64 results

Potential and net nitrogen mineralization in soils

Renato Yagi, Manoel Evaristo Ferreira, Mara Cristina Pessôa da Cruz, José Carlos Barbosa

01/Apr/2009

The soil incubation methods can be used as tools to a better evaluation of N mineralization and availability. The objective of this study was to evaluate the potential and net soil organic N mineralization, and relate them to N availability to plants. Twenty two soil samples (0-20 cm) were incubated at 35 ºC for 30 weeks in aerobic conditions and at 40 ºC for seven days in anaerobic conditions, and tested in a greenhouse experiment on corn plants. During the 30 weeks-incubation period […]

Soil organic carbon budget under crop-livestock integration in southern Brazil

Rodrigo da Silveira Nicoloso, Thomé Lovato, Telmo Jorge Carneiro Amado, Cimélio Bayer, Mastrângello Enívar Lanzanova

01/Dec/2008

In southern Brazil, crop-livestock integration is increasing in areas traditionally used for extensive beef cattle production. The poor winter pasture management associated to the use of soybean monoculture in the summer may be restrictive for the incorporation of plant residues into the soil and reduce soil organic carbon stocks. The objective of this study was to evaluate the impact of the increase of winter pasture grazing frequencies and summer crop systems on the soil organic C stock. The experiment was […]

Soil organic carbon and total nitrogen as related with coffee spacing

Otacílio José Passos Rangel, Carlos Alberto Silva, Paulo Tácito G. Guimarães, Leônidas Carrijo Azevedo Melo, Antônio Claret de Oliveira Junior

01/Oct/2008

The density and arrangement of trees influences the production of plant residues in coffee agroecosystems. This differentiated input of biomass regulates the contents of soil-C and -N. This study aimed to evaluate the contents of organic C and total N in a Typic Hapludox, in different spacings of (Coffea arabica L.) trees and tree rows. The experiment was carried out from 1992 to 2004 on an experimental farm of EPAMIG, in Machado (Minas Gerais State, Brazil). The treatments consisted of […]

Determination of total organic carbon and nitrogen stocks and their fractions in and ultisol under different land uses

Arley Figueiredo Portugal, Ivo Jucksch, Carlos Ernesto G.R. Schaefer, Beno Wendling

01/Oct/2008

Soil carbon stocks are the result of interaction of factors that determine their formation and decomposition. This study aimed to quantify the total organic recovery in various C pools under the following different land uses of an Ultisol: secondary forest, rubber tree plantation, pasture, and citrus plantation. The soil was sampled at depths of 0 to 10 cm and 10 to 20 cm and the following characteristics were determined: total organic carbon (TOC), total nitrogen (TN), fulvic acid fraction-C (FA), humic acid […]

Nitrogen doses and sources in marandu pasture. I – changes in soil chemical properties

Kátia Aparecida de Pinho Costa, Valdemar Faquin, Itamar Pereira de Oliveira, Cristiane Rodrigues, Eduardo da Costa Severiano

01/Aug/2008

Nitrogen deficiency is one of the important causes of degradation of cultivated pasture, mainly in the case of Brachiaria pastures. Soil recovery is a way to restore the productive capacity of pastures in degradation. Among nutrients, nitrogen is considered essential and largely responsible for pasture area recovery. The research objective was to evaluate the effects of application of nitrogen doses and sources on marandu grass pasture over a period of three years, based on soil chemical characteristics such as pH, […]

Soil carbon and nitrogen in pasture soil reforested with eucalyptus and guachapele

Fabiano de Carvalho Balieiro, Marcos Gervasio Pereira, Bruno José Rodrigues Alves, Alexander Silva de Resende, Avílio Antonio Franco

01/Jun/2008

In spite of the normally low content of organic matter found in sandy soils, it is responsible for almost the totality of cation exchange capacity (CEC), water storage and availability of plant nutrients. It is therefore important to evaluate the impact of alternative forest exploitation on the improvement of soil C and N accumulation on these soils. This study compared pure and mixed plantations of Eucalyptus grandis and Pseudosamanea guachapele, a N2-fixing leguminous tree, in relation to their effects on […]

Soil elasticity as affected by water and organic carbon content

João Alfredo Braida, Jose Miguel Reichert, Dalvan Jose Reinert, Letícia Sequinatto

01/Apr/2008

The organic carbon accumulation observed in soils under no-till system can increase the soil elasticity, resulting in a higher resistance to soil compaction. This study was carried out to evaluate the effects of water content and soil organic carbon (SOC) enrichment on soil elasticity. Samples of a Hapludalf and a Typic Hapludox in southern Brazil, both with a significant variation in SOC content, were equilibrated at four different water tensions, and then loaded and unloaded on a uniaxial apparatus. The […]

Soil aggregation and aggregate stability under crop-pasture systems in Mato Grosso do Sul state, Brazil

Júlio Cesar Salton, João Mielniczuk, Cimélio Bayer, Madalena Boeni, Paulo Cesar Conceição, Amoacy Carvalho Fabrício, [...]

01/Feb/2008

Soil management systems, with crops under no-tillage (NT), crops (soybean) in rotation with pastures under NT and permanent pastures (Brachiaria sp.), were evaluated for soil aggregation and aggregate stability. Three long-term experiments (9 and 11 years) in the state of Mato Grosso do Sul were sampled in the layers 0-5, 5-10 and 10-20 cm for determination of the aggregate stability in wet and dry sieving. The mean weight diameter (MWD) and the aggregate stability index (IAS) were calculated. In all experiments, the […]

Organic carbon and nitrogen in aggregates of a Dystrophic Red Latosol under two vegetation covers

Renato Ribeiro Passos, Hugo Alberto Ruiz, Reinaldo Bertola Cantarutti, Eduardo de Sá Mendonça

01/Oct/2007

Soil organic matter is constituted by a vast array of compounds that include active and more stable fractions, with different cycling rates. Management practices affect organic carbon and nitrogen contents, organic matter quality, and soil aggregation. The present study aimed to characterize organic carbon and nitrogen in aggregates of a Dystrophic Red Latosol of Minas Gerais State, Brazil, in an area of native vegetation (Cerradão) and another one that has been for 30 years under conventional corn cultivation. Soil samples […]

Humic substances, microbial activity and labile organic carbon in aggregates of a Dystrophic Red Latosol under two vegetation covers

Renato Ribeiro Passos, Hugo Alberto Ruiz, Eduardo de Sá Mendonça, Reinaldo Bertola Cantarutti, Adailson Pereira de Souza

01/Oct/2007

Organic matter is an indicator of the soil quality. Knowledge about its different components, explaining the influence of management practices on organic matter and soil aggregation, is essential for the sustainability of agricultural systems. In the present work, we evaluated humic substances, microbial activity and labile organic carbon in a Dystrophic Red Latosol from Minas Gerais state, Brazil, under natural vegetation (Cerradão) or under 30-years of conventional corn cultivation. Soil samples were collected from depths of 5-10 and 15-20 cm […]

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