Upland Field Soils Research Articles

Insights into the formation and stability of soil aggregates in relation to the structural properties of dissolved organic matter from various organic amendments

Organic matter is an important determinant of soil aggregate formation and stability. However, the role of its structure, especially that of dissolved organic matter (DOM) from organic amendments (OAs), in the aggregation process remains imprecise. The purpose of this study was to understand the relationship between the chemical structure of water-extractable organic matter (WEOM), potential source of DOM from OAs, and their aggregate formation/stability functionality through model experiment. The WEOM samples were prepared from bark compost (BC), coffee residue compost (CRC), cattle manure compost (CMC), sewage sludge compost (SSC), fish cake (FC), and rapeseed oil cake (ROC) and characterized using high-performance size exclusion chromatography and 13C nuclear magnetic resonance and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopies. An upland field soil was packed in glass columns and each WEOM solution or ultrapure water (Control) was applied repeatedly during a 30-day period. Aggregate size distribution (>2000, 500–2000, 250–500, 53–250, and <53 µm) was then measured and aggregate stability indices, mean weight diameter (MWD), and geometric mean diameter (GMD) were calculated. The addition of WEOM increased the distributions of soil mass and soil organic carbon (C) into the > 2000 µm aggregate fraction compared to Control treatment, and the ROC-, CRC-, and SSC-WEOM treatments resulted in greater MWD and GMD than Control and/or the other WEOM treatments. The % O-alkyl C (29–59% of total C) and the relative abundance of high-molecular-weight (HMW) fraction (>10 kDa; 2.3–7.1% of total) in WEOM correlated positively with the proportion of > 2000 µm aggregate fraction. The relative abundance of HMW fraction also correlated positively with MWD. These findings suggest that the high amounts of polysaccharides, suggested by % O-alkyl C and supported by DRIFT spectra, and/or other HMW components are desirable structural characteristics of WEOM for promoting macroaggregate formation and aggregate stability.

Pool size of microbial biomass potassium in various farmland soils

ABSTRACT Potassium (K) is the major intracellular cation in all kinds of organisms including soil microorganisms. This study for the first time presented the potassium pool size in microbial cells in various farmland soils and the effect of land use and organic matter application on the contents. Microbial biomass potassium was determined for several paddy field soils under various managements in different areas, together with some upland, orchard, and pasture field soils, to estimate the potassium pool size in microbial cells in the farmland soils. The contents of microbial biomass potassium ranged from 9 to 65 mg K kg−1 soil in the paddy field soils and showed no difference among soil groups of the paddy fields. The biomass potassium content was higher in the pasture field (183–187 mg K kg−1 soil) than that in the paddy, upland (8–51 mg K kg−1 soil) and orchard (25–50 mg K kg−1 soil) field soils. The average ratio of microbial biomass potassium to exchangeable potassium was 0.25 for all the soils and the average values for paddy field (0.31) and pasture field (0.53) soils were higher than those for upland field (0.06) and orchard field (0.08) soils. Positive correlations were found between the contents of microbial biomass potassium and microbial biomass carbon and nitrogen. Application of organic matter significantly increased microbial biomass potassium in the farmland soils. These findings indicate that microbial biomass potassium plays an important role in potassium supply to crops as a reservoir of potassium and also suggest that the contribution of microbial biomass potassium to the potassium source for crops could be relatively higher in paddy field and pasture field soils than upland field and orchard field soils.

Anthropogenic Pedofeature in Andosols in Santome Shinden, One of the Representative Sites of the Satoyama Environment in Japan

Santome Shinden, a representative site of the Satoyama landscape in Japan, has its origins in 1696 when the common land of wild grass on the Musashino plateau was developed into a strip-shaped land division, which consists of residential area, upland field, and secondary forest. We investigated soils with different land use over 300 years; they are under the secondary forest, and in the upland field where fallen leaves compost derived from secondary forest has been applied continuously for about 300 years since the development. The measured exchangeable cation values suggested that the nutrients in the secondary forest were taken out to the field as fallen leaves. On the surface layer of the upland field soil, characteristic granules of dark brown coated peds (DBC peds) were developed strongly. However, on the surface layer of the secondary forest soil, the DBC peds were not found. Electron probe micro analyzer analysis showed that the outside (dark brown part) of the DBC peds, which was observed only in the upland fields was rich in carbon. The dark brown coated pedofeature was suggested to have an anthropogenic effect due to the long-term application of fallen leaves compost. The anthropogenic activities, which were fallen leaves compost application and cultivation for about 300 years, were thought to affect the soil micromorphology. Therefore, the peds newly found in the Santome shinden field were considered to be a soil microstructure that symbolizes anthropogenic activities.

Extractability of global fallout Pu from agricultural soils and its potential indication of bioavailability

We present the first investigation of the extractability of global fallout Pu from agricultural soils under natural conditions and its potential for indication of Pu bioavailability. On average, the nominal water soluble and exchangeable Pu fractions in sampled upland field soils were 0.07 ± 0.07% and 0.02 ± 0.01%, respectively, while those fractions in the rice paddy soils were 0.10 ± 0.06% and 0.03 ± 0.02%, respectively. Sequential extraction results indicated that the dominant sinks of Pu in both upland and paddy soils were the immobile organic matter fraction and the immobile residual fraction. Furthermore, both the water soluble and NH4OAc exchangeable Pu percentages showed a significant negative correlation with the exchangeable Ca2+ concentration in the soils. Regarding the potential plant bioavailability of Pu, we observed a positive correlation (r = 0.549, p = 0.034) between the Pu concentration in rice and the water soluble Pu concentration in the corresponding rice paddy soils, and that illustrated the water soluble Pu fraction was likely to be available for rice plant uptake. This bioavailable fraction was further applied in evaluating the available transfer factor (ATF) of Pu by dividing the Pu concentration in rice with the bioavailable Pu concentration in the corresponding soil. The ATFs of Pu from soil to rice plant ranged from 6.9 × 10−3 to 1.7 × 10−1. Statistical analysis indicated the ATF data were less discrete compared with the conventional transfer factor (TF). Therefore, we consider the ATF to be more representative than the TF to illustrate the transfer ability of Pu from soil to rice plant.

Changes in Soil Chemical Properties of Rice Paddy, Upland Field, and Greenhouse in Incheon from 2015 to 2019

This study was performed with the monitoring data of soil chemical properties of rice paddy, upland field and greenhouse soils in Ganghwa, Incheon metropolitan city from 2015 to 2019. Soil pH values tended to increase gradually in three soils, but there was no significant change in that of greenhouse soil. The concentration of organic matter (OM) and available phosphate (Av. P2O5) have fluctuated from 2015 to 2019, showing significant differences. In 2019, the average value of OM and Av. P2O5 were distributed within the appropriate level suggested by Rural Development Administration. In rice paddy field, the available silicate (SiO2) were found to be proper within the standard concentration every year. The contents of exchangeable cations were higher than the proper standard, showing significant differences among the years, except greenhouse soil. The mean concentration of EC for five years in upland and greenhouse soils were 2.5 and 5.9 dS m-1 above the proper standard. The optimal frequencies of pH were 46.8% and 47.1% at rice paddy and upland soil, but the excessive frequency ratio of pH was 48.5% at greenhouse soil in 2019. The exchangeable cations seemed to be seriously disproportionate exceeding the optimal level by 95%. In Pearson correlation matrix, the value of exchangeable Ca had a significantly positive correlation with exchangeable Mg content at upland and greenhouse soils. By principal component analysis, the exchangeable K, Mg and OM could distinguish between greenhouse and other soils on the first principal component and the pH and Av. P2O5 could differentiate between rice paddy and upland soils on the second principal component. Scatter plot of chemical properties investigated from rice paddy (P), upland (U) field and greenhouse (F) soils from 2015 to 2019.

Long-term submergence of non-methanogenic oxic upland field soils helps to develop the methanogenic archaeal community as revealed by pot and field experiments

The community structure of methanogenic archaea is relatively stable, i.e., it is sustained at a high abundance with minimal changes in composition, in paddy field soils irrespective of submergence and drainage. In contrast, the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils. This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments. In the pot experiment, a soil sample obtained from an upland field was incubated under submerged conditions for 275 d. Soil samples periodically collected were subjected to culture-dependent most probable number (MPN) enumeration, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of archaeal 16S rRNA gene, and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene (mcrA) of methanogenic archaea. The abundance of methanogenic archaea increased from 102 to 103 cells g−1 dry soil and 104 to 107 copies of mcrA gene g−1 dry soil after submergence. Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis, members from Methanocellales, Methanosarcinaceae, and Methanosaetaceae proliferated in the soils, and the community structure was relatively stable once established. In the field experiment, the number of viable methanogenic archaea in a rice paddy field converted from meadow (reclaimed paddy field) was monitored by MPN enumeration over five annual cycles of field operations. Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer's paddy field was dressed onto the meadow (dressed paddy field) and an upland crop field converted from the meadow (reclaimed upland field). The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field. Then, the number gradually increased over five years and finally reached 103–104 cells g−1 dry soil, which was comparable to that in the dressed paddy field. These findings showed that the low abundance of autochthonous methanogenic archaea in the non-methanogenic oxic upland field soils steadily proliferated, and the community structure was developed following repeated and long-term submergence. These results suggest that habitats suitable for methanogenic archaea were established in soil following repeated and long-term submergence.

Conversion factor (k factor) for estimation of soil microbial biomass potassium by the chloroform-fumigation extraction method

ABSTRACTThe conversion factor, kK, for estimation of microbial biomass potassium (K) by the chloroform-fumigation extraction method was determined for some arable soils: upland field soils under different fertilization conditions, an upland field soil under a greenhouse condition, and a paddy field soil under a flooded condition. The kK value varied with land utilization (paddy or upland) or fertilization (chemical or organic fertilizer). Value of kK was different between paddy field soil (0.28–0.38) and upland field soil (0.41–0.73). This study indicates that the value could be useful for the estimation of microbial biomass K in soil by the chloroform-fumigation extraction method and further investigation of the amounts of biomass K in different types of soils under conditions with varied field managements will be necessary.

Factors on soil pH decrease in sandy upland field soil application with livestock manure

Factors on soil pH decrease in sandy upland field soil application with livestock manure

K-土壌とBa(またはCa)-土壌のpH値の差と熟畑化との関係

K-土壌とBa(またはCa)-土壌のpH値の差と熟畑化との関係

30年間の有機物(牛ふんバーク堆肥および収穫残さ)連用が北海道の淡色黒ボク土の全炭素,全窒素および物理性に及ぼす影響

30年間の有機物(牛ふんバーク堆肥および収穫残さ)連用が北海道の淡色黒ボク土の全炭素,全窒素および物理性に及ぼす影響

Changes in the composition of humic acids in various upland field soils with a continuous application of an organic amendment as revealed by fractional precipitation analysis

The effect of the continuous application of an organic amendment (OA) on the accumulation and composition of humic acids (HAs) in various upland field soils was analyzed using a fractional precipitation technique. Fractionation patterns of HAs from plots treated with farmyard manure (FYM) or composted rice straw plus chemical fertilizer (CF) and from plots treated with CF alone were obtained by the step-wise addition of ethanol, 200–800 mL L−1, to HAs dissolved in 0.01 M sodium hydroxide (NaOH), and their degrees of humification were compared. HAs with a higher degree of humification precipitated in more dilute ethanol concentrations. The largest distribution shifted to a fraction that precipitated at a lower ethanol concentration with increasing degree of humification of bulk HAs, without an accompanying decrease in the amount of fractions with lower degrees of humification. A continuous OA application resulted in larger HA fractions with lower degrees of humification in most of the fields. The progression of humification in OA-derived HAs and interactions with indigenous soil HAs were also suggested from the fractionation patterns. The structural properties of the sub-fractions were evaluated using Miyagi soil (Cambisol) HAs. High performance size exclusion chromatography indicated that the larger molecular size molecules tended to precipitate at lower ethanol concentrations. The contribution of FYM-derived materials to the FYM+CF plot HA sub-fractions was suggested by a larger distribution of larger molecular size molecules compared to the corresponding HA sub-fractions from the CF plot soil. 13C cross polarization/magic angle spinning nuclear magnetic resonance analysis indicated that the fractions that precipitated at lower ethanol concentrations had more aromatic characteristics than the fractions that precipitated at higher ethanol concentrations and were soluble in 800 mL L−1 ethanol. These samples were characterized by a high alkyl carbon (C) content and intense signals corresponding to methoxyl and phenolic C. A correlation analysis for the HA sub-fractions both from the FYM+CF and CF plots indicated that their degree of humification corresponds to the composition of C functional groups.

Iodine transfer from agricultural soils to edible part of crops

Abstract Information about the distribution and cycling of stable iodine (I) in the environment is useful for dose estimation from its long-lived radioiodisotpe, 129I, which is one of the most critical radionuclides to be managed for the safe disposal of nuclear fuel waste. The soil-to-plant transfer factor (TF) is an important parameter to predict internal radiation exposure pathways through the food chains using mathematical models. Therefore, we have measured stable I and bromine (Br) for comparison, in 142 crop samples and associated agricultural field soil samples collected throughout Japan. The crops were classified into eight groups, i.e. leafy vegetables, white part of leeks, fruit vegetables, tubers, root crops, legumes, wheat and barley (WB), and rice. The results showed that Br and I concentrations were higher in upland field soil samples than in paddy field soil samples. However, when we compared TF values of WB and brown rice, no statistical difference was observed. The highest geometric mean of TF for I, 1.4 × 102, was obtained for leafy vegetables and fruit vegetables and that for Br, 1.5, was for fruit vegetables. TF for I was much lower than Br, as reported previously, maybe due to their different chemcial forms in soil and uptake behaviors by plant roots.

Effect of Soil Type and Fertilizer Management on Archaeal Community in Upland Field Soils

The effects of soil and fertilizer types on archaeal communities were evaluated by real-time PCR and PCR-denaturing gradient gel electrophoresis (DGGE) targeting the 16S rRNA gene of total DNA directly extracted from upland field soils. Twelve experimental upland field plots containing four different soil types, i.e., Cumulic Andosol, Low-humic Andosol, Yellow Soil and Gray Lowland Soil, were maintained under three different fertilizer management systems for 8 years (chemical fertilizer, rice husks and cow manure, and pig manure, respectively). Two-way ANOVA and RDA analyses showed that the copy number and PCR-DGGE profile of archaeal 16S rRNA gene were affected mainly by soil type, especially between Andosol and non-Andosol, but were also influenced by fertilizer type. Among several soil chemical properties, total N content showed a significant correlation to archaeal community. Sequence analyses showed that most of the major DGGE bands corresponded to uncultured Crenarchaeota of Group I.1b that contained ammonia-oxidizing archaea (AOA). These sequences were separated into two clusters in the phylogenetic tree and each lineage showed a different response to total N content.

Estimation of Plant‐Unavailable Iodine Concentrations in Agricultural Fields

In this study, a method for the estimation of plant‐unavailable I concentrations in soils was developed. Concentrations of total I and potentially plant‐available I (i.e., water‐soluble and organically bound I) were measured in 141 agricultural soil samples. For total I measurements, pressed powder pellets were prepared from soil samples, and concentrations of I were measured by energy dispersive x‐ray fluorescence. Potentially plant‐available I contents were measured by inductively coupled plasma mass spectrometry after the soil samples had been extracted with tetramethyl ammonium hydroxide and their soluble and organically bound I concentrations had been measured (TMAH‐extractable I). The results showed a high correlation between the total and TMAH‐extractable I concentrations. The geometric means of total and TMAH‐extractable I in the paddy field samples were 1.9 and 1.1 mg kg−1 dry weight, respectively, while those in the upland field soil samples were 5.7 and 4.2 mg kg−1 dry weight, respectively. For the agricultural soils having &lt;5 mg kg−1 total I, it was estimated that the average concentrations of plant‐unavailable I in paddy fields and upland fields were 0.7 ± 0.2 and 0.7 ± 0.4 mg kg−1 dry weight, respectively. The different total I concentrations for the fields from the two agricultural uses could be explained by the differences in their redox conditions; I is mobile under reducing conditions so that it was removed from the paddy fields by leaching from the plowed layer or by I volatilization from the soil.

Soil Clone Library Analyses to Evaluate Specificity and Selectivity of PCR Primers Targeting Fungal 18S rDNA for Denaturing-Gradient Gel Electrophoresis (DGGE)

We evaluated the fungal specificity and detection bias of four fungal 18S rRNA gene (18S rDNA) primer sets for denaturing-gradient gel electrophoresis (DGGE). We constructed and compared clone libraries amplified from upland and paddy field soils with each primer set (1, NS1/GCFung; 2, FF390/FR1-GC; 3, NS1/FR1-GC; and 4, NS1/EF3 for the first PCR and NS1/FR1-GC for the second PCR). Primer set 4 (for nested PCR) showed the highest specificity for fungi but biased specific sequences. Sets 1, 2, and 3 (for single PCR) amplified non-fungal eukaryotic sequences (from 7 to 16% for upland soil and from 20 to 31% for paddy field soil) and produced libraries with similar distributions of fungal 18S rDNA sequences at both the phylum and the class level. Set 2 tended to amplify more diverse fungal sequences, maintaining higher specificity for fungi. In addition, clone analyses revealed differences among primer sets in the frequency of chimeras. In upland field soil, the libraries amplified with primer sets 3 and 4, which targeted long fragments, contained many chimeric 18S rDNA sequences (18% and 48%, respectively), while the libraries obtained with sets 1 and 2, which targeted short fragments, contained fewer chimeras (5% and 10%, respectively).

Levels and Chemical Forms of Heavy Metals in Soils from Red River Delta, Vietnam

Levels and chemical forms of heavy metals in forest, paddy, and upland field soils from the Red River Delta, Vietnam were examined. Forest soils contained high Cr and Cu levels that were higher in subsurface than in surface layers. Levels of Cu, Pb, and Zn that exceeded the limits allowed for Vietnamese agricultural soils were found in the surface layer of a paddy field near the wastewater channel of a copper casting village. High amounts of Zn accumulated in the surface soil of paddy fields close to a fertilizer factory and an industrial zone. In these cases, larger proportions of Cu, Pb, and Zn were found in the exchangeable and acid-soluble fractions compared to the low-metal soils. We conclude that no serious, large-scale heavy metal pollution exists in the Red River Delta. However, there are point pollutions caused by industrial activities and natural sources.

Distribution of uranium in soil components of agricultural fields after long-term application of phosphate fertilizers

Long-term application of phosphate fertilizers causes accumulation of U in the surface soil of agricultural fields. We investigated the soil constituents that contribute to the accumulation of U by using chemical extraction methods. Surface soil samples were obtained from upland fields, pastures, and paddy fields cultivated without any phosphate fertilizer (control site), with NPK fertilizer (NPK site), and with both NPK fertilizer and compost (NPK + compost site) for more than 20 years. In addition to the total U (U t) concentration in soil, the concentrations of pyrophosphate- and acid oxalate-extractable U were determined as a measure of U associated with soil organic matter and poorly crystalline Fe/Al minerals in soil, respectively. The total, pyrophosphate-extractable, and acid oxalate-extractable U concentrations were higher in the soil obtained from the NPK and NPK + compost sites than in that obtained from the control site. The difference in the U concentrations between the NPK or NPK + compost site and the control site corresponded with the increased U concentration observed after the application of the phosphate fertilizer or both the fertilizer and compost. In the upland field and pasture soil, the increase in pyrophosphate-extractable U was 83–94% of that in U t. On the other hand, the increase in acid oxalate-extractable U was 44–58% of that in U t in the upland field and pasture soil, but it was almost equivalent to the increase in U t in the paddy soil with NPK. In conclusion, most of the phosphate fertilizer-derived U was either incorporated into the soil organic matter or poorly crystalline Fe/Al minerals in the surface soil of agricultural fields. Thus, soil organic matter is an important pool of U in upland field and pasture soil, whereas poorly crystalline Fe/Al minerals are important pools of U in paddy soil experiencing alternating changes in redox conditions.

Effect of organic amendment on amount and chemical characteristics of humic acids in upland field soils

SummaryTo assess the effect of continuous organic material (OM) application on soil humic acids, the amount and chemical characteristics of humic acids in various types of soils (n = 10) were compared between plots treated with farmyard manure (FYM) or rice straw compost (RSC) plus chemical fertilizer (CF) and plots treated with CF alone. The degree of humification (degree of darkening), molecular size distribution and 13C cross polarization/magic angle spinning nuclear magnetic resonance spectra of humic acids from CF‐treated soils showed wide variation among the soils. Humic acid content was generally larger in OM + CF soils than in corresponding CF soils, and the stable C isotopic ratio suggested partial replacement of indigenous humic acids with OM‐derived ones even where no apparent increase in humic acid content was observed. The rate of OM application and the indigenous humic acid content were related positively and negatively, respectively, to the apparent accumulation rate of humic acids among soils. The degree of humification of humic acids was generally smaller in OM + CF soils than in CF soils. Humic acids extracted from FYM and RSC exhibited chemical characteristics typical of humic acids having a smaller degree of humification, which suggested the contribution of OM‐derived humic acids to the differences between OM + CF and CF soil humic acids, such as larger average molecular sizes and smaller and larger proportions of aromatic C and O‐alkyl C, respectively, relative to total C in the OM + CF soil humic acids. Little change was observed in the chemical characteristics of humic acids when the degree of humification of indigenous humic acids was small. The effect of OM application on the chemical characteristics of humic acids was most conspicuous in soils containing humic acids having an intermediate degree of humification, possibly resulting from the combination of accelerated degradation of indigenous humic acids and the accumulation of OM‐derived humic acids.

Comparison of the closed-chamber and gas concentration gradient methods for measurement of CO2 and N2O fluxes in two upland field soils

We measured nitrous oxide (N2O) and carbon dioxide (CO2) fluxes from Gray Lowland soil (onion field) and Andosol soil (maize field) using the closed-chamber method and the concentration-gradient method based on Fick's law (gradient method). Measurements of gas concentration (at a depth of 0.05 m) and relative gas diffusion coefficients (D/D 0) (0–0.05 m depth) in the soil were carried out every week during the snow-free season (May–October) each year for 6 years in the Gray Lowland soil (1995–2000) and for 3 years in the Andosol soil (1998–2000). The seasonal pattern of N2O and CO2 fluxes using the chamber method was similar to those using the gradient method, and there were significant positive correlations between the fluxes using the chamber and gradient methods when extremely high N2O flux values were excluded (Smirnov–Grubbs’ outlier test, P < 0.01). There were no significant differences in N2O fluxes between the two methods, but CO2 flux using the chamber method was higher than that using the gradient method. As the gradient method could not measure the production, consumption and gas diffusion in the surface soil above the soil-air sampling tube (upper 0.05 m), differences in extremely high N2O and CO2 fluxes between the two methods resulted when the production and consumption of these gases were active in the soil above the installed location of the soil-air sampling tube. Measurements of gas concentration and D/D0 in the soil were required at every measurement during the investigation period because these values showed large seasonal variation. The measurement of CO2 flux was more influenced by plants than the N2O measurements. Therefore, it is necessary to consider the distance between the instruments (chambers and soil-air sampling tubes) and nearby plants. Our results suggest that the gradient method could lead to under or over estimation of CO2 flux and to extremely high N2O flux measurements. In contrast, the gradient method could be used for N2O flux measurement, excluding extremely high fluxes, and to understand seasonal patterns in CO2 flux. The gradient method is useful because it can estimate gas fluxes both in the soil and from soil to the atmosphere at the same time.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi