ABUNDANCE AND BIODIVERSITY OF SOIL ARTHROPODS IN ONE CONVENTIONAL AND TWO ORGANIC FIELDS OF MAIZE IN STOCKLESS ARABLE SYSTEMS

Soil arthropod community was evaluated, in three different farming systems in Central Italy, in the context of a long-term experimental stockless arable system (MOLTE). The soil arthropodofauna was recorded in two organic agrosystems of different age (16-year old organic, named OldO; 6-year young organic, named YngO) and in one conventional (Co), at a fixed time on maize. Arthropods, extracted by Berlese-Tullgren funnels, were counted and identified at order or suborder taxonomic level. In the three maize fields, the farming system affected both abundance and biodiversity of arthropods. The arthropod density ranged from about 20,000 individuals/m(2) in OldO to about 45,000 in YngO. The number of oribatid mites was higher in Co than in OldO, while YngO showed the highest density of collembolans. The mite/collembolan ratio was the highest in Co (6.43), the lowest in YngO (1.95). Both biodiversity indices adopted - Delta V, synthetic index of degree of diversity change of ecological systems and QBS, index of biological soil quality - showed the highest values for YngO. On the whole, differences in the arthropod community were higher in the YngO-OldO comparison than in OldO-Co. The soil arthropod community tended to be characterized by lower density of specimens and lower number of taxa in the OldO organic system than in the YngO.