Universidade Federal Rural do Rio de Janeiro

About: Universidade Federal Rural do Rio de Janeiro is a education organization based out in Seropédica, Brazil. It is known for research contribution in the topics: Population & Species richness. The organization has 6405 authors who have published 9852 publications receiving 105911 citations.

Decomposição e liberação de nitrogênio de resíduos culturais de plantas de cobertura em um solo de cerrado

Abstract: Dry mass production, decomposition rate and nitrogen (N) release were evaluated in a field experiment under seven cover crop types: pearl millet (Pennisetum americanum sin. typhoides), brachiaria grass (Brachiaria brizantha), sorghum (Sorghum bicolor L. Moench), pigeon pea (Cajanus cajan (L.) Mill sp), sunn hemp (Crotalaria juncea) and black oat (Avena strigosa Schreb), compared to a fallow and a traditional cropping system (control) in a cerrado soil (Uberaba-MG, Brazil). Among the tested cover crops, pearl millet and sunn hemp presented higher dry mass yield and nitrogen accumulation and release. Brachiaria grass had the highest decomposition rate and shortest half-life time. All crops reached the highest N liberation rate 42 days after desiccation.

Aggregate distribution and soil organic matter under different tillage systems for vegetable crops in a Red Latosol from Brazil

Abstract: Several management systems can improve soil productivity. By studying aggregate stability it is possible to quantify whether or not the management is ameliorating the natural soil properties and the land capability for agriculture. The effect of three tillage systems on the stability of soil aggregates and soil organic carbon was studied in comparison to reference plots with grass and bare soil. Samples were collected at the Pesagro Experimental Research Station in Paty do Alferes, state of Rio de Janeiro, Brazil, from an experiment that has been carried out from 1995 to 2001, on a Dystrophic Red Latosol (Typic Haplorthox). Aggregate size distribution mean weight diameter, geometric mean diameter of the aggregates, and total organic carbon in each aggregate size fraction were determined. The proportion of aggregates with diameter ≥2 mm appeared to be a suitable indicator of the influence of tillage systems on aggregation. At a depth of 0–5 cm, aggregates ≥2 mm were 50% of soil under no-tillage, which was greater than under animal traction (35%) and conventional tillage (30%). Total organic carbon concentration was greater under no-tillage (19 g kg −1 ) than under conventional tillage (11 g kg −1 ) at a depth of 0–5 cm, but not significantly different (average 13 g kg −1 ) at a depth of 5–10 cm. Soil exposure with tillage and lack of residue inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to erosion. Adoption of no-tillage led to a decline in aggregation compared with grass reference, but did significantly alter soil organic concentration, suggesting it was a valuable conservation practice for vegetable production on sloping soils. © 2003 Elsevier B.V. All rights reserved.

Propriedades químicas de um Cambissolo cultivado com cana-de-açúcar, com preservação do palhiço e adição de vinhaça por longo tempo

Abstract: This study was undertaken in Campos dos Goytacazes, northern State of Rio de Janeiro, based on soil samples of a vertic Fluventic Eutrochrepts, which had been cultivated with sugarcane for several decades. In one situation, the crop had been cultivated for 55 years without burning the residues at harvesting. On another sugarcane plantation, harvest residues had been burned, and vinasse inputs applied by sprinkle irrigation at a rate of 120 m3 ha-1 yr -1 during 35 years. Soil samples were collected from the soil layers 0-0,20 m and 0,20-0,40 m to evaluate and determinate the pH, available P, exchangeable bases, cation exchange capacity, double acid extractable micronutrients, total N, and oxidizable carbon, as well as the fractionation of the humified organic matter. Results indicate that the preservation of crop residue on the soil surface and, to a lesser extent, the addition of vinasse, increase the macro and micronutrients contents. Carbon contents in the superficial layer (0-0,20 m) ranged from 13.13 g kg-1 in the burned cane to 22.34 g kg-1 in the unburned cane, and from 15.71 g kg-1 in the cane without vinasse to 18.33 g kg-1 in the cane under vinasse application. The improvement of the chemical soil attributes favored the formation of more polymerized alkaline-soluble humic substances.

Multi-level governance and power in climate change policy networks

Abstract: This article proposes an innovative theoretical framework that combines institutional and policy network approaches to study multi-level governance. The framework is used to derive a number of propositions on how cross-level power imbalances shape communication and collaboration across multiple levels of governance. The framework is then applied to examine the nature of cross-level interactions in climate change mitigation and adaptation policy processes in the land use sectors of Brazil and Indonesia. The paper identifies major barriers to cross-level communication and collaboration between national and sub-national levels. These are due to power imbalances across governance levels that reflect broader institutional differences between federal and decentralized systems of government. In addition, powerful communities operating predominantly at the national level hamper cross-level interactions. The analysis also reveals that engagement of national level actors is more extensive in the mitigation and that of local actors in the adaptation policy domain, and specialisation in one of the climate change responses at the national level hampers effective climate policy integration in the land use sector.

Soil organic carbon and fractions of a Rhodic Ferralsol under the influence of tillage and crop rotation systems in southern Brazil

Abstract: Soil organic matter (SOM) and its different pools have key importance in optimizing crop production, minimizing negative environmental impacts, and thus improving soil quality. The objective of this study was to evaluate the soil C and N contents in bulk soil and in different SOM pools (light and heavy fractions) of a clayey Rhodic Ferralsol after 13 years of different tillage and crop rotations in Passo Fundo, State of Rio Grande do Sul, Brazil. Soil samples were collected from no-tillage (no soil disturbance except for sowing; NT) and conventional tillage (disc plough followed by light disc harrowings; CT) applied to wheat/soybean (W/S) and wheat/soybean–vetch/maize (W/S–V/M) rotations. As reference, soil was sampled from a non-cultivated area adjacent to the field experiment. The greatest soil C and N contents were found in non-cultivated soils in the 0–5 cm depth (45 g C kg −1 soil and 3.6 g N kg −1 soil). Crop cultivation led to a decrease in SOM content which was higher for CT soils (approx. 60% decrease in C and N contents) than NT soils (approx. 43% decrease in C and N contents) at 0–5 cm. Tillage had the greatest impact on soil C and N storage. Soils under NT did not contain higher C and N storage than CT soils below 5 cm depth. Significantly, higher amounts of organic carbon of FLF in CT (0.5–0.7 g C kg −1 soil) than in NT soils (0.2 g C kg −1 soil) at 10–20 cm depth were also observed and the differences in C and N storage between CT and NT soils in the 0–30 cm layer were not significant. Silt and clay fractions contained the largest amount of organic carbon (60–95% of total organic carbon), and free light fraction was the most sensitive pool of organic carbon to detect changes in SOM due to soil tillage and crop rotations.