The use of sewage sludge in the agricultural is an organic recycle alternative material in the soil. The CONAMA resolution 375/2006 indicates that in certain relief condition the sewage sludge could be applied without soil incorporation, making it possible to use in areas with no-till. The present study was carried out with the aim to evaluate nitrogen and carbon mineralization dynamics during the sewage sludge and oat straw decomposition in the surface or in the soil incorporation. The treatments consisted of the sewage sludge application, in the presence and in the absence of oat straw, with and without soil incorporation. During 110 days of incubation, the CO2 emission and the mineral N dynamics was evaluated after the organic materials soil application. The sewage sludge soil incorporation not affected by the C and N mineralization. In the treatment with only sewage sludge 30% of C and 50% of N added with the sewage sludge were mineralized in 110 days. The application of sewage sludge with the straw of oats increased the C mineralization of oat straw only when those organic materials remained in the soil surface. The N immobilization is not affected by the sewage sludge incorporation and oat straw in the soil, however it is stimulated in the presence of the straw. / O uso agrícola do lodo é uma alternativa para a reciclagem desse material orgânico no solo. Recentemente a resolução 375/2006 do CONAMA indica que em certas condições de relevo o lodo de esgoto pode ser aplicado sem a necessidade de realizar a sua incorporação ao solo, possibilitando o seu uso em áreas manejadas em sistema plantio direto. O presente trabalho foi conduzido com o objetivo de avaliar a mineralização do carbono e a dinâmica do nitrogênio durante a decomposição de lodo de esgoto e palha de aveia mantidos na superfície ou incorporados ao solo. Os tratamentos consistiram da aplicação de lodo de esgoto, na presença e na ausência de palha de aveia, com e sem incorporação ao solo. Durante 110 dias foi avaliada a evolução do C-CO2 e a dinâmica do N mineral após aplicação dos materiais orgânicos ao solo. A mineralização do C e do N não foi afetada pela incorporação do lodo ao solo. No tratamento com o uso isolado do lodo de esgoto 30% do C e 50% do N adicionados com o lodo foram mineralizados em 110 dias. A aplicação de lodo de esgoto juntamente com a palha de aveia aumentou a mineralização do C da palha somente quando esses materiais orgânicos permaneceram na superfície do solo. A imobilização do N não é afetada pela incorporação conjunta do lodo de esgoto e da palha de aveia ao solo, mas é estimulada na presença da palha.

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Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.

Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.

Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).