The influence of a 3-years cultivation of legumes on macroarthropod community composition was investigated. Soil samples were taken from a field experiment which was conducted for three years to characterize the agronomic characteristics of eight cover crops: Crotalaria juncea L., Crotalaria spectabilis Roth, Crotalaria ochroleuca G. Don., Canavalia ensiformis (L.) DC., Mucuna pruriens (L.) DC., Dolichos lablab L., Neonotonia wightii (Wight & Arn.) J.A. Lackey, and Brachiaria decumbens Stapf. cv. Basilisk. The highest values of diversity in the macroarthropod community were found on the plot where M. pruriens was cultivated. Brachiaria decumbens cultivation showed lower values of species richness, Shannon's diversity index and Simpson's dominance index compared to the other studied plant species. Our findings suggest that the cultivation of legume cover crops can change positively the macroarthropod community composition. The results highlight the importance of considering the effects of legumes on the diversity of this biological component and their effect on plant growth and soil organic carbon contents. Thus, legumes may exploit positive feedback in semiarid conditions on a Regosol.

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The effects of a non-legume cover crop on total soil nematode abundance and soil groups of nematodes were investigated in a long-term field study. We compared total abundance of soil nematode and the abundance of both free-living soil nematode and root-feeding soil nematode under three different treatments (Pennisetum glaucum (L.) R. Br., native weeds and Caatinga moist-forest enclaves treatments) in a long-term field study cultivated on a Regosol. We found the highest abundance of free-living soil nematode in the Caatinga moist-forest enclaves treatment, whereas the highest abundance of root-feeding nematode was found in the native weeds treatment. We did not find any difference among P. glaucum and native weeds treatments for total abundance of soil nematode. Our findings suggest that the introduction of P. glaucum in sandy soil of Brazilian semiarid can increase the abundance of free-living nematode, but in other hand this cover crop did not reduce the abundance of root-feeding nematode. Our results also highlight the importance of considering the identification of soil nematode groups as indicator of soil quality and impacts of soil management.