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Efficiency of organic nitrogen fertilisation of potato in Northeast Portugal

Rodrigues, M.A.; Coutinho, João; Martins, Fernando
Fonte: International Society for Horticultural Science Publicador: International Society for Horticultural Science
Tipo: Conferência ou Objeto de Conferência
ENG
Relevância na Pesquisa
56.41%
The study was conducted over a 4 year period with the purpose of measuring N mineralization using an in situ incubation technique, following the application of farmyard manure, poultry manure or municipal solid waste. The results varied from –10 % (net immobilization) to +28 % (net mineralization) in relation to the total organic N applied. N fluxes were assessed through plant N analysis during the growing season and through determination of potato tuber dry weight (TDW), N uptake by tubers and the apparent N recovery (ANR) of added N at harvest. Organic material applications slightly increased TDW above the control treatment (9 to 25%), although the results indicate a shortage of N, where no N was added to the crop. The effect of organic fertilization on N uptake by tubers was also limited. Petiole nitrate concentration and estimated net N mineralization were in agreement with trends in TDW and N uptake by tubers, with no differences in soil N availability between the control and organic treatments. Values of ANR were particularly low, ranging from 4 to 23 %. The results suggest that caution is needed when judging the contribution of organic fertilization to N nutrition of crops, which have a short growing season. Synchronization between N release and plant uptake is discussed.

Nitrogen mineralized during sorghum growth after soil incorporation of different winter cover crops

Dias, D.; Aguiar, Carlos; Arrobas, Margarida; Rodrigues, M.A.
Fonte: Claudia S.C. Marques dos Santos Cordovil Publicador: Claudia S.C. Marques dos Santos Cordovil
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.15%
Growing catch crops during the autumn/winter period is a strategy of high ecological significance since it allows reducing the residual inorganic-N present in the soil after the summer season (Rodrigues et al., 2002). Thus, winter catch crops reduce the risk of denitrification and nitrate leaching associated to the excess of rain of the autumn/winter months. Incidentally, the evergreen systems confer several other additional benefits, including protection against soil erosion and increasing soil organic matter. In recent years, agronomists and soil scientists have studied the pros and cons of the introduction of cover crops/catch crops in different agro-ecological conditions and cropping systems. Some were focused in comparing the performance of different plant species when they were used as catch crops (Jensen, 1992; Chapot and Robin, 1994). In addition, since winter catch crops precedes summer cash crops, it is important to know the effect of the catch crop in the performance of the cash crop. As a general rule, the catch crop should present good growth rate in winter and improve soil fertility to promote the growth of the summer crop. Theoretically, lupine (Lupinus albus) seems to have both features. It is a species of high biomass production in autumn/winter period (Rodrigues et al....

Introducing Acacia mangium trees in Eucalyptus grandis plantations: consequences for soil organic matter stocks and nitrogen mineralization

Voigtlaender, Maureen; Laclau, Jean Paul; Gonçalves, José Leonardo de Moraes; Piccolo, Marisa de Cassia; Moreira, Marcelo Zacharias; Nouvellon, Yann Pierre; Ranger, Jacques; Bouillet, Jean Pierre
Fonte: SPRINGER; DORDRECHT Publicador: SPRINGER; DORDRECHT
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.41%
Background and aims Eucalyptus plantations cover 20 million hectares on highly weathered soils. Large amounts of nitrogen (N) exported during harvesting lead to concerns about their sustainability. Our goal was to assess the potential of introducing A. mangium trees in highly productive Eucalyptus plantations to enhance soil organic matter stocks and N availability. Methods A randomized block design was set up in a Brazilian Ferralsol soil to assess the effects of mono-specific Eucalyptus grandis (100E) and Acacia mangium (100A) stands and mixed plantations (50A:50E)on soil organic matter stocks and net N mineralization. Results A 6-year rotation of mono-specific A. mangium plantations led to carbon (C) and N stocks in the forest floor that were 44% lower and 86% higher than in pure E. grandis stands, respectively. Carbon and N stocks were not significantly different between the three treatments in the 0-15 cm soil layer. Field incubations conducted every 4 weeks for the two last years of the rotation estimated net soil N mineralization in 100A and 100E at 124 and 64 kg ha(-1) yr(-1), respectively. Nitrogen inputs to soil with litterfall were of the same order as net N mineralization. Conclusions Acacia mangium trees largely increased the turnover rate of N in the topsoil. Introducing A. mangium trees might improve mineral N availability in soils where commercial Eucalyptus plantations have been managed for a long time.; ANR (Agence Nationale de la Recherche) SYSTERRA; ANR (Agence Nationale de la Recherche) SYSTERRA [ANR-2010-STRA-004 (Intensfix)]; ATP Neucapalm (CIRAD); ATP Neucapalm (CIRAD); USP/COFECUB [22193PA]; USP/COFECUB

Dinâmica do nitrogênio no solo e sua implicação na qualidade da água em uma bacia hidrográfica com diferentes tipos de uso de solo com ênfase no papel da floresta ripária; Nitrogen dynamic in the soil and its implication on the water quality of a watershed where different land uses are present with emphasis on the role of riparian forest

Bezerra, Maíra Ometto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 13/10/2009 PT
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36.52%
Embora o nitrogênio seja um nutriente limitado, em excesso, ele pode causar a degradação de sistemas aquáticos. Apesar de, no âmbito nacional, o Brasil não apresentar problemas de escassez hídrica, regiões altamente populosas já tem enfrentado problemas de déficit hídrico, inclusive em função da poluição difusa de nitrogênio. Zonas ripárias têm sido apontadas como um dos atributos da bacia hidrográfica que pode ajudar na melhoria e manutenção da qualidade hídrica devido a sua capacidade de retirar nitrogênio do sistema terrestre oriundo de fontes difusas. Essa característica lhe é conferida por serem ambientes favoráveis ao processo de desnitrificação. A desnitrificação é um dos processos, se não o primeiro, responsável por converter o nitrato para formas gasosas N2O e N2. Considerando que os estudos sobre a função desempenhada por vegetações ripárias como sumidouro de nitrogênio se concentraram em países de clima temperado e que paisagens alteradas são o uso da terra majoritário no Estado de São Paulo, onde o problema de déficit hídrico já é uma realidade. Entender o papel que zonas ripárias desempenham sobre a dinâmica do nitrogênio torna-se fundamental para o desenvolvimento de estratégias de manejo do uso da terra voltadas para a manutenção da qualidade de sistemas aquáticos em regiões tropicais. O objetivo do trabalho é investigar se existe mudança dos processos que regulam a dinâmica do nitrogênio no solo em paisagens alteradas...

Mineralização e disponibilidade de nitrogênio em solos cultivados com cana-de-açúcar; Nitrogen mineralization and availability in soils cropped with sugarcane

Mariano, Eduardo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/01/2011 PT
Relevância na Pesquisa
56.39%
A colheita sem queima da cana-de-açúcar favorece o acúmulo de resíduos na superfície, aumentando os teores de C e N no solo. A quantificação do N mineralizado é de grande interesse, pois a matéria orgânica do solo (MOS) é o principal reservatório de N para as plantas. Embora a mineralização da MOS forneça quantidades apreciáveis de N mineral, a fertilização nitrogenada se faz necessária para a manutenção de produtividades elevadas na cultura. Devido à espessa camada de palha, a aplicação dos fertilizantes nitrogenados é realizada geralmente sobre o solo, intensificando o processo de volatilização de NH3 quando a uréia é utilizada. A primeira parte deste estudo avaliou e comparou métodos biológicos para estimativa do N mineralizável em solos cultivados com cana-de-açúcar. Foram utilizadas amostras de cinco solos, coletadas nas profundidades de 0-20, 20-40 e 40-60 cm. As amostras de solo foram incubadas aerobiamente a 35°C, durante 32 semanas, e anaerobiamente (waterlogged) a 40°C, por 7 dias. Os teores de areia, silte e argila foram os melhores índices para estimar o N mineralizável do solo. Na incubação aeróbia de longa duração, o N mineralizado acumulado apresentou maior sensibilidade em relação N potencialmente mineralizável para a predição da mineralização líquida de N. A incubação anaeróbia de curta duração pode ser utilizada em rotina de laboratórios. A manutenção do N-NH4+ pré-existente nas amostras proporcionou melhores estimativas do N mineralizável do solo com o método da incubação anaeróbia. O segundo experimento avaliou a variação temporal do N inorgânico em um LATOSSOLO VERMELHO distrófico (LVd) e LATOSSOLO VERMELHO-AMARELO eutrófico (LVAe) relacionada à fertilização nitrogenada em soqueiras de cana-de-açúcar. Os tratamentos constaram das fontes: Ajifer®...

Vinhaça concentrada de cana-de-açúcar: monitoramento das propriedades químicas do solo e mineralização líquida de nitrogênio; Concentrated vinasse from sugarcane: monitoring of soil chemical properties and net nitrogen mineralization

Silva, Alinne da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 16/07/2012 PT
Relevância na Pesquisa
56.31%
A geração de grande quantidade de vinhaça resultante da produção de etanol induziu questionamentos a respeito de sua disposição e possível armazenamento. No Estado de São Paulo, a norma P4.231 da CETESB restringiu a aplicação de vinhaça em muitos solos, resultando na necessidade de distribuí-la em áreas distantes da usina. Porém, devido a grande quantidade de água no resíduo, o transporte torna-se inviável do ponto de vista econômico. Uma alternativa para diminuir os custos de transporte é reduzir o volume por evaporação, originando a vinhaça concentrada (VC). No entanto, as temperaturas altas durante o processo de concentração provocam modificações na matéria orgânica, consequentemente, alterando a dinâmica das transformações do N no solo e, considerando ainda que a sua aplicação é realizada na linha de plantio, diferentemente da vinhaça não concentrada (VNC) que é aplicada em área total, pouco se conhece sobre os efeitos no solo e a sua eficiência agronômica. Com o objetivo de (1) conhecer algumas propriedades físico-químicas da VC e compará-la com a VNC, (2) avaliar os efeitos das doses de VC na fertilidade do solo, percolação de íons, produtividade de soqueira de cana-de-açúcar e qualidade tecnológica dos colmos e (3) determinar a mineralização líquida do N (Nm) foram: (I) coletadas amostras de VC e VNC em duas usinas entre os anos de 2010 e 2011...

Assessment of N mineralization and leaching in soil using a new in-situ incubation method

Cabral, F.; Sousa, J.R.; Coutinho, J.
Fonte: Cordovil, C. e Ferreira, L. Publicador: Cordovil, C. e Ferreira, L.
Tipo: Conferência ou Objeto de Conferência
Publicado em /09/2010 ENG
Relevância na Pesquisa
46.36%
RAMIRAN International Conference; Towards sustainable soil management, the application of organic residues to the soil has to be based on criteria sustained by experimental studies. Several methods for estimating the amount of N that mineralizes from landapplied organic residues can be used but laboratory incubations has been the main methodology used due to several advantages related to practical and economical aspects (Qafoku et al., 2001). However, this type of methodology is performed under controlled temperature and moisture content, at optimal conditions for the mineralization process, limiting the extrapolation of laboratory derived values to the field conditions (Hanselman et al., 2004). Since N mineralization process can be affected by the dynamic of these factors, several authors consider field incubations as a more realistic method to assess N mineralization (Subler et al., 1995; Halselman et al., 2004). Nevertheless, the quality of the results obtained depends on the type of reactor devices used for measuring N mineralization under these conditions. In fact, various reactors devices described in the specific literature, like buried bags (Eno, 1960) or covered cylinders (Raison et al., 1987), reveal some disadvantages or limitations in monitoring N mineralization in field conditions. More recently...

Effect of compaction on microbial activity and carbon and nitrogen transformations in two oxisols with different mineralogy

Silva,Sérgio Ricardo; Silva,Ivo Ribeiro da; Barros,Nairam Félix de; Sá Mendonça,Eduardo de
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2011 EN
Relevância na Pesquisa
56.44%
The use of machinery in agricultural and forest management activities frequently increases soil compaction, resulting in greater soil density and microporosity, which in turn reduces hydraulic conductivity and O2 and CO2 diffusion rates, among other negative effects. Thus, soil compaction has the potential to affect soil microbial activity and the processes involved in organic matter decomposition and nutrient cycling. This study was carried out under controlled conditions to evaluate the effect of soil compaction on microbial activity and carbon (C) and nitrogen (N) mineralization. Two Oxisols with different mineralogy were utilized: a clayey oxidic-gibbsitic Typic Acrustox and a clayey kaolinitic Xantic Haplustox (Latossolo Vermelho-Amarelo ácrico - LVA, and Latossolo Amarelo distrófico - LA, respectively, in the Brazil Soil Classification System). Eight treatments (compaction levels) were assessed for each soil type in a complete block design, with six repetitions. The experimental unit consisted of PVC rings (height 6 cm, internal diameter 4.55 cm, volume 97.6 cm³). The PVC rings were filled with enough soil mass to reach a final density of 1.05 and 1.10 kg dm-3, respectively, in the LVA and LA. Then the soil samples were wetted (0.20 kg kg-1 = 80 % of field capacity) and compacted by a hydraulic press at pressures of 0...

Incubation methods for assessing mineralizable nitrogen in soils under sugarcane

Mariano,Eduardo; Trivelin,Paulo Cesar Ocheuze; Leite,José Marcos; Megda,Michele Xavier Vieira; Otto,Rafael; Franco,Henrique Coutinho Junqueira
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
Relevância na Pesquisa
56.42%
Considering nitrogen mineralization (N) of soil organic matter is a key aspect for the efficient management of N fertilizers in agricultural systems. Long-term aerobic incubation is the standard technique for calibrating the chemical extraction methods used to estimate the potentially mineralizable N in soil. However, the technique is laborious, expensive and time-consuming. In this context, the aims of this study were to determine the amount of soil mineralizable N in the 0-60 cm layer and to evaluate the use of short-term anaerobic incubation instead of long-term aerobic incubation for the estimation of net N mineralization rates in soils under sugarcane. Five soils from areas without previous N fertilization were used in the layers 0-20, 20-40 and 40-60 cm. Soil samples were aerobically incubated at 35 ºC for 32 weeks or anaerobically incubated (waterlogged) at 40 ºC for seven days to determine the net soil N mineralization. The sand, silt and clay contents were highly correlated with the indexes used for predicting mineralizable N. The 0-40 cm layer was the best sampling depth for the estimation of soil mineralizable N, while in the 40-60 cm layer net N mineralization was low in both incubation procedures. Anaerobic incubation provided reliable estimates of mineralizable N in the soil that correlated well with the indexes obtained using aerobic incubation. The inclusion of the pre-existing NH4+-N content improved the reliability of the estimate of mineralizable N obtained using anaerobic incubation.

Effects of fire on soil nitrogen dynamics and microbial biomass in savannas of Central Brazil

Nardoto,Gabriela Bielefeld; Bustamante,Mercedes Maria da Cunha
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2003 EN
Relevância na Pesquisa
56.42%
The objective of this work was to study the effects of fire on net N mineralization and soil microbial biomass in burned and unburned cerrado stricto sensu sites. The study was carried out from April 1998 to April 2000. The pH values were significantly higher in the burned site while soil moisture content was significantly higher in the unburned site (P<0.05). The soil C/N ratio was 22/1 and the available NO3-N ranged between 1.5 and 2.8 mg kg-¹ dry weight. However, the NH4-N concentration ranged between 3 and 34 mg kg-1 dry weight in the burned site and between 3 and 22 mg kg-1 dry weight in the unburned site. The NH4-N increased after fire, but no significant changes were observed for NO3-N (P<0.05). The NO3-N accumulation occurred in short periods during the rainy season. The rates of net N mineralization increased during the rainy season while reductions in soil microbial biomass were observed at both sites. This suggested that the peak in microbial activities occurred with the first rain events, with an initial net immobilization followed by net mineralization. Both sites presented the same pattern for mineralization/immobilization, however, the amount of inorganic-N cycled annually in unburned site was 14.7 kg ha-1 per year while the burned site presented only 3.8 kg ha-¹ of inorganic-N...

Inorganic nitrogen availability after severe stand-replacing fire in the Greater Yellowstone ecosystem

Turner, Monica G.; Smithwick, Erica A. H.; Metzger, Kristine L.; Tinker, Daniel B.; Romme, William H.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.53%
Understanding ecosystem processes as they relate to wildfire and vegetation dynamics is of growing importance as fire frequency and extent increase throughout the western United States. However, the effects of severe, stand-replacing wildfires are poorly understood. We studied inorganic nitrogen pools and mineralization rates after stand-replacing wildfires in the Greater Yellowstone Ecosystem, Wyoming. After fires that burned in summer 2000, soil ammonium concentration peaked in 2001 (33 mg NH4-N· kgsoil−1); soil nitrate increased subsequently (2.7 mg NO3-N·kgsoil−1 in 2003) but was still low. However, annual net ammonification rates were largely negative from 2001 to 2004, indicating ammonium depletion. Thus, although net nitrification rates were positive, annual net nitrogen mineralization (net ammonification plus net nitrification) remained low. Aboveground net primary production (ANPP) increased from 0.25 to 1.6 Mg·ha−1·yr−1 from 2001 to 2004, but variation in ANPP among stands was not related to net nitrogen mineralization rates. Across a broader temporal gradient (stand age zero to >250 yr), negative rates of net annual ammonification were especially pronounced in the first postfire year. Laboratory incubations using 15N isotope pool dilution revealed that gross production of ammonium was reduced and ammonium consumption greatly exceeded gross production during the initial postfire years. Our results suggest a microbial nitrogen sink for several years after severe...

Soil warming alters nitrogen cycling in a New England forest: implications for ecosystem function and structure

Butler, S. M.; Melillo, J. M.; Johnson, J. E.; Mohan, J.; Steudler, P. A.; Lux, H.; Burrows, E.; Smith, R. M.; Vario, C. L.; Scott, L.; Hill, T. D.; Aponte, N.; Bowles, F.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.11%
Global climate change is expected to affect terrestrial ecosystems in a variety of ways. Some of the more well-studied effects include the biogeochemical feedbacks to the climate system that can either increase or decrease the atmospheric load of greenhouse gases such as carbon dioxide and nitrous oxide. Less well-studied are the effects of climate change on the linkages between soil and plant processes. Here, we report the effects of soil warming on these linkages observed in a large field manipulation of a deciduous forest in southern New England, USA, where soil was continuously warmed 5°C above ambient for 7 years. Over this period, we have observed significant changes to the nitrogen cycle that have the potential to affect tree species composition in the long term. Since the start of the experiment, we have documented a 45% average annual increase in net nitrogen mineralization and a three-fold increase in nitrification such that in years 5 through 7, 25% of the nitrogen mineralized is then nitrified. The warming-induced increase of available nitrogen resulted in increases in the foliar nitrogen content and the relative growth rate of trees in the warmed area. Acer rubrum (red maple) trees have responded the most after 7 years of warming...

Post-Fire Spatial Patterns of Soil Nitrogen Mineralization and Microbial Abundance

Smithwick, Erica A. H.; Naithani, Kusum J.; Balser, Teri C.; Romme, William H.; Turner, Monica G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/11/2012 EN
Relevância na Pesquisa
56.41%
Stand-replacing fires influence soil nitrogen availability and microbial community composition, which may in turn mediate post-fire successional dynamics and nutrient cycling. However, fires create patchiness at both local and landscape scales and do not result in consistent patterns of ecological dynamics. The objectives of this study were to (1) quantify the spatial structure of microbial communities in forest stands recently affected by stand-replacing fire and (2) determine whether microbial variables aid predictions of in situ net nitrogen mineralization rates in recently burned stands. The study was conducted in lodgepole pine (Pinus contorta var. latifolia) and Engelmann spruce/subalpine fir (Picea engelmannii/Abies lasiocarpa) forest stands that burned during summer 2000 in Greater Yellowstone (Wyoming, USA). Using a fully probabilistic spatial process model and Bayesian kriging, the spatial structure of microbial lipid abundance and fungi-to-bacteria ratios were found to be spatially structured within plots two years following fire (for most plots, autocorrelation range varied from 1.5 to 10.5 m). Congruence of spatial patterns among microbial variables, in situ net N mineralization, and cover variables was evident. Stepwise regression resulted in significant models of in situ net N mineralization and included variables describing fungal and bacterial abundance...

In Situ Nitrogen Mineralization, Nitrification, and Ammonia Volatilization in Maize Field Fertilized with Urea in Huanghuaihai Region of Northern China

Zhang, Xuelin; Wang, Qun; Xu, Jun; Gilliam, Frank S.; Tremblay, Nicolas; Li, Chaohai
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/01/2015 EN
Relevância na Pesquisa
46.31%
Nitrogen (N) fertilization potentially affects soil N mineralization and leaching, and can enhance NH3 volatilization, thus impacting crop production. A fertilizer experiment with five levels of N addition (0, 79, 147, 215 and 375 kg N ha-1) was performed in 2009 and 2010 in a maize field in Huanghuaihai region, China, where > 300 kg N ha-1 has been routinely applied to soil during maize growth period of 120 days. Responses of net N mineralization, inorganic N flux (0–10cm), NH3 volatilization, and maize yield to N fertilization were measured. During the growth period, net N mineralization and nitrification varied seasonally, with higher rates occurring in August and coinciding with the R1 stage of maize growth. Soil NO3−-N contributed to more than 60% of inorganic N flux during maize growth. Cumulative NH3 volatilization increased with N additions, with total NH3 volatilization during maize growth accounting for about 4% of added N. Relative to the control, mean maize yield in the fertilizer treatments increased by 17% and 20% in 2009 and 2010, respectively. However, grain yield, aboveground biomass, and plant N accumulation did not increase with added N at levels > 215 kg N ha-1. These results suggest that the current N rate of 300 kg N ha-1 is not only excessive...

Effects of fire on soil nitrogen dynamics and microbial biomass in savannas of Central Brazil.

NARDOTO, G.B.; BUSTAMANTE, M.M. da C.
Fonte: Pesquisa Agropecuária Brasileira, Brasília, v.38, nº 8, p.955-962, ago. 2003. Publicador: Pesquisa Agropecuária Brasileira, Brasília, v.38, nº 8, p.955-962, ago. 2003.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
56.42%
The objective of this work was to study the effects of fire on net N mineralization and soil microbial biomass in burned and unburned cerrado stricto sensu sites. The study was carried out from April 1998 to April 2000. The pH values were significantly higher in the burned site while soil moisture content was significantly higher in the unburned site (P<0.05). The soil C/N ratio was 22/1 and the available NO3-N ranged between 1.5 and 2.8 mg kg-1 dry weight. However, the NH4-N concentration ranged between 3 and 34 mg kg-1 dry weight in the burned site and between 3 and 22 mg kg-1 dry weight in the unburned site. The NH4-N increased after fire, but no significant changes were observed for NO3-N (P<0.05). The NO3-N accumulation occurred in short periods during the rainy season. The rates of net N mineralization increased during the rainy season while reductions in soil microbial biomass were observed at both sites. This suggested that the peak in microbial activities occurred with the first rain events, with an initial net immobilization followed by net mineralization. Both sites presented the same pattern for mineralization/immobilization, however, the amount of inorganic-N cycled annually in unburned site was 14.7 kg ha-1 per year while the burned site presented only 3.8 kg ha-1 of inorganic-N...

Gross and net nitrogen transformation rates and availability in late summer in tall shrub and birch hummock ecosystems of the Canadian low Arctic

Zufelt, Erik
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 3478016 bytes; application/msword
EN
Relevância na Pesquisa
76.5%
Climate change is occurring most rapidly in the Arctic where warming has been twice as fast as the rest of the globe over the last few decades. Arctic soils contain a vast store of carbon and warmer arctic soils may mediate current atmospheric CO2 concentrations and global warming trends. Warmer soils could increase nutrient availability to plants, leading to increased primary production and sequestration of CO2. Presumably because of these effects of warming on shrub ecosystems, shrubs have been expanding across the arctic over the last 50 years, Arctic shrub expansion may track or cause changes in nutrient cycling and availability that favour growth of larger, denser shrubs. This study aimed at measuring gross and net nitrogen cycling rates, major soil nitrogen and carbon pool sizes, and elucidating controls on nutrient cycling and availability between a mesic birch (Betula nana) hummock tundra ecosystem and an ecosystem of dense, tall, birch (B. nana) shrubs. Nitrogen cycling and availability was enhanced at the tall shrub ecosystem compared to the birch hummock ecosystem. Net nitrogen immobilization by microbes was approximately threefold greater at the tall shrub ecosystem. This was in part because of larger microbial biomass nitrogen and carbon (interpreted as a larger microbial community) at the tall shrub ecosystem. Nitrogen inputs via litter were significantly larger at the tall shrub ecosystem and were hypothesized to be the major contributor to the higher dissolved organic and inorganic nitrogen pools in the soil at the tall shrub ecosystem. The results from this study suggest a positive feedback mechanism between litter nitrogen inputs and the enhancement of nitrogen cycling and availability as a driver of shrub expansion across the Arctic.; Summary 1. Nitrogen cycling was enhanced at the tall shrub ecosystem. The immobilization rate was approximately three times higher at the tall shrub ecosystem than at the birch hummock ecosystem. There was a net nitrogen immobilization by microbes in the soil at both the birch hummock and the tall shrub ecosystem late in the growing season. 2. Microbial biomass carbon (MBC) and nitrogen (MBN) were greater at the tall shrub ecosystem. The greater MBC and MBN at the tall shrub ecosystem may explain why net immobilization was greater at the tall shrub ecosystem because the greater microbial biomass at the tall shrub ecosystem can be expected to immobilize more nitrogen. 3. MBC:MBN was lower at the tall shrub ecosystem...

Nematode abundance and diversity in relation to soil nitrogen dynamics within three Canadian low arctic ecosystems

Laidlaw, Meghan Jr
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 2929974 bytes; application/pdf
EN
Relevância na Pesquisa
46.02%
Soil nematode predation on microbial populations can speed up microbial turnover rates, increase nitrogen mineralization and the availability of N in soils, and ultimately enhance plant N uptake. However, this soil food web interaction has not been tested in arctic soils, where plants are limited by N and there is often net immobilization of N by soil microbes during the growing season. Experiments were conducted to determine the spatial and temporal factors regulating nematode abundance and diversity in the arctic, and to establish whether the interaction between nematode grazing and microbial N cycling is also evident in arctic ecosystems. The field experiment was conducted in tall birch, birch hummock and lichen heath low arctic ecosystems over a growing season. Nematode abundances were highest in the tall birch plots, corresponding with the largest pools of DON and NH4+-N and previously recorded higher rates of N cycling. Microbial biomass did not differ significantly between ecosystem types. Therefore, larger soil N pool sizes in tall birch sites may be explained by faster N cycling rates due to nematode grazing on microbes at these sites. Nematode communities were strongly dominated by bacterial and fungal feeders in generally equal proportions...

APPRAISAL OF THE SNAP MODEL FOR PREDICTING NITROGEN MINERALIZATION IN TROPICAL SOILS UNDER EUCALYPTUS

Smethurst,Philip James; Gonçalves,José Leonardo de Moraes; Pulito,Ana Paula; Gomes,Simone; Paul,Keryn; Alvares,Clayton Alcarde; Arthur Júnior,José Carlos
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 EN
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The Soil Nitrogen Availability Predictor (SNAP) model predicts daily and annual rates of net N mineralization (NNM) based on daily weather measurements, daily predictions of soil water and soil temperature, and on temperature and moisture modifiers obtained during aerobic incubation (basal rate). The model was based on in situ measurements of NNM in Australian soils under temperate climate. The purpose of this study was to assess this model for use in tropical soils under eucalyptus plantations in São Paulo State, Brazil. Based on field incubations for one month in three, NNM rates were measured at 11 sites (0-20 cm layer) for 21 months. The basal rate was determined in in situ incubations during moist and warm periods (January to March). Annual rates of 150-350 kg ha-1 yr-1 NNM predicted by the SNAP model were reasonably accurate (R2 = 0.84). In other periods, at lower moisture and temperature, NNM rates were overestimated. Therefore, if used carefully, the model can provide adequate predictions of annual NNM and may be useful in practical applications. For NNM predictions for shorter periods than a year or under suboptimal incubation conditions, the temperature and moisture modifiers need to be recalibrated for tropical conditions.

Soil carbon and nitrogen dynamics along replicated chronosequences of abandoned agricultural lands in southeastern Ontario

Foote, Robyn Louise
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 1476391 bytes; application/pdf
EN; EN
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Widespread abandonment of agricultural land has occurred in northeastern North America over the past two centuries. Soil carbon often increases as sites naturally regenerate towards perennial grasslands or forests. Understanding the large-scale controls on the potential and rate of soil carbon sequestration is necessary in order to evaluate the significance of this sink to the global carbon cycle. Furthermore, we need to understand the key roles soil microorganisms play in regulating ecosystem processes through their control over soil carbon and nitrogen dynamics. Such studies are rare at the century long time scale of temperate forest succession. Additionally, research has taken place primarily on productive agricultural soils, while abandonment is more common on marginal agricultural soils. We characterized patterns of total and labile soil carbon and nitrogen and microbial dynamics in mature forest and adjacent agricultural field sites, and in replicated chronosequences of forest successional sites on marginal soils of southeastern Ontario, Canada. Total soil carbon was significantly depleted in the top 10 cm of current agricultural fields as compared to forest sites and increased at a rate of 10 g C m-2 yr-1 across our 100-year chronosequences. There was no difference in carbon loss or accumulation over time in three soil types differing in texture and parent material...

Net mineralization nitrogen and soil chemical changes with application of organic wastes with 'Fermented Bokashi Compost'

Boechat,Cácio Luiz; Santos,Jorge Antonio Gonzaga; Accioly,Adriana Maria de Aguiar
Fonte: Editora da Universidade Estadual de Maringá - EDUEM Publicador: Editora da Universidade Estadual de Maringá - EDUEM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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The use of organic wastes in agricultural soils is one of the possible ways to employ these materials. The aims of this study were to evaluate the effectiveness of organic wastes and Fermented Bokashi Compost (FBC), to establish the most efficient use of organic wastes for a soil, changing the net nitrogen mineralization and soil chemical properties. The experimental design was completely randomized in a 6 x 2 x 5 factorial, being five organic wastes plus an control (soil without waste), with or without FBC, evaluated at 0, 7, 42, 70 and 91 days of incubation, with three replicates, under laboratory conditions. The organic wastes enhanced the soil chemical properties and increased nitrogen concentration in soil. However, the net nitrogen mineralization was affected by C/N ratio of wastes and incubation time. The FBC mixed with the wastes accelerated and enhanced organic matter degradation, resulting in quickly available quantity of net nitrogen. The wastes can be considered potentially useful as organic fertilizer but their usefulness appears to depend on knowing the C/N ratio of each one. The FBC can be used when one wants a more accelerated degradation, resulting in a quicker quantity of available nutrients to the plants.