SOIL QUALITY IN RELATION TO FOREST CONVERSION TO PERENNIAL OR ANNUAL CROPPING IN SOUTHERN BRAZIL

Many forested areas have been converted to intensive agricultural use to satisfy food, fiber, and forage production for a growing world population. There is great interest in evaluating forest conversion to cultivated land because this conversion adversely affects several soil properties. We examined soil microbial, physical, and chemical properties in an Oxisol (Latossolo Vermelho distrófico) of southern Brazil 24 years after forest conversion to a perennial crop with coffee or annual grain crops (maize and soybeans) in conventional tillage or no-tillage. One goal was to determine which soil quality parameters seemed most sensitive to change. A second goal was to test the hypothesis that no-tillage optimized preservation of soil quality indicators in annual cropping systems on converted land. Land use significantly affected microbial biomass and its activity, C and N mineralization, and aggregate stability by depth. Cultivated sites had lower microbial biomass and mineralizable C and N than a forest used as control. The forest and no-tillage sites had higher microbial biomass and mineralizable C and N than the conventional tillage site, and the metabolic quotient was 65 and 43 % lower, respectively. Multivariate analysis of soil microbial properties showed a clear separation among treatments, displaying a gradient from conventional tillage to forest. Although the soil at the coffee site was less disturbed and had a high organic C content, the microbial activity was low, probably due to greater soil acidity and Al toxicity. Under annual cropping, microbial activity in no-tillage was double that of the conventional tillage management. The greater microbial activity in forest and no-tillage sites may be attributed, at least partially, to lower soil disturbance. Reducing soil disturbance is important for soil C sequestration and microbial activity, although control of soil pH and Al toxicity are also essential to maintain the soil microbial activity high.

A favor dels clàssics d'aventures de la literatura juvenil

No entengueu aquest article com un clam nostalgic als herois i hero'ines de tots els temps. No el vegeu tampoc com una manca de reconeixement al gran esforç realitzat per escriptors i escriptores, món educatiu i editorial per ampliar l'oferta de literatura infantil i juvenil i posar a l'abast deis adolescents un ventall de títols i col-leccions que els motivin per a la lectura. Aquestes pagines ni tan sois pretenen entrar en la polemica sobre la funció literaria i pedagógica del corrent anomenat "realisme crític", amb reflexió psicológica, on s'hi tracten temes que permeten als adolescents identificar-se, de manera explícita, amb els infortunis que succeeixen als joves protagonistes. Adhuc, en aquest escrit es vol deixar al marge la qüestió deis límits entre literatura per a nens i joves i literatura per a adults.

Ikääntyvät 1990-luvun Virossa: selviytyminen työssä ja elämässä

Summary: Elderly people in Estonia in the 1990s: works and coping

Myocardial MIBG scintigraphy: a useful clinical tool? : A retrospective study in 50 parkinsonian patients.

Meta-iodbenzylguanidine scintigraphy (MIBG scintigraphy) shows reduced uptake in idiopathic Parkinson's disease (IPD), idiopathic REM sleep behavior disorder (IRBD) and Lewy body dementia (LBD), but not in other parkinsonian or dementia syndromes. We retrospectively reevaluated 50 patients. Concordance rate between last clinical diagnosis and scintigraphy diagnosis was only given in two-thirds of the patients. Confounding factors were: decreasing heart/mediastinum ratio (HMR) with progressive age, higher HMR in women and possibly interference with antihypertensive medication. Standardization of the methods and precise clinical guidelines are warranted for better clinical use.