There is a growing awareness among farmers about the importance of soil for sustaining crop production and soil health. Marked interests in “environmentally-friendly” soil fertilization in agriculture has attracted significant attention in the last decades. A wide range of commercial humic products (HPs) are used as soil supplements to improve the nutrient utilization efficiency of plants as well as to increase crop production. However, the implications of increased HPs use for soil biology are being questioned, but a comprehensive review on this topic is lacking. The aims of this review are to understand behavior of HPs applied to soil, with a special focus on environmental protection issues, and to summarize the available data how HPs may influence the soil microbial communities, including fungi and bacteria strains. The interaction between HPs and soil inhabitants is highly complex and is controversial to a certain extent for several reasons. First, applying HPs may promote specific bacteria communities (Acidobacteria, Actinobacteria, Bacteriodeites, etc.) rather than other microbiome species. Soil enzymes such as laccase, peroxidase and dehydrogenase were seemingly affected as well. Applying HPs may result in the microbial respiration of CH₄, preventing the production of CO₂ from microbial respiration. These results would potentially lead to an overall decrease in the microbial respiration of CH₄, which is associated with a deficit in CO₂. Furthermore, HPs can control the nematode population in different soils. Finally, applying HPs in terms of physiological functioning can also have various consequences for different groups of soil fungi. However, the conditions that promote specific effects (chemical composition of HPs, environmental conditions, etc.) have yet to be investigated. Given the surveyed data, we conclude that there are gaps in the current knowledge of this topic. We propose an integrated approach including a targeted research involving not only species of plants but also the integrated chemical, toxicological and biological analyses as a useful approach of soil health protection.

The methodological and organizational problems of the practical application of soil bioassay to monitor the state of soils for environmental, agricultural, and sanitary-epidemiological purposes are analyzed. To improve the efficiency of the integral valuation of soil toxicity, soil bioassay should be performed with a set of organisms (sensors) representing the major trophic levels of the ecosystems, i.e., producers, consumers, and decomposers.

Analysis of methodological documents, Russian and foreign standards, and scientific publications has been performed to reveal best global practices and current trends in the improvement of laboratory phytotesting. It is proposed to increase the number of simultaneously used test cultures and the range of simultaneously controlled test functions at the first (screening) stage of phytotest to increase the information value of laboratory phytotests. Attention is focused on the assurance of the statistical reliability of test results. The advisability of creating universal regulations of Russian Federation for phytotesting methods to unify approaches to the ecological evaluation of soils.

The diversity of responses of test organisms (higher plants, microalgae, protozoa, crustaceans, bacteria, and mammal cell cultures in vitro) to the action of humates produced industrially from...