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Conventional agricultural in the Venezuelan Llanos has generated gradual soil degradation. Therefore, conservationist agriculture has been proposed. According to several works, this type of management favors soil macrofauna. To test this hypothesis, the response of soil macrofauna to the establishment of conservationist maize crops, associated with Brachiaria dictyoneura (Bd) and Centrosema macrocarpum (Cm), was evaluated. The samples of soil and soil macrofauna were taken per vegetation cover at different climatic season over 2 years and 10 months. For this period and under the conditions studied, the results partially refute the hypothesis; on the one hand, they showed that the soil macrofauna of a natural savanna (NS) is the most diverse and equitable (N1 = 4.5 ± 2.8), followed by the cultivation of maize associated with Cm (N1 = 3.2 ± 1.9) and the least diverse with Bd (N1 = 2.6 ± 2.1). Additionally, some taxonomic groups apparently did not tolerate soil intervention, while Termitidae was favored. On the other hand, the temporal variation of the soil macrofauna did not differ between vegetation covers (F: 1.18; p = 0.37). This variation could be due to the decrease in TP (r = −0.55) and increased BD (r = 0.56). [ABSTRACT FROM AUTHOR]

In the well-drained savannahs of Venezuelan Llanos, intensive agricultural activities could be causing damage to the soil, with negative consequences for the ecosystem. In order to avoid this problem, some agroecological alternatives are needed. Consequently, it is necessary to know the biologic dimension in this ecosystem, and within this, the soil macroinvertebrate community. The purpose of this work was to characterize this community in the natural savannah: its structure and diversity, its time variation and its relationship with the physical-chemical properties of the soil. A total of 72 samples were taken in different season along a period of time of 1405 days. The results revealed that the soil macrofauna had an average density of 243.5 ± 183.6 ind·m −2 , distributed in 32 families of 11 orders, with a diversity of N 1 = 4.5 ± 2.8 families. Coleoptera, Hymenoptera and Isoptera was the most dominants orders. The density, richness and diversity of families showed a temporal variation ( r ≥ −0.5; p < 0,05). Additionally, the structure of the soil macroinvertebrate community showed a vertical variation. The relationship with soil properties differed according families: Lampyridae, Aphodiidae and Formicidae had a positive correlation with soil macro-porosity (radius of the pores > 15 μm); Tenthredinidae and Tenebrionidae had a positive correlation with the micro-porosity (pores ≤ 15 μm). The community in general, correlated positively with soil porosity and negatively with bulk density. This suggests that these soil properties need to be considered when designing agroecological technics in this area. [ABSTRACT FROM AUTHOR]