Studies in tropical soils: IV. Organic transformations in soils, composts and peat

1937 ◽  
Vol 27 (2) ◽  
pp. 162-177 ◽  
Author(s):  
D. W. Duthie
Keyword(s):  
Clay Soil ◽  
Tropical Soils ◽  
Tropical Soil ◽  
Soil Samples ◽  
Organic Transformations ◽  
Surface Layers ◽  
Prairie Soil ◽  
Nitrogenous Substances ◽  
Chemical Characters ◽  
Organic Decomposition

1. Waksman's simplified scheme of fractionation was used in attempts to trace the organic transformations occurring in some tropical samples of composts, soils and peats.2. It was found that a useful partition of the nitrogenous substances into hydrolysable and resistant fractions could be effected by boiling with 5 per cent sulphuric acid for 6 hours.3. Two profile layers of a black calcareous Trinidadian clay soil were compared with two horizons of a prairie soil examined by Waksman & Stevens. The surface layers of both soils were found to be similar in chemical characters, but the lower subsoil layers of the Trinidadian soil gave evidence of a more advanced and profound degree of organic decomposition.4. Serial soil samples, taken from eight undisturbed natural profiles representative of humid tropical soil types occurring in Jamaica and Trinidad, were similarly examined.

The Arthropod Population of the Soil in some East African Pastures

1952 ◽  
Vol 43 (1) ◽  
pp. 203-220 ◽  
Author(s):  
George Salt
Keyword(s):  
Tropical Soils ◽  
Tropical Soil ◽  
Soil Samples ◽  
East African ◽  
Pasture Soil ◽  
Three Samples ◽  
Earthworm Population

A method is described for the extraction of arthropods from soil.Eleven soil samples from pastures in the neighbourhood of Moshi, Tanganyika, and at Kawanda, Uganda, yielded collections representing a population of 54,565 arthropods per sq. metre in the top 6 ins. of soil or, if three samples are adjusted in conformity with biological indications, of 38,417 per sq. metre.Nine soil samples from coffee and cassava plantations and from fallow ground gave collections representing a population of 24,423 arthropods per sq. metre in the top 12 ins. (in some cases 8 ins.) of soil.Twenty-five soil samples from a pasture near Cambridge, examined in a strictly comparable manner, gave collections representing a population of 90,238 arthropods per sq. metre in the top 6 ins. of soil.It appears that the arthropod population in the uppermost 6 ins. of East African pasture soil is much smaller than, and only about half as large as, that in an English pasture.The causes and consequences of the smaller arthropod population of tropical soil are briefly discussed, and a connection is suggested between the meagre arthropod (and earthworm) population and the large amount of ligneolis material found in the soil samples examined, This connection may also bear on the paucity of humus in some tropical soils.

scholarly journals The Phytoextraction of Copper from Tropical Soil 21 Years after Amendment with Heavy-Metal Containing Waste

2021 ◽  
Vol 26 (1) ◽  
pp. 11
Author(s):  
Gianluigi Silva ◽  
Septi Nurul Aini ◽  
Henrie Buchari ◽  
Abdul Kadir Salam
Keyword(s):  
Heavy Metal ◽  
Industrial Waste ◽  
Translocation Factor ◽  
Growth Period ◽  
Tropical Soils ◽  
Tropical Soil ◽  
Soil Samples ◽  
Lettuce Plant ◽  
Water Spinach ◽  
Plant Parts

Several particular plants are suggested to extract significant parts of heavy metals from soils and accumulate them in their roots and shoots.  This research aimed to study the phytoextraction of Cu by several plants from heavy-metal contaminated tropical soils.  Soil samples collected from plots treated in 1998 with 0, 15 and 60 Mg industrial waste ha-1 were planted with three different plants, i.e., caisim, water spinach, and lettuce.   Plant parts (roots and shoots) and soil samples were harvested after a four-week growth period and analyzed for plant and soil Cu.  The results show that the growth of plants was depressed by the increase in the soil Cu (extracted by 1 N HNO3) as affected by waste levels, with water spinach being the most progressive and produced the most significant biomass.  The absorption of Cu by caisim and water spinach increased with the soil extracted Cu (linear R2 = 0.71* for caisim and 0.32* for water spinach) and accumulated greater in plant roots than that in shoots. The translocation factor (TF << 1.00) indicates that all plants were good Cu phytostabilizators rather than phytoextractors, with water spinach being the best Cu extractor.

scholarly journals New thermal inducible Streptomyces phages isolated from tropical soils

1997 ◽  
Vol 20 (4) ◽  
pp. 547-552 ◽  
Author(s):  
Andrea Balan ◽  
Gabriel Padilla
Keyword(s):  
Host Range ◽  
Incubation Temperature ◽  
Tropical Soils ◽  
Tropical Soil ◽  
Soil Samples ◽  
Streptomyces Species ◽  
Streptomyces Sp ◽  
Long Tails ◽  
Large Host ◽  
Adsorption Curve

Two new Streptomyces phages, øBP1 and øBP2, were isolated from tropical soil samples. These phages presented a large host range and developed both lytic and lysogenic responses in different Streptomyces species tested. Variations in the incubation temperature showed to be important in the development of the replication cycle. Increasing incubation temperature from 30oC to 42oC induced the lytic response of øBP2 and lysogenic of øBP1 in the host strain Streptomyces sp. WL6. øBP1 and øBP2 have icosahedral heads with long tails and were characterized in relation to morphology, G + C content, genome size and adsorption curve

scholarly journals The use of N HNO3 to determine copper and zinc levels in heavy-metal polluted tropical soils

2021 ◽  
Vol 905 (1) ◽  
pp. 012001
Author(s):  
A K Salam ◽  
M Milanti ◽  
G Silva ◽  
F Rachman ◽  
I M T D Santa ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Tropical Soils ◽  
Correlation Study ◽  
Relative Strength ◽  
Soil Samples ◽  
Water Spinach ◽  
Polluted Soils ◽  
Chemical Extractants ◽  
Soil Zn ◽  
Zinc Levels

Abstract This study compared N HNO3 to other methods to determine plant available heavy metals in heavy-metal polluted soils. Soil samples were obtained from an experimental field treated with industrial waste after 22 years of the amendment and employed to conduct the comparative and correlation study. Soil samples were analyzed for Cu using various methods, planted in a glass house with several plants, and analyzed for soil and plant Cu and Zn. The relative strength of the chemical extractants followed the order of N HNO3 ≈ N HCl > Buffered DTPA ≈ Unbuffered DTPA > M CaCl2 ≈ N NH4OAc pH 7. A high correlation was observed for soil extracted Cu by M CaCl2 or N NH4OAc pH 7 or N HCl vs. Buffered DTPA and N HNO3 or N NH4OAc pH 7 vs. N HCl. High correlations of plant and soil Cu extracted by N HNO3 were shown by caisim, water spinach, land spinach, and corn, while plant and soil Zn were shown by caisim, water spinach, land spinach, and lettuce.

Soil and cotton responses to tillage and ameliorant treatments in a brown clay soil. 1. Soil responses and water use

1970 ◽  
Vol 10 (44) ◽  
pp. 313 ◽  
Author(s):  
J Loveday ◽  
JE Saunt ◽  
PM Fleming ◽  
WA Muirhead
Keyword(s):  
Organic Matter ◽  
Water Use ◽  
Clay Soil ◽  
Aggregate Stability ◽  
Surface Layers ◽  
Peak Period ◽  
Relative Water ◽  
Rate Of Decline ◽  
The Hill ◽  
Soil Responses

Furrow-irrigated cotton was grown for two seasons on a previously uncultivated dense clay soil to which the following treatments had been applied :--normal ploughing (18 cm), precision ripping (30 cm), deep ploughing (40 cm), deep ripping (60 cm), and deep ploughing and deep ripping combined, with and without applications of gypsum at 10 tons an acre or organic matter at 2 1/2 tons an acre. The deep tillage significantly increased the porosity of the subsoil, but this extra porosity had largely been lost by the end of the second season. Neither the gypsum nor the organic matter addition had a significant effect upon its rate of decline. Despite the effect on porosity the deep tillages had only small and mostly non-significant effects upon water increment at irrigation. The gypsum treatment, but not the organic matter, increased water entry to the subsoil at irrigation, and this W-as apparently a result of improved hydraulic conductivity and aggregate stability, particularly in the surface layers. Considerable leaching of chloride occurred from the 30-60 cm subsoil zone in both gypsum treated and deep-tilled plots, but not in organic matter plots, and an accumulation of chloride occurred in the 0-10 cm layer (the hill) in gypsum treated plots. The increased water intake to the subsoil resulting from gypsum treatment was matched by increased water use in the following period, and hence a reduction in relative water deficit of Leaves during the peak period of water demand. Neither the organic matter nor the deep tillages had appreciable influence on water uptake. Water use during periods of peak demand was about 6 mm a day for gypsum treated plots, and this was probably lower than mould have been obtained with water freely available at all times. On the other treatments it can he inferred that water use was even further reduced by lack of available water.

scholarly journals Quality evaluation of processed clay soil samples

2016 ◽  
Vol 24 ◽  
Author(s):  
Matilda Steiner-Asiedu ◽  
Obed Akwaa Harrison ◽  
Frederick Vuvor ◽  
Kwaku Tano-Debrah
Keyword(s):  
Quality Evaluation ◽  
Clay Soil ◽  
Soil Samples

The effects of cement and natural zeolite additives on problematic clay soils

2013 ◽  
Vol 20 (4) ◽  
pp. 395-405 ◽  
Author(s):  
Murat Turkoz ◽  
Pinar Vural
Keyword(s):  
Natural Zeolite ◽  
Clay Soil ◽  
Expansive Soils ◽  
Chemical Properties ◽  
Soil Samples ◽  
Clay Soils ◽  
Engineering Structures ◽  
Significant Strength ◽  
Strength Tests ◽  
Physical And Chemical

AbstractDispersive and expansive soils are considered problematic, and these soil properties cause serious problems for many engineering structures. For many years, comprehensive studies have been carried out with the aim of improving the swelling and dispersive qualities of soils by using additives. Each feature in the literature associated with the improvement of the dispersive and swell properties of clay soil with additives was separately evaluated. In this study, the effect of cement and natural zeolite additives on the characteristics of dispersibility and swelling potential of clay soils were investigated. A fixed percentage of cement (3%) plus different percentages of natural zeolite (1%, 3%, 6%, 10%, 15%, and 20%) were mixed with four different clay soil samples. In this context, first, the physical and chemical properties of the soil samples were determined. Next, the swell percentage, swell pressure, crumb, pinhole and unconfined compressive strength tests at different curing times were performed on samples with and without the additive by compressing the sample to achieve particular compaction characteristics. Significant strength value increases depended on curing time, and the properties were improved with the mixture of cement and zeolite additives, depending on the sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) values of clay soil samples with different plasticity characteristics that exhibit dispersive and swell properties. This study not only showed that a mixture of cement and zeolite additives improved the dispersive and swell properties of clay soil samples with four different plasticity characteristics, depending on their SAR and ESP values, but also significant increases in strength values were observed.

Comparison of Soil Water Retention Functions for Humid Tropical Soils

2014 ◽  
Vol 567 ◽  
pp. 8-13 ◽  
Author(s):  
Nuraddeen Muhammad Babangida ◽  
Muhammad Askari ◽  
Khamaruzaman Wan Yusof ◽  
Raza Ul Mustafa Muhammad
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Tropical Soils ◽  
Soil Samples ◽  
Analytical Models ◽  
Water Retention Curve ◽  
Tropical Region ◽  
Soil Water Retention ◽  
Model Quality ◽  
Humid Tropical Soils

The determination of soil hydraulic properties is of paramount importance as they are needed in many models of water and solute transport in soils, however conventional methods are quite difficult, expensive and sometimes cumbersome to use. Most studies of soil water retention functions are for temperate soils and their soil water retention curve (SWRC) cannot be extrapolated to tropical region, as such this study focused solemnly on SWRC of soils of tropical region (Malaysia and Indonesia to be specific). The analytical models of Brooks & Corey, van Genuchten and Kosugi were applied to model the SWRC for humid tropical soils, parameters of the three models were optimised by fitting them to 191 soil samples, of 10 different classes (International society of soil science classification) using VBA & MS excel solver add in. A comparison of the fitting capabilities and model quality was made using the sum of square of errors (SSQE) between observed and modelled values and, Akaike information criterion (AIC) respectively. The Kosugi model was found to describe the SWRC of the tropical soil samples better than the other models, as it has the lowest SSQE and AIC values.

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