Influence of organic amendments on soil quality potential indicators in an urban horticultural system

The short-term response of some soil physical, chemical and biological properties, and the growth of beet, to the application of vermicompost–compost mix and/or bone meal at different doses in an organic system was evaluated in the present work. Fractions of soil organic matter after amendment application were also evaluated. Though no differences were found in oxidizable carbon, the particulate organic carbon was incremented in treatments with the application of vermicompost–compost mix (VC) and the combination of compost and bone meal (VC–BM). When analyzing the fulvic, humic and humin fractions, the highest fulvic acids were found in vermi-compost and bone meal mix, at the higher dose (VC2–BM2). In general, the addition of compost and/or bone meal stimulated microbial respiration. The treatments produced a slight but significant increase in electrical conductivity, thought it was still far from limits that involve risk of salinization. An increment in extractable P was found in all the treatments with amendment application with the exception of bone meal applied at the lower dose (1 kg m−2). The cation exchange capacity showed a significant increment in VC2–BM2. A single application of VC at dose of 2 kg m−2 was enough to significantly reduce bulk density. An increment in kg dry matter m−2 of beet was observed in all the treatments, but it only was significant in VC2–BM2. However, the highest N and P concentration was found in beet aerial tissues from the treatments with the higher dose of the compost–vermicompost mix (VC2 and VC2–BM2). Particulate organic carbon, fulvic acid fraction, C from respiration, and bulk density were the soil properties that showed a positive change after amendment application. Treatment combining vermicompost–compost and bone meal (VC2–BM2) seemed to be the best option to achieve an improvement both in soil and crop production and quality.