Soil Types In China Research Articles

Rhizosphere microbiota assemblage associated with wild and cultivated soybeans grown in three types of soil suspensions

ABSTRACTSoil microbial community composition is determined by the soil type and the plant species. By sequencing the V3-V4 region of the bacterial 16S rRNA gene amplicons, the current study assessed the bacterial community assemblage in rhizosphere and bulks soils of wild (Glycine soja) and cultivated (Glycine max) soybeans grown in the suspensions of three important soil types in China, including black, red and soda-saline-alkali soils. The alpha-diversity of the bacterial community in the rhizosphere was significantly higher than that of the bulk soils suggesting that bulk soil lacks plant nurturing effect under the current study conditions. Black and red soils were enriched with nitrifying and nitrogen-fixing bacteria but the soda-saline-alkali soil suspension had more denitrifying bacteria, which may reflect agronomic unsuitability of the latter. We also observed a high abundance of Bradyrhizobium and Pseudomonas, enriched cellulolytic bacteria, as well as a highly connected molecular ecological network in the G. soja rhizosphere soil. Taken all, the current study suggest that wild soybeans may have evolved to recruit beneficial microbes in its rhizosphere that can promote nutrients requisition, biostasis and disease-resistance, therefore ecologically more resilient than cultivated soybeans.

Rice husk biochar impacts soil phosphorous availability, phosphatase activities and bacterial community characteristics in three different soil types

To assess the effects of rice husk biochar (400°C, 0.5h) on the conversion of soil phosphorus in different soil types in China, a nine week microcosm incubation experiment was performed using acid red soil, organic brown soil, and saline soil, which were amended with 0, 10, 20 and 40t/hm2 biochar. Soil physico-chemical properties, microbial biomass, phosphatase activities, phosphate solubilizing bacteria, and bacterial community characteristics were investigated. The results showed that rice husk biochar significantly modulated the pH of the three studied soils by 0.1–0.2 units and increased the soil gravimetric water content by 0.3–1.4% over that of the controls. The addition of biochar significantly enhanced the Olsen-P and microbial biomass carbon in all studied soils, and this was partly dependent on the rate of biochar application. The levels of soil microbial biomass phosphorus and phosphatase activities were most significantly increased with 20t/hm2 biochar treatment. These results showed that treatment with rice husk biochar could provide more suitable growth conditions for soil bacteria and significantly enhance soil phosphorus availability and related enzymes. Furthermore, bacterial communities were investigated in all three soils using Illumina MiSeq pyrosequencing to generate tentative taxonomic assignments, which differed statistically over time. The results of a heat map with principal component analyses suggested that the biochar tended to shape the structure of bacterial communities in degraded soils such as acid red soil and saline soil. The most significant variation could be observed in the acid red soil. Biochar increased the relative abundance and distribution of Thiobacillus, Pseudomonas, and Flavobacterium in soils by varying degrees; all three are reported to be genera of phosphate solubilizing bacteria. In conclusion, biochar had a positive effect on phosphate solubilizing bacteria and contributed to increasing phosphorous availability.

An evaluation on using soil aggregate stability as the indicator of interrill erodibility

Aggregate stability is a very important predictor of soil structure and strength, which influences soil erodibility. Several aggregate stability indices were selected for estimating interrill erodibility of four soil types with contrasting properties from temperate and subtropical regions of China. This study was conducted to investigate how closely the soil interrill erodibility factor in the Water Erosion Prediction Project (WEPP) model relates to soil aggregate stability. The mass fractal dimension (FD), geometric mean diameter (GMD), mean weight diameter (MWD), and aggregate stability index (ASI) of soil aggregates were calculated. A rainfall simulator with a drainable flume (3.0 m long ×1.0 m wide ×0.5 m deep) was used at four slope gradients (5°, 10°,15° and 20°), and four rainfall intensities (0.6, 1.1, 1.7 and 2.5 mm/min). Results indicated that the interrill erodibility (Ki) values were significantly correlated to the indices of ASI, MWD, GMD, and FD computed from the aggregate wet-sieve data. The Ki had a strong positive correlation with FD, as well as a strong negative correlation with ASI, GMD, and MWD. Soils with a higher aggregate stability and lower fractal dimension have smaller Ki values. Stable soils were characterized by a high percentage of large aggregates and the erodible soils by a high percentage of smaller aggregates. The correlation coefficients of Ki with ASI and GMD were greater than those with FD and MWD, implying that both the ASI and GMD may be better alternative parameters for empirically predicting the soil Ki factor.ASI and GMD are more reasonable in interrill soil erodibility estimation, compared with Ki calculation in original WEPP model equation. Results demonstrate the validation of soil aggregation characterization as an appropriate indicator of soil susceptibility to erosion in contrasting soil types in China.

Bioavailability of 2, 4, 6-Trinitrotoluene (TNT) to Earthworms in Three Different Types of Soils in China

ABSTRACTTo study the effects of aging time (the length of time when contaminants are sequestered in soil) and soil properties on TNT bioavailability in soil, earthworms (Eisenia fetida) were exposed to three types of soils (fluvo-aquic soil, loessal soil, and black soil) contaminated by TNT for 7, 14, 21, 28, 35, and 42 days. The Earthworm-Soil Accumulation Factor (ESAF) of TNT and soil properties were analyzed. The ESAFs in black soil were significantly lower than those in fluvo-aquic soil and loessal soil (P < 0.05). In loessal soils, the ESAF increased with aging time, while that in black soils decreased. The ESAF of TNT had a significantly negative correlation with soil organic matter content, clay contents, and cation exchange capacity, which were the main factors affecting the TNT bioavailability in soils (P < 0.01). There was more quartz and feldspar in black soil, as well as more particles and micropores on the surface, which resulted in the easy adsorption and lower bioavailability of TNT. In conclusion, TNT bioavailability in soils is affected by aging time, soil physical and chemical properties, and mineral and surface properties, which must be considered when biotreatment for TNT in soils is applied.

Influence of soil factors on the soil enzyme inhibition by Cd

A comparative study was conducted on the toxicity of Cd to alkaline phosphatase activity (ALP) and dehydrogenase activity (DHA) in 18 top soils with contrasting soil properties representative of 14 major soil types in China. Soil pH and carbonate content, soil organic matter, and cation exchange capacity (CEC) largely affected the Cd toxicity on two enzyme activities; with the soil pH having only minor effect on the median ecological dose values based on total Cd concentrations (ED50 T). The values of ED50 T/ED50 W (based on water-soluble Cd content) of alkaline phosphatase and dehydrogenase were strongly influenced by pH and CEC contents, which explained up to 71% of the variation for alkaline phosphatase, 82% of the variation for dehydrogenase, and also were significantly correlated with the parameter KF derived from Freundlich adsorption isotherms. This study suggests that the values of ED50 T/ED50 W could be useful to evaluate the buffer capacity of soils which protects soil enzymes from harmful effects of heavy metal.

Quantifying the effect of biochar amendment on soil quality and crop productivity in Chinese rice paddies

China needs to produce about 20% more rice by 2030 to meet the growing demand for food that will result from population growth and economic development. This is not an easy task with soil quality being one of the major limiting factors. Improving the recycling of organic manures can be an important step toward stabilizing and optimizing soil quality in crop production systems. Recently, the pyrolysis conversion of crop straw into biochar and using it as a soil amendment has begun to attract increasing attention in China. Here, we performed a comprehensive analysis of 6 published studies with 11 field experiments to quantify the biochar amendment effect on soil quality and crop productivity in Chinese rice paddies. Our analysis showed that short-term application of biochar amendment had a positive effect on soil quality in rice paddies across a wide range of climates and soil types in China. However, the average effect of biochar amendment on rice yield was neutral. In contrast to biochar amendment, N fertilizer was less effective for improving soil quality but more effective for increasing rice yield. More interestingly, we found that biochar amendment had a positive effect on rice yield under N fertilizer application conditions, and there was a tight relationship between the effect of biochar amendment on rice yield and that on agronomic N use efficiency. The results lead us to conclude that further investigations are needed to determine (1) the long-term effect of biochar amendment on rice productivity, (2) the effect of biochar amendment on N uptake and metabolism in rice, and (3) the effect of biochar amendments produced from different feedstock and under different process conditions on soil quality and rice productivity in Chinese paddies.

A Comparison of Three Indophenol Blue Methods for Measuring Ammonium in Five Types of Soils in China

Three indophenol blue methods have been used to analyze ammounium-N in five typical soils in China. Method I and II, using the same catalyst of sodium nitroprusside but different quantity and types of reagents, are suggested by Soil Science Society of America (SSSA) and Soil Science Society of China (SSSC), respectively. Method III adopts acetone as the catalyst. It was shown that three methods yielded similar ammonium-N contents with each type of soil. But the use of sodium nitroprusside resulted in higher experimental sensitivity; and Method II by SSSC was recommended due to its lower cost.

A quantification of the effects of erosion on the productivity of purple soils

Research on the effects of soil erosion on soil productivity has attracted increasing attention. Purple soil is one of the main soil types in China and plays an important role in the national economy. However, the relationship between erosion and the productivity of purple soils has not been well studied. The purpose of this research was to determine if soil depth, which is dependent on the rate of erosion, has an influence on crop yield and growth. Plot and pot experiments at different soil depths were performed. Results indicate that soils from different parental materials had different growth features and crop yields due to the differential fertility of the derived soils. The yield reduction rate increases exponentially with the depth of eroded soil (level of erosion). The yield reduction rate per unit eroded soil horizon (10 cm) is approximately 10.5% for maize and wheat.

A Comparison of Two Analytical Methods for Measuring Nitrate in Five Types of Soils in China

Nitrate is one of the major nitrogen forms absorbed by plants. Dual-wavelength Ultraviolet Spectrophotometry (DUS) is a simple, rapid and environmental method to measure soil nitrate. In this study, DUS as well as Phenol Disulfonic Acid Procedure (PDAP) were adopted to analyze nitrate in five types of soils in China. It was showed that the concentrations of soil nitrate determined by DUS were higher than those by PDAP. Meanwhile, these two series of measurements were significantly correlated. Therefore, the DUS is worthy in rapid detection of soil nitrate.

Carbon storage and spatial distribution patterns of paddy soils in China

Carbon storage in agricultural soils plays a key role in terrestrial ecosystem carbon cycles. Paddy soil is one of the major cultivated soil types in China and is of critical significance in studies on soil carbon sequestration. This paper estimated the organic and inorganic carbon density and storage in paddy soils, and analyzed the paddy soil stock spatial distribution patterns in China based on subgroups and regions using the newly compiled 1:1 000 000 digital soil map of China as well as data from 1 490 paddy soil profiles. Results showed that paddy soils in China cover an area of about 45.69 Mhm2, accounting for 4.92% of total soil area in China. Soil organic and inorganic carbon densities of paddy soils in China showed a great heterogeneity. Paddy soil organic carbon densities (SOCD) in soil profile ranged from 0.53 to 446.2 kg/m2 (0 to 100 cm) while the paddy soil inorganic carbon densities (SICD) ranged from 0.05 to 90.03 kg/m2. Soil organic carbon densities of paddy soils in surface layer ranged from 0.17 to 55.38 kg/m2 (0 to 20 cm), with SICD of paddy soils ranging from 0.01 to 21.85 kg/m2. Profile based and surface layer based paddy soil carbon storages (SCS) are 5.39 Pg and 1.79 Pg, respectively. Paddy soil organic carbon storage (SOCS) accounts for 95% of the total carbon storage. Profile based and surface layer based SOCS of paddy soils are 5.09 Pg and 1.72 Pg, respectively. Soil inorganic carbon storage (SICS) of paddy soils accounts for 5% of the total carbon storage in China. Profile based and surface layer based paddy SICS are 0.30 Pg and 0.07 Pg respectively. Among all the eight paddy soil subgroups, hydromorphic, submergenic and percogenic paddy soils account for 85.2% of the total paddy soil areas all over China. Consequently, profile based carbon storages of these three subgroups account for 78.1% of the total profile based paddy SCS in China. Most paddy soils in China are distributed in the East-China, South-China and South-west China regions, therefore, 92.6% of China’s profile based paddy SCS focuses on these three regions. The estimates of soil carbon stocks in paddy soils will help to identify areas or soil subgroups which are of particular interest for soil carbon gains and losses.

CHARACTERISTICS OF NATURAL CONTENTS OF CHEMICAL ELEMENTS IN PROFILES OF SOME SOIL TYPES IN CHINA AND THEIR RELATIONSHIP

The natural contents of 23 elements in the main soil types in China, the degree of enrichment of those elements and the characteristics of regional differences of the element arrangement are discussed in this paper. Through comparison between the element contents of 10 soils in China and the soils of the world, we have found that it is necessary to consider the equilibrium of the compositions of the soil types, when we try to find out a soil background content of the world or large region. The paper also deals with the concept and model of the regional differential coefficients of the elements. In the end of the paper, we analyse the correlation between 23 elements. The results show that there is a correlation between some elements of different soils in different geographical zones.

DISTRIBUTION OF CLAY MINERALS IN THE SOILS OF CHINA

ABSTRACTThis paper gives an account of the clay mineral composition of several major soil types in China and discusses its relationship with the hydrothermal condition, topography, and parent materials. Various soils formed on analogous igneous rocks are conspicuously characterized by horizontal or

Chemistry in China

THE four volumes of the Journal of the Chinese Chemical Society1 covering the years 1941–44 contain more than a hundred papers on all branches of the science. Many of the papers deal with problems of nutrition, vitamin content of food, fertilizers and soil types in China, and the analysis of Chinese drugs. There are investigations of the properties of vegetable gasoline made from native materials, cracking of vegetable oils, and the oxidation of natural fats and oils. The indican content of Szechwan indigo, the fixation of Chinese valonia by hide powder, and similar problems have been studied.