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PubMed2002

[Effects of organic manure on the conformation and biological availability of soil Cd].

Pot experiments were conducted to investigate the effect of organic manure on the conformation and availability of both native and added Cd in red soil and moisture soil under rice planting. Most of the added Cd existed in exchangeable form, while the native Cd existed more evenly in four forms. The organic manure did not influence apparently on the forms of native Cd, whereas influenced significantly on those of the added Cd. From tillering to mature stage, the exchangeable form of the native Cd increased, while that of the added Cd decreased. The application of organic manure could promote the uptake of Cd under the treatments without adding Cd. Under the treatments of adding Cd, the application of the organic manure could depress the uptake of Cd, and the effect of applying pig's manure was stronger than that of applying peat. There existed a significant antagonism between the accumulation of Cd and Fe in rice roots.

Agriculture↗
PubMed2006

Evaluation of the interaction mechanisms between red muds and heavy metals.

This paper investigated the heavy metal adsorption of non-treated (RM(nt)) and acid-treated red muds (RM(a)), bauxite ore processing waste, in order to evaluate how efficient they are in reducing metal solubility and bioavaliability in polluted soils. Red mud samples were artificially polluted with solutions containing increasing concentrations of Pb, Cd and Zn. Cancrinite and hematite were the main phases of the red muds, and were also the components which adsorbed most heavy metals. The results showed that the RM(nt) adsorption capacity for the three heavy metals was Zn> or =Pb>Cd. Acid treatment with HCl decreased the red mud's capacity to adsorb the heavy metals by 30%. In order to study the different heavy metal-RM interaction mechanisms, all samples after artificial contamination were treated with solutions with gradually increasing extraction capacity. H(2)O and Ca(NO(3))(2) treatments only extracted very low concentrations of Pb, Cd and Zn, while EDTA treatment extracted the most adsorbed heavy metals from the sorbent particles. In particular the water-soluble and exchangeable metal fractions were higher in the RM(a) than they were in the RM(nt), while the concentrations of Pb, Cd and Zn extracted with EDTA were lower. The results showed that red muds can be used successfully to reduce the solubility and bioavailability of heavy metals in polluted soils.

Adsorption↗
PubMed2003

Soil CO2 flux in relation to dissolved organic carbon, soil temperature and moisture in a subtropical arable soil of China.

Soil CO2 emission from an arable soil was measured by closed chamber method to quantify year-round soil flux and to develop an equation to predict flux using soil temperature, dissolved organic carbon(DOC) and soil moisture content. Soil CO2 flux, soil temperature, DOC and soil moisture content were determined on selected days during the experiment from August 1999 to July 2000, at the Ecological Station of Red Soil, the Chinese Academy of Sciences, in a subtropical region of China. Soil CO2 fluxes were generally higher in summer and autumn than in winter and spring, and had a seasonal pattern more similar to soil temperature and DOC than soil moisture. The estimation was 2.23 kgCO2/(m2 x a) for average annual soil CO2 flux. Regressed separately, the reasons for soil flux variability were 86.6% from soil temperature, 58.8% from DOC, and 26.3% from soil moisture, respectively. Regressed jointly, a multiple equation was developed by the above three variables that explained approximately 85.2% of the flux variance, however by stepwise regression, soil temperature was the dominant affecting soil flux. Based on the exponential equation developed from soil temperature, the predicted annual flux was 2.49 kgCO2/(m2 x a), and essentially equal to the measured one. It is suggested the exponential relationship between soil flux and soil temperature could be used for accurately predicting soil CO2 flux from arable soil in subtropical regions of China.

Carbon Dioxide↗
PubMed2006

[Effects of nitrification inhibitors on nitrate content in soil and pakchoi and on pakchoi yield].

A field experiment was conducted on two soil types in the Changsha suburb of Hunan Province to study the effects of hydroquinone (HQ), dicyandiamide (DCD) and thiourea (TU) on the nitrate content in soil and pakchoi and on the yield of pakchoi. The results showed that all the test nitrification inhibitors could significantly decrease the nitrate content in soil and pakchoi during whole growth stage, among which, DCD had the best effect, but the effect was differed on different soil types. Nitrification inhibitors could increase pakchoi yield, DCD was also the best one, and the effect was significantly better on vegetable garden red soil than on vegetable garden alluvial soil. The nitrate content in soil and pakchoi was the highest about 40 days after pakchoi transplanting.

Guanidines↗
PubMed2006

Cosorption of zinc and glyphosate on two soils with different characteristics.

Agricultural application of large amounts of glyphosate [N-(phosphonomethyl)-glycine] may affect soil metal behaviors to some extend, because glyphosate can react with many kinds of metals to form metal complexes. Cosorption of Zn and glyphosate on a Red soil (RS, Udic Ferrosols) and a Wushan soil (WS, Anthrosol) was studied. In comparison with the WS, the RS has less adsorption capacity for Zn and higher for glyphosate. The presence of glyphosate decreased Zn adsorption on the two soils, which are resulted from the decreased equilibrium solution pH caused by the added glyphosate, and also the formation of water-soluble complexes of glyphosate with solution Zn(2+) that had lower affinity to soil surface in comparison with Zn(2+) itself. Such effect is more significant on the RS than on the WS, mainly because of the less adsorption quantity of Zn on the former one. On the contrary, the presence of Zn increased the adsorption quantities of glyphosate on the RS and WS, which is resulted from the decreasing pH value of the equilibrium solution caused by Zn(2+) exchange with H(+) ions of soil surface. Such results suggest that glyphosate in field may increase the mobility and bioavailability of Zn and correspondingly increase its environmental risk.

Adsorption↗
PubMed2000

Chemical methods and phytoremediation of soil contaminated with heavy metals.

The effects of chemical amendments (calcium carbonate (CC), steel sludge (SS) and furnace slag (FS)) on the growth and uptake of cadmium (Cd) by wetland rice, Chinese cabbage and wheat grown in a red soil contaminated with Cd were investigated using a pot experiment. The phytoremediation of heavy metal contaminated soil with vetiver grass was also studied in a field plot experiment. Results showed that treatments with CC, SS and FS decreased Cd uptake by wetland rice, Chinese cabbage and wheat by 23-95% compared with the unamended control. Among the three amendments, FS was the most efficient at suppressing Cd uptake by the plants, probably due to its higher content of available silicon (Si). The concentrations of zinc (Zn), lead (Pb) and Cd in the shoots of vetiver grass were 42-67%, 500-1200% and 120-260% higher in contaminated plots than in control, respectively. Cadmium accumulation by vetiver shoots was 218 g Cd/ha at a soil Cd concentration of 0.33 mg Cd/kg. It is suggested that heavy metal-contaminated soil could be remediated with a combination of chemical treatments and plants.

Calcium Carbonate↗
PubMed2002

[Fractionation and relevant influencing factors of rare-earth elements (REEs) in a soil-plant system].

A potted method was carried out in this paper to research fractionation and some influencing factors (including the concentrations of REEs, humic acids and pH of soil) of the REEs (La, Ce, Nd, Sm, Eu, Gd, Tb and Yb) in a soilplant- system. The results showed that the fractionation model of REEs in red soil used in this experiment was similar to the average fractionation model of soil in China. The fractionation model of REEs in wheat root was similar to the model of the soil, but the fractionation model of REEs in wheat tops was not similar to that one. When REEs were added, the fractionation model of REEs in wheat root was changed similarly to that of the soil, but the model of wheat tops was kept constant. The results suggest the adsorbing way of REEs by wheat root and wheat tops were different. Humic acid showed little influence on the fractionation of REEs in wheat. High pH value (pH = 6.7) promoted the adsorption of light REEs by wheat; whereas, low pH value (pH = 4.2) promoted the adsorption of heavy REEs by wheat.

Humic Substances↗
PubMed1997

Dissipation and distribution of atrazine, simazine, chlorpyrifos, and tetradifon residues in citrus orchard soil.

An environmental fate study was conducted in a citrus orchard plot in València (Spain) in the fall of 1993. Dissipation and distribution of atrazine, simazine, chlorpyrifos and tetradifon residues following their controlled addition for agricultural purposes in a mediterranean red soil (Luvic Calcisol, Rhodoxeralf) were evaluated. During a two-month period, the amounts of applied pesticides in different soil layers (0-0.05, 0.05-0.22, 0.22-0.42, and 0.42-0.52 m) were monitored. In addition, information on soils, weather and agricultural practice were collected. Degradation half-lives were calculated, assuming zero-order kinetics: 11 days for atrazine, 12 days for simazine, 10 days for chlorpyrifos, and 18 for tetradifon. The distribution through the soil profile shows that the pesticide concentrations were always highest in the upper layer (0-0.05 m) of soil, and that atrazine was the most mobile of all the four pesticides investigated.

Chlorpyrifos↗
PubMed2006

Phytotoxicity of lanthanum in rice in haplic acrisols and cambisols.

Growth and physiological responses of rice to lanthanum were studied to elucidate the function of lanthanum in plants and its critical concentration relative to environmental safety. Shoot La content increased with the increasing added La concentrations. When shoot La content exceeded a toxic value, plant growth and chlorophyll a/b decreased and peroxidase (POD) activity, cell membrane permeability, and content of proline in the leaf increased. Leaf chlorophyll a/b and POD activity might provide useful criteria for early diagnoses of phytotoxicity of soil contaminated by La. In the present study, the critical concentration of La for rice relative to environmental safety was suggested to be 42.03 mg kg(-1) in red soil and 83.33 mg kg(-1) in paddy soil.

Cell Membrane Permeability↗
PubMed2004

[Soil water environment of artificial vegetation in Jinshajiang dry-hot volley].

Jinshajiang dry-hot volley has the characteristics of extremely hot and dry climate due to its specific local climate, where universally exists moisture deficit and the problem of soil water environment of artificial vegetation becomes more serious than other arid and semi-arid areas. The environmental determination in the typical sector of dry-hot volley Yuanmou showed that the existed arboreous forests evidently showed the characteristics of soil drying. Soil was short of moisture for a long term. In November after the rain season was over, soil water content in two-meter-deep soil layer was only 15% (equal to 35% of field capacity). Later on, soil water content continued decreasing and reached the lowest point in May (9%), which was near to wilting moisture of trees (the wilting moisture of surface eroded dry red soil of Yuanmou was 9.0%). As a result, trees grew slowly. As for Radonaea wiscosa shrubbery, its soil water content at the same layer was relatively 42.68% higher than that of arboreous trees. The soil moisture of natural grass slope was evidently better than that of arboreous trees and shrubbery, and was 34.36% and 22.22% higher, respectively. This kind of soil drying problem didn't come into notice in the vegetation restoration of Jinshajiang dry-hot volley, which would greatly restrict the sustainable development of artificial vegetation.

Climate↗
PubMed1991

Studies on the effects of some organic pollutants on the heavy metal transport in an Indian soil.

The translocation of some heavy metals, such as Hg, Cd, Cu, Co, Ni and Zn, as affected by organic pollutants, i.e. methanol, ethanol, propanol, formaldehyde, acetaldehyde, benzaldehyde, acetone, ethyl methyl ketone and cyclo-hexanone, was studied in an Indian red soil using soil thin layer chromatography. It was observed that an increase in the concentration of organic compounds in developer enhances the heavy metal mobility, except in the case of Cu and Hg which show a decreasing trend. The results are discussed in relation to the physico-chemical characteristics of the soil and adsorption/desorption phenomena.

Journal Article↗
PubMed2004

Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillside.

Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15 x 8 m2 and separated by 2 m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.

Agriculture↗
PubMed2005

[Analysis on the geologic background and physicochemical properties of soil for the cultivation of Panax notoginseng in Yunnan province].

OBJECTIVE: To study the relationship between the geo-authentic and geologic background system (GBS) and physicochemical properties of soil for the cultivation of Panax notoginseng. METHOD: The physicochemical properties of soil were analyzed, the geologic background system between producing areas of Yunnan and Guanxi of P. notogiseng was compared. RESULT: The distribution of P. notoginseng was restricted by GBS, The yellow-red soil of fragmentary rock mixed with carbonate seems to be most suitable for the growth. CONCLUSION: The most suitable soil for growing P. notoginseng is the neutral or weakly acidic soil with loam clay, particularly that with low base saturation percentage.

China↗
PubMed2007

Analysis of the sesquiterpenoids in processed Atractylodis Rhizoma.

In Asia, processed Atractylodis Rhizoma, the dried rhizome of Atractylodes ovata De Candolle (Compositae), is widely used as a tonic agent in herbal diets; stir-frying with soil is the most common processing method. In this study, we focused on determining variations in the function and concentrations of sesquiterpenoids in processed Atractylodis Rhizoma. Raw Atractylodis Rhizoma was processed by stir-frying it with different assistant substrates (i.e., red soil and burnt clay). The results indicated that there was less atractylon in stir-fried materials than in raw materials. However, there were higher levels of atractylenolides II and III in stir-fried materials than in raw materials. We also found that the heavy-metal content in burnt clay exceeded regulations set by the Taiwanese government. Moreover, commercial Atractylodis Rhizoma in Taiwan exhibited great differences in concentrations of the active components. In addition, atractylon showed stronger cytotoxicity than atractylenolides II and III in various cell lines. Therefore, we suggest that the toxic effects of atractylon are reduced following atractylon degradation to atractylenolides II and III. In conclusion, the toxicity of Atractylodis Rhizoma is reduced through processing.

Atractylodes↗
PubMed2025

Influence of soil types with different soil-forming process on the qualitative and quantitative detection of microplastics by near-infrared spectroscopy.

Microplastics (MPs) have become a pressing global environmental threat, with soils-acting as sinks for MPs from multiple sources-gaining increasing attention. Near-infrared (NIR) spectroscopy offers a promising tool for MPs detection due to its rapid, non-destructive, and field-applicable features. Although previous studies have focused on the effects of individual soil components on the NIR detection performance of MPs, there is still a lack of systematic research on how the complex background-formed by the coupling of multiple physicochemical properties in natural soils-affects detection performance. This study focuses on soil types with different soil-forming processes, selected five representative agricultural soils to systematically evaluate how the combinations of physicochemical properties they represented affect the performance of NIR-based qualitative and quantitative analysis of MPs in soils. The results demonstrated that soil type significantly affected both the spectral response and detection performance of MPs. Brown Pedocals and Brown Earth exhibited clearer characteristic absorption and stronger linear responses, achieving higher identification accuracy under low (<1.5 %) or zero MPs concentrations and the best quantitative performance (R2 &#x2265; 0.988, prediction set root mean square error (RMSEP) &#x2264; 0.110 %). In contrast, Phaeozem and Red Soil were more prone to misclassification at low concentrations, while Fluvo-aquic Soil showed the poorest quantitative performance. This study is the first to reveal, at a holistic level, the critical constraints posed by natural soil complexity on the NIR detection of MPs, offering targeted empirical evidence to support the application of NIR technology in real-world soil environments.

Soil↗
PubMed2002

[Chemical depletion of cumulative phosphorus in soils].

Cumulative phosphorus was defined as the phosphorus which was unavailable for plants and accumulated in soils fertilizer application. In this paper, chemical depletion of cumulative phosphorus in soils was studied by methods of batch equilibrium, kinetic, and anionic exchange resin membrane. The results showed that desorption amount of cumulative P increased with time increasing, and the desorption process was consonant with second-order kinetic equation. Release rate of P in different treatments was in order of PK > NPK > NK. The amount and rate of P released from red soil were higher than those of Fluvio-aquic soil. Desorbed P was significantly correlated with soil available P and P uptake by Plant. The maximum utilization of cumulative P in soils was about 45% of total phosphorus.

Phosphorus↗
PubMed1976

Endemic elephantiasis of the lower legs in Rwanda and Burundi.

The distribution of non-filarial elephantiasis of the lower legs in Rwanda and Burundi in Central Africa has been studied in order to test the previous observation of an association between the disease and the volcanic rocks and soils on which the people live. Using the method of market counts, a total of 26,602 adults were observed in 23 markets; 189 had elephantiasis. In addition, 264 cases were observed in specially arranged clinics and a further 77 while travelling. Prevalence per thousand adults varied from 0.0 to 20.7. It was noted that the areas of high prevalence corresponded with the areas of volcanic lava. A differential market count at the edge of the red soils in two of these areas showed a raised prevalence among people living on these soils, similar to that observed in Ethiopia. The observations confirm that the disease occurs in barefooted people who dig in soil developed from volcanic rocks, under tropical conditions, at altitudes around 1500 m. It is suggested that the high proportion of iron and other transitional metals may be important as irritant or toxic to the lymphatic vessels of the legs after absorption.

Adult↗
PubMed2002

Quantification of the effects of management factors on maize (Zea mays L.) and cotton (Gossypium hirsutum L.) residues decomposition rate.

Efforts to quantify management effects on decomposition rate of added substrates to the soil is important especially where such information is to be used for prediction in mathematical or simulation models. Using data from a short-term (60 days) greenhouse simulation study, a procedure for quantifying effects of management on SOM and substrate decomposition is presented. Using microbial growth rate u(q), microbial efficiency in substrate utilization e(q), specific decomposition rates for added plant residues to two contrasting soils, red earth (Ferrasol) and black earth (Acrisol) were estimated. The treatments included straw addition + buried, (T1); straw addition + mineral N (T2); and straw addition + tillage, (T3). Sampling was done every 15 days. Straw decomposition rate was affected by external mineral N sources (Urea 46% N). Addition of an external N source significantly increased decomposition rates. The study could not, however, fully account for the effect of tillage on residues because of the limited effect of the tillage method due to the artificial barrier to mechanical interference supplied by the mesh bags. It is concluded that using few decomposer parameters, decomposition rates and consequently SOM trends in a soil system can be monitored and quantification of the influence of perturbations on decomposition rate of added substrates possible.

Agriculture↗