Effects of two organic mulches on soil chemical, physical and biological properties

Previous research showed that organic mulches, especially coarse green compost, increased growth of some widely used shade tree species. The aim of this work was to evaluate changes in soil physical, chemical, and biological properties induced by mulch, which led to increased plant growth. In 2004, 72 Aesculus × carnea Hayne (red horsechestnut) and 72 Tilia × europaea D.C. (European linden) were planted in an experimental plot following the randomized block design. Two organic mulches were distributed in the rows and compared to an unmulched treatment. Soil respiration, soil oxygen content, and soil temperature were recorded using a soil respiration chamber and a temperature sensor applied to an infrared gas analyzer. In 2007, at the end of the trial, soil bulk density, soil moisture, soil temperature, total organic carbon, total nitrogen content, microbial biomass, and nitrous oxide emissions were measured. Result showed that, in 2006, summer soil temperature under both mulches was significantly lower than in the unmulched treatment. Soil biological activity was also enhanced by mulches. No difference in soil oxygen content was found among the treatments. Conversely, soil moisture, total organic carbon, carbon:nitrogen ratio, and microbial biomass were significantly higher under mulch. Composting also had a fertilizing action, as showed by higher total soil nitrogen content and nitrous oxide emission. In conclusion, mulch affected soil properties and created a more favorable environment for roots, which resulted in enhanced plant growth.