Mirla Andrade Weber

Decomposição da fitomassa de plantas de cobertura e liberação de nitrogênio em função da quantidade de resíduos aportada ao solo sob sistema plantio direto

The no-tillage system success relies on higher addition of different types of crop residues to the soil, each one with specific decomposition kinetics which drives the net mineralization and immobilization of the nitrogen (N) in the soil. This manuscript had as objective to evaluate the decomposition rate and N released from winter cover crops residues under different above ground biomass input to the soil. The experiment was carried out in the experimental area of the Soil Department at Federal University of Santa Maria, in random complete block design, with three replications, during 2003/04 and 2004/05. The decomposition and the N released from black oat, oil radish and hairy vetch residues were investigated using mesh bags of decomposition containing fitomass equivalent to 3, 6 and 9 Mg of dry matter ha-1 placed in plots with 80 m² with the same level of crop residues used in the mesh bags. They were collected at 7, 14, 28, 42, 63, 84, 113 and 141 days after cover crops management. The amount of residues input did not influence the decomposition rate. However, the N mineralization and immobilization processes were affected by the level of residues input and they were driven by C/N ratio. The larger decomposition residues rate and higher N release followed the order: vetch, radish oil and black oat. The C/N ratio drives the size of labil and recalcitrant compartiments of cover crops fitomass.

A população da cidade de São Gabriel, RS e o grau de satisfação em relação à qualidade ambiental urbana

The growth of environmental impacts in the cities comes from the increase in population and the constant expansion of urban areas. These conflicts coupled with the lack of infrastructure contribute to the deterioration of environmental quality and life of the urban population and consequently to the physical, chemical and biological changes that compromise ecosystems and alter the landscape in these centers. The theme of this study relates to the perception and satisfaction of urban environmental quality has, as social actors, residents of a sample of the population of five districts in Sao Gabriel, RS. Through interviews addressed issues such as solid waste, noise, visual, air, soil, deforestation, the presence of sewage, illegal occupation, floods, urban sanitation and municipal environmental policies. The result of the survey showed satisfaction with some environmental aspects, but dissatisfaction with public policy indifferent to the quality of life of citizens.

Improving Acid Soil Fertility and Initial Growth of Eucalyptus by Compost of Bovine Ruminal Residues in a Pot Experiment

This study aimed to evaluate the potential of a compost of bovine ruminal residues to improve soil fertility and initial growth of eucalyptus cultivated in acid soil. Eucalyptus was cultivated in pots with a Hapludalf amended with 0 (Control 1), 5, 10, and 15 m3compost ha−1, and with only liming and mineral fertilization (Control 2). The compost enhanced all evaluated parameters of plant growth and soil and plant chemical analysis; overcoming, or at least equalizing to results from the Control 2. The compost can be used as alternative to liming and mineral fertilization in Eucalyptus urograndis plantations in acid soils of the Brazilian Pampa.

Boron fertilization and liming for Eucalyptus urograndis cropped on sandy arenosol of Brazilian pampa

ABSTRACT Boron (B) requirement and its interaction with liming for eucalyptus plantations in sandy soils of Brazilian Pampa are poorly understood. Aiming to diminish this gap, seedlings of Eucalyptus urograndis were grown in pots with Arenosol fertilized with B at rates 0.0, 1.0, 2.5, 5.0 and 10.0 mg B dm−3, with and without liming. Results of shoot and root dry matter and stem diameter did not evidence the necessity of B fertilization. With the exception of the 1.0 mg B dm−3+lime, all other B-fertilized treatments promoted visual symptoms of toxicity, which were partially mitigated by liming. Liming exacerbated the B loss by leaching, but after five months, limed soils had higher content of available B and their plants had higher B concentration in shoots and roots. For our conditions, application of ≥2.5 mg B dm−3 can cause serious toxic injuries to plants and enlarge dramatically the B losses leaching.