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Agricultural practices that reduce soil degradation and improve agricultural sustainability are needed particularly for tropical/subtropical soils. No-tillage planting causes minimal soil disturbance and combined with crop rotation may hold potential to meet these goals. Soil enzyme activities can provide information on how soil management is affecting the potential to perform the processes in soils such as decomposition and nutrient cycling. Soil enzyme activities were investigated in a split-plot experiment (3 replications) where tillage (no till and conventional) was the main plot and crop rotation (soybean/wheat, S/W; maize/wheat, M/ W or cotton/wheat, C/W) was the subplot. The experiment was established in 1976 in southern Brazil. Soil samples were taken at 0-5, 5-10 and 10-20 cm depths in 1997 and 1998. The 0-5 cm layer under NT system showed increases up 68% for amylase, 90% for cellulase, 219% for arylsulfatase, 46% for acid phosphatase, and 61% for alkaline phosphatase. There were significant correlations of soil enzyme activities with total organic C, and C and N microbial biomass. These results showed that NT increased microbial activity and that soil enzyme activity is a sensitive indicator of alteration soil quality by management.

The objective of this work was to evaluate the effect of coffee (Coffea arabica L.) population densities on the chemical and microbiological properties of an Oxisol. The work was carried out on soil samples of 0-20 cm depth originated from an experimental site which had been used for coffee tree spacing studies during 15 years, in Paraná State, Brazil. Eight coffee tree populations were evaluated: 7143, 3571, 2381, 1786, 1429, 1190, 1020, and 893 trees/ha. Increasing plant population increased soil pH, exchangeable Ca, Mg, K, extractable P, organic carbon, moisture content and coffee root colonization by vesicular arbuscular mycorrhizal fungi, and decreased exchangeable Al and microbial biomass. Such results were attributed to better erosion control, improved plant residue management and nutrient cycling, and decreased leaching losses. Increasing coffee tree population per unit of area has shown to be an important reclamation recuperation strategy for improving fertility of the acid soils in Paraná, Brazil.

II RESUMO O objetivo neste trabalho foi de avaliar o efeito da inoculação de fungos micorrízicos arbusculares no crescimento de mudas de peroba rosa (Aspidosperma polyneuronPalavras-chave: Aspidosperma polyneuron, Acaulospora scrobiculata, Gigaspora margarita, Glomus clarum, Scutellospora heterogama. ABSTRACT The aim of this study was to examine the effects of arbuscular mycorrhizal fungi (AMF) inoculation on

Avaliou-se a ocorrência de fungos micorrízicos arbusculares (FMAs) no solo rizosférico e nas raízes de cafeeiro (Coffea arabica L.) e de Crotalaria breviflora DC., cultivada na entrelinha como adubo verde. Amostras de solo rizosférico e raízes foram coletadas em julho de 1997, em parte de um experimento de longa duração conduzido no campo pelo Instituto Agronômico do Paraná, no município de Mirasselva, PR. Determinou-se a diversidade de FMAs, por meio da identificação morfológica dos esporos, a freqüência de ocorrência de populações de FMAs por meio da contagem direta de esporos no solo, e a colonização radicular. Extraiu-se DNA de raízes de cafeeiro colonizadas e não-colonizadas e de esporos de Acaulospora longula e Scutellospora gilmorei, coletados na rizosfera, realizando-se a PCR ("Polimerase chain reaction") com primers ITS ("Internal transcribed spacer") e comparando os perfis de bandas obtidos. O cultivo de crotalária na entrelinha do cafeeiro aumentou a concentração de esporos de FMAs na rizosfera do cafeeiro. A crotalária e o cafeeiro estimularam populações diferentes de FMAs. O gênero Acaulospora predominou na rizosfera do cafeeiro, e Scutellospora e Gigaspora na rizosfera da crotalária. Usando técnicas moleculares, foi possível caracterizar FMAs na rizosfera e nas raízes colonizadas do cafeeiro. O fungo micorrízico Scutellospora gilmorei, de ocorrência comum em cafeeiro e crotalária, não foi encontrado colonizando as raízes do cafeeiro. O uso de técnicas moleculares pode auxiliar no estudo da dinâmica populacional de FMAs no campo.