Estimated nitrogen concentrations in humus based on initial nitrogen concentrations in foliar litter: a synthesis. XII. Long-term decomposition in a Scots pine forest

2000 ◽  
Vol 77 (12) ◽  
pp. 1712-1722
Author(s):  
Björn Berg ◽  
Ryszard Laskowski ◽  
Amalia Virzo Santo
Keyword(s):  
Linear Relationship ◽  
Limit Values ◽  
Significant Linear Relationship ◽  
Limit Value ◽  
N Concentration ◽  
Linear Relationships ◽  
Significant Difference ◽  
Nitrogen Concentrations ◽  
Scots Pine Forest

The final (limit) values for litter decomposition were estimated and, by extrapolating a linear relationship between accumulated litter mass loss and litter N concentration, the N concentration at the limit value (Nlimit) was estimated. The values for Nlimit were compared with those of the A01 layer (Nhumus) and of newly shed litter (Ninit). No difference was found between the A01 and A02 layers when their N concentrations were compared with the values for Nlimit. There was a highly significant linear relationship between Nlimit and Ninit (R2 = 0.769 and p < 0.001). Likewise, there was a highly significant linear relationship between Nhumus and Ninit. When these two linear relationships were compared, there was no significant difference in slope, while there was a significant difference in the intercepts of 6.76 and 7.25 mg·g-1 for Nhumus and Ninit, respectively. Thus, for a given site in our investigation, the estimated value for N concentration in humus would be 6.8% lower than the measured one.

Maximum decomposition limits of forest litter types: a synthesis

1996 ◽  
Vol 74 (5) ◽  
pp. 659-672 ◽  
Author(s):  
Björn Berg ◽  
Maj-Britt Johansson ◽  
Gunnar Ekbohm ◽  
Charles McClaugherty ◽  
Flora Rutigliano ◽  
...  
Keyword(s):  
Litter Decomposition ◽  
Forest Litter ◽  
Limit Values ◽  
Limit Value ◽  
Needle Litter ◽  
Linear Relationships ◽  
Asymptotic Function ◽  
Linear Regressions ◽  
Negative Linear Relationship

We used long-term litter decomposition data to estimate final decomposition levels using an asymptotic function. The estimated final limit values for decomposition were compared with available chemical data for the different litter types. A total of 41 limit values were estimated from as many different decomposition studies, and 20 different litter types were incubated in eight different forest systems. The limit values estimated varied with litter type. They ranged from about 35 to about 100% decomposition and were linearly related to the initial litter concentrations of N, Mn, and Ca in the newly shed litter. For these three nutrients, there are causal relationships to lignin degradation and to the lignin-degrading microbial community. Using all available data, we made simple and multiple linear regressions and obtained a negative linear relationship between limit value and initial N concentration ([Formula: see text]; n = 41; p < 0.001). For needle litter alone, we obtained a better relationship ([Formula: see text]; n = 23; p < 0.001). Manganese concentrations in litter gave a positive relationship ([Formula: see text]; n = 25; p < 0.001), with a clear improvement when needle litter was tested for alone ([Formula: see text]; n = 16; p < 0.001). Calcium alone gave a barely significant relationship. When combining nutrients in multiple linear relationships we obtained high R2 values, indicating that the models were good. Thus for all sites and litter types, N, Mn, and Ca combined gave an [Formula: see text] value of 0.640 with n = 25 (p < 0.001). All needle litters combined gave an [Formula: see text] of 0.745 (n = 16; p < 0.001). The significance of this finding is discussed. Keywords: litter decomposition, limit values, maximum decomposition, nitrogen, manganese, calcium.

scholarly journals Using crop analysis in the precision nutrient supply system of maize

2012 ◽  
pp. 183-186
Author(s):  
Zoltán Izsáki
Keyword(s):  
Grain Yield ◽  
Nutrient Supply ◽  
Limit Values ◽  
Leaf Analysis ◽  
Yield Level ◽  
Limit Value ◽  
P Concentration ◽  
Maize Leaves ◽  
K Concentration

The effect of the N, P and K supplies of soil on the grain yield and N, P and K status of maize was studied in a long-term mineral fertilisation experiment between 2001 and 2008 and nutrient supply limit values were determined to plant analysis. Based on the interaction between the N concentrtion of maize leaves measured at the beginnig of tasseling and grain yield, the satisfactory limit value of N supply to reach 10–14 t ha-1 yield was between 2.0–4.0%. Leaf analysis at the beginning of tasselling indicated that better P and K supplies were associated with a higher P and K concentration in the maize leaves. Correlation analysis on the P concentration of the maize leaves and the grain yield showed that at a grain yield level of 10–14 t ha-1 a P concentration of 0.20–0.37% represented a satisfactory P supply level. The satisfactory K supply limit value to reach 10–14t ha-1 grain yield was 1.5–2.6%.

Biozeolite capping for reducing nitrogen load of the ancient canal in Yangzhou City

2012 ◽  
Vol 66 (2) ◽  
pp. 336-344 ◽  
Author(s):  
Tinglin Huang ◽  
Zhenming Zhou ◽  
Jinlan Xu ◽  
Yuhua Dong ◽  
Gai Wang
Keyword(s):  
Biofilm Formation ◽  
Surface Sediments ◽  
Ammonia Nitrogen ◽  
Effective Technique ◽  
Overlying Water ◽  
Significant Difference ◽  
Reduction Efficiency ◽  
Nitrogen Concentrations ◽  
Different Origins

Biozeolite capping for reducing nitrogen (N) load of an eutrophic canal in Yangzhou City was studied. Biofilm formation on biozeolite was cultivated by use of isolated nitrifiers and denitrifiers. Varying conditions including dissolved oxygen (DO) and origins of isolated bacteria were considered in our experiments. Long-term sediment incubation experiment results showed that the reduction efficiency of total nitrogen (TN) of overlying water by biozeolite capping were in the range of 47.61–57.64% under the condition of DO&lt;1 mg L−1. There was no obvious difference in TN reduction efficiency between natural biozeolite (indigenous bacteria) and artificial biozeolite (isolated bacteria). However, the reduction efficiency of TN and nitrate nitrogen (NO3−-N) were respectively in the ranges of 67.38–76.12% and 69.38–76.12% under the condition of DO 1.5–5 mg L−1. The reduction efficiencies of TN and NO3−-N by artificial biozeolite were improved by 25.99–27.25% and 17.50–24.15% respectively than those by natural biozeolite. Moreover, no significant difference was found for reducing N load by the isolated bacteria with different origins. TN contents of surface sediments and ammonia nitrogen concentrations of sediment interstitial water in biozeolite capping systems declined obviously after experiments. Biozeolite capping is an effective technique for reducing N load of the Yangzhou canal.

scholarly journals Study of size-segregated particle (PM1, PM2,5, PM10) concentrations over Greece

2013 ◽  
Vol 10 (2) ◽  
pp. 132-139 ◽  
Keyword(s):  
Regional Scale ◽  
Monitoring Network ◽  
Quality Standard ◽  
Anthropogenic Source ◽  
Data Sets ◽  
Limit Values ◽  
Back Trajectories ◽  
Dust Transport ◽  
Limit Value

This study reports particulate matter levels of various size fractions (PM10, PM2.5, and PM1) and identify their controlling factors, in various locations over Greece. It combines long-term data sets involving particle concentrations as measured in the island of Crete in the Eastern Mediterranean and the Greater Area of Athens. Measurements were carried out in various sites at urban (Central Athens and Heraklion, Crete), suburban (Lykovrissi, Athens) and natural background (Finokalia, Crete) locations, for a time period extending from 2004 to 2006. Size-segregated mass measurements of 3 sizes (PM10, PM2.5 and PM1) are reported. The EU annual limit value of 40 μg m-3 for PM10 was exceeded on a yearly basis at both of measurement sites in Athens, while frequent exceedances of the 24-h limit value of 50 μg m-3 were recorded. Concentration levels of PM2.5 and PM1 were also found elevated, when regarded in perspective to either existing limit values (for PM2.5) or levels reported for other large metropolitan areas (for PM1). In addition even at the background station of Finokalia in Crete, average PM10 concentrations exceeded 30 μg m-3. Moreover, at the same station, average concentrations of PM2.5, notably exceed 15 μg m-3 (a characteristic value, relative to the USEPA PM2.5 air quality standard). At all sites coarse particles have been found to comprise a noteworthy portion of total PM10 particles (with PM2.5/PM10 ratios ranging between 45-60%), while fine particle mass concentrations heavily relied on those of particles in the submicron range (PM1/PM2.5 ratios spanning between 55-75%). The short and long-term temporal variability of each fraction were examined and spatial associations were statistically analyzed, in an attempt to identify possible affinities in particle level profiles, effective over a larger regional scale. It has been observed that at several instances, severe particle episodes recorded in the region of Crete have largely affected the Greek mainland and have triggered a response to the monitoring network in Athens. Special focus has been given to events of dust transport from N. Africa, which is found to be more frequent during spring and fall, and during which the PM10 limit value of 50 μg m-3 is violated and concentrations of even finer particle fractions are affected. Air mass back trajectories were studied, for episode days during dust transport events. Data of particle chemical composition were utilized, contributing to an initial identification and characterization of major natural and anthropogenic source types, which determine particle concentrations.

AN ASSESSMENT OF LONG-TERM EFFECTS FROM SPRING AND SUMMER APPLICATIONS OF AMMONIUM NITRATE ON ORCHARDGRASS

1984 ◽  
Vol 64 (3) ◽  
pp. 651-657
Author(s):  
H. T. KUNELIUS ◽  
J. A. MacLEOD ◽  
K. B. McRAE
Keyword(s):  
Ammonium Nitrate ◽  
Sandy Loam ◽  
Dactylis Glomerata ◽  
Long Term Effects ◽  
N Concentration ◽  
Significant Difference ◽  
The Mean ◽  
Dactylis Glomerata L ◽  
Almost All

Orchardgrass (Dactylis glomerata L.) was grown for 5 yr on a fine sandy loam fertilized with ammonium nitrate at 40–120 kg N∙ha−1 applied in either spring or summer or in combination. Stands were cut two or three times during each growing season. Single N applications in spring increased annual yield by about 11% over equivalent summer applications. For split applications no significant difference in annual yield was found regardless of whether the greater fraction was applied in spring or summer. A second order polynomial was found to explain almost all of the variation in the response curve over time for dry matter yield. Application of 120–165 kg N∙ha−1 were required to maintain a uniform yearly production. There was variation in the mean seasonal N concentration over years but with few clear trends. The N concentrations in cuts 1 and 2 were principally determined by the rate of N applied in the spring and summer but there was a carryover effect from the first to the second cut for the highest rate of applied N in the 4th and 5th years.Key words: Dactylis glomerata L., herbage production, tissue N concentration

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Percutaneous glycerol rhizotomy for trigeminal neuralgia in patients with multiple sclerosis: a long-term retrospective cohort study

2020 ◽  
Vol 132 (5) ◽  
pp. 1405-1413 ◽  
Author(s):  
Michael D. Staudt ◽  
Holger Joswig ◽  
Gwynedd E. Pickett ◽  
Keith W. MacDougall ◽  
Andrew G. Parrent
Keyword(s):  
Multiple Sclerosis ◽  
Pain Relief ◽  
Trigeminal Neuralgia ◽  
Retrospective Chart Review ◽  
Medication Usage ◽  
Free Response ◽  
Free Survival ◽  
Time To Recurrence ◽  
Significant Difference

OBJECTIVEThe prevalence of trigeminal neuralgia (TN) in patients with multiple sclerosis (MS-TN) is higher than in the general population (idiopathic TN [ITN]). Glycerol rhizotomy (GR) is a percutaneous lesioning surgery commonly performed for the treatment of medically refractory TN. While treatment for acute pain relief is excellent, long-term pain relief is poorer. The object of this study was to assess the efficacy of percutaneous retrogasserian GR for the treatment of MS-TN versus ITN.METHODSA retrospective chart review was performed, identifying 219 patients who had undergone 401 GR procedures from 1983 to 2018 at a single academic institution. All patients were diagnosed with medically refractory MS-TN (182 procedures) or ITN (219 procedures). The primary outcome measures of interest were immediate pain relief and time to pain recurrence following initial and repeat GR procedures. Secondary outcomes included medication usage and presence of periprocedural hypesthesia.RESULTSThe initial pain-free response rate was similar between groups (p = 0.726): MS-TN initial GR 89.6%; MS-TN repeat GR 91.9%; ITN initial GR 89.6%; ITN repeat GR 87.0%. The median time to recurrence after initial GR was similar between MS-TN (2.7 ± 1.3 years) and ITN (2.1 ± 0.6 years) patients (p = 0.87). However, there was a statistically significant difference in the time to recurrence after repeat GR between MS-TN (2.3 ± 0.5 years) and ITN patients (1.2 ± 0.2 years; p < 0.05). The presence of periprocedural hypesthesia was highly predictive of pain-free survival (p < 0.01).CONCLUSIONSPatients with MS-TN achieve meaningful pain relief following GR, with an efficacy comparable to that following GR in patients with ITN. Initial and subsequent GR procedures are equally efficacious.

scholarly journals A206 EVOLUTION OF PEDIATRIC AUTOIMMUNE CHOLANGITIS AND PRIMARY SCLEROSING CHOLANGITIS INTO ADULTHOOD

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 234-236
Author(s):  
P Willems ◽  
J Hercun ◽  
C Vincent ◽  
F Alvarez
Keyword(s):  
Primary Sclerosing Cholangitis ◽  
Sclerosing Cholangitis ◽  
Response To Treatment ◽  
Similar Proportion ◽  
Autoimmune Cholangitis ◽  
Significant Difference ◽  
One Year ◽  
Liver Tests

Abstract Background The natural history of primary sclerosing cholangitis (PSC) in children seems to differ from PSC in adults. However, studies on this matter have been limited by short follow-up periods and inconsistent classification of patients with autoimmune cholangitis (AIC) (or overlap syndrome). Consequently, it remains unclear if long-term outcomes are affected by the clinical phenotype. Aims The aims of this is study are to describe the long-term evolution of PSC and AIC in a pediatric cohort with extension of follow-up into adulthood and to evaluate the influence of phenotype on clinical outcomes. Methods This is a retrospective study of patients with AIC or PSC followed at CHU-Sainte-Justine, a pediatric referral center in Montreal. All charts between January 1998 and December 2019 were reviewed. Patients were classified as either AIC (duct disease on cholangiography with histological features of autoimmune hepatitis) or PSC (large or small duct disease on cholangiography and/or histology). Extension of follow-up after the age of 18 was done for patients followed at the Centre hospitalier de l’Université de Montréal. Clinical features at diagnosis, response to treatment at one year and liver-related outcomes were compared. Results 40 patients (27 PSC and 13 AIC) were followed for a median time of 71 months (range 2 to 347), with 52.5% followed into adulthood. 70% (28/40) had associated inflammatory bowel disease (IBD) (78% PSC vs 54% AIC; p=0.15). A similar proportion of patients had biopsy-proven significant fibrosis at diagnosis (45% PSC vs 67% AIC; p=0.23). Baseline liver tests were similar in both groups. At diagnosis, all patients were treated with ursodeoxycholic acid. Significantly more patients with AIC (77% AIC vs 30 % PSC; p=0.005) were initially treated with immunosuppressive drugs, without a significant difference in the use of Anti-TNF agents (0% AIC vs 15% PSC; p= 0.12). At one year, 55% (15/27) of patients in the PSC group had normal liver tests versus only 15% (2/13) in the AIC group (p=0.02). During follow-up, more liver-related events (cholangitis, liver transplant and cirrhosis) were reported in the AIC group (HR=3.7 (95% CI: 1.4–10), p=0.01). Abnormal liver tests at one year were a strong predictor of liver-related events during follow-up (HR=8.9(95% CI: 1.2–67.4), p=0.03), while having IBD was not (HR=0.48 (95% CI: 0.15–1.5), p=0.22). 5 patients required liver transplantation with no difference between both groups (8% CAI vs 15% CSP; p=0.53). Conclusions Pediatric patients with AIC and PSC show, at onset, similar stage of liver disease with comparable clinical and biochemical characteristics. However, patients with AIC receive more often immunosuppressive therapy and treatment response is less frequent. AIC is associated with more liver-related events and abnormal liver tests at one year are predictor of bad outcomes. Funding Agencies None

scholarly journals 1005 Antibiotic-Impregnated Calcium Sulfate Beads Are Not Effective in the Primary Prevention of Infection in Open Femur and Tibia Fractures

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
A Fung ◽  
A Ward ◽  
K Patel ◽  
M Krkovic
Keyword(s):  
Primary Prevention ◽  
Infection Rate ◽  
Calcium Sulfate ◽  
Acute Infection ◽  
Open Fractures ◽  
Prevention Of Infection ◽  
Significant Difference ◽  
Tibia Fractures ◽  
Systemic Antibiotics

Abstract Introduction Infection is a major complication of open fractures. Antibiotic-impregnated calcium sulfate (AICS) beads are widely used as an adjuvant to systemic antibiotics. Whilst their efficacy in the secondary prevention of infection is established, we present the first retrospective study evaluating AICS beads in the primary prevention of infection in open fractures. Method 214 open femur and tibia fractures in 207 patients were reviewed over a seven-year period. 148 fractures received only systemic antibiotic prophylaxis. 66 fractures also received AICS beads. The occurrence of acute infection (wound infection and acute osteomyelitis) was recorded, as well as that of long-term complications (chronic osteomyelitis, non-union and death). Results Fractures that received AICS with systemic antibiotics had an overall acute infection rate of 42% (28/66), compared to 43% (63/148) in fractures that received only systemic antibiotics (p &gt; 0.05). There was no significant difference in infection rate even when fractures were stratified by Gustilo-Anderson grade. There was also no significant difference in the rate of long-term complications. Conclusions Our results indicate that the adjuvant use of AICS beads is not effective for the primary prevention of acute infection or long-term complications in open leg fractures. Further research is needed to elucidate the factors influencing the outcomes of AICS use.

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