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131.
Hanyeh Sepahvand Reza Mirzaeitalarposhti Torsten Müller 《Archives of Agronomy and Soil Science》2013,59(13):1820-1830
ABSTRACTThe aim of this study was to examine the usefulness of physical and chemical fractionation in quantifying soil organic matter (SOM) in different stabilized fraction pools. Soil samples from three land use types in Lorestan province, Southwest Iran were examined to account for the amount of organic carbon and nitrogen in different SOM fractions. Size/density separation and chemical oxidation methods were applied to separate the SOM fractions including particulate organic matter (POM), Si + C (silt and clay), DOC (dissolved organic C), rSOM (oxidation-resistant organic carbon and nitrogen) and S + SA (sand and stable aggregates). The values obtained for TOC, TN, and HWC were highest in forest lands followed by the range and agricultural lands. Among the SOM fractions, S + SA showed the highest values (5.75, 5.77 and 20.6 g kg?1 for agriculture, range and forest lands respectively) followed by POM, Si + C, rSOM, and DOC. The concentrations of C and N in the labile fractions obtained the higher values than in the stabilized fractions. Forest lands had the highest amounts of organic C and N among all fractions whereas agricultural lands showed highest values for inorganic C content of soils in different fractions. 相似文献
132.
Ingeborg F. Pedersen Peter Srensen Jim Rasmussen Paul J. A. Withers Gitte Holton Rubk 《植物养料与土壤学杂志》2019,182(4):541-551
We investigated the interacting effects of inorganic nitrogen and the main inorganic phosphorus form in dairy manure (dicalcium phosphate, CaHPO4) on growth, nutrient uptake, and rhizosphere pH of young maize plants. In a pot experiment, three levels of CaHPO4 (0, 167, and 500 mg P pot?1) were combined with nitrogen (637 mg N pot?1) applied at five NH4‐N : NO3‐N ratios (0 : 100, 25 : 75, 50 : 50, 75 : 25, and 100 : 0) and a nitrification inhibitor in a concentrated layer of a typical acid sandy soil from Denmark. 15N‐labeled NH4‐N was applied to differentiate the role of nitrification and to partition nitrogen uptake derived from NH4‐N. Among treatments including nitrogen, shoot biomass, rooting and phosphorus uptake were significantly higher at the five‐leaf stage when CaHPO4 was applied with NH4‐N : NO3‐N ratios of 50 : 50 and 75 : 25. In these treatments, rhizosphere pH dropped significantly in direct proportion with NH4‐N uptake. The fertilizers in the concentrated layer had a root‐inhibiting effect in treatments without phosphorus supply and in treatments with pure NO3‐N or NH4‐N supply. Increased nitrogen uptake as NH4‐N instead of NO3‐N reduced rhizosphere pH and enhanced acquisition of applied CaHPO4 by young maize plants, which may have positive implications for the enhanced utilization of manure phosphorus. 相似文献
133.
Environmental effects on soil NO concentrations and root N uptake in beech and spruce forests 下载免费PDF全文
Fang Dong Judy Simon Michael Rienks Jürgen Schäffer Klaus von Wilpert Heinz Rennenberg 《植物养料与土壤学杂志》2016,179(2):244-256
This study aimed to investigate the shifts in net nitrogen (N) uptake and N compounds of fine roots over the vegetation period (i.e., spring, summer, autumn) and correlate this with NO concentration in the soil. Soil NO concentration was measured using gas lysimeters for collection and a chemiluminescence analyzer for quantification. Net N uptake by the roots was determined using the 15N enrichment technique. N pools were quantified using spectrophotometric techniques. Soil NO concentrations at beech and spruce forest sites were highest in spring (June), and lowest in winter (December). Total N of the roots was similar during the seasons and between the two years under study despite considerable variation of different N compounds. Net N uptake generally increased with higher N supply. Correlation analysis revealed a positive relationship between soil NO concentration and net N uptake only for spruce trees. This relationship seemed to be modulated by environmental factors and tree species. 相似文献
134.
D'Agostina A Antonioni C Resta D Arnoldi A Bez J Knauf U Wäsche A 《Journal of agricultural and food chemistry》2006,54(1):92-98
This paper describes a pilot process for obtaining protein isolates from white lupin seed with improved water solubility and technofunctional properties as well as reduced thermal damage. After a careful optimization of the process parameters, two valuable food ingredients were prepared: lupin protein isolate type E, with a useful emulsifying capacity, and lupin protein isolate type F, with a high capability of foam formation and stabilization. The spray-drying process was particularly critical for inducing some thermal damage, but a careful selection of the conditions permitted ingredients having only marginally impaired lysine bioavailability to be obtained. The reproducibility of the protein extraction process was tested on two different lupin varieties. 相似文献
135.
Background, Aim and Scope
Part 1: Behaviour of Polycyclic Musks in Sewage Sludge of Different Treatment Plants in Summer and Winter
Part 2: Investigation of Polycyclic Musks in Soils and Plants
- Preamble. In Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludges.
For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence,
Part 2 examined the adsorption of PCMs to soil, their dissipation and leaching in soil and their uptake by plants.
Background, Aim and Scope Polycyclic Musks (PCMs) enter the environment via the waste water system. Because of their persistence, they can accumulate
in different matrices like sewage sludge or biota. By the use of sewage sludge as a fertilizer, PCMs are transferred to agricultural
soils. Therefore, in Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludge.
For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence,
Part 2 of the study examined the adsorption of PCMs to soil, their dissipation and leaching in soil, and their uptake by plants.
Materials and Methods:
In the screening study, samples of activated sewage sludge were taken both in summer and in winter at 21 treatment plants.
In order to get an overview of the contamination situation, sampling covered different types of treatment plants (in rural,
urban, industrial areas). Analytical methods for the determination of HHCB, AHTN, ADBI, ATTN, AHDI and ATII in the sludge
samples were developed and applied.
Results:
The analytical screening of PCMs showed their presence in activated and dried sewage sludge samples. HHCB and AHTN represented
about 95% of the PCMs investigated. Their concentrations in the activated sludge samples varied between 2.9 and 10.4 mg/kg
dry mass (dm) and 1.1 to 4.2 mg/kg dm, respectively. Although different types of sewage treatment plants were investigated,
similar PCM levels were found, showing the widespread input of these compounds into domestic waste water.
Discussion:
PCM concentrations in activated sludge varied widely. The variation drops substantially when concentrations are related to
the varying dry mass. In dehydrated sludge, PCM concentrations were up to 24 mg/kg dm for HHCB and up to 6.9 mg/kg dm for
AHTN. These high values are comparable to those obtained in other investigations analysing PCMs. If the degradation of organic
mass during anaerobic decomposition is included in the evaluation, the figures obtained are comparable to those for activated
sludge. Elimination in sewage sludge was higher in summer than in winter. Therefore, the contamination of the sludges in winter
reached higher levels compared to the summer.
Conclusions:
The results show that PCMs are widespread contaminants in sewage sludge.
Recommendations and Perspectives:
PCM should be considered in a risk assessment as potential contaminants of sewage sludge destined for agricultural use.
Due to the high PCM levels in sewage sludge, further investigations into the degradation and elimination behaviour in sewage
sludge have to be carried out, including that involving PCM metabolites such as lactone derivatives. 相似文献
136.
Pakdeechanuan P Intarapichet KO Fernando LN Grün IU 《Journal of agricultural and food chemistry》2005,53(4):923-927
Rhodium heterogeneous catalyst was used to catalyze isomerization of linoleic acid in soybean oil to conjugated linoleic acid (CLA). A central composite rotatable design with five levels of three variables, namely, reaction temperature, stirring speed, and reaction time, was used to determine the maximum CLA yield. The formation of CLA during isomerization was greatly dependent on the reaction temperature and time. The CLA content of soybean oil increased from 0.63 to 202.42 mg/g oil when isomerization was done at 200 degrees C, with a stirring speed of 200 rpm for 49 min. Analysis of triacylglycerol positions showed that linoleic acid at any position in a triacylglyceride could possibly be isomerized to CLA. 相似文献
137.
De Wilde T De Meulenaer B Mestdagh F Govaert Y Vandeburie S Ooghe W Fraselle S Demeulemeester K Van Peteghem C Calus A Degroodt JM Verhé R 《Journal of agricultural and food chemistry》2005,53(16):6550-6557
A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment. 相似文献
138.
Agriculture as a source of phosphorus causing eutrophication in Central and Eastern Europe 总被引:5,自引:0,他引:5
139.
E López Agüero N Bosch Bosch C Barrera Vázquez B López Ruiz 《Journal of agricultural and food chemistry》1999,47(11):4682-4685
A new, simple, precise, and rapid ion chromatography (IC) method has been developed to determine chloride in mustard sauces using a mixture of phthalic acid, acetone, and water adjusted to pH 5.0 as eluent. Conductometric detection was carried out. The retention time for chloride was 1.5 min. Linearity was obtained up to a concentration level of 100 mg/L NaCl. The method was statistically evaluated for accuracy and precision after being used to assay the chloride from mustard sauces. Within the same samples, the chloride levels obtained by IC were compared with the sodium concentrations quantified by atomic absorption spectrophotometry. 相似文献
140.
Mathias?FosuEmail author Ronald?F.?Kühne Paul?L.?G.?Vlek 《Biology and Fertility of Soils》2003,39(2):117-122
In order to understand the efficiency of residue-N use and to estimate the minimum input required to obtain a reasonable level of crop response, it is important to quantify the fate of the applied organic-N. The recovery of N from 15N-labelled Crotalaria juncea was followed in the soil and the succeeding maize crop. Apparent N recovery (ANR) by maize from unlabelled Crotalaria juncea, Crotalaria retusa, Calopogonium mucunoides, Mucuna pruriens and mineral fertilizer at three locations were also evaluated. The maize crop recovered 4.7% and 7.3% of the 15N-labelled C. juncea-N at 42 days after sowing (DAS) and at final harvest, respectively. The corresponding 15N recovery from the soil was 92.4% and 58.5%. The highest mean ANR of 57.4% was with mineral fertilizer, whereas the mean ANR of 14.3% from C. retusa was the lowest. A large pool substitution and added-N interaction effect was observed when comparing N recovery from the labelled and unlabelled C. juncea. The amount of residue-N accounted for by the isotope dilution method at 42 DAS was 97.1% and at final harvest 65.8%. The large residue-N recovery in the soil organic-N pool explains the residual effect usually observed with organic residue application. 相似文献