scholarly journals Utilization of organic soils in Puerto Rico

1969 ◽  
Vol 35 (2) ◽  
pp. 57-65
Author(s):  
M. A. Lugo López ◽  
J. A. Bonnet
Keyword(s):  
Puerto Rico ◽  
Mineral Soil ◽  
Point Of View ◽  
Organic Soils ◽  
Available Phosphorus ◽  
Physical Point ◽  
Precise Knowledge ◽  
Total Acreage ◽  
Phosphorus And Potassium ◽  
Management And Conservation

There are more than 25,000 acres of organic soils in Puerto Rico, of which approximately 10 percent are under cultivation. They occupy very low topographical positions and in many instances brackish waters affect the profile. They were formed from the accumulation of leaves, twigs, roots, and other materials in lagoons and bays. The characteristic vegetation consists primarily of mangroves associated with other hydrophylic plants. Tiburones muck and Saladar muck make up more than 50 percent of the total acreage of Puerto Rican organic soils. These soils are generally well supplied with humus and nitrogen. Although they seem to be well supplied with calcium, and available phosphorus and potassium, it should be remembered that they contain smaller total amounts of these nutrients than the average mineral soil, because of their lighter weight per unit volume. From the physical point of view they seem to be well adapted to cultivation and rather easy to handle, if a sound program of management and conservation is followed. In cultivated areas yields of 45 tons of ratoon cane per acre have been obtained under the local management methods of the region, without a precise knowledge of the properties of organic soils, which probably require more specialized techniques to attain maximum yields and higher quality crops. The total cost of draining the marshes, where practicable, as well as of getting rid of the harmful salts, if present, will be high, but its beneficial effect on the economy of Puerto Rico can be far reaching.

GROUNDWATER TIME SERIES

1970 ◽  
Vol 1 (3) ◽  
pp. 181-205 ◽  
Author(s):  
ERIK ERIKSSON
Keyword(s):  
Time Series ◽  
Point Of View ◽  
Hydrologic Models ◽  
Physical Point ◽  
Run Off ◽  
Fort Collins ◽  
Statistical Sense ◽  
Full Benefit ◽  
Future Work ◽  
Prediction Problems

The term “stochastic hydrology” implies a statistical approach to hydrologic problems as opposed to classic hydrology which can be considered deterministic in its approach. During the International Hydrology Symposium, held 6-8 September 1967 at Fort Collins, a number of hydrology papers were presented consisting to a large extent of studies on long records of hydrological elements such as river run-off, these being treated as time series in the statistical sense. This approach is, no doubt, of importance for future work especially in relation to prediction problems, and there seems to be no fundamental difficulty for introducing the stochastic concepts into various hydrologic models. There is, however, some developmental work required – not to speak of educational in respect to hydrologists – before the full benefit of the technique is obtained. The present paper is to some extent an exercise in the statistical study of hydrological time series – far from complete – and to some extent an effort to interpret certain features of such time series from a physical point of view. The material used is 30 years of groundwater level observations in an esker south of Uppsala, the observations being discussed recently by Hallgren & Sands-borg (1968).

scholarly journals Influence of Slope Gradient and Aspect on Soil Organic Carbon Content in the Region of Niš, Serbia

2021 ◽  
Vol 13 (15) ◽  
pp. 8332
Author(s):  
Snežana Jakšić ◽  
Jordana Ninkov ◽  
Stanko Milić ◽  
Jovica Vasin ◽  
Milorad Živanov ◽  
...  
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Slope Aspect ◽  
Available Phosphorus ◽  
Organic Carbon Content ◽  
Slope Gradient ◽  
Phosphorus And Potassium ◽  
Uncultivated Land

Topography-induced microclimate differences determine the local spatial variation of soil characteristics as topographic factors may play the most essential role in changing the climatic pattern. The aim of this study was to investigate the spatial distribution of soil organic carbon (SOC) with respect to the slope gradient and aspect, and to quantify their influence on SOC within different land use/cover classes. The study area is the Region of Niš in Serbia, which is characterized by complex topography with large variability in the spatial distribution of SOC. Soil samples at 0–30 cm and 30–60 cm were collected from different slope gradients and aspects in each of the three land use/cover classes. The results showed that the slope aspect significantly influenced the spatial distribution of SOC in the forest and vineyard soils, where N- and NW-facing soils had the highest level of organic carbon in the topsoil. There were no similar patterns in the uncultivated land. No significant differences were found in the subsoil. Organic carbon content was higher in the topsoil, regardless of the slope of the terrain. The mean SOC content in forest land decreased with increasing slope, but the difference was not statistically significant. In vineyards and uncultivated land, the SOC content was not predominantly determined by the slope gradient. No significant variations across slope gradients were found for all observed soil properties, except for available phosphorus and potassium. A positive correlation was observed between SOC and total nitrogen, clay, silt, and available phosphorus and potassium, while a negative correlation with coarse sand was detected. The slope aspect in relation to different land use/cover classes could provide an important reference for land management strategies in light of sustainable development.

scholarly journals Percolation and tortuosity in heart-like cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Rabinovitch ◽  
Y. Biton ◽  
D. Braunstein ◽  
I. Aviram ◽  
R. Thieberger ◽  
...  
Keyword(s):  
Action Potential ◽  
Forest Fire ◽  
Sinus Node ◽  
Heart Tissue ◽  
Point Of View ◽  
Physical Point ◽  
Electrical Currents ◽  
Single Wave ◽  
Heart Arrhythmia ◽  
The One

AbstractIn the last several years, quite a few papers on the joint question of transport, tortuosity and percolation have appeared in the literature, dealing with passage of miscellaneous liquids or electrical currents in different media. However, these methods have not been applied to the passage of action potential in heart fibrosis (HF), which is crucial for problems of heart arrhythmia, especially of atrial tachycardia and fibrillation. In this work we address the HF problem from these aspects. A cellular automaton model is used to analyze percolation and transport of a distributed-fibrosis inflicted heart-like tissue. Although based on a rather simple mathematical model, it leads to several important outcomes: (1) It is shown that, for a single wave front (as the one emanated by the heart's sinus node), the percolation of heart-like matrices is exactly similar to the forest fire case. (2) It is shown that, on the average, the shape of the transport (a question not dealt with in relation to forest fire, and deals with the delay of action potential when passing a fibrotic tissue) behaves like a Gaussian. (3) Moreover, it is shown that close to the percolation threshold the parameters of this Gaussian behave in a critical way. From the physical point of view, these three results are an important contribution to the general percolation investigation. The relevance of our results to cardiological issues, specifically to the question of reentry initiation, are discussed and it is shown that: (A) Without an ectopic source and under a mere sinus node operation, no arrhythmia is generated, and (B) A sufficiently high refractory period could prevent some reentry mechanisms, even in partially fibrotic heart tissue.

scholarly journals Focal transformation, an imaging concept for signal restoration and noise removal

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. A55-A59 ◽  
Author(s):  
A. J. Berkhout ◽  
D. J. Verschuur
Keyword(s):  
Input Data ◽  
Noise Removal ◽  
Point Of View ◽  
Data Interpolation ◽  
Signal Restoration ◽  
Physical Point ◽  
Seismic Processing ◽  
Promising Tool ◽  
Focal Area ◽  
Forward Operator

Interpolation of data beyond aliasing limits and removal of noise that occurs within the seismic bandwidth are still important problems in seismic processing. The focal transform is introduced as a promising tool in data interpolation and noise removal, allowing the incorporation of macroinformation about the involved wavefields. From a physical point of view, the principal action of the forward focal operator is removing the spatial phase of the signal content from the input data, and the inverse focal operator restores what the forward operator has removed. The strength of the method is that in the transformed domain, the focused signals at the focal area can be separated from the dispersed noise away from the focal area. Applications of particular interest in preprocessing are interpolation of missing offsets and reconstruction of signal beyond aliasing. The latter can be seen as the removal of aliasing noise.

GHG mitigation potential of agricultural management practises on mineral and organic soils

2021 ◽  
Author(s):  
Saara Lind ◽  
Marja Maljanen ◽  
Merja Myllys ◽  
Mari Räty ◽  
Sanna Kykkänen ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Agricultural Soils ◽  
Mineral Soil ◽  
Ghg Emissions ◽  
Grassland Management ◽  
Organic Soils ◽  
Carbon Dioxide Exchange ◽  
Ghg Mitigation ◽  
Nutrient Quality ◽  
Effect On Yield

<p>Agricultural soils are a significant source of greenhouse gas (GHG) emissions. To study these emissions, we are currently building three research platforms that consist of full eddy covariance instrumentation for determination of net ecosystem carbon dioxide exchange and fluxes of methane and nitrous oxide. These platforms will be completed with supporting weather, plant and soil data collection. Two of our platforms are sites on organic soils with a thick peat layer (>60 cm) and the third one is on a mineral soil (silt loam). To study the role of the grassland management practises at these sites, we have initiated ORMINURMI-project. Here, we will characterise the effects of ground water table (high vs. low), crop renewal methods (autumn vs. summer) and plant species (tall fescue vs. red glover grass) on greenhouse gas budgets of grass production. Also effect on yield amount and nutrient quality will be determined. In this presentation, we will present the preliminary data collected at these research platforms and our plans for the use of these data in the coming years.</p>

scholarly journals Comparison of Different Approaches to Predict the Performance of Pumps As Turbines (PATs)

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 1016 ◽  
Author(s):  
Mauro Venturini ◽  
Stefano Alvisi ◽  
Silvio Simani ◽  
Lucrezia Manservigi
Keyword(s):  
Simulation Model ◽  
Ad Hoc ◽  
Polynomial Regression ◽  
Point Of View ◽  
Box Model ◽  
Physical Point ◽  
Evolutionary Polynomial Regression ◽  
Box Models ◽  
Performance Curves ◽  
Physics Based Simulation

This paper deals with the comparison of different methods which can be used for the prediction of the performance curves of pumps as turbines (PATs). The considered approaches are four, i.e., one physics-based simulation model (“white box” model), two “gray box” models, which integrate theory on turbomachines with specific data correlations, and one “black box” model. More in detail, the modeling approaches are: (1) a physics-based simulation model developed by the same authors, which includes the equations for estimating head, power, and efficiency and uses loss coefficients and specific parameters; (2) a model developed by Derakhshan and Nourbakhsh, which first predicts the best efficiency point of a PAT and then reconstructs their complete characteristic curves by means of two ad hoc equations; (3) the prediction model developed by Singh and Nestmann, which predicts the complete turbine characteristics based on pump shape and size; (4) an Evolutionary Polynomial Regression model, which represents a data-driven hybrid scheme which can be used for identifying the explicit mathematical relationship between PAT and pump curves. All approaches are applied to literature data, relying on both pump and PAT performance curves of head, power, and efficiency over the entire range of operation. The experimental data were provided by Derakhshan and Nourbakhsh for four different turbomachines, working in both pump and PAT mode with specific speed values in the range 1.53–5.82. This paper provides a quantitative assessment of the predictions made by means of the considered approaches and also analyzes consistency from a physical point of view. Advantages and drawbacks of each method are also analyzed and discussed.

scholarly journals Adsorption of Copper in Soil and its Dependence on Physical and Chemical Properties

2018 ◽  
Vol 66 (1) ◽  
pp. 219-224 ◽  
Author(s):  
Vítězslav Vlček ◽  
Miroslav Pohanka
Keyword(s):  
Soil Properties ◽  
Solid Phase ◽  
Chemical Properties ◽  
Total Content ◽  
Exchange Capacity ◽  
Soil Reaction ◽  
Available Phosphorus ◽  
Copper Adsorption ◽  
Phosphorus And Potassium ◽  
Physical And Chemical

Soil samples (n = 11) were collected in the chernozem areas of the Czech Republic (the Central Europe) from the topsoil and used as representative samples. All sampling areas have been used for agricultural purposes (arable soil) and they were selected as typical representatives of agricultural soil. These samples represented the soil with same genesis (to reduction differencies between soil types) but with different soil properties (physical and chemical). Complete chemical and physical analyses were made for confirmation of copper adsorption on solid phase: we analysed the particle size distribution, content of oxidizable carbon (Cox), the cation exchange capacity (CEC), supply of exchange calcium, magnesium, sodium, phosphorus and potassium, soil reaction and the total supply of Fe, Al, Mn, Ca, Mg, K, P and N. The strongest simple correlation between analysed soil properties and copper concentration had content of available magnesium (r = 0.44) and available phosphorus (r = −0.51). In the case of multiple correlations (i. e. collective influence of multiple soil properties) had the strongest influence combination of clay, soil reaction, total content of phosphorus, available magnesium and available phosphorus. The main influence of phosphorus and magnesium is evident. We suppose that copper and phosphorus enter into specific complex. Influence of these five soil properties can explain 92.7 % (r = 0.927) changes in the content of copper changes in the experiment.

scholarly journals Radioecological assessment of forage agricultural land in the southwestern areas of the Bryansk region based on a set of statistical models

2021 ◽  
Vol 30 (2) ◽  
pp. 38-49
Author(s):  
S.I. Spiridonov ◽  
◽  
V.V. Ivanov ◽  
I.E. Titov ◽  
V.E. Nushtaeva ◽  
...  
Keyword(s):  
Soil Contamination ◽  
Statistical Models ◽  
Agricultural Land ◽  
Sandy Loam ◽  
Probabilistic Approach ◽  
Point Of View ◽  
Content Standards ◽  
Organic Soils ◽  
137Cs Content ◽  
Wide Range

This paper presents a radioecological assessment of forage agricultural land in the southwestern districts of the Bryansk region based on data characterizing the variability of the radionuclides content in the soil. Concentration of 137Cs in forage was calculated taking into account the proba-bility distributions of 137Cs soil contamination density and the soil to plant transfer factor. The pro-cessing data of the radioecological survey has shown the soil contamination density with 137Cs of agricultural lands in the southwestern areas of the Bryansk region obeys a lognormal law. The authors have used statistical models and software modules for the radioecological assessment of forage lands. Risks of exceeding the 137Cs content standards in forage obtained on soils with different texture have been calculated. The limiting levels of contamination of pastures and hay-fields with 137Cs, ensuring compliance with the specified risks for forage, have been estimated. The lowest limiting soil contamination density is characteristic of organic soils, which can be con-sidered “critical” from the point of view of 137Cs intake into forage. The authors have predicted the time of remediation of forage lands in the southwestern districts of the Bryansk region in the ab-sence of protective measures based on a probabilistic approach. The time period during which the risk of forage contamination for sandy, sandy loam and clay loam soils will decrease to 10% varies for the areas under consideration in a wide range, not exceeding 64 years. It is concluded that it is advisable to substantiate the value of the acceptable risk of forage contamination, taking into account radiological and socio-economic aspects.

scholarly journals State of Heavy Metals Pollution of Flooded Agricultural Land in the North Part of Republic of Srpska

2017 ◽  
Vol 17 (1) ◽  
pp. 19
Author(s):  
Tihomir Predić ◽  
Petra Nikić Nauth ◽  
Bojana Radanović ◽  
Alen Predić
Keyword(s):  
Heavy Metals ◽  
Soil Contamination ◽  
Agricultural Land ◽  
Total Content ◽  
Soil Samples ◽  
Available Phosphorus ◽  
The North ◽  
North Part ◽  
Grid Points ◽  
Phosphorus And Potassium

This paper presents the results of the research of soil contamination in flooded area located at the confluence of Bosna and Sava rivers. The sampling was performed according to a network of points Etrs89 reference European Network based on grid points of 500 m x 500 m. The total number of soil samples was 31 and 13 samples of sediment-mud. In the soil samples and sediment-mud samples various parameters were analyzed: pH H2O and 1 M KCl, humus (method by Tjurin), and the readily available phosphorus and potassium (AL method). The interpretation of total content of heavy metals in the soil was conducted according to Dutch Soil Remediation Circular (2009). The samples were analyzed for the total content of heavy metals: Pb, Cd, Cr, Ni, Zn, Cu (aqua regia digestion, AAS) and the elevated concentrations of Ni. However, Ni content in mud was from 240.5 mg/kg to 294.5 mg/kg, in soil it was from 128.9 mg/kg to 452.1 mg/kg. All mud samples were alkaline, and 79% of soil samples were alkaline and of neutral reaction. The analysis indicated that the flood in May 2014 was not caused by soil contamination with heavy metals, which however contributed to the increase of the overall content of these elements in the soil.

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