Universidade Federal de Santa Maria

About: Universidade Federal de Santa Maria is a education organization based out in Santa Maria, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 21178 authors who have published 35632 publications receiving 371665 citations.

Fate of carbon and nitrogen in water‐stable aggregates during decomposition of 13C15N‐labelled wheat straw in situ

Abstract: When incorporated in soil, plant residues and their decomposition products are in close contact with mineral particles with which they can be bound to form aggregates. We measured the incorporation of carbon (C) and nitrogen (N) derived from crop residues in water-stable aggregate fractions of a silty soil in a field experiment in Northern France using 13 C 15 N-labelled wheat straw (Triticum aestivum L.). Soil samples were taken seven times for 18 months and separated into slaking-resistant aggregate size fractions which were analysed for total C and N contents, and 13 C and 15 N enrichments. During the early stages of decomposition (approximately 200 days), the enrichment of 13 C increased rapidly in the macroaggregates (> 250 μm) but decreased thereafter. The macroaggregates represented only < 20% of the soil mass and at any one time, they accounted for <25% of the residual 13 C in the soil. The proportion of 13 C recovered in the <50-μm and 50-250-μm fractions increased during decomposition of the residues; at day 574, the 50-250-μm fraction accounted for close to 50% of the residual 13 C. A greater proportion of 15 N than 13 C was recovered in the <50-μm fraction. The results indicate that during decomposition in soil, C and N from crop residues become rapidly associated with stable aggregates. In this silty soil the 50-250-μm stable aggregates appear to be involved in the storage and stabilization of C from residues.

Taking stock of the Brazilian "zero-till revolution": a review of landmark research and farmers' practice

Abstract: Two decades of extensive research and experimentation with zero‐till methods has allowed “ideal” zero‐till systems to emerge in Brazil, involving no soil turning, maintenance of a permanent vegetative cover, and rotations of both cash and cover crops. By exploiting rapid successions of suitable crops, for example, as well as through careful temporal and spatial planning, Brazilian examples show that it is possible to continuously cover soil, gradually increase soil organic matter (SOM) stocks, integrate livestock, move surface‐applied lime through the soil profile, break compact soil layers, and reduce reliance on agrochemicals in zero‐till, all under a variety of edaphic and climatic conditions, and levels of mechanization/farm sizes. Various such technologies and systems are reviewed in this chapter. However, we also note that among smallholder zero‐till farmers, for example, the adaptations of “ideal” zero‐till systems are manifold and complex, partial adoption of certain components and technologies rather than full adoption of zero‐till systems being the norm. By examining farmers' experiences and practice, we ascertain that in many cases there is perhaps a divorce between the ideal, originating mainly from individual technology research on agricultural research stations, and farmers' reality, given the complexity of socioeconomical constraints facing the latter. We conclude that although there is a wealth of valuable zero‐till experience and technologies precipitating from the Brazilian zero‐till “revolution,” numerous challenges in zero‐till research, especially in respect to resource‐poor smallholder farmers, still remain, and perhaps more holistic, participatory and adaptive on farm‐research is necessary in future. © 2006, Elsevier Inc.

The association between fracture and obesity is site-dependent: a population-based study in postmenopausal women.

Abstract: The association between obesity and fracture is controversial. We investigated the relationship between body mass index (BMI) and fracture at different skeletal sites in women aged ≥50 years using data from the Sistema d' Informacio per al Desenvolupament de la Investigacio en Atencio Primaria (SIDIAP) database. SIDIAP contains the computerized medical records of >3400 general practitioners in Catalonia (northeastern Spain), with information on a representative 80% of the population (>5 million people). In 2009, 1,039,878 women aged ≥50 years were eligible, of whom 832,775 (80.1%) had a BMI measurement. These were categorized into underweight/normal (302,414 women), overweight (266,798), and obese (263,563). Fractures were ascertained using the International Classification of Diseases, 10th revision (ICD-10) codes. Multivariate Poisson regression models were fitted to adjust for age, smoking, high alcohol intake, type 2 diabetes, and oral corticosteroid use. Hip fractures were significantly less common in overweight and obese women than in normal/underweight women (rate ratio [RR] 0.77 [95% confidence interval (CI) 0.68 to 0.88], RR 0.63 [95% CI 0.64 to 0.79], p < 0.001, respectively). Pelvis fracture rates were lower in the overweight (RR 0.78 [95% CI 0.63 to 0.96], p = 0.017) and obese (RR 0.58 [95% CI 0.47 to 0.73], p < 0.001) groups. Conversely, obese women were at significantly higher risk of proximal humerus fracture than the normal/underweight group (RR 1.28 [95% CI 1.04 to 1.58], p = 0.018). Clinical spine, wrist, tibial, and multiple rib fracture rates were not significantly different between groups. An age-related increase in incidence was seen for all BMI groups at all fracture sites; obese women with hip, clinical spine, and pelvis fracture were significantly younger at the time of fracture than normal/underweight women, whereas those with wrist fracture were significantly older. The association between obesity and fracture in postmenopausal women is site-dependent, obesity being protective against hip and pelvis fractures but associated with an almost 30% increase in risk for proximal humerus fractures when compared with normal/underweight women. The reasons for these site-specific variations are unknown but may be related to different patterns of falls and attenuation of their impact by adipose tissue.