Nitrogen fluxes in surface soils of young Eucalyptus nitens plantations in Tasmania

Soil Research ◽  
2002 ◽  
Vol 40 (3) ◽  
pp. 543 ◽  
Author(s):  
M. T. Moroni ◽  
P. J. Smethurst ◽  
G. K. Holz
Keyword(s):  
Forest Site ◽  
N Availability ◽  
Soil Core ◽  
Eucalyptus Nitens ◽  
Surface Soils ◽  
Mineral N ◽  
Eucalypt Plantations ◽  
Wide Range ◽  
Study Sites

Nitrogen (N) fluxes in surface soils (0–10 cm) were measured by an in situ soil-core technique at 5 sites supporting 1- to 4-year-old Eucalyptus nitens plantations in Tasmania. Rates of net N mineralisation (NNM) ranged from 13 to 188 kg N/ha.year. The highest rate was from an ex-pasture site, which was almost double the highest rate of NNM measured on an ex-forest site. Although there was a tendency towards lower rates of NNM in uncultivated versus cultivated soils, and in the final versus previous year or two of measurement, these differences were not significant. Concentrations of mineral N, however, decreased at all study sites during the first 3–4 years, significantly at 4 of these sites. Within the errors of measurement, most N that was mineralised was also nitrified and leached. Seasonal patterns in NNM and concentrations of nitrate (NO3–) occurred only at one site, which also had the highest annual rate of NNM. The balance of mineral N remaining in surface soil each October was 2–17 kg N/ha. We concluded that there was little evidence of a decrease in rates of NNM between 1 and 4 years after planting, and that high rates of NNM at some sites were accompanied by high rates of leaching that limited the accumulation of mineral N. Sitespecific management of N fertiliser may be warranted to compliment the wide range of N availability in eucalypt plantations. mineralisation, nitrification, leaching, uptake, forests, Australia.

Nitrogen fluxes in surface soils of 1 - 2-year-old eucalypt plantations in Tasmania

Soil Research ◽  
1998 ◽  
Vol 36 (1) ◽  
pp. 17 ◽  
Author(s):  
X. J. Wang ◽  
P. J. Smethurst ◽  
G. K. Holz
Keyword(s):  
Late Summer ◽  
Soil Core ◽  
N Mineralisation ◽  
Surface Soils ◽  
Mineral N ◽  
Total N ◽  
Available N ◽  
Organic C ◽  
Linear Relationships ◽  
Eucalypt Plantations

To improve our understanding of nitrogen (N) supply in eucalypt plantations in Tasmania, N fluxes were determined in surface soils (0–10 cm) at 4 sites supporting 1–2-year-old plantations of E. nitens. Net N mineralisation, nitrification, leaching, and uptake were measured by an in situ soil-core technique. Soils were derived from basalt (3 sites) or mudstone (1 site). Average rates of net N mineralisation ranged from 18 to 91 kg N/ha·year, and most mineralised N was nitrified and leached. There were significant linear relationships among net N mineralisation, nitrification, and leaching (r = 0·61–0·83). Annual rates of net N mineralisation varied as much within sites as between them, and rates in individual plots were significantly correlated with anaerobically mineralisable N (r = 0·82) or total N (r = 0·66), but were not correlated or only weakly correlated with C: N ratio, loss-on-ignition, organic C, water content, or temperature. Leaching was weakly correlated with effective rainfall (rainfall minus evaporation, r = 0·39). Soil contained most mineral N during February–April (i.e. late summer–early autumn) and least during October–November (i.e. late spring). We concluded that available N at these sites was highly variable spatially and temporally, and at a plot scale was closely related to concentrations of mineralisable substrate and not to soil water or temperature.

scholarly journals Remote sensing of ecosystem light use efficiency with MODIS-based PRI

2011 ◽  
Vol 8 (1) ◽  
pp. 189-202 ◽  
Author(s):  
A. Goerner ◽  
M. Reichstein ◽  
E. Tomelleri ◽  
N. Hanan ◽  
S. Rambal ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Vapour Pressure Deficit ◽  
Ground Truth ◽  
Light Use Efficiency ◽  
Wide Range ◽  
Evaluation Exercise ◽  
Use Efficiency ◽  
Study Sites ◽  
Absorbed Photosynthetically Active Radiation

Abstract. Several studies sustained the possibility that a photochemical reflectance index (PRI) directly obtained from satellite data can be used as a proxy for ecosystem light use efficiency (LUE) in diagnostic models of gross primary productivity. This modelling approach would avoid the complications that are involved in using meteorological data as constraints for a fixed maximum LUE. However, no unifying model predicting LUE across climate zones and time based on MODIS PRI has been published to date. In this study, we evaluate the effectiveness with which MODIS-based PRI can be used to estimate ecosystem light use efficiency at study sites of different plant functional types and vegetation densities. Our objective is to examine if known limitations such as dependence on viewing and illumination geometry can be overcome and a single PRI-based model of LUE (i.e. based on the same reference band) can be applied under a wide range of conditions. Furthermore, we were interested in the effect of using different faPAR (fraction of absorbed photosynthetically active radiation) products on the in-situ LUE used as ground truth and thus on the whole evaluation exercise. We found that estimating LUE at site-level based on PRI reduces uncertainty compared to the approaches relying on a maximum LUE reduced by minimum temperature and vapour pressure deficit. Despite the advantages of using PRI to estimate LUE at site-level, we could not establish an universally applicable light use efficiency model based on MODIS PRI. Models that were optimised for a pool of data from several sites did not perform well.

Indices of soil nitrogen availability in five Tasmanian Eucalyptus nitens plantations

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 719 ◽  
Author(s):  
M. T. Moroni ◽  
P. J. Smethurst ◽  
G. K. Holz
Keyword(s):  
Soil Solution ◽  
Nitrogen Availability ◽  
Native Forest ◽  
N Availability ◽  
Eucalyptus Nitens ◽  
Soil Nitrogen Availability ◽  
Mineral N ◽  
Total N ◽  
Available N ◽  
Total P

Several soil analyses were used to estimate available N in surface soils (0–10 cm) over a 2-year period at 5 sites that supported 1- to 4-year-old Eucalyptus nitens plantations, and once in subsoils (10–120 cm) at 3 of these sites. Soils were derived from basalt (1 site previously pasture, 1 Pinus radiate, and 2 native forest) or siltstone (previously native forest). Soil analyses examined were total N, total P, total C, anaerobically mineralisable N (AMN), hot KCl-extractable N (hot KCl-N), and NH4+ and NO3– in soil solution and KCl extracts. AMN, KCl-extractable NH4+ and NO3–, and soil solution NH4+ and NO3– varied considerably with time, whereas hot KCl-N, total N, total P, and total C were temporally stable except for a gradual decline in total C with time at one site. Only total P was correlated with net N mineralisation (NNM) across all sites (r2 = 0.91, P < 0.05, n = 5). At 2–3 years after planting, soil solution and KCl-extractable NO3– dropped below 0.1 mm N and 1 μg N/g soil, respectively, at sites with NNM ≤24 kg N/ha.year (n = 3). Sites with NNM ≤24 kg N/ha.year also had ≤0.8 Mg P/ha. Although concentrations of indices of soil N availability decreased with depth, the contribution of subsoil (10–120 cm depth) to total profile N availability was estimated to be at least twice that of the top 10 cm. At an ex-pasture site, high concentrations of mineral N were found at 75–105 cm depths (KCl-extractable N, 289.3 μg N/g soil; 2.8 mm mineral N in soil solution), which may have become available to plantations as their root systems developed.

The use of diffuse reflectance spectroscopy for in situ carbon and nitrogen analysis of pastoral soils

Soil Research ◽  
2008 ◽  
Vol 46 (7) ◽  
pp. 623 ◽  
Author(s):  
Bambang H. Kusumo ◽  
C. B. Hedley ◽  
M. J. Hedley ◽  
A. Hueni ◽  
M. P. Tuohy ◽  
...  
Keyword(s):  
Diffuse Reflectance Spectroscopy ◽  
Soil Surface ◽  
Soil Core ◽  
Least Squares Regression ◽  
Soil C ◽  
Wide Range ◽  
In Situ Assessment ◽  
Soil C And N ◽  
C And N

A field method has been developed for rapid in situ assessment of soil carbon (C) and nitrogen (N) content using a portable spectroradiometer (ASD FieldSpecPro). The technique was evaluated at 7 field sites in permanent pasture, and in 1-year, 3-year, and 5-year pine-to-pasture conversions on Pumice, Allophanic, and Tephric Recent Soils in the Taupo and Rotorua region of New Zealand. A total of 210 samples were collected from 2 depths: 37.5 and 112.5 mm. Field measurement of diffuse spectral reflectance was recorded from a flat sectioned horizontal soil surface of a soil core using a purpose-built contact probe attached by fibre optic cable to the spectroradiometer. A 15-mm soil slice was collected from each cut surface for analysis of total C and N using a LECO Analyser. Soils had a wide range of total C and N (0.26–11.21% C, 0.02–1.01% N). Partial least-squares regression analysis was used to develop calibration models between smoothed-first derivative 5-nm-spaced spectral data and LECO-measured total C and N. The models successfully predicted total C and N in the validation sets with the best prediction for C (RPD 2.01, r2 0.75, RMSEP 1.21%) and N (RPD 2.66, r2 0.86, RMSEP 0.07%). Prediction accuracy using different selection methods of calibration and validation set is reported. This study indicates that in situ assessment of soil C and N by field spectroscopy has considerable potential for spatially rapid measurement of soil C and N in the landscape.

scholarly journals Available Nitrogen in the Surface Mineral Layer of Natural Meadows

2017 ◽  
Vol 65 (5) ◽  
pp. 1483-1492
Author(s):  
Željko S. Dželetović ◽  
Nevena Lj. Mihailović
Keyword(s):  
N Availability ◽  
Aerobic Incubation ◽  
Mineral Layer ◽  
Mineral N ◽  
Total N ◽  
Available N ◽  
Organic C ◽  
Wide Range ◽  
Surface Mineral ◽  
Total Organic C

Based on a greenhouse experiment, we evaluated nitrogen availability in the surface mineral layer of soil under various natural meadow stands by analyzing the following soil characteristics: total organic C, total N, initial content of easily available N inorganic forms, mineralized N content obtained by aerobic and anaerobic incubations and A-value. The experiment was performed on a test plant and through the application of urea enriched with 5.4 % 15N. The investigated soils under natural meadows are characterized with comparatively high mineralization intensity and high N availability indices. Contents of mineral N produced by aerobic incubation and the intensity of the mineralization correlate with the total organic C in the soil and the total N in the soil. Correlation of the availability index of the soil N produced by aerobic incubation with the total organic C and the total N in the soil under natural meadows is almost linear (r = 0.9981 and r = 0.9997, respectively). Contents of mineral N produced by anaerobic incubation, as well as the corresponding N availability and mineralization intensity indices correlate poorly with the mentioned parameters. Efficiency of nitrogen utilization from the applied N-fertilizer by the test crop varies within a wide range of values and correlates with the biomass yields of the test crop.

scholarly journals Use of In Situ Soil Solution Electric Conductivity to Evaluate Mineral N in Commercial Orchards: Preliminary Results

Horticulturae ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 39
Author(s):  
Elena Baldi ◽  
Maurizio Quartieri ◽  
Enrico Muzzi ◽  
Massimo Noferini ◽  
Moreno Toselli
Keyword(s):  
Pearson Correlation ◽  
Fertilizer Application ◽  
N Availability ◽  
Silty Clay ◽  
Soil Electrical Conductivity ◽  
Mineral N ◽  
Preliminary Results ◽  
Pearson Coefficient ◽  
High Pearson Correlation Coefficient

The aim of the present experiment was to evaluate the effectiveness of soil electrical conductivity (EC) measurement as a fast tool to assess mineral nitrogen (N) in orchards, in order to define precise N inputs that can help farmers to reduce useless fertilizer application. During one vegetative season, seven orchards of different species, supplied with mineral or organic fertilization, were monitored. Nitrate soil concentration was measured monthly by laboratory analyses, while soil EC and moisture were recorded continuously by soil probes. Nitrate and EC were positively correlated, laying the foundation for the identification of a fast and reliable index. However, while some dates showed a high Pearson correlation coefficient, no correlation was found for others. The correlation was not affected by type of fertilizer, and was higher in silty-clay-loam than in loam soils. Pooling all of the data, a significant correlation with a Pearson coefficient of 0.75 was found. The soil optimal nitrate N availability was defined by an EC in the range of 0.3 to 0.6 mS cm−1. Although these are only preliminary results, our data are promising, showing a good suitability of soil EC measurement as a means to monitor soil mineral N availability.

scholarly journals Remote sensing of ecosystem light use efficiency with MODIS-based PRI – the DOs and DON'Ts

2010 ◽  
Vol 7 (5) ◽  
pp. 6935-6969 ◽  
Author(s):  
A. Goerner ◽  
M. Reichstein ◽  
E. Tomelleri ◽  
N. Hanan ◽  
S. Rambal ◽  
...  
Keyword(s):  
Meteorological Data ◽  
Vapour Pressure Deficit ◽  
Ground Truth ◽  
Light Use Efficiency ◽  
Wide Range ◽  
Evaluation Exercise ◽  
Use Efficiency ◽  
Study Sites ◽  
Absorbed Photosynthetically Active Radiation

Abstract. Several studies sustained the possibility that a photochemical reflectance index (PRI) directly obtained from satellite data can be used as a proxy for ecosystem light use efficiency (LUE) in diagnostic models of gross primary productivity. This modelling approach would avoid the complications that are involved in using meteorological data as constraints for a fixed maximum LUE. However, no unifying model predicting LUE across climate zones and time based on MODIS PRI has been published to date. In this study, we evaluate the efficiency with which MODIS-based PRI can be used to estimate ecosystem light use efficiency at study sites of different plant functional types and vegetation densities. Our objective is to examine if known limitations such as dependance on viewing and illumination geometry can be overcome and a single PRI-based model of LUE (i.e. based on the same reference band) can be applied under a wide range of conditions. Furthermore, we were interested in the effect of using different faPAR (fraction of absorbed photosynthetically active radiation) products on the in-situ LUE used as ground truth and thus on the whole evaluation exercise. We found that estimating LUE at site-level based on PRI reduces uncertainty compared to the approaches relying on a maximum LUE reduced by minimum temperature and vapour pressure deficit. Despite the advantages of using PRI to estimate LUE at site-level, we could not establish an universally applicable light use efficiency model based on MODIS PRI. Models that were optimised for a pool of data from several sites did not perform well.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Site specific agricultural soil management with the use of new technologies

2013 ◽  
Vol 16 (1) ◽  
pp. 59-67
Keyword(s):  
New Technologies ◽  
Digital Interface ◽  
Appropriate Treatment ◽  
Wide Range ◽  
Soil Variation ◽  
Soil Information ◽  
Remote Sensing Techniques ◽  
Agricultural Areas

<p>The Soil Science Institute of Thessaloniki produces new digitized Soil Maps that provide a useful electronic database for the spatial representation of the soil variation within a region, based on in situ soil sampling, laboratory analyses, GIS techniques and plant nutrition mathematical models, coupled with the local land cadastre. The novelty of these studies is that local agronomists have immediate access to a wide range of soil information by clicking on a field parcel shown in this digital interface and, therefore, can suggest an appropriate treatment (e.g. liming, manure incorporation, desalination, application of proper type and quantity of fertilizer) depending on the field conditions and cultivated crops. A specific case study is presented in the current work with regards to the construction of the digitized Soil Map of the regional unit of Kastoria. The potential of this map can easily be realized by the fact that the mapping of the physicochemical properties of the soils in this region provided delineation zones for differential fertilization management. An experiment was also conducted using remote sensing techniques for the enhancement of the fertilization advisory software database, which is a component of the digitized map, and the optimization of nitrogen management in agricultural areas.</p>

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

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