摘要:

A laboratory study was made to assess the sorption of collidine on a Ritzville silt loam soil and a retorted oil shale from the Laramie Energy Research Center. Collidine sorption was found to fit a Langmuir isotherm type sorption on both the soil and spent shale systems. In the case of the soil, two Langmuir type equations were resolved from the data, though only a single equation was resolved from the retorted shale data. Langmuir sorption capacity and bonding term parameters were determined for both systems by linear regression analysis.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Twelve reference soil samples from the University of Kentucky were analyzed in the Geochemistry Section of the Indiana Geological Survey for major and trace element composition of whole soil samples. Previous analytical data derived by x-ray fluorescence included with the soil samples are inaccurate and incomplete. The application of inductively coupled plasma-atomic emission spectrometry to solutions generated by digestion in mixed acids yielded improved major element determinations and trace element data that were previously unavailable.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Chemical and greenhouse studies were conducted to show that exchange acidity Y1, determined by titration of 125 ml of N KC1 soil extract (soil:N KC1 = 100:250) with 0.1 N NaOH, was a useful, realistic measure of aluminum toxicity potential in acid Andosols from northeastern Japan. Twenty-eight soil samples consisted of allophane-imogolite soils (11 samples; pH(H2O) 4.6 to 5.9, Y10.4 to 3.1 ml/100g), chloritized 2:1 mineral soils (13 samples; pH(H2O) 3.9 to 5.0, Y16.8 to 38.2 ml/100g), and allophane-imogolite-chloritized 2:1 mineral soils (4 samples; pH(H2O) 4.6 to 5.3, Y13.3 to 5.0 ml/100g). Three test plants, burdock cv. Takinogawa (Arctium lappa), barley cv. Norin-24 (Hordeum vulgare), and dent corn cv. Choko-1 (Zea mays), were grown on these soils in a greenhouse, and their root length and acid-injury were observed. Root length of all the test plants had a significant relationship with exchange acidity Y1, shown by exponential equations. Degrees of acid-injury determined by root length and root morphology were also closely related to exchange acidity Y1. Chloritized 2:1 mineral Andosols had “critical” pH(H2O) of about 5.0 and “critical” pH(KCl) of about 4.5, whereas allophane-imogolite Andosols did not have these “critical” pHs and did not restrict the root growth greatly even at low pH(H2O), such as 4.6.Acid substances relating to exchange acidity Y1were found to consist mainly of Al3+ions whose amount was closely correlated with total exchangeable Al. A comparative study of exchange acidity Y1, pH(H2O), pH(KCl), fluoride-reactive Al, etc., showed that exchange acidity Y1was a useful realistic measure of aluminum toxicity in the acid Andosols.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Laboratory incubation experiments were conducted with three clay loam, lowland rice soils (Haplustalf) to study the effect of applying three different levels of phosphorus (0, 50, and 100 ppm) and zinc (0, 5, and 10 ppm), in all possible combinations, on the changes in DTPA-extractable zinc, copper, iron, and manganese wand Bray's 2 extractable phosphorus in soil. We sought to understand whether the effect of such interaction is responsible, at least partly, for the decreased uptake of some of the nutrient elements in rice on phosphorus and zinc fertilization, as reported by others. The results showed that applying phosphorus decreased the content of DTPA-extractable Zn, Cu, Fe, and Mn in soils, the rate of decrease gradually declining with the progress of the incubation period. The depressive effect of P on extractable Zn content was found to be more prominent in respect of soil native Zn than of the applied one. Application of Zn also depressed the content of extractable Cu, Fe, and P, but increased that of extractable Mn. The decrease in the uptake of Zn or P, Cu, and Fe by rice, resulting from the application of P or Zn as reported by others, was attributed at least partly to the decrease in the availability of these elements in soil.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Scanning electron microscopy combined with energy-dispersive x-ray analysis (SEM-EDXRA) facilitated the identification of microfeatures observed in the study of thin sections of gleyed C horizons of a soil. Black to brown pellets, approximately 20 μm in diameter, which had been designated micromorphologically as fecal pellets, were shown to have diverse compositions ranging from pyrite, to iron-rich material associated with several other elements. Reddish brown material with apparent cell structure, which was designated as humified root fragments, was shown to be composed dominantly of iron oxide, as indicated by the high counting rate and low background. The dominant detectable element in rare yellow-brown nodules was sulfur with lesser amounts of calcium and aluminum. The high background and low counting rate indicated that the material was dominantly organic. EDXRA was also useful in confirming the identification of sponge spicules and diatom shells.The results indicate that soil micromorphologists should be cautious in attempting to estimate by light microscopy alone the nature and composition of microfeatures seen in soil thin sections.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We observed water tables in a heavy clay soil using: (1) a 1.2-m deep perforated pipe; (2) two series of shallow, unlined boreholes to depths of 30 and 50 cm below the surface; and (3) one series of piezometers to 30 cm. All holes had a diameter of 2 cm, as required in clay soils. Pressure potentials were measured in duplicate by transducer tensiometry at 10-cm depth intervals. Under natural conditions, different water levels were observed in the unlined boreholes at the shallow depths, while pressure potentials in surrounding soil were negative. Only the level in the deep hole corresponded with the level of zero pressure potential, as obtained by tensiometry. Occurrence of water in the shallow holes, which initially seemed to suggest the presence of a shallow water table, was explained by applying artificial rain containing chloride as a tracer. An estimated 10 percent of this rain was absorbed by the upper 20 cm of the soil; about 10 percent was found within 10 minutes in the shallow boreholes (not in the piezometers); and the remainder moved rapidly downward in the soil along vertically continuous larger voids, as documented in earlier studies. The water table at the 60-cm depth showed a rapid temporary rise. The shallow boreholes form artificial cavities in a three-dimensional system of interconnected, larger natural voids, which conduct the water. These voids may intercept and feed these cavities through their vertical walls. Drainage through their bottom is usually slow, allowing the presence of water during several days, even though the surrounding soil is unsaturated. Water tables should, therefore, not be observed by shallow, unlined boreholes, but by installing tensiometers or piezometers. Deep, unlined boreholes can be used when none of the soil horizons has a low hydraulic conductivity.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Solar heating of soils by mulching with transparent polyethylene during the hot season results in increased soil temperatures and the killing of certain pathogens. Mulching increases temperatures by up to 10 to 12°C in the upper soil layer. We studied the effect of this treatment on the chemical properties and hydraulic conductivity (HC) of soil. Field experiments showed enhanced plant growth in solar heated soils, even in the absence of known pathogens. Saturated extracts of the upper soil layers of eight different solar heated soils showed increased concentrations of soluble organic matter and minerals. The greatest increase was in NO3-concentration; NH4+, K+, Ca2++ Mg2+, and Cl-were also found to increase. Changes in soil pH, total organic matter, NaHCCv extractable P, and HC were small or inconsistent. Tomato seedlings grown on extracts of heated soils showed enhanced growth in comparison with seedlings grown on extracts of unheated soils.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We monitored the movement of technetium-99 through 41 samples of Minnesota soils, using soil column layer chromatography (CLC), a modification of soil thin layer chromatography. Under the aerobic conditions of soil CLC,99Tc occurs as the pertechnetate anion. Pertechnetate movement in the soils was characterized by the traditional Rfchromatographic parameter. Reduced Rfvalues were statistically related to elevated levels of soil organic matter. Complexation of99Tc, related to soil organic matter, was weak. Elution patterns of99Tc in the soil CLC colums were asymmetric, with pertechnetate retardation associated with both hydrodynamic dispersion and weak retention. Pertechnetate was less mobile than was Cl-in selected soils by soil CLC.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Nitrogen balance studies based on Kjeldahl data are reported for several crops of rice (Oryza sativa) grown in continuously flooded soil in pots under greenhouse conditions in the Philippines. Flooded soil planted to rice had a statistically significant positive nitrogen balance. The positive nitrogen balance was found to be the result of photo-trophic and heterotrophic nitrogen-fixing agents. Adding phosphorus and iron to the pots of flooded soil planted to rice significantly increased the positive nitrogen balance. Blue-green algal (cyanobacterial) inoculation of the soils fertilized with these nutrients did not have a statistically significant effect, although azolla inoculation in combination with these nutrients did significantly increase the positive nitrogen balance. Heterotrophic fixation depended upon the presence of rice plants. It is not possible to determine from these nitrogen balance data if the rice plant enhances fixation or simultaneously enhances fixation and reduces nitrogen losses.These experiments offer an explanation for the natural nitrogen fertility of flooded rice fields and indicate that rice plants can significantly improve the nitrogen economy of flooded soils.

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0038-075X    

出版商:OVID    

年代:1980

数据来源: OVID