Changes in soil C, N and δ15N along three forest–pasture chronosequences in New Zealand

Changes in total soil carbon (C), nitrogen (N) and natural-abundance N isotopes (δ15N) were measured along three forest-to-pasture chronosequences on pumice soils in the Central North Island of New Zealand. On each of the three chronosequences, exotic pine forests had been converted to intensive dairy pastures 2–11 years before sampling and samples were also taken from remaining pine forests and long-term pastures (40–80 years old). The primary objective of the study was to test the hypothesis that surface-soil δ15N would increase over time following conversion of forest to pasture, due to greater N inputs and isotope-fractionating N losses (e.g. ammonia volatilisation) in pasture systems. Results supported our hypothesis, with linear regression revealing a significant (P < 0.001) positive correlation between log-transformed pasture age (log10[pasture age + 1]) and surface-soil δ15N. There was also a positive correlation (P < 0.001) between pasture age and total soil C and N, and a negative correlation of pasture age with C : N ratio. Surface-soil δ15N was also positively correlated (P < 0.001) with total soil N, and negatively correlated with C : N ratio when C : N was <13.6. These results suggested that as soils became more N-‘saturated’, isotope-fractionating N loss processes increased. Surface-soil δ15N in the pine forests was significantly less than subsoil δ15N, but there was no significant difference between the surface and subsoil in the long-term pastures, due to 15N enrichment of the surface soil. The difference in δ15N between the surface soil and subsoil may be a useful indicator of past land management, in addition to absolute δ15N values of surface soils.

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EFFECT OF EXCESS FEEDLOT MANURE ON CHEMICAL CONSTITUENTS OF SOIL UNDER NONIRRIGATED AND IRRIGATED MANAGEMENT

Canadian Journal of Soil Science ◽

10.4141/cjss86-031 ◽

1986 ◽

Vol 66 (2) ◽

pp. 303-313 ◽

Cited By ~ 6

Author(s):

J. F. DORMAAR ◽

T. G. SOMMERFELDT

Keyword(s):

Organic Matter ◽

Chemical Constituents ◽

Soil C ◽

Soil P ◽

Total Soil ◽

Labile Phosphorus ◽

Moisture Regimes ◽

Labile P ◽

Recommended Level

A long-term field experiment was initiated in 1973 to determine the safe loading capacity of a Lethbridge loam (Dark Brown Chernozemic) with feedlot manure. The effect of 10 yr of feedlot manure loading was examined by analyzing a number of inorganic and organic matter constituents of the Ap horizon. Although soil C, P, and enzyme activities increased as feedlot manure additions to the soil increased, these increases diminished at triple the recommended loading regimes. Phosphatase activity was checked by increased labile phosphorus levels. Levels of adenosine 5′-triphosphate increased but fluctuated with time under various moisture regimes. The C:N ratios, percent monosaccharide C of total soil C, and the ratio of deoxyhexoses to pentoses remained constant while the percentage of manure C retained decreased as feedlot manure loading increased. The distribution between pentoses and hexoses was strongly affected by feedlot manure levels while the deoxyhexose percentage of the sum of the eight monosaccharides determined remained about the same. Feedlot manure additions, at triple the recommended level, increased the labile P as a percentage of total soil P to around 50%. Although mineralization did not keep pace with the quantities applied, the presence of undecomposed manure did not seem to have harmful agronomic effects. Key words: ATP, feedlot manure, labile phosphorus, monosaccharides, organic matter

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Seven years of continuously planted Bt corn did not affect mineralizable and total soil C and total N in surface soil

Plant and Soil ◽

10.1007/s11104-008-9836-5 ◽

2008 ◽

Vol 318 (1-2) ◽

pp. 269-274 ◽

Cited By ~ 6

Author(s):

Alexandra N. Kravchenko ◽

Xinmei Hao ◽

G. Philip Robertson

Keyword(s):

Surface Soil ◽

Bt Corn ◽

Total N ◽

Soil C ◽

Total Soil

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No long-term effect of land-use activities on soil carbon dynamics in tropical montane grasslands

10.5194/bg-2017-113 ◽

2017 ◽

Author(s):

Viktoria Oliver ◽

Imma Oliveras ◽

Jose Kala ◽

Rebecca Lever ◽

Yit Arn Teh

Keyword(s):

Land Use ◽

Organic Matter ◽

Co2 Fluxes ◽

Soil Co2 ◽

Soil C ◽

C Dynamics ◽

Total Soil ◽

C Stocks ◽

Montane Grasslands

Abstract. Montane tropical soils are a large carbon (C) reservoir, acting as both a source and a sink of CO2. Enhanced CO2 emissions originate, in large part, from the decomposition and losses of soil organic matter (SOM) following anthropogenic disturbances. Therefore, quantitative knowledge of the stabilization and decomposition of SOM is necessary in order to understand, assess and predict the impact of land management in the tropics. In particular, labile SOM is an early and sensitive indicator of how SOM responds to changes in land use and management practices, which could have major implications for long term carbon storage and rising atmospheric CO2 concentrations. The aim of this study was to investigate the impacts of grazing and fire history on soil C dynamics in the Peruvian montane grasslands; an understudied ecosystem, which covers approximately a quarter of the land area in Peru. A combination of density and particle-size fractionation was used to quantify the labile and stable organic matter pools, along with soil CO2 flux and decomposition measurements. Grazing and burning together significantly increased soil CO2 fluxes and decomposition rates and reduced temperature as a driver. Although there was no significant effect of land use on total soil C stocks, the combination of burning and grazing decreased the proportion of C in the free LF, especially at the lower depths (10–20 and 20–30 cm). The free LF in the control soils made 20 % of the bulk soil mass and 30 % of the soil C content compared to the burnt-grazed soils, which had the smallest recovery of free LF (10 %) and significantly lower C content (14 %). The burnt soils had a much higher proportion of C in the occluded LF (12 %) compared to the non-burnt soils (7 %) and there was no significant difference among the treatments in the heavy F (~ 70 %). The synergistic effect of burning and grazing caused changes to the soil C dynamics. CO2 fluxes were increased and the dominant temperature driver was obscured by some other process, such as changes in plant C and N allocation promoting autotrophic respiration. In addition, the free LF was negatively affected when these two anthropogenic activities took place on the same site. Most likely a result of reduced detritus being incorporated into the soil. A positive finding from this study is that the total soil C stocks were not significantly affected and the long term C storage in the occluded LF and heavy F were not negatively impacted. Possibly this is because of low intensity fire, fire-resilient grasses and the grazing pressure is below the threshold to cause severe degradation.

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Association of BMI with markers of angiogenesis in healthy population

International Journal of Advances in Medicine ◽

10.18203/2349-3933.ijam20183148 ◽

2018 ◽

Vol 5 (4) ◽

pp. 1065

Author(s):

Shivani Jaswal ◽

Harjeet Kaur ◽

Jasbinder Kaur ◽

Seema Gupta

Keyword(s):

Serum Levels ◽

Healthy Population ◽

Study Group ◽

Lifestyle Modifications ◽

Positive Correlation ◽

Increased Risk ◽

Significant Difference ◽

History Of ◽

Student’S T

Background: Obesity is associated with an increased risk of atherosclerosis, which can be mediated by an increase in angiogenesis and inflammation. The objective of the present study was to explore the relationship between BMI and levels of VEGF, a circulating biomarker of angiogenesis.Methods: 225 healthy volunteers in the age group of >18 years formed the subjects of the study. Individuals with any acute or chronic illness including history of HT, DM, and smoking, alcohol or drug abuse or on any long term medication were excluded from the study. Anthropometric measurements were taken, and BMI calculated. Blood samples were taken, and serum levels of VEGF were estimated using commercially available ELISA kits. Student’s ‘t’ test was done for comparison and correlation was assessed using Pearson’s method.Results: A statistically significant difference in the levels of VEGF was found in subjects with BMI < 25 kg/m2 as compared to subjects with BMI > 25 kg/m2 (p<0.001). A significant positive correlation was found between the levels of VEGF and BMI in both males and female subjects of the study group (r=0.68 and 0.73 respectively).Conclusions: The positive correlation of levels of VEGF with BMI in the healthy subjects of the study group may be related to the expansion of adipose tissue and to the concomitant formation of new vessels to support tissue deposition. These factors may predispose an individual to an increased risk of atherosclerotic damage later in life. VEGF may therefore, have a potential as a biomarker for the prediction of cardiovascular risk and estimation may allow intervening with lifestyle modifications and nutritional changes before the disease is manifested and pharmacotherapy is required.

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Modelling long-term changes in soil phosphorus and carbon under contrasting fertiliser and grazing management in New Zealand hill country

Journal of New Zealand Grasslands ◽

10.33584/jnzg.2019.81.397 ◽

2019 ◽

pp. 171-178 ◽

Cited By ~ 2

Author(s):

Franco Bilotto ◽

Ronaldo Vibart ◽

Alec Mackay ◽

Des Costall

Keyword(s):

New Zealand ◽

Current Knowledge ◽

Soil Phosphorus ◽

National Level ◽

Transfer Model ◽

Soil C ◽

Hill Country ◽

C Stocks ◽

Long Term Changes

Soil carbon (C) stocks under permanent New Zealand pastures vary with slope and aspect due to differences in primary production, animal behaviour and nutrient return. An existing nutrient transfer model was extended using a web-based, general-purpose modelling tool to simulate long-term changes in soil phosphorus (P) and C in hill country under contrasting fertiliser and sheep stocking regimes. Three self-contained farmlets were examined: no P applied; 125 kg single superphosphate (SSP)/ha/year; and 375 kg SSP/ha/year, since 1980. The refined spatial model was able to simulate P and C distribution with varying slopes and aspects. For example, the mean annual changes in soil P and C were greater on low slopes and eastern aspects than on the other two slope and aspect positions, consistent with observed changes in these nutrients. However, the model overestimated changes in soil C, which highlighted both gaps in current knowledge and key factors influencing change in soil C stocks. Understanding the spatial patterns of soil C across the landscape will be critical in the design of soil C monitoring regimes, should soil C stocks be considered at a national level as a sink or source of CO2 emissions.

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Stability of Woodchips Biochar and Impact on Soil Carbon Stocks: Results from a Two-Year Field Experiment

Forests ◽

10.3390/f12101350 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1350

Author(s):

Irene Criscuoli ◽

Maurizio Ventura ◽

Katja Wiedner ◽

Bruno Glaser ◽

Pietro Panzacchi ◽

...

Keyword(s):

Climate Change ◽

Field Experiment ◽

Priming Effect ◽

Soil Organic C ◽

Organic C ◽

Soil C ◽

Total Soil ◽

C Stock ◽

The Stability

Biochar has been shown to improve soil quality and crop yields. Furthermore, thanks to its high carbon content (C) and stable chemical structure, biochar can sequester C in the soil for a long time, mitigating climate change. However, the variability in published biochar stability in the soil makes verifying this trait under different environmental and agricultural conditions necessary. Moreover, most of the published literature refers to short-term incubation experiments, which are considered to not adequately represent long-term dynamics under field conditions. This article reports the results of a field experiment carried out in a vineyard near Merano, northern Italy, where the stability of woodchips biochar in soil, its impact on the total soil C stocks as well as on the original soil organic C (priming effect) were studied over two years. Vineyard soil (Dystric Eutrochrept) was amended with biochar (25 and 50 t ha−1) alone or together with compost (45 t ha−1) and compared with unamended control soil. Two methods assessed the stability of biochar in soil: the isotopic mass balance approach and the quantification of Benzene PolyCarboxylic Acids (BPCAs), molecular markers of biochar. The amount of C in the soil organic matter (SOM-C) was determined in the amended plots by subtracting the amount of biochar-C from the total soil organic C stock, and the occurrence of priming effect was verified by comparing SOM-C values at the beginning and at the end of the experiment. Results did not show any significant biochar degradation for both application rates, but results were characterized by a high variation. The application of 50 t ha−1 of biochar significantly increased soil C stock while no effect of biochar on the degradation of SOM-C was observed. Results were confirmed in the case of biochar application together with compost. It can be concluded that the use of woodchips biochar as a soil amendment can increase soil C content in the medium term. However, further analyses are recommended to evaluate the impact of biochar on climate change mitigation in the long term.

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Source and Accumulation of Soil Carbon along Catena Toposequences over 12,000 Years in Three Semi-Natural Miscanthus sinensis Grasslands in Japan

Agriculture ◽

10.3390/agriculture12010088 ◽

2022 ◽

Vol 12 (1) ◽

pp. 88

Author(s):

David S. Howlett ◽

J. Ryan Stewart ◽

Jun Inoue ◽

Masanori Saito ◽

DoKyoung Lee ◽

...

Keyword(s):

Soil Carbon ◽

Accumulation Rate ◽

Miscanthus Sinensis ◽

C4 Plant ◽

Soil C ◽

Radiocarbon Age ◽

Total Soil ◽

Natural Grasslands ◽

The Difference

Miscanthus-dominated semi-natural grasslands in Japan appear to store considerable amounts of soil C. To estimate the long-term effect of Miscanthus vegetation on the accumulation of soil carbon by soil biota degradation in its native range, we measured total soil C from the surface to a 1.2 m depth along a catena toposequence in three annually burned grasslands in Japan: Kawatabi, Soni, and Aso. Soil C stock was estimated using a radiocarbon age and depth model, resulting in a net soil C accumulation rate in the soil. C4-plant contribution to soil C accumulation was further estimated by δ13C of soil C. The range of total soil C varied among the sites (i.e., Kawatabi: 379–638 Mg, Soni: 249–484, and Aso: 372–408 Mg C ha−1). Catena position was a significant factor at Kawatabi and Soni, where the toe slope soil C accumulation exceeded that of the summit. The soil C accumulation rate of the whole horizon in the grasslands, derived C mainly from C4 plant species, was 0.05 ± 0.02 (Average ± SE), 0.04 ± 0.00, and 0.24 ± 0.04 Mg C ha−1 yr−1 in Kawatabi, Soni, and Aso, respectively. Potential exists for long-term sequestration of C under M. sinensis, but the difference in the C accumulation rate can be influenced by the catena position and the amount of vegetation.

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The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

Biogeosciences ◽

10.5194/bg-14-5633-2017 ◽

2017 ◽

Vol 14 (24) ◽

pp. 5633-5646 ◽

Cited By ~ 3

Author(s):

Viktoria Oliver ◽

Imma Oliveras ◽

Jose Kala ◽

Rebecca Lever ◽

Yit Arn Teh

Keyword(s):

Land Use ◽

Organic Matter ◽

Co2 Fluxes ◽

Soil Co2 ◽

Soil C ◽

C Dynamics ◽

Total Soil ◽

C Stocks ◽

Montane Grasslands

Abstract. Montane tropical soils are a large carbon (C) reservoir, acting as both a source and a sink of CO2. Enhanced CO2 emissions originate, in large part, from the decomposition and losses of soil organic matter (SOM) following anthropogenic disturbances. Therefore, quantitative knowledge of the stabilization and decomposition of SOM is necessary in order to understand, assess and predict the impact of land management in the tropics. In particular, labile SOM is an early and sensitive indicator of how SOM responds to changes in land use and management practices, which could have major implications for long-term carbon storage and rising atmospheric CO2 concentrations. The aim of this study was to investigate the impacts of grazing and fire history on soil C dynamics in the Peruvian montane grasslands, an understudied ecosystem, which covers approximately a quarter of the land area in Peru. A density fractionation method was used to quantify the labile and stable organic matter pools, along with soil CO2 flux and decomposition measurements. Grazing and burning together significantly increased soil CO2 fluxes and decomposition rates and reduced temperature as a driver. Although there was no significant effect of land use on total soil C stocks, the combination of burning and grazing decreased the proportion of C in the free light fraction (LF), especially at the lower depths (10–20 and 20–30 cm). In the control soils, 20 % of the material recovered was in the free LF, which contained 30 % of the soil C content. In comparison, the burnt–grazed soil had the smallest recovery of the free LF (10 %) and a significantly lower C content (14 %). The burnt soils had a much higher proportion of C in the occluded LF (12 %) compared to the not-burnt soils (7 %) and there was no significant difference among the treatments in the heavy fraction (F) ( ∼  70 %). The synergistic effect of burning and grazing caused changes to the soil C dynamics. CO2 fluxes were increased and the dominant temperature driver was obscured by some other process, such as changes in plant C and N allocation. In addition, the free LF was reduced when these two anthropogenic activities took place on the same site – most likely a result of reduced detritus being incorporated into the soil. A positive finding from this study is that the total soil C stocks were not significantly affected and the long-term (+10 years) C storage in the occluded LF and heavy F were not negatively impacted. Possibly this is because of low-intensity fire, fire-resilient grasses and because the grazing pressure is below the threshold necessary to cause severe degradation.

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Soil properties and not inputs control carbon, nitrogen, phosphorus ratios in cropped soils in the long-term

SOIL Discussions ◽

10.5194/soild-2-995-2015 ◽

2015 ◽

Vol 2 (2) ◽

pp. 995-1038 ◽

Cited By ~ 2

Author(s):

E. Frossard ◽

N. Buchmann ◽

E. K. Bünemann ◽

D. I. Kiba ◽

F. Lompo ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Microbial Biomass ◽

Soil Properties ◽

Nutrient Concentrations ◽

Nutrient Ratios ◽

Wagga Wagga ◽

Soil C ◽

Positive Correlation

Abstract. Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies explicitly considered the effects of agricultural management practices on soil C : N : P ratio. The aim of this study was to assess how different input types and rates would affect the C : N : P molar ratios of bulk soil, organic matter and microbial biomass in cropped soils in the long-term. Thus, we analysed the C, N and P inputs and budgets as well as soil properties in three long-term experiments established on different soil types: the Saria soil fertility trial (Burkina Faso), the Wagga Wagga rotation/stubble management/soil preparation trial (Australia), and the DOK cropping system trial (Switzerland). In each of these trials, there was a large range of C, N and P inputs which had a strong impact on element concentrations in soils. However, although C : N : P ratios of the inputs were highly variable, they had only weak effects on soil C : N : P ratios. At Saria, a positive correlation was found between the N : P ratio of inputs and microbial biomass, while no relation was observed between the nutrient ratios of inputs and soil organic matter. At Wagga Wagga, the C : P ratio of inputs was significantly correlated to total soil C : P, N : P and C : N ratios, but had no impact on the elemental composition of microbial biomass. In the DOK trial, a positive correlation was found between the C budget and the C to organic P ratio in soils, while the nutrient ratios of inputs were not related to those in the microbial biomass. We argue that these responses are due to differences in soil properties among sites. At Saria, the soil is dominated by quartz and some kaolinite, has a coarse texture, a fragile structure and a low nutrient content. Thus, microorganisms feed on inputs (plant residues, manure). In contrast, the soil at Wagga Wagga contains illite and haematite, is richer in clay and nutrients and has a stable structure. Thus, organic matter is protected from mineralization and can therefore accumulate, allowing microorganisms to feed on soil nutrients and to keep a constant C : N : P ratio. The DOK soil represents an intermediate situation, with high nutrient concentrations, but a rather fragile soil structure, where organic matter does not accumulate. We conclude that the study of C, N, and P ratios is important to understand the functioning of cropped soils in the long-term, but that it must be coupled with a precise assessment of element inputs and budgets in the system and a good understanding of the ability of soils to stabilize C, N and P compounds.

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IMMUNOREACTIVE GROWTH HORMONE IN PLASMA AND URINE IN LONG TERM INSULIN TREATED DIABETICS IN RELATION TO DIABETIC RETINOPATHY

Acta Endocrinologica ◽

10.1530/acta.0.0750064 ◽

1974 ◽

Vol 75 (1) ◽

pp. 64-74 ◽

Cited By ~ 3

Author(s):

Kristian F. Hanssen

Keyword(s):

Growth Hormone ◽

Diabetic Retinopathy ◽

List Type ◽

Positive Correlation ◽

Significant Difference ◽

Median Plasma ◽

Insulin Dependent ◽

The Mean ◽

The Individual

ABSTRACT In 15 long term insulin dependent diabetics with a normal excretion of albumin in the urine (< 25 mg/24 h), plasma immunoreactive growth hormone (IRHGH) was measured serially together with the urinary immunoreactive growth hormone (IRHGH) during 24 hours. A positive correlation was shown between mean plasma IRHGH and urinary IRHGH in the individual patient (0.05 > P > 0.02). No significant difference between median plasma IRHGH in the diabetics and controls was observed. However, urinary IRHGH was higher in the diabetics than in the controls (0.05 > P > 0.02). A near positive correlation was shown between urinary IRHGH and glucosuria (R = 0.50, 0.1 > P > 0.05). No correlation was shown between the degree of diabetic retinography and the mean plasma IRHGH or urinary IRHGH.

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