Effect of Soil Toxicity on the Growth and Development of Crimson Clover (Trifolium incarnatum L.) and Blue Alfalfa (Medicago sativa L.)

A vegetation trial was conducted to test, establish and compare the abilities of crimson clover (Trifolium incarnatum L.) and blue alfalfa (Medicago sativa L.) to grow, sequester arsenic and improve microbial soil status in soils with deteriorated water and physical properties and with naturally and technogenically reached toxic levels of arsenic. The experiment is based on cultivation of two types of legume crops under the same controlled climatic conditions, but in different soil environments. Contaminated Regosols and control uncontaminated Rhodic Cambisols, ChromicCalcaric Cambisols and Fluvisols, collected from four geographical points, distributed (4 kg.) in a total of 24 pots/samples and sown with the two investigated crops (2x12) were included in the study. Crop growth and development were monitored during the vegetative and reproductive phenological phases, taking timely biometric measurements. According to the observations made and the results obtained, the crimson clover (Trifolium incarnatum L.) is suitable for remediation and improvement of the agrochemical, biological, physical and physicochemical properties of arsenic-contaminated soils - Regosols, by forming a dense root system with a relative abundance of tubers of symbiotic nitrogen-fixing microorganisms in it, in conditions of Interventional contents of arsenic, significant compaction and deteriorated water permeability of the soils. Contamination with arsenic (in association with a number of heavy metals) suppresses the germination of both crops - crimson clover and alfalfa, vegetative phenophases, nutrition, growth and development of clover, but not the fertility of the obtained crop of the studied crops. The main factors limiting the fertility of the two crops in the experiment were the low content of soil colloids (humus and clay) and the poorer soil microbiome. The observed better adaptability in feeding alfalfa in contaminated soils allows this crop to be applied in longer-term remediation measures.