The Effect of Peat and Vermicompost Cavitation Products on the Soil Biological Activity

Commercial products with humic substances have often been recommended for plant growth stimulation and yield improvement. The aim of this study was to clarify the effects of two products, containing cavited peat and vermicompost respectively on the soil biological activity. Vegetation experiments with garden cress and cucumbers were arranged in pots with a peat substratum in the greenhouses of the Latvia University of Agriculture. The plants were treated with the preparations once a month. The first treatment was done at sowing. Dose of 20, 2, 0.2 mL per m² during each treatment time were used. A control variant was without peat or vermicompost preparation. Field experiments with onions were carried out in the organic farming experimental field of the Latvia State Institute of Cereal Breeding. Plant growth and soil (substratum) biological activity (respiration and enzymatic activity) were tested. Plant growth and response to the different preparations depended on the plant species and its development stage. The effect of preparations decreases during plant development. The impact of peat or vermicompost preparation on soil biological activity depended not only on the concentration of preparation, but was influenced by the soil or growth media type. The decrease of onion yield in field conditions as a result of preparations was observed.