Reaction of soil enzymes and spring barley to copper chloride and copper sulphate

Study was carried out to compare the effect of the degree of contamination of soil with copper on the soil enzyme activity, depending on the type of chemical compound with which a metal reaches the soil and on the method of soil use. An effect of increasing doses of copper on growth and the development of spring barley has been studied. The study was carried out as a pot experiment on two types of soil: loamy sand and light loam. Copper was introduced to soil as copper(II) sulphate(VI) and copper(II) chloride at four doses: 150, 300, 450 and 600 mg Cu²⁺ kg^?1 d.m. of soil. Soil without copper was used as a control sample. The experiment showed that contamination of soil with copper applied as CuCl₂ and CuSO₄·5H₂O upset the homeostasis of soil. Dehydrogenases and urease were the most sensitive to contamination of soil with Cu²⁺, both as copper(II) chloride and as copper(II) sulphate(VI), and acid phosphatase and alkaline phosphatase were the least sensitive. Greater changes in enzymatic activity were observed in loamy sand than in light loam. The differences in the impact of copper(II) sulphate(VI) and copper(II) chloride on the soil microbiome were relatively small, because mean ED₅₀ for copper(II) chloride was 341 mg Cu²⁺ kg^?1 d.m. of soil, and for copper(II) sulphate(VI) it was 364 mg Cu²⁺ kg^?1 d.m. of soil. This inhibitory effect of copper persisted throughout the period of the experiment. The sensitivity of spring barley to copper compounds was lower than the enzymes under study.