of the parameters of integrated indices revealed, which reflects the reaction of plants to the complex effect of environmental factors, in particular to general phytotoxicity. Differences recorded between the results of the assessment using dicotyledonous and monocotyledonous crops, which confirms the different sensitivity of plants to individual types of toxicants. The feasibility of using several test crops for a more objective assessment of the state of the soil environment indicated.