Improved Method for Manual, Colorimetric Determination of Total Kjeldahl Nitrogen Using Salicylate

Willis, Raymond B.; Montgomery, Michael E.; Allen, Philip R.

doi:10.1021/jf950522b

Cited by 205 publications

(103 citation statements)

References 19 publications

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“…The chloroform-labile C concentration is the difference between fumigated and non-fumigated soil which was multiplied by 2.64 to calculate MBC (Vance et al, 1987). For microbial biomass N (MBN), the ammonium concentration in the K 2 SO 4 extract was determined (Willis et al, 1996;Moore et al, 2000). The difference between fumigated and non-fumigated soil was multiplied by 1.75 to calculate MBN (Moore et al, 2000).…”

Section: Analysesmentioning

confidence: 99%

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Soil water content during and after plant growth influence nutrient availability and microbial biomass

Ran

Shen

Marschner

2017

J. Soil Sci. Plant Nutr.

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Two experiments were conducted to study the effect of soil water content on soil respiration, microbial biomass and nutrient availability in planted and unplanted soil. In the first experiment, wheat was grown in pots for four weeks in soil that was kept dry between one and four weeks. In the second experiment, soil was maintained at 50% of water-holding capacity (WHC) for four weeks and either planted with wheat or left unplanted. After removal from the pots, soil was kept at 50% WHC or quickly dried to 40, 30, 20 or 10% of WHC. The soils were incubated four weeks during which soil respiration, microbial biomass and nutrient availability were measured. In the first experiment, shoot and root biomass and microbial biomass carbon were higher in constantly moist than constantly dry soil, but the reverse was true for available N. In the second experiment, cumulative respiration was two-fold higher in planted than unplanted soil and decreased with water content, with a smaller decrease in planted soil. Microbial biomass carbon on days 5 and 10 was higher at 10% than at 50% WHC in planted soil, but not affected by water content in unplanted soil. We conclude that soil microbes can maintain higher respiration at low water content despite low biomass because activity per unit biomass is high.

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Section: Analysesmentioning

confidence: 99%

“…For determining soil available N (ammonium + nitrate), soil was extracted with 2 M KCl at a 1:5 soil to extractant ratio in a horizontal shaker at 80 rpm for one hour. Ammonium-N in the filtered extracts was measured as described for MBN after Willis et al (1996). Nitrate-N was determined as described in Miranda et al (2001).…”

Section: Analysesmentioning

confidence: 99%

Soil water content during and after plant growth influence nutrient availability and microbial biomass

Ran

Shen

Marschner

2017

J. Soil Sci. Plant Nutr.

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“…SO 4 2− and dissolved Fe concentrations were analyzed by ICP-OES (Thermo Scientific, Schaumburg, IL, USA). TAN was determined by the modified salicylate method [31]. NO 3 − and NO 2 − concentrations were measured colorimetrically using an auto-analyzer (QuickChem 8500, Lachat Instruments, Milwaukee, WI, USA) according to Standard Methods [30].…”

Section: Analysesmentioning

confidence: 99%

Removal of Nitrate from Drinking Water by Ion-Exchange Followed by nZVI-Based Reduction and Electrooxidation of the Ammonia Product to N2(g)

et al. 2017

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Ion-exchange (IX) is common for separating NO 3− from drinking water. From both cost and environmental perspectives, the IX regeneration brine must be recycled, via nitrate reduction to N 2(g) . Nano zero-valent iron (nZVI) reduces nitrate efficiently to ammonia, under brine conditions. However, to be sustainable, the formed ammonia should be oxidized. Accordingly, a new process was developed, comprising IX separation, nZVI-based nitrate removal from the IX regeneration brine, followed by indirect ammonia electro-oxidation. The aim was to convert nitrate to N 2(g) while allowing repeated usage of the NaCl brine for multiple IX cycles. All process steps were experimentally examined and shown to be feasible: nitrate was efficiently separated using IX, which was subsequently regenerated with the treated/recovered NaCl brine. The nitrate released to the brine reacted with nZVI, generating ammonia and Fe(II). Fresh nZVI particles were reproduced from the resulting brine, which contained Fe(II), Na + , Cl − and ammonia. The ammonia in the nZVI production procedure filtrate was indirectly electro-oxidized to N 2(g) at the inherent high Cl − concentration, which prepared the brine for the next IX regeneration cycle. The dominant reaction between nZVI and NO 3 − was described best (Wilcoxon test) by 4Fe (s) + 10H + + NO 3 − → 4Fe 2+ + NH 4 + + 3H 2 O, and proceeded at >5 mmol·L −1 ·min −1 at room temperature and 3 < pH < 5.

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“…Já na determinação de nitrogênio por espectrofotometria, é necessária a substituição do cobre por selênio ( WILLIS, 1996). Este também é tóxico e pode causar fadiga, irritabilidade e danos neurológicos.…”

Section: Gerenciamento De Resíduos Sólidos No Laaunclassified

Gerenciamento de Resíduos de Ensaios Químicos de Solo e Planta no Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF)

et al. 2016

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resumo: Este trabalho relata o gerenciamento de resíduos sólidos gerados nas análises de solo e planta do Laboratório de Análise Agroambiental (LAA) do Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF) como experiência única da bibliografia nacional por englobar conjuntamente: identificação dos riscos toxicológicos, descrição da composição química, classificação, redução da geração e tratamento dos resíduos. Por isso, esse gerenciamento de resíduos sólidos está em consonância com a Política Nacional de Resíduos Sólidos -PNRS (Lei nº 12.305, de 2010). Detalham-se a origem, toxicidade e tratamento dos resíduos tóxicos do LAA e as medidas adotadas para diminuição do passivo ambiental gerado. Os resíduos desse laboratório advêm das análises químicas de solo e tecido vegetal, dentre os quais se destacam pela toxicidade: o cianeto que é tratado por oxidação a gás carbônico; e o cromo que é tratado por precipitação, reduzindo seu volume em 90%. O LAA avaliou ainda a possibilidade de reciclagem ou reutilização como pigmento cerâmico do resíduo contendo cromo. O LAA destaca-se por aplicar de forma eficaz a PNRS, mas os resultados apontam necessidade de automatização para viabilizar a reciclagem ou reutilização dos resíduos.

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Improved Method for Manual, Colorimetric Determination of Total Kjeldahl Nitrogen Using Salicylate

Cited by 205 publications

References 19 publications

Soil water content during and after plant growth influence nutrient availability and microbial biomass

Soil water content during and after plant growth influence nutrient availability and microbial biomass

Removal of Nitrate from Drinking Water by Ion-Exchange Followed by nZVI-Based Reduction and Electrooxidation of the Ammonia Product to N2(g)

Gerenciamento de Resíduos de Ensaios Químicos de Solo e Planta no Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF)

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