Influence of humic extracts on germination and growth of ryegrass

Abstract

The object of this work was to study the influence of humic extracts prepared from peat, sheep manure, and compost from municipal solid waste on germination and growth of ryegrass. Germination tests, using different concentrations of humic extracts, showed that doses higher than 20% (v/v) inhibited seed germination. Therefore, doses of 20 and 10% were used in a first growth experiment, using a control consisting of a complete nutrient solution. A 20% dose caused adverse effects on plant growth. Hence, doses of 10 and 5% were used in the next growth experiments. Also, plants were watered with the extracts or with the nutrient solution (control) and with distilled water alternately in the next experiments. After the first cut of the ryegrass, sixteen days after the sowing, the watering was implemented only with distilled water in order to assess the residual effects of the different fertilizers. A second cut was performed thirty six days after the sowing. The harvested ryegrass was analyzed for: a) fresh weight; b) dry matter; c) nitrogen, phosphorus, and potassium contents; d) chlorophylls; and e) carotenoids. The data show that the best effects were achieved with sheep manure extracts, followed by compost and peat. Differences among the three kinds of fertilizers were more remarkable than those between the two doses of the same fertilizer.