scholarly journals Functional relationships between moisture at several equilibrium points and the clay content of tropical soils

1969 ◽  
Vol 35 (2) ◽  
pp. 66-70
Author(s):  
M. A. Lugo López
Keyword(s):  
Equilibrium Points ◽  
Clay Content ◽  
Field Capacity ◽  
Tropical Soils ◽  
Regression Equations ◽  
Saturation Field ◽  
Functional Relationships ◽  
Humid Region ◽  
Moisture Equivalent ◽  
Very High

The tropical soils of the humid region studied in this investigation have been grouped into two broad categories: (a) Lateritic and (b) nonlateritic. Regression equations are presented which may serve to predict any of the moisture constants considered, namely, maximum saturation, field capacity, moisture equivalent, permanent wilting percentage, and hygroscopic coefficient, on the exclusive basis of the clay content of the soils. Very high correlations were obtained in all cases for lateritic soils. Very high correlations were also found for the nonlateritic soils of the humid Tropics, excepting the values for maximum saturation.

scholarly journals Comparative value of various methods of approximating the permanent wilting percentage

1969 ◽  
Vol 36 (2) ◽  
pp. 122-133
Author(s):  
M. A. Lugo López
Keyword(s):  
Puerto Rico ◽  
Organic Matter Content ◽  
Clay Content ◽  
Matter Content ◽  
Regression Equations ◽  
Accurate Approximation ◽  
Time Saving ◽  
Laboratory Equipment ◽  
Pressure Plate ◽  
Humid Region

Very accurate estimations of the permanent wilting percentage can be obtained for soils of all regions of Puerto Rico by use of regression equations based on the hygroscopic coefficient. Reliable estimates can also be obtained for humid-region soils by using the clay content as a basis. Attempts to correlate permanent wilting-percentage values with moisture equivalents and organic-matter content did not give such satisfactory results. The 15-atmosphere percentage as determined by using pressure plates gives an accurate approximation of permanent wilting-percentage values. It is time-saving, but initial expense in laboratory equipment is rather high. This approach is to be preferred whenever feasible. A regression equation is given relating pressure-plate values to the permanent wilting percentage. Whenever less precise estimates are acceptable and time is not a factor, advantage should be taken of the established correlation between the hygroscopic coefficient and the permanent wilting percentage.

Predicting clay content on field-moist intact tropical soils using a dried, ground VisNIR library with external parameter orthogonalization

Geoderma ◽  
2015 ◽  
Vol 259-260 ◽  
pp. 196-204 ◽  
Author(s):  
Jason P. Ackerson ◽  
José A.M. Demattê ◽  
Cristine L.S. Morgan
Keyword(s):  
Clay Content ◽  
Tropical Soils ◽  
External Parameter

Denitrification and immobilisation in flood-irrigated alkaline grey clays as affected by nitrification inhibitors, wheat straw, and soil texture

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 633 ◽  
Author(s):  
I. J. Rochester ◽  
G. A. Constable
Keyword(s):  
Wheat Straw ◽  
Soil Texture ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Clay Content ◽  
Field Capacity ◽  
Nitrification Inhibitors ◽  
N Loss ◽  
Waterlogged Soil ◽  
Nitrate N

Published field studies have shown that etridiazole and other nitrification inhibitors may significantly improve N fertiliser recovery in alkaline grey clays. Laboratory experiments were conducted to examine the extent to which nitrification inhibitors could suppress denitrification directly in waterlogged soil, and determine whether this may contribute significantly to the conservation of N fertiliser in the field. Etridiazole reduced the loss of added nitrate-N from waterlogged soil in the short term (days) only. All other nitrification inhibitors failed to suppress N loss. Little nitrate-N was lost from soil maintained at field capacity, whereas 15–85% of applied nitrate was lost from soil that was waterlogged for 10 days. The addition of milled wheat straw encouraged both denitrification and biological N immobilisation to similar extents, although both processes were probably restricted by C availability. Where no straw was added, little N was immobilised and denitrification was halved. Soil texture (clay content) also had a profound influence on N fertiliser recovery (N loss). The laboratory experiments indicated that a component of the responses to etridiazole observed in published field experiments conducted on these soils could be attributed to direct suppression of denitrification by etridiazole.

scholarly journals Assessment of Water Quality and Soil Salinity in the Agricultural Coastal Plain (Ravenna, North Italy)

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 369 ◽  
Author(s):  
Livia Vittori Antisari ◽  
Maria Speranza ◽  
Chiara Ferronato ◽  
Mauro De Feudis ◽  
Gilmo Vianello ◽  
...  
Keyword(s):  
Oxygen Demand ◽  
Clay Content ◽  
Field Capacity ◽  
Soil Salinization ◽  
Soil Samples ◽  
Winter Period ◽  
Negative Effects ◽  
Soil C ◽  
Salt Leaching ◽  
Water Volumes

To improve knowledge on salt leaching suitability on different soils, in Arenosols and Cambisols croplands in the coastal area of Ravenna (Italy), soil samples were collected in the non-irrigation winter period and irrigation summer period. Concurrently, waters of the canal network were also investigated. Soil samples were analyzed for pH, carbonate, total organic carbon (TOC), particle size distribution, electrical conductivity (EC), bulk density (BD) and water content at field capacity (FC). Water samples were investigated for pH, EC, biological and chemical oxygen demand, sodium adsorption ratio, phosphorus, nitrogen, sulfates and chlorides. All soils had low TOC concentrations and Arenosols showed the lowest clay content, BD and FC. Soils had similar EC values in winter, but in summer the lowest ones were observed in Arenosols, suggesting that irrigation mitigated salinization in Arenosols, while the high clay content, BD and FC prevented or limited the salt leaching in Cambisols. In summer, the increase of total nitrogen and biological oxygen demand, especially in drainage channels, might suggest the leaching of soluble nutrients and organic matter from soils due to the high irrigation water volumes. Finally, our findings stress the need to consider soil type and properties to contrast soil salinization without negative effects on soil C leaching caused by salt leaching practice.

Environmental and chemical factors regulating methane oxidation in a New Zealand forest soil

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 767 ◽  
Author(s):  
Sally J. Price ◽  
Francis M. Kelliher ◽  
Robert R. Sherlock ◽  
Kevin R. Tate ◽  
Leo M. Condron
Keyword(s):  
New Zealand ◽  
Water Content ◽  
Forest Soil ◽  
Oxidation Rate ◽  
Field Capacity ◽  
Soil Disturbance ◽  
Great Sensitivity ◽  
Ch4 Oxidation ◽  
Chemical Factors ◽  
Very High

Tropospheric methane (CH4) is oxidised by soil microbes called methanotrophs. We examined them in soil samples from a pristine Nothofagus forest located in New Zealand. Laboratory incubations indicated the presence of high-affinity methanotrophs that displayed Michaelis–Menton kinetics (Km = 8.4 µL/L where Km is the substrate concentration at half the maximal rate). When the soil was dried from its field capacity water content of 0.34 to 0.16 m3/m3, CH4 oxidation rate increased nearly 7-fold. The methanotrophs were thus metabolically poised for very high activity, but substrate availability was commonly limiting. When water content was held constant, CH4 oxidation rate nearly doubled as temperature increased from 5 to 12°C, a range found in the forest. By contrast, CH4 oxidation rate did not change much from 12 to 30°C, and it was zero at 35°C. When water content and temperature were held constant, the optimal soil pH for CH4 oxidation was 4.4, as found in the forest. Soil disturbance by nitrogen (N) and non-N salt amendment decreased CH4 oxidation rate, but this depended on the amendment species and concentration. The methanotrophs were adapted to native conditions and exhibited a great sensitivity to disturbance.

The relationship between the digestibility of a sward and the herbage consumption of grazing calves

1968 ◽  
Vol 70 (1) ◽  
pp. 47-51 ◽  
Author(s):  
J. Hodgson
Keyword(s):  
Food Intake ◽  
Linear Relationship ◽  
Full Range ◽  
Chromic Oxide ◽  
Regression Equations ◽  
Faecal Output ◽  
Herbage Intake ◽  
The Relationship ◽  
Very High

SUMMARYNitro-chalk was applied to S.23 ryegrass swards, at approximately monthly intervals, at two contrasting levels in 1961 and three levels in 1962. Steer calves, 3–6 months old, grazed in rotation round a series of four paddocks on each treatment. Paddocks were trimmed and fertilizer applied after each grazing. The herbage intakes of the calves were determined on three occasions in 1961 and four occasions in 1962. Faecal output was estimated by chromic oxide dilution. In vitro digestibility determinations were carried out on samples of herbage clipped from the swards.There was a close linear relationship between the digestibility of the herbage and the amount eaten, over the full range of digestibility encountered (68–82%). Regression equations calculated within seasons and fertilizer levels, and within years, did not differ significantly. The regressions of faecal output on herbage digestibility were not significantly different from zero.The observed relationship between herbage digestibility and herbage intake may reflect (a) the greater sensitivity of young ruminants than adult stock to changes in the digestibility of the diet, and (b) the reduced importance of the chemostatic control of food intake, except at very high levels of digestibility, in young rapidly growing animals.

THE MOISTURE EQUIVALENT AS A MEASURE OF THE FIELD CAPACITY OF SOILS

Soil Science ◽  
1931 ◽  
Vol 32 (3) ◽  
pp. 181-194 ◽  
Author(s):  
F. J. VEIHMEYER ◽  
A. H. HENDRICKSON
Keyword(s):  
Field Capacity ◽  
Moisture Equivalent

scholarly journals Barium and Cadmium in Tropical Soils Cropped and Under Native Forest

2021 ◽  
Author(s):  
Iolanda Maria Soares Reis ◽  
Wanderley José de Melo ◽  
Erica Souto Abreu Lima ◽  
Marcos Gervásio Pereira ◽  
Ulisses Sidnei da Conceição Silva ◽  
...  
Keyword(s):  
Multivariate Analyses ◽  
Clay Content ◽  
Tropical Soils ◽  
Native Forest ◽  
Strongly Correlated ◽  
Paulo State ◽  
Potential Availability ◽  
Iron Iron ◽  
Soil Clay ◽  
Soil Clay Content

Abstract Toxic elements pose a high environmental risk because of their long persistence in soil, water, and food chain. This study aimed to estimated potentially available and pseudototal contents of barium (Ba) and cadmium (Cd) in tropical soil under native forest vegetation, sugarcane and maize crops. Soil samples were collected at 0.00–0.20 m depth in different municipalities in São Paulo State, Brazil, and analyzed for fertility, texture, total iron, iron oxides, pseudototal and available Ba and Cd contents. Heavy metals were extracted using different extraction solutions (Mehlich-1, Mehlich-3, and DTPA). Data were subjected to descriptive and multivariate analyses. Correlations between soil clay content, mineralogy, and fertility were also investigated. Of the three extraction solutions tested, Mehlich-3 was the most effective to estimate the potential availability of Ba and Cd. Ba extracted by Mehlich-3 was negatively correlated with goethite, and pseudototal barium was positively correlated with pH CaCl2. Cd extracted by Mehlich-3 was positively correlated with pH CaCl2, and pseudototal cadmium was strongly correlated with iron oxide, clay, and organic matter contents.

scholarly journals HUBUNGAN KETERSEDIAAN AIR TANAH DAN SIFAT-SIFAT DASAR FISIKA TANAH

2004 ◽  
Vol 6 (2) ◽  
pp. 46-50
Author(s):  
Kukuh Murtilaksono ◽  
Enny Dwi Wahyuni
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Organic Matter Content ◽  
Clay Content ◽  
Total Porosity ◽  
Field Capacity ◽  
Sand Content ◽  
Wilting Point

This research was conducted to study relationship between soil moisture content and soil physical characteristics that affected the moisture.The soil samples were collected from 22 scattered sites of West Java and Central Java. Analysis of soil physical properties (texture, bulk density, particle density, total porosity and soil moisture retention) and soil chemical property (organic matter) was conducted at the laboratory of Department of Soil Sciences, Faculty of Agriculture, Bogor Agricultural University. Analysis of simple linier regression was applied to know the correlation between soil moisture content and other basic soil physical properties.Availability of soil moisture (pF 4.20 – pF 2.54) significantly correlated with organic matter, total porosity, and micro pores. The higher organic matter content as well as total porosity and micro pores the higher available soil moisture. Soil moisture of field capacity significantly correlated with clay content, sand content, micro and macro pores. The higher clay content and micro pores the higher soil moisture of field capacity. In the contrary, the higher macro pores and sand content the lower the field capacity. Soil moisture of wilting point significantly correlated with clay content and macro pores. The higher clay content the higher the wilting point, while the higher macro pores the lower soil moisture of wilting point. Keywords : Available soil water, field capacity, organic matter, soil pores, wilting point

scholarly journals THE EFFECT OF USING SOCIAL MEDIA TOWARDS STUDENTS’ READING COMPREHENSION

2020 ◽  
Vol 13 (2) ◽  
Author(s):  
Prima Gusti Yanti ◽  
Fairul Zabadi ◽  
Fauzi Rahman
Keyword(s):  
Social Media ◽  
Reading Comprehension ◽  
Simple Random Sampling ◽  
Descriptive Statistics ◽  
Regression Equations ◽  
Simple Linear Regression ◽  
Reading Tests ◽  
Correlational Method ◽  
Use Of Social Media ◽  
Very High

This study aims to determine the effect of the activity of using social media on the ability of college students to reading comprehension. This type of research is quantitative with a correlational method. The sample in this study was taken with simple random sampling. PBSI FKIP UHAMKA active students approximately 600 students who if taken a sample of 25% at random, would choose 150 students. Data collection techniques using questionnaires and reading tests, while data analysis using descriptive statistics and simple linear regression equations. The results of this study indicate that the intensity of the use of social media in the percentage of students is 45% moderate, 25% low, 25% high, and 7% very high, obtained the regression equation . These findings indicate that the more activity on social media, the lower the level of reading comprehension although not significantly.

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