scholarly journals Nature of Aggregation in Two Tropical Soils of Puerto Rico

1969 ◽  
Vol 52 (3) ◽  
pp. 227-232
Author(s):  
Raul Pérez Escolar ◽  
M. A. Lugo López
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Mechanical Analysis ◽  
Matter Content ◽  
Clay Particles ◽  
General Data ◽  
The Tropics ◽  
Cementing Agent

In both Catalina clay and Cialitos clay there are no marked differences in the properties of the different-sized aggregates and the corresponding whole soils studied. Although well-drained upland soils in the Tropics are supposed to contain less organic matter than those in the cooler Temperate Zones, the organic-matter content of Catalina clay and Cialitos clay was as great as that found in many soils of the same texture in Temperate Zones. Organic matter has a very definite influence as a cementing agent between clay particles. This was shown by the low clay values obtained when or ganic matter was not removed by pretreating the soil with hydrogen per oxide prior to mechanical analysis. From the general data obtained in the study of the aggregates of both soils, it can be inferred that they are formed largely as a result of the breakdown of large massive units of soils. If synthesis occurred to a larger extent, more marked differences could be expected in their constitutional makeup.

scholarly journals The status of phosphorus and other fertility parameters in soils of Puerto Rico

1969 ◽  
Vol 90 (3-4) ◽  
pp. 145-157 ◽  
Author(s):  
David Sotomayor-Ramírez ◽  
Gustavo A. Martínez
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Soil Fertility ◽  
Temporal Dynamics ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Matter Content ◽  
Soil Test ◽  
Commercial Laboratory ◽  
Soil Fertility Status

There is a need to quantitatively assess the soil fertility status of tropical soils. Descriptive summaries help describe the effectiveness of liming programs, nutritional limitation in soils and the relative risk of off-field nutrient transport. A database of 1,168 soil test results collected from 1989 to 1999 from nearly 400 cultivated farms in Puerto Rico was used. Samples were analyzed for pH, organic matter (Walkley-Black method), extractable phosphorus (P) (Olsen and Bray 1), and exchangeable bases (NH4Oac method) by a commercial laboratory. Thirty-six percent of the samples had acidity problems (pH <5.5). Twenty-three percent of the samples had low organic matter content (<20 g/kg), and 16% had high category (>40 g/kg) values. Fifty-three and 56% of the samples showed a need to fertilize with magnesium (Mg) and potassium (K), respectively, because they had values below the suggested critical levels of 2.5 cmolc/kg for soil exchangeable Mg and of 0.4 cmolc/kg for K. On the basis of current soil fertility criteria, P fertilization would be required in 69% of the samples with pH less than 7.3, but only in 28% of the samples with pH greater than or equal to 7.3. Although the soils grouped with pH >7.3 had a greater proportion of samples in the "extremely high" soil test P category, the potential environmental impact may be lessened because the climatic and topographic conditions where these soils occur favor less runoff. Follow-up studies are needed to assess the spatial variability and the temporal dynamics of the nutritional status of soils of Puerto Rico. 

Mobility of metsulfuron-methyl in tropical soils

Soil Research ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 1291 ◽  
Author(s):  
B. S. Ismail ◽  
K. Kalithasan
Keyword(s):  
Organic Matter ◽  
Soil Column ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Matter Content ◽  
Fresh Weight ◽  
Downward Movement ◽  
Natural Conditions ◽  
Metsulfuron Methyl ◽  
Rainfall Total

The mobility of metsulfuron-methyl in 5 soil series with different organic contents was determined in a greenhouse as well as under natural conditions. In these studies, the movement and biological activity of metsulfuron-methyl were determined by the bioassay method using long bean as a bioassay species. Bioactivity and movement of the herbicide down the soil profile were inversely related to the organic matter content of the soil. Phytotoxic levels of metsulfuron-methyl were restricted to the 10-cm depth of the column containing Selangor Series soil except when it received 40 mL of water daily (depth, 10–15 cm). In Munchung Series, the phytotoxic level was also mainly in the 5–10 cm layer. However, when the column received 40 mL daily or every 4 days, the residue was detected in 15–20 cm and 10–15 cm zones, respectively. The phytotoxic level moved downward to the 20–25 cm layer both in Sogomana and Holyrood Series when 40 mL of water was given daily. A phytotoxic level of metsulfuron herbicide was detected in the 20–25 cm layer when the soil column containing Serdang Series was leached with 40 mL of water every 4 days or with 20 mL daily; the phytotoxic level was detected at a depth of 25–30 cm when this soil was watered daily with 40 mL. The downward movement of metsulfuron under natural conditions showed a pattern similar to that found under simulated conditions. Phytotoxic effects of the residue could be detected in the 25–30 cm and 15–20 cm zone of Serdang and Holyrood Series, respectively, after exposure to 20 days of rainfall (total 111·9 mm). Phytotoxic residue in both Sogomana and Munchung Series soil was detected in the 10–15 cm layer, and in the 5–10 cm layer for Selangor Series soil, after exposure to 20 days of rainfall. After exposure to 40 days of rainfall (total 152·8 mm) under natural conditions, the residue could be detected in the 15–20 cm layer of Selangor Series. The phytotoxic level moved deeper in soil with low organic matter after exposure to 40 days of rainfall. Fresh weight reduction was greater in the 20–30 cm layer in Serdang Series than in the top layer.

scholarly journals RELATIONSHIP BETWEEN NITRATE AMOUNT IN GROUNDWATER AND NATURAL FACTORS

2005 ◽  
Vol 13 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Alma Pociene ◽  
Skirmantas Pocius
Keyword(s):  
Organic Matter ◽  
Groundwater Level ◽  
Precipitation Amount ◽  
Organic Matter Content ◽  
Matter Content ◽  
Nitrate Content ◽  
Clay Particles ◽  
Surface Precipitation ◽  
Natural Factors ◽  
Nitrate Concentrations

In Lithuania almost the whole drinking water is derived from groundwater sources. The concept of ground@water vulnerability is based on an assumption that a physical environment may provide some degree of protection to groundwater against human impact.The earth materials may act as natural filters to screen out some contaminants. Groundwater vulnerability depends on the natural characteristics of a site and relates to the pathways and rate of downward movement of pollutants. Pollutant migration through the soil zone depends just on the depth of waterlogging, texture, organic matter content, quantity of precipitation.. Pollutants accumulating in shallow groundwater in the Lithuanian area are, first of all, nitrates and organic matter. Regularities of groundwater chemistry can be determined only after investigation into the processes of their formation. That is why we need to find out the main factors of nitrate concentrations in groundwater. Investigation took place in Karkiškes object of Educational Farm of Lithuanian University of Agriculture in 1997–2002. Also, the data from publications were used. The regime of groundwater level and the quantity of nitrates in it was an object of the investigation. The objective of the thesis is to estimate correlation between nitrate concentrations in groundwater and natural factors, such as textural composition of the soil, the quantity of clay and humus particles in the soil, the depth up to the groundwater level, the depth of a restrictive layer and annual precipitation amount. The correlation analysis was used to determine relationship among these factors. The investigation shows that the concentration of nitrogen in groundwater and nitrate leaching are under the influence of humus and clay particles in the soil. It also shows that, when the content of clay particles in the soil increases, nitrogen leaching decreases. Relationship between nitrate content in groundwater and its level from the soil surface, precipitation amount were identified by the investigation. The obtained relationship is close enough, and the correlation coefficients are high (0,86–0,98).

Dissipation of Herbicides at Three Soil Depths

Weed Science ◽  
1969 ◽  
Vol 17 (1) ◽  
pp. 27-31 ◽  
Author(s):  
C. I. Harris ◽  
E. A. Woolson ◽  
B. E. Hummer
Keyword(s):  
United States ◽  
Organic Matter ◽  
Puerto Rico ◽  
Soil Organic Matter ◽  
Organic Matter Content ◽  
The United States ◽  
Vertical Movement ◽  
Matter Content ◽  
Soil Organic Matter Content ◽  
Positive Correlation

Twelve locations in the United States and Puerto Rico were the sites for determining the loss of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) and 2,3,6-trichlorophenylacetic acid (fenac) from soil. The herbicides were contained in tubes (1.88 by 6 inches) placed at depths of 3, 9, and 15 inches in the field. The samples were placed horizontally to minimize losses due to vertical movement of water from the tubes. After at least 3 months in the soil, the samples were returned to Beltsville and analyzed. Average recoveries showed 61% more atrazine and 41% more fenac from the 15-inch depth than from the 3-inch depth. Five northern samples contained more than twice as much atrazine and fenac residue as four southern samples. A positive correlation existed between fenac retention and soil organic matter content. Increasing soil organic matter and depth of placement, and decreasing temperature, tended to make the herbicides more persistent. However, the data were quite variable and the variations were often unexplainable.

scholarly journals Sorption and Desorption of Tembotrione and its Metabolite AE 1417268 in Soils with Different Attributes

2019 ◽  
Vol 37 ◽  
Author(s):  
A.T. FARIA ◽  
C.A. FIALHO ◽  
M.F. SOUZA ◽  
N.M. FREITAS ◽  
A.A. SILVA
Keyword(s):  
Organic Matter ◽  
High Performance ◽  
Organic Matter Content ◽  
Clay Content ◽  
Tropical Soils ◽  
Matter Content ◽  
Direct Relation ◽  
Carryover Effects ◽  
Physical Attributes ◽  
Low Levels

ABSTRACT: Tembotrione is registered in Brazil for maize and is used in large areas of the country in each harvest. In recent years, producers have reported carryover effects of this herbicide in succeeding crops to maize. This fact can be attributed to tembotrione recommendations without knowing their interactions with tropical soils colloids. In this study, using high-performance liquid chromatography, it was possible to evaluate the influence of chemical and physical attributes on the sorption and desorption of tembotrione, as well as its metabolite AE 1417268, on seven soils from different regions of Brazil. The coefficients referring to sorption and desorption, as well as the hysteresis index (Kf, 1/n and H) of tembotrione and its metabolite were influenced by pH, clay content and organic matter. In soil samples with low levels of clay and organic matter, values of sorption coefficients were reduced as pH increased. The desorption of tembotrione and its metabolite in all soils were low, mainly in the clayey ones and in soils with higher organic matter content. The sorption of tembotrione and its metabolites varies with the attributes of soil, presenting a direct relation with clay and organic matter contents and an inverse one with soil pH. The desorption of tembotrione and its metabolite decreased with the increase in clay and organic matter contents in the evaluated soils.

scholarly journals Organic-Matter Activity of Some Typical Soils of Puerto Rico

1969 ◽  
Vol 39 (2) ◽  
pp. 65-76
Author(s):  
Fernando Abruña-Rodríguez ◽  
José Vicente-Chandler
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Soil Organic Matter ◽  
Close Association ◽  
C:N Ratio ◽  
Organic Matter Content ◽  
Exchange Capacity ◽  
Matter Content ◽  
Soil Samples ◽  
Considerable Portion

The exchange capacity of the organic matter in typical soils of Puerto Rico was evaluated from: (1) The variation in the exchange capacity of soil samples following destruction of the organic matter, (2) titration curves of extracted organic matter, (3) and the correlations between exchange capacity and organic-matter content of soil samples. The first method was the most practical and gave fairly accurate results. The second method gave results which were in all cases too high. The third method, though probably the most accurate, is impractical. Results obtained with the first and third methods were similar. The exchange capacity of the organic matter varied rather widely, but was generally between 100 and 150 m.e. per 100 gm. On the average it accounted for about 25 percent of the total exchange capacity of the soils studied. The organic matter removed by flotation had the highest exchange capacity and the more readily oxidizable portions generally appeared to be the most active. This suggests the importance of conserving the more readily lost portions of the soil organic matter. A considerable portion of the soil organic matter was extremely resistant to oxidation, had a narrow C:N ratio, and apparently little exchange capacity. This suggests a close association between the organic matter and the inorganic soil colloids. The marked resistance to oxidation of a considerable portion of the organic matter may partly explain the high contents found even in continuously cultivated soils in Puerto Rico.

scholarly journals Evaluation of the Effects of Organic Matter and Other Soil Characteristics Upon the Aggregate Stability of Some Tropical Soils

1969 ◽  
Vol 43 (4) ◽  
pp. 268-272 ◽  
Author(s):  
M. A. Lugo-López ◽  
J. Juárez, Jr.
Keyword(s):  
Organic Matter ◽  
Soil Aggregates ◽  
Organic Matter Content ◽  
Aggregate Stability ◽  
Tropical Soils ◽  
Development Project ◽  
Matter Content ◽  
Degree Of Stability ◽  
Statistical Studies ◽  
Level Of Significance

This paper reports on statistical studies conducted to evaluate the degree of stability of soil aggregates in terms of the respective organic-matter, clay, and silt contents of selected soils from the Lajas Valley irrigation development project. Simple regression analyses revealed that there was no correlation between aggregate stability and clay or silt content. However, a highly significant correlation was obtained when organic-matter content was considered as the independent variable. In spite of the level of significance only 16 percent of the variability in aggregate stability can be explained on a basis of the soil organic-matter content, thus limiting the possible usefulness of estimates made by using the equation developed.

scholarly journals Prediction of soil organic matter content by combining data from Nix ProTM color sensor and portable X-ray fluorescence spectrometry in tropical soils

2022 ◽  
Vol 28 ◽  
pp. e00461
Author(s):  
Alvaro José Gomes de Faria ◽  
Sérgio Henrique Godinho Silva ◽  
Renata Andrade ◽  
Marcelo Mancini ◽  
Leônidas Carrijo Azevedo Melo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Matter Content ◽  
Tropical Soils ◽  
Matter Content ◽  
Fluorescence Spectrometry ◽  
Soil Organic Matter Content ◽  
X Ray ◽  
Color Sensor ◽  
Combining Data

HEAVY METAL SPECIATION IN BOTTOM SEDIMENTS OF THE VYSHNEVOLOTSKY RESERVOIR

2018 ◽  
pp. 46-54
Author(s):  
O. A. Lipatnikova
Keyword(s):  
Heavy Metal ◽  
Organic Matter ◽  
Bottom Sediments ◽  
Metal Speciation ◽  
Organic Matter Content ◽  
Water Reservoir ◽  
Matter Content ◽  
Heavy Metal Speciation ◽  
Mobile Forms ◽  
Manganese Hydroxides

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.

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