Effect of different management strategies on soil quality of citrus orchards in Southern Italy

Summary

Twenty-six soil samples were collected from 13 paired orchards (organically vs. conventionally managed)
homogeneous for age, rootstock and cultivars, belonging to the Eastern Sicily Organic Citrus
farm Network. The soil quality was evaluated by chemical and biochemical indicators. The total
organic C, humification parameters and isoelectric focusing of extracted organic matter were measured
to quantify the size of relevant soil C pools. In addition, C turnover was evaluated by determining
microbial C mineralization, C microbial biomass and by calculating the mineralization and metabolic
quotient (qCO2). The results obtained demonstrated that organic citrus soils were characterized by a
general increase in all the organic matter pools, which means a greater C supply for soil metabolic
processes. This observed trend did not directly influence the organic matter turnover, indicating that
the organic approach could act as a soil C-sink. The soil microflora of organically managed soils
showed an improved efficiency in use of energy and organic resources, corresponding to an increased
ability of soils under organic management to sustain biological productivity in the long term.