The objective of this study was evaluate the organic carbon stock and chemical and physical properties of soils in management systems with different deployment times under clayey Red Latosol in western region of Paraná, Brazil. Five managed areas and a reference area (native forest) without anthropic action were analyzed in completely randomized design with five repetitions. Management systems include three areas with different time of first adoption of no-till: 6 years -NT 6 (transition phase), 14 years -NT 14 (consolidation phase) and 22 years -NT 22 (maintenance phase); 16 years of no-till, and in the last four years with integration of maize and ruzigrass (Brachiaria ruziziensis) -(NT+B) and an area of permanent and continuous extensive cattle pasture of coast-cross (Cynodon dactylon) -(Pa). Physical and chemical properties, total soil organic carbon (TOC) stock and carbon stratification index (SI) of soils were evaluated in depths of 0-0.05; 0.05-0.10; 0.10-0.20 and 0.20-0.40 m. The macroporosity (MA) was higher in the area of native forest, ranging from 0.23 to 0.30 m 3 m -3 and the microporosity (MI) was higher in cultivated areas. The areas of NT+B and P presented lower ratio macroporosity/total pore volume (MA/TPV). For soil bulk density (BD) and soil penetration resistance (SPR), the managed areas show higher values, suggesting the occurrence of compacted subsurface layers. Native forest area showed the highest TOC levels in the depths of 0-0.05 and 0.05-0.10 m, reaching 30.5 g kg -1 in the 0-0.05 m soil layer. There was negative change on TOC stocks in the managed areas in relation to forest area, being more evident in the more superficial soil layers. The SI was greater than one, however there is a reduction in function of adoption time of no-till. There was higher soil compaction in the managed areas, and the NT in soybean/maize succession system does not contribute effectively to the increase of TOC stocks. ResumoO objetivo do presente estudo foi avaliar os estoques de carbono, atributos químicos e físicos do solo em sistemas de manejo com diferentes tempos de implantação na região oeste do Paraná, Brasil. Foi utilizado o delineamento inteiramente casualizado com cinco repetições, e as áreas com diferentes tempos de adoção do sistema plantio direto (SPD) foram: 6 anos (fase de transição), 14 anos (fase de consolidação) e 22 anos (fase de manutenção); 16 anos de SPD, sendo nos últimos quatro anos com integração milho safrinha e Brachiaria; uma área de pastagem permanente coast-cross (Cynodon dactylon) e uma área de mata nativa. Os atributos químicos e físicos, o estoque de carbono e o índice de estratificação (IE) foram avaliados nas camadas de 0-0,05, 0,05-0,1, 0,1-0,2 e 0,2-0,4 m. A macroporosidade (MA) foi superior na área de mata, variando de 0,23 a 0,30 m 3 m -3 e a microporosidade (MI) foi superior nas áreas cultivadas. As áreas de SPD+B e pastagem apresentaram menor relação macroporos/volume total de poros (MA/VTP). Tanto para a densidade do solo (DS), quanto para a resistência à pen...

Efeito da época e sistema de semeadura da Brachiaria brizantha em consórcio com o milho, sobre os componentes de produção e propriedades físicas do solo Effect of time of sowing and system Brachiaria brizantha intercropped with maize on yield components and soil physical properties AbstractThe objective of this study was to evaluate the development of Brachiaria brizantha-MG-4; sown in two seasons and two seeding systems in space between two rows, and to evaluate the effect of intercropping on maize yield, as well as evaluating the physical properties of the soil after the consortium. experimental design was randomized blocks as a factorial 2x2, and an additional treatment that was corn cultivation single, with four replications. The treatments consisted two intercropping systems: corn intercropped with Brachiaria brizantha in the row, and corn intercropped with Brachiaria brizantha in space between two rows, and two times of sowing Brachiaria brizantha: simultaneously corn, and twenty-five days after sowing corn. The seed was planted mechanically in no-tillage system, with spacing between the lines of 0,70 m. The ears were harvested by hand and in the laboratory were evaluated: yield components and productivity. Brachiaria brizantha-MG-4 was sown and harvested manually. We evaluated the production of fresh and dry mass and yield components. For soil analyzes the soil was sampled at 0-0.10 and 0,10-0,20 m. Were determined the total porosity, macroporosity and microporosity. The results demonstrated that the production components of Brachiaria brizantha were lower when it was sown twenty-five days after sowing corn, and between sowing systems when Brachiaria brizantha was sown in line. There was no reduction in grain yield of maize intercropped with Brachiaria system independent and sowing date. The consortium of pasture with corn increased the total porosity, and reduced soil bulk density.

The objective of the present study was to gather information on the effects of liming on changes in soil physical attributes. Soil acidity, caused by natural ways, such as rain, weathering and decomposition of organic matter and by human interference, by the use of nitrogen fertilizer mainly ammonia and urea fertilizer contribute to the acidification of the soil. In this context liming is perform to correct soil pH and neutralize the effect of toxic elements. Numerous benefits of liming are known, but their influence on soil physical attributes is poorly studied. Liming directly affects some physical properties of the soil, such as flocculation, aggregates, density and porosity. Flocculation of soil particles initially is smallest, which promotes greater particle dispersion. However, it changes over time, since H+ and Al3+ ions tend to be subsumed by Ca2+ and Mg2+ increasing particle flocculation power which favors its approximation and aggregate formation. For soil aggregates, surface liming in improves soil aggregation by increasing the mean aggregate diameter with positive responses as dose increases. Density and porosity of soil also undergo changes. It is important to point out that liming also has the potential to alter the porous structure of the soil. Porosity liming promotes soil density reduction and increase influenced reducing macroporosity values and increase of total porosity and micropores values. The results of studies carried out present divergent and similar results according to the evaluated physical attributes. This is possibly due to the dynamics between liming under different edaphoclimatic conditions.

No abstract

RESUMO. As perdas de nitrogênio (N) do solo na forma gasosa dependem das características intrínsecas dos solos e das condições ambientais. Em solos da mesma classe textural, a mineralogia da fração argila e o teor de matéria orgânica são os principais fatores que podem afetar a dinâmica do N. No Norte do Estado do Paraná, variações nestas características são encontradas em toposeqüências de solos derivadas do basalto onde no terço superior ocorrem solos altamente intemperizados como os Latossolos e nas outras seções do relevo ocorrem solos mais jovens como Neossolos e eventualmente Vertissolos. O objetivo do presente trabalho foi avaliar as perdas de N por volatilização da amônia, utilizando três solos argilosos (Latossolo Vermelho distroférrico -LVdf, Neossolo litólico -RL e Vertissolo Hidromórfico órtico -VGo) submetidos a duas condições de umidade (S8 e SS) e que foram tratados com uréia. A volatilização da amônia proveniente dos solos foi avaliada em recipientes plásticos de 2000cm 3 que receberam 500g de terra e 200mg de uréia por um período acumulativo de 10 dias. As perdas de N-NH3 foram avaliadas utilizando-se filtros de papel coletores, previamente umedecidos com H2SO4, que foram colocados 5cm da superfície do solo. Os resultados mostraram que os solos apresentaram diferenças quanto às perdas de amônia em função da umidade inicial e da mineralogia da fração argila. No tratamento com baixo teor de água (S8), os solos menos intemperizados (RL e VGo) apresentaram as menores perdas por volatilização da amônia devido a presença de elevadas percentagens de minerais de argila do tipo 2:1. No tratamento, solo saturado (SS), não houve diferenças estatisticamente significantes, nas perdas de N-NH3, entre os solos estudados.Palavras-chave: solos tropicais, fixação, matéria orgânica, teor de água, minerais de argila, ASE.ABSTRACT. Nitrogen losses by ammonia volatilization of three clayey soils treated with urea. The soil nitrogen (N) losses in gaseous form depend on their intrinsic characteristics and also on the environmental conditions. In soils with the same texture class, the mineralogy of the clay size fraction and the amount of organic matter are the main factors that may affect the N dynamics. In the State of Paraná northerner region, variations in these characteristics are found in the toposequence of soils derived from basalts where, in the landscape upper part, highly weathered soils, such as the Latosols, are found and, in the other sections, younger soils, such as Neosols and eventually Vertisols, are found. The aim of the present work was to evaluate the N volatilization losses from ammonia, using three clayey soils (Red Dystroferric Latosol-LVdf, Litholic Neosol-RL and Ortic Hydromorphic Vertisol-VGo) submitted to two soil moisture contents (S8 and SS) and treated with urea. The ammonia volatilization of the applied urea was evaluated in 2000cm 3 plastic recipients that received 500g of soil and 200mg of urea, for an accumulative period of 10 days. Paper filter collectors, previously humidified with H...