Soil fauna in different soil management for watermelon

Resumo

An experiment was carried out in Santa Maria, RS, to study the effects of different soil and leaf diseases management for watermelon on soil fauna. The treatments were: 1) Conventional Tillage (CT) 2) CT with strip (s) without plowing; 3) No-Till (NT)+Chisel (Ch)+Herbicide (H); 4) NT+Ch without H; 5) NT+H and 6) NT. All NT had black oat straw over the soil. The subplots had the leaf disease control treatments: 1) Check Plot, without control; 2) Chemical, with fungicide; Ecological, with a mixture of "calda bordalesa� + "Supermagro� + "Alhol�. Tretzel pitfalls traps were placed in plots before seeding and in subplots during watermelon vegetative cycle. Samplings were done: at 45 and 5 days before and at 30, 67 and 90 days after watermelon seeding. Each trap stayed 4 days at field. Were calculated richness, abundance and Simpson's diversity index (SDI). Acari population was higher in CTs than NT+Ch and Collembola population was higher in CTs than in NT+Ch+H, NT+Ch e NT+H, before watermelon seeding. However, Collembola population in CT and CTs was smaller than NT at 90 DAS. Coleoptera population was smaller in CTs than in NT+Ch+H and NT, while Hymenoptera population was not affected by soil management. Conventional tillage in strips decreased richness at 5 and 30 days before watermelon seeding and abundance at 90 DAS. NT treatments didn´t affect richness and abundance. Chemical leaf disease management increased abundance. Simpson's diversity index was not affected by soil management nor by leaf disease management.