The influence of SHF radiation on soil streptomycetes

Streptomycete cultures isolated from chernozem, soddy-podzolic, and low-moor peat soils were used in the experiment. The spore suspensions responded to SHF radiation (superhigh frequency radiation) at a shorter (30 s) exposition than the suspensions of vegetative streptomycete cells (60 s) did. The SHF radiation affected all the streptomycetes investigated. Both the suppression and stimulation of the respiration intensity, as well as a higher biomass accumulation and a resonance effect, were observed for different species of streptomycetes under the influence of microwaves. The effect of the SHF radiation on the biomass accumulation and the intensity of the other physiological processes may lead to the changes in the number of streptomycetes and their activity in the microbial complex of the soils. The changes in the capability of the streptomycetes concerning the assimilation of substrates under the influence of SHF radiation were revealed using multisubstrate testing.     

Effect of soil pH and organic matter on desorption hysteresis of chlorimuron-ethyl in two typical Chinese soils

Purpose  

Chlorimuron-ethyl is a sulfonylurea herbicide widely used to control many annual broadleaf weeds, and the residue for a long period posed a heavy hazard to rotational crops or vegetables. Knowledge about effect of soil pH and organic matter on desorption processes of chlorimuron-ethyl remains obscure. In this study, desorption behavior of chlorimuron-ethyl as a function of soil pH and organic matter was investigated.     

Changes in soil pH due to the storage of soils

Abstract. The pH of soil samples was remeasured after storage for 20 years in the laboratory. The pH decreases were minor in acid to neutral soils (-0.3), but greater in alkaline soils (-0.63). The pH differences were statistically significant only for alkaline soils. The decreases of pH with time are probably mainly due to the decomposition of organic matter, the CO₂ produced, the hydroscopic water and the presence of CaCO₃.     

Studies on the association of humic acid in soils

Introduction

The purpose of this study was to find the form of association of humic acid in volcanic ash soils, in which humus was accumulated more than 10%. Some consideration was taken, on the other hand, on the reason of this accumulation.     

The influence of acid soil factors on the growth of snapbeans in major appalachian soils

Abstract

Acid soil limitations to plant growth were assessed In 55 horizons of 14 major Appalachian hill land soils. Aluminum sensitive “Romano” and Al‐tolerant “Dade” snapbeans (Phaseolus vulgaris L.) were grown for 5 weeks in limed and unlimed treatments of the 55 horizons. Shoot and root growth was depressed >20% in unlimed relative to limed treatments in approximately 2/3 of the horizons. Dade snapbeans were generally more tolerant of the acid soil conditions and had higher Ca concentrations in the shoots than Romano snapbeans. However, the sensitive‐tolerant snapbean pair could not consistently be used to identify horizons with soil Al problems. Growth of both snapbeans was generally best in A horizons and worst in E horizons. The E horizons in this study were characterized by low Ca saturation (exchangeable Ca x 100/cation exchange capacity) and high Al saturation (exchangeable Al x 100/cation exchange capacity). Exchangeable Ca, soil Ca saturation and total soil solution Ca were positively correlated (p<0.01) with snapbean root and shoot growth. Soil Al saturation, total soil solution Al and soil solution Al reacting in 15 seconds with 8‐hydroxyquinoline were negatively correlated (p<0.01) with growth. The ratio of Ca/Al in soil solution was more closely related to snapbean growth than the soil solution concentration of any individual element. Soil and soil solution Mn were, in general, not significantly correlated with snapbean growth. Many of the horizons in this study had both Al toxicity and Ca deficiency problems and interaction between Ca and Al affected both snapbean growth and Ca uptake. These findings confirm the importance of considering Ca as well as Al when investigating Al phytotoxicity.     

Studies on soils of Peaty paddy fields II

Chemical changes ordinarily occuring in flooded paddy soils in Japan had been investigated in detail by Dr. SHIOIRI and his coworkers (1). The problem of degraded paddy soils had also been discussed by them on the basis of the experimental results on the deficiency of free iron oxides which affect the root of rice plant. As described in the previous report (2), causes for low rice production in the peaty Paddy fields seemed to be different from those in the degraded paddy ones. Thereupon, for a comprehensive understanding of the properties of peaty paddy soils, many important aspects such as the nature and role of each soil layer, and the behaviour of iron and nitrogen in soil Will have to be studied.     

Model organic compounds differ in their effects on pH changes of two soils differing in initial pH

The mechanisms by which organic materials affect soil pH are not fully understood. This study for the first time compared the short-term effect of various model organic compounds on pH change of two soils differing in initial pH (Podosol of pH 4.4 and Tenosol of pH 6.1). Eight organic compounds, representing common compounds in plant residues, were selected based on the number and type of chemical functional groups. The addition of organic acids (acetic, malic, citric, and benzoic acid) reduced soil pH immediately due to H⁺ dissociation. The magnitude of pH decrease depended on the rate of application, degree of dissociation of the acids, and initial soil pH. During a subsequent incubation, pH was slowly restored as these compounds were decomposed. The degree to which pH was restored was reduced with increasing addition rate. The production of H⁺ ions was increased with increasing rate of acid addition and decreased over time. When potassium citrate (organic anion) was added, soil pH increased due to H⁺ consumption upon decomposition. Compounds with amine groups (glucosamine hydrochloride) and less easily decomposable compounds (phenol) did not significantly alter pH during 16-day shaking. Changes in pH after glucose addition were relatively small compared with other compounds and were not expected because hydroxyl chemical groups of glucose are neutral. The present study demonstrated that the addition of model organic compounds to soil caused soil pH to increase, decrease, or remains unaffected. The extent and direction of pH change was dependent on the chemical functional group, addition rate, decomposition, and the initial soil pH.     

Low pH and aluminum tolerance of Bradyrhizobium strains isolated from acid soils in Indonesia

Sixty-seven strains of Bradyrhizobium isolated from soybean plants growing on acid soils in West Java and Sumatra, Indonesia, were examined for the effect of the pH and aluminum concentration on their growth in nutrient media, compared with 61 strains of Bradyrhizobium from soils in Japan. The results in this study indicated that the indigenous population of Bradyrhizobium in the soils of Indonesia showed a large difference in acid- and Al-tolerance from that of Japan. Eighty-five and 48% of the isolates from Japanese soils and Indonesian soils, respectively, were unable to grow in YEM broth at pH below 4.5. The acid-tolerance was correlated with AI-tolerance of the isolates on YEM agar plates at pH 4.4. Seventy-five percent of the isolates that grew in YEM broth at pH 4.5 were also resistant to 400 µM Al on the YEM plates. Acetylene reduction assay of the root nodules revealed that 3 of the acid- and Al-tolerant isolates from Indonesian soils showed a significantly high nitrogen fixation activity.     

Determination of soil microbial biomass phosphorus in acid red soils from southern China

A CHCl₃ fumigation and 0.03 M NH₄F-0.025 M HCl extraction procedure was used to measure microbial biomass P (P_mic) in 11 acid red soils (pH <6.0) from southern China and the results compared to those obtained by the commonly-used CHCl₃ fumigation and 0.5 M NaHCO₃ extraction method. Extraction with NH₄F-HCl was found to be more effective and accurate than NaHCO₃ extraction for detecting the increase of P from microbial biomass P following chloroform fumigation due to its higher efficiency in extracting both native labile phosphate and added phosphate (³²P) in the soils. This was confirmed by the recovery of ³²P from in situ ³²P-labeled soil microbial biomass following fumigation and extraction by the NH₄F-HCl solution. Soil microbial biomass P, measured by the NH₄F-HCl extraction method, was more comparable with soil microbial biomass C (with a more narrow C:P ratio range of 4.3 to 22.3 and a mean of 15.6 in the microbial biomass), than that obtained by NaHCO₃ solution (with a mean C:P ratio of 30.7 and a wide range of 14.9 to 48.9). K_p, the fraction of soil microbial biomass P extracted after CHCl₃ fumigation, by the NH₄F-HCl solution was 0.34. The amount of microbial biomass P determined (using K_p =0.34) was 3–400% (mean 131%) higher than that obtained by the NaHCO₃ extraction (using K_p =0.40) for the 11 red soils studied. The results suggest that the CHCl₃ fumigation and NH₄F-HCl extraction method is more reliable for measuring microbial biomass P than the NaHCO₃ extraction method in acid red soils.     

Psychrotolerant actinomycetes in soils of the tundra and northern taiga

Actinomycetes adapted to low-temperature conditions are present in the cold soils of the tundra and northern taiga in quantities comparable to mesophylic forms and dominate in the soil actinomycete complex. Actinomycetes isolated from cold soils were identified as Streptomyces. Most actinomycetes relate to psychrotolerant forms according to habitation temperature. Two of them are conditionally psychrophilic. Specific properties of the investigated populations were identified by multirespirometrical testing.     

The influence op soil treatments on elemental composition of corn and on zinc soil tests on two Missouri soils

Abstract

Corn (Zea mays L) was grown at three locations on soil treated with Zn at two levels of soil fertility. Corn leaves were sampled at 2 stages of growth and analyzed for several elements. Yields were measured and soils were analyzed for O.lN HCl and DTPA extractable Zn and by standard testing methods for other components.

Zinc at 10 and 20 lb/A did not affect corn grain yields. The Zn treatments significantly increased leaf Zn concentrations. The influence of leaf sampling time differed between locations. The DTPA and O.lN HCl extractable soil Zn both reflected the Zn soil treatments. The DTPA appeared to extract a more soluble component of soil Zn which became more un‐extractable with time. In general, the extractable soil Zn was poorly correlated with Zn concentrations in the corn leaves. Under the conditions of the experiment the soil Zn levels as measured by the 2 extractants were a poor predictor of plant Zn when soil Zn levels were adequate.     

The retention of nitrate in acid soils from the tropics

Abstract. In most soils of temperate regions nitrate is not held on soil surfaces and moves freely in solution. But when soils carry positive charges, nitrate is held as an exchangeable anion. As a result, leaching of nitrate is delayed relative to the movement of water. The delay can be predicted provided the anion exchange capacity (AEC) can be measured and the concentration of counter-anions is known. For soils with variable charge, the AEC varies with both pH and ionic strength, and the effective AEC should be determined under conditions similar to those in soil solution. A simple leaching method is described which satisfies this requirement. Delays in the leaching of nitrate measured in columns of repacked soil were strongly related to the AEC.     

Regulation of potential denitrification by soil pH in long-term fertilized arable soils

 The denitrifying enzyme activity (DEA), denitrification potential (DP) and anaerobic respiration (RESP) together with chemical characteristics were measured in three contrasting soils collected from experimental arable plots that had been subjected to long-term (21–23 years) fertilizer treatments. The plots sampled were either unfertilized or had received either annual inorganic NPK, manure and lime, or inorganic NPK and manure treatments. Addition of inorganic NPK, manure and lime led to large increases in the DEA for two of the three soils, but in the absence of lime, inorganic NPK and manure caused only small increases in DEA compared to unfertilized soils. Both DP and RESP were increased by the addition of inorganic NPK, manure and lime, but were substantially decreased by fertilizer treatments without lime. In most cases there was a simple relationship between soil pH and either DEA and DP, with those treatments that reduced soil pH also leading to reduced denitrification and vice versa. The effects of artificially increasing the pH to a value close to the pH in unfertilized soils (6.3) by addition of NaOH to the soils that had received inorganic NPK, and which had the lowest soil pH values, were to increase substantially DEA, DP and RESP. In soil from one of the sites that had been stored for 5 weeks, the DP values responded differently between the fertilizer treatments. The DP value was lowest in the soil that had inorganic NPK and manure, higher in the soil that received inorganic NPK, manure and lime and it was the highest in unfertilized (control) soil. The soil pH values for these treatments were 4.47, 5.79 and 6.58, respectively. However, when the soil pHs were adjusted by addition of either H₂SO₄ or NaOH to give a range between pH 2 and 12, the DP values from all three fertilizer treatments showed almost identical responses. The optimum pH value for DP was between 7 and 8 for all three fertilizer treatments. Substrate-induced respiration values from all fertilizer treatments showed a similar trend to DP when the soil pHs were modified. The results show that soil pH was an important factor which in the studied soils controls the microbial community in general and the community of denitrifiers in particular. However, denitrifiers showed a high pH resilience leading to no marked change of the pH optimum for potential denitrification. Received: 10 September 1998     

Effect of manganese and soil pH on the iron content of crops grown on podzol soils

In a greenhouse study on three podzol soils with pH values of 5.4–5.6, liming to pH 7.6 or higher decreased the Fe concentration of pea plant tissues from 47 to 42 ppm. In the case of barley, liming the soil increased the mean tissue Fe concentration from 104 to 119 ppm at pH 7.6 and to 107 ppm at pH 7.7. Field experiments on wheat, oats, alfalfa, and timothy showed that Mn applied to the soil or as foliar spray did not affect the Fe concentration of cereal or forage plant tissues. Liming did not affect the Fe concentration of cereal kernels but on a few locations it increased the Fe concentration of the boot stage tissue. The Fe concentration in oats was higher than that in wheat. Based on the results of a survey, it was found that forage legumes contained more Fe than did timothy. The survey also showed that a few Fe values in timothy and cereals would be considered low, although Fe deficiency has not been experienced in this region. A number of the samples would be in the deficiency range from the animal nutrition standpoint.     

pH regulation of carbon and nitrogen dynamics in two agricultural soils

Soil pH is often hypothesized to be a major factor regulating organic matter turnover and inorganic nitrogen production in agricultural soils. The aim of this study was to critically test the relationship between soil pH and rates of C and N cycling, and dissolved organic nitrogen (DON), in two long-term field experiments in which pH had been manipulated (Rothamsted silty clay loam, pH 3.5-6.8; Woburn sandy loam, pH 3.4-6.3). While alteration of pH for 37 years significantly affected crop production, it had no significant effect on total soil C and N or indigenous mineral N levels. This implies that at steady state, increased organic matter inputs to the soil are balanced by increased outputs of CO₂. This is supported by the positive correlation between both plant productivity and intrinsic microbial respiration with soil pH. In addition, soil microbial biomass C and N, and nitrification were also significantly positively correlated with soil pH. Measurements of respiration following addition of urea and amino acids showed a significant decline in CO₂ evolution with increasing soil acidity, whilst glucose mineralization showed no response to pH. In conclusion, it appears that changes in soil pH significantly affect soil microbial activity and the rate of soil C and N cycling. The evidence suggests that this response is partially indirect, being primarily linked to pH induced changes in net primary production and the availability of substrates. In addition, enhanced soil acidity may also act directly on the functioning of the microbial community itself.     

Volatilisation of aromatic hydrocarbons from soil: Part II,Fluxes from coal tar contaminated soils residing below the soil surface

The non-steady-state fluxes of aromatic hydrocarbons from coal tar contaminated soil, placed below a 5 cm deep layer of uncontaminated soil, were measured in the laboratory over a period of 53 days. The contaminated soil originated from a former gasworks site and contained concentrations of 11 selected aromatic hydrocarbons between 50 to 840 µg/cm³. Where the microbial activity was inhibited, the fluxes stabilized on a semi-steady-state level for the monocyclic aromatic hydrocarbons, naphthalene and 1-methylnaphthalene after a period of 10–20 days. Fluxes of acenaphthene and fluorene were only measurable in an experiment that utilized a cover soil with a low organic content. The fluxes were predicted by a numerical model assuming that the compounds acted independently of each other and that local equilibrium between the air, water, and sorbed phases existed. The model overestimated the fluxes for all the detected aromatic hydrocarbons by a factor of 1.3 to 12. When the cover soil was adapted to degrade naphthalene, the fluxes of naphthalene and 1-methylnaphthalene approached the detection limit after 5 to 8 days. Thereafter the fluxes of these two compounds were less than predicted by the model employing half-life values of 0.5 and 1 day for naphthalene and 1-methylnaphthalene respectively.     

Studies on the organo-mineral colloidal complexes of paddy soil II

In the preceding paper (1) the authors reported the humus status in the organo-mineral colloidal complexes of the degraded paddy soils, which is characterized by the leaching of active iron, manganese and the other elements such as silica, magnesium and phosphoric acid from the furrow slice (2). And it was concluded that the organo-mineral colloidal complexes (Gl colloidal complexes) of the degraded paddy soil is characterized by the marked accumulation of humus, especially the readily soluble humus as compared with those of the normal.     

Effect of soil compaction on hydraulic properties of two loess soils in China

Soil compaction affects hydraulic properties, and thus can lead to soil degradation and other adverse effects on environmental quality. This study evaluates the effects of three levels of compaction on the hydraulic properties of two silty loam soils from the Loess Plateau, China. Undisturbed soil cores were collected from the surface (0–5 cm) and subsurface (10–15 cm) layers at sites in Mizhi and Heyang in Shaanxi Province. The three levels of soil compaction were set by increasing soil bulk density by 0% (C0), 10% (C1) and 20% (C2) through compression and hammering in the laboratory. Soil water retention curves were then determined, and both saturated hydraulic conductivity (K_s) and unsaturated hydraulic conductivity were estimated for all of the samples using standard suction apparatus, a constant head method and the hot-air method, respectively. The high level of compaction (C2) significantly changed the water retention curves of both the surface and subsurface layers of the Heyang soil, and both levels of compaction (C1 and C2) changed the curves of the two layers from the Mizhi site. However, the effects of compaction on the two soils were only pronounced below water tensions of 100 kPa. Saturated hydraulic conductivities (K_s) were significantly reduced by the highest compaction level for both sampled layers of the Heyang soil, but no difference was observed in this respect between the C0 and C1 treatments. K_s values decreased with increasing soil compaction for both layers of the Mizhi soil. Unsaturated hydraulic conductivities were not affected by soil compaction levels in the measured water volume ratio range, and the values obtained were two to five orders of magnitude higher for the Mizhi soil than for the Heyang soil. The results indicate that soil compaction could strongly influence, in different ways, the hydraulic properties of the two soils.