Ecila Maria Nunes Giracca

AVALIAÇÃO POPULACIONAL DE OLIGOQUETAS E CARACTERÍSTICAS FÍSICAS DO SOLO EM DIFERENTES SISTEMAS DE CULTIVO

This research was conducted in Teutonia, RS, during 1990 of a Purple Structured (Paleudult) Soil. Four areas were submitted to different soil tillage sistems (no till, conventional and natural forest). The number of oligochaetes per area was counted and identified and water stable agregates for each season of the year was determined. The average geometric diameter of the water stable agregates was greater under forest and no tillage. Little variation was observed on the distribuition of water stable agregates for the different soil tillage systems and seasons. The largest oligochaetes populations were observed under no tillage and the majority of the individuals beonged to the genus Pheretima.

QUEBRA DE DORMÊNCIA EM SEMENTES DE CROTALARIA

Seed germination of four Crotalaria species were evaluated after physical, chemical and mechanical treatments to overcome impermeability of seed coat. The most efficient methods to break dormancy were: for C. retusa mechanical seed scarfication followed by seed imbibition in boiling water for five minutes; for C. spectabilis seed imbibing in destilated water at room temperature and seed chemical scarification in H2SO4 ; and rinsed in tap water for C. mucronata mechanical seed scarification; for C. grantiana none tested treatments improved dormancy break. The dormancy break efficiency was measured based on percentage of normal seedling.

Influência da aplicação de calcário na população da meso e macrofauna do solo sob sistema plantio direto

No presente estudo avaliou-se o efeito de diferentes doses e modos de aplicacao de calcario em plantio direto em campo nativo sobre a fauna edafica, apos cinco anos da aplicacao. Organismos da fauna epiedafica foram coletados com armadilhas tipo Provid e macrorganismos euedaficos utilizando monolitos de solos em duas epocas de amostragem: inverno e verao. Os organismos foram identificados ao nivel de classe e ordem. Foram identificados 17 grupos taxonomicos, com ocorrencia de cinco classes: Arachnida, Diplopoda, Crustacea, Oligochaeta e Insecta. A abundância de organismos apresentou maior variacao em funcao das diferentes epocas de coleta e nao sofreu influencia das diferentes doses e modos de aplicacao de calcario avaliados.

EFEITOS DE DIFERENTES SISTEMAS DE CULTIVO SOBRE A POPULAÇÃO DE OLIGOQUETAS E CARACTERÍSTICAS FÍSICAS DO SOLO

SUMMARY Purple Structured (Paleudult) Soil, in autumn, winter and spring seasons, during 1991, in Teutonia-RS, evaluations were done of the effects from different soil tillage systems (no till, conventional and natural forest) on soil physical and biological characteristics. The average geometric diameter of the water stable agregates and the number of oligoquetes for each season. The results from natural forest soil were greater in ali seasons, for average geometric diameter of the water stable agregates as much as for oligoquete population, continued from no till and conventional soil tiliage systems. This indict that the frequent mobilizations and incorporation from the soil mulching, allied with climatic factors, have large participation of soil characteristics.

EFEITO DA TRIFLURALINA SOBRE A ATIVIDADE BIOLÓGICA EM DOIS SOLOS

The effects of Trifluralin 600 CE on microbial activity measured by CO2 evolution were studied in a Red Yellow Podzolic soil (Sao Pedro [soil mapping unit] and a Dark Red Latosol (Cruz Alta [soil mapping unit]. The experiment was conducted during 140 days. Treatments with two and four liters of Trifluralin per hectar, in saturated soil and soil with at equivalent to of field capacity. The CO2 evoluted was measured each seven days. After CO2 evolution a biossay using Sorghum bicolor L. Moench was performed to test herbicide persistance. The herbicide did not affect microbial activity. Abnormal seedlings were detected in soil with moisture at 80% of field capacity but none for saturated soil. The abnormal seedling usually indicates persistence of Trifluralin when it is applyed in unsaturated soil conditions.