• Volume 49,Issue 4,2012 Table of Contents
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    • >Research Articles
    • Response of spatial variability of soil total nitrogen to expansion of uplands in scale in Northeast China

      2012, 49(4):625-635. DOI: 10.11766/trxb201108300327

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      Abstract:Soil nitrogen is not only an essential nutrient element for crops, but also an important ecological element. The study on spatial variability of soil total nitrogen content at different scales is the basis for evaluating soil quality and predicting nitrogen storage in soil accurately. Based on the data of 1 041 soil profiles obtained during the second soil survey in Northeast China, three scales were set in this study, namely, administration region scale (county, city, province and region), soil taxonomy scale (family, sub-group, great group and order of soil) and soil type- administration scale (zonal soil and intrazonal and azonal soil), to study variability of soil total nitrogen (STN) content in the surface soil layer (0~20 cm) and the soil profile (0~100 cm) and its response to expansion of upland in scale. Results show that variability of STN content in the surface layer and in the profile increased with the expansion of scale. At the administration scale, a strong logarithmic relationship was found between the area of uplands or of the administrative region and the mean CV of STN content. At the taxonomy scale, though the mean CV of STN content of each soil order increased with the extension of scale from family to order, amplitude of the variation varied. At the soil type-administration region scale, zonal, intrazonal and azonal soils displayed a similar trend in variability of STN content, but differed in variation rate, and a strong logarithmic relationship between the area of uplands and the mean CV of intrazonal and azonal STN content was observed. These findings may provide a basis for assessing soil nitrogen storage in uplands clustered by soil type at various scales in Northeast China, and some theoretical guidance for determining the number of soil samples to be taken in investigation of soil resources in that region.

    • Assessment of soil erosion of the three gorges reservoir region (Chongqing) based on landscape fragmentation

      2012, 49(4):636-645. DOI: 10.11766/trxb201102270067

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      Abstract:Based on the principles of landscape ecology, the Chongqing Section of the Three Gorges Reservoir Region was studied and analyzed for composition, intensity and spatial distribution of soil erosion, using the ArcGIS 9.3 software and the Two-way indicator species analysis (TWINSPAN) and Detrended canonial correspondence analysis (DCCA) technique. In addition, the lands of the 22 districts and counties under Chongqing were classified according to fragmentation degrees of their landuse landscape, and the relations between the landscape fragmentation and the soil erosion were evaluated. Results show that light and moderate erosions were the main types in the study area. Farmlands were the highest in soil erosion intensity, woodlands, waterbodies and virgin lands were relatively lower, and the lower and middle reaches of the area were significantly higher than the upper reaches. Spatially, the 22 districts and counties could be ruled into three highly fragmented landuse landscape zones, i.e. agriculture -grassland zone, woodland zone and construction-land-waterbody zone, lined and decreased in soil erosion intensity from east to west. And higher grades of soil erosion intensified land-use landscape fragmentation, but when soil erosion reached its extremity, this effect of intensification showed a reverse trend, i.e. intensive soil erosion > highly intensive soil erosion > extremely intensive soil erosion.

    • Mechanisms of soil and water conservation measures regulating gravitational erosion in small watersheds on Loess Plateau

      2012, 49(4):646-654. DOI: 10.11766/trxb201107050251

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      Abstract:Mechanism of gravitational erosion in small watersheds with or without vegetation or check dam on the Loess Plateau was explored with the aid of FLAC3D, a finite difference software, so as to reveal mechanisms of some major engineering measures (building of check dams) and biological measures (maintenance of vegetation) regulating gravitational erosion. By comparing watersheds with and without controlling measures in distribution of displacement field, stress field and plastic deformation zone, effects of check-dam and vegetation reducing gravitational erosion were explored. Results show that hat vegetation may reduce displacement of hill tops and mid/lower slopes by 9.8% and 11%, respectively, while a check dam could only reduce displacement of the dam site by 10%. Moreover, vegetation could reduce volume of the plastic zone by 46% while a check dam could do only by 11%. A check dam increased concave slopes, while vegetation or roots reinforcement improved surface soil mass stress, both being able to reduce stress concentration of the soil mass on the slope and volume of the plastic deformation zone, but unable to alter the yielding model dominated by shear failure in the small watershed. However, within a small-scale range of a small watershed, the effect of a check dam was better than vegetation in erosion reduction, whereas in a large-scale range, it was just the reverse. The findings of the research can be cited as scientific basis for rationalization of the disposition of soil and water conservation measures for a small watershed.

    • Contribution of soil water at different depths in profile to winter wheat in Fengqiu in Huang-Huai-Hai Plain of China

      2012, 49(4):655-664. DOI: 10.11766/trxb201107010246

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      Abstract:Crop water source is an important aspect in the study on water cycling in SPAC (Soil Plant Atmosphere Continuum) and water-saving agriculture. Traditional approaches are not adequate to determine contributions of different water sources to the crop. Based on the winter wheat field experiment in Fengqiu, using the stable hydrogen and oxygen isotope techniques, a new model coupling a linear mixing model with δD- δ18O curves was established and used to calculate contributions of different water sources to the winter wheat at various growth stages in the Huang-Huai-Hai Plain of China. Results show that contributions of the sources to winter wheat varied with the growth stage. Soil water in the top soil layer (0~20 cm) was the main water source to winter wheat at the tillering, regreening, and jointing stages; At the booting stage, the crop got its water mainly from the soil at 80 cm in depth; At the flowering stage, it turned to the soil at 80 and 180 cm in depth for water supply; To wheat at the milk stage, soil water at 40 and 80 cm in depth contributed 47.5% and 39.5%, respectively, of the total the crop needed; And at the booting and flowering stages, the crop took 9.0% and 16.4%, respectively, of the water it used up from groundwater.

    • Classification of soil alkalization based on halophyte coverage

      2012, 49(4):665-672. DOI: 10.11766/trxb201105220185

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      Abstract:Qitai Oasis in Xinjiang has a large tract of sodic alkali soil and was hence selected as a study zone to explore relationships of halophyte coverage with soil alkalization indices (pH, exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), total alkalinity (TA)). It was found that in the soil of the study zone, existed large volumes of exchangeable sodium, strongly alkalizing the soil. Halophyte coverage was negatively related to all the soil alkalization indices to an extremely significant extent, especially to soil pH, being the highest (0.810), which was followed by ESP. Soil alkalization was the major factor affecting halophyte coverage, which could, therefore, be used as a good indicator of the former. Based on halophyte coverage as the major index in combination with some soil alkalizaiton indices, such as pH and ESP, alkalized soil in the study zone was classified. Soils 50% or so in halophyte coverage, <8.0 in pH, <3% in ESP and <3 in SAR were classified as non-alkaline soil, those 10%~40% in halophyte coverage, 8.0~9.5 in pH, 3%~35% in ESP and 3~40 in SAR as alkaline soil, and those <10% in halophyte coverage, >9.5 in pH, >35% in ESP and >40 in SAR as Solonetz. Such classification not only broadens the look angle of the study on grading of alkalized soils, but also tallies with the local practical situation.

    • The classification study on NO3-1 -soil secondary salinization in cucumber-based greenhouse

      2012, 49(4):673-680. DOI: 10.11766/trxb201106170218

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      Abstract:In China, nitrogen fertilizer application rates in intensive agricultural systems have increased dramatically in recent years, especially in protected vegetable production systems. This excessive use of nitrogen fertilizer has resulted in soil secondary salinization (SSS), which has become a significant environmental stress for crops such as cucumber, in the protected farmland of China. So it is necessary to propose some guidelines to direct the management of SSS in facility agricultural areas. In this study, the NO3-1-SSS classification was studied in greenhouses planted with cucumber ( Cucumis sativus L. cv. Dongfangmingzhu) in Taizhou, Jiangsu Province, East China. After the soils in these greenhouses were treated by different concentrations of nitrate, the SSS levels expressed by electrical conductivity (EC) were studied at 0.89 dS m-1 for control, 2.78 dS m-1 for treatment 1 (T1), 3.65 dS m-1 for treatment 2 (T2), 4.66 dS m-1 for treatment 3 (T3) and 6.15 dS m-1 for treatment 4 (T4). The results showed that there were significant relationships between NO3-1 contents and soil EC in the surface soils, implying that the change in soil quality resulted from the difference of nitrate contents could be expressed by the level of the NO3-1-SSS. The level of the NO3-1-SSS was significantly related with the cucumber height and yield (p < 0.05). Then, the classification for NO3-1-SSS in cucumber-based greenhouse in Yangtze River Delta was identified as five levels according to the effects of SSS on the cucumber height and yield (level Ⅰ: EC < 2.03 dS m-1, level Ⅱ: 2.03 dS m-1 < EC < 3.76 dS m-1, level Ⅲ: 3.76 dS m-1 < EC < 5.32 dS m-1, level Ⅳ: 5.32 dS m-1 < EC < 6.15 dS m-1, level Ⅴ: EC > 6.15 dS m-1).

    • Characterization of soil salinization in arid area based on canonical correspondence analysis

      2012, 49(4):681-687. DOI: 10.11766/trxb201107160261

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      Abstract:Analysis of characteristics of spatial distributions of total salt content (TS), ion composition, exchangeable sodium percentage (ESP), pH value and electrical conductivity (EC) of salt-affected soils in the Arid Area was conducted, using conventional statistics and canonical correspondence analysis. Results show that (1) the soils in the region are heavily to slightly alkalized, e.g. heavy in topsoil ( 0~10 cm ) and slight in bottom ( 30~50 cm );(2) close correlation exists between Na+ and Cl- , and between Ca2+ and Mg2+ in all soil layers; (3) Cl-, HCO3-and Na+ are the main factors controlling spatial distribution of soil total salt throughout the whole profile ( 0~50 cm ), which though varies slightly from layer to layer, where Na+ and Cl- remain to main factors; (4) the spatial distribution of ESP in the profile is less affected by environmental factors, however, it is restricted mainly by Na+and Cl- in the 0~10 cm soil layer, by HCO3-in the 10~30 cm soil layer, and by none in the 30~50 cm soil layer; (5) pH is quite evenly distributed throughout the profile and only slightly affected by salt ions, that is, it is very slightly affected by ions in the 0~10 cm soil layer, and only weakly influenced by HCO3-in the 10~30 cm and 30~50 cm soil layers; (6) the spatial distribution of EC is controlled by Ca2+ and Mg2+ throughout the whole profile, except in the 30~50 cm soil layer where K+ is the dominant controlling factor.

    • The transport of heavy metals in soils with different initial redox potentialⅠ:Single Cd, Cu, Zn in the soil column experiments

      2012, 49(4):688-697. DOI: 10.11766/trxb201107070254

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      Abstract:Heavy metal cadmium , copper and zinc were used to study single and the effect of five different redox potential for transport amounts through an outflow experiment using saturated soil column. The results indicate that oxidizing conditions in the soil, the sequence of the cadmium in the BTCs was Eh = 490mv> 350mv> 240mv. Reducing conditions in the soil, the sequence of the cadmium in the BTCs was Eh = 490mv> 350mv> 240mv. In oxidizing conditions, high redox potential of soil can significantly promote the transport of copper. In reducing conditions, low redox potential of soil can inhibit the transport of copper, which has nothing to do with the reducing agent concentration. The BTCs peak value of zinc in the highly oxidized conditions were significantly higher than the lowly oxidation conditions; and the effect of different reduction conditions for transport of zinc is not obvious. The transport of three heavy metals ions cadmium , copper and zinc in the flow of liquid pH value decreased, then increased and final equilibrium, the flow of fluid oxidizing condition of the soil pH value is less than reducing conditions; and Eh value of just the opposite.

    • Aggregation of humic colloidal particles as affected by electrolyte and pH

      2012, 49(4):698-707. DOI: 10.11766/trxb201104180139

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      Abstract:The interactions between humus particles and metal ions profoundly affect occurrence of some soil micro-and macro-phenomena. As humic acid is the main component of soil humus, process of the aggregation of humic colloidal particles and structure of the resultant aggregates as affected by concentrations of Ca(NO3)2 and Cu(NO3)2in the solution was studied for comparison analysis in this research project using the light scattering technique. Results show that the difference between Ca(NO3)2and Cu(NO3)2 in adsorption to the surface of charged colloids greatly affected aggregation of humic colloids. The stability of scattered light intensity reflected stability of the system. Scattered light intensity could remain steady in the Ca(NO3)2 system with the electrolyte varying in a wide range from 0 mmol L-1 to 20 mmol L-1 in concentration, but in the Cu(NO3)2 system, the range was much narrower, from 0 mmol L-1 to 3 mmol L-1 only. In the two electrolyte systems, with rising electrolyte concentration, effective diameter of the humic aggregates increased linearly first and then as a power function of time, but the process of humic aggregation is much more sensitive to the variation of Cu(NO3)2 concentration than to that of Ca(NO3)2 concentration. The mean aggregation rate of humus colloids in the solution of 1 mmol L-1 Cu2+ reached 69.55 nm min-1, which is nearly 3 times as high as that (23.94 nm min-1) in the solution of 7.5 mmol L-1 Ca2+. Obviously the mean aggregation rate is much higher under the action of Cu2+ than under the action of Ca2+. In the Ca(NO3)2 system, the higher the electrolyte concentration, the more open, the structure of the resultant aggregates, which became more open or loose in structure and smaller in fractal dimension after being set aside for 50 days, suggesting that the aggregation process is reversible. However, in the Cu(NO3)2 system, the aggregates formed under the action of Cu2+ were quite open in structure at their initial stage, but they became higher in fractal dimension and more compact in structure after being set aside for 50 days, suggesting that the aggregation process is irreversible. All the findings provide a new way of thinking for understanding the mechanism of the formation of humic supermolecular aggregates.

    • Effect of low-molecular-weight organic acids on dynamics of mobilization of Al in variable charge soils

      2012, 49(4):708-715. DOI: 10.11766/trxb201012260549

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      Abstract:Effects of low-molecular-weight (LMW) organic acids on mobilization of Al and distribution of mobilized Al between soil solid and solution phase were studied in two acid soils from the angle of dynamics. Results show that LMW organic acids weak in chelating ability, such as lactic acid and acetic acid, promoted Al mobilization mainly with the aid of protons. They were less effective than HCl in promoting Al mobilization. While LMW organic acids strong in chelating ability, such as malic acid, oxalic acid and citric acid, promoted Al release mainly through chelation with organic anions. This effect was more effective for organic acids stronger in chelating ability with Al. In latosol high in content of iron oxides, malic acid, oxalic acid and citric acid increased the content of exchangeable Al mainly through specific adsorption of organic anions. While they decreased the content of exchangeable Al in red soil low in content of iron oxides mainly through formation of soluble Al-organic complexes. Distribution ratio of mobilized Al between soil solution and soil solid depended on competition between organic anions in soil solution and negative charge sites on soil surface for Al ions. Thus, most Al mobilized by lactic acid and acetic acid existed as exchangeable Al, while Al mobilized by oxalic acid and citric acid was mainly distributed as soluble Al-organic complexes in soil solution, which was especially significant in red soil low in content of free iron oxides, and would promote Al mitigation from soil to water body.

    • Effects of organic matter on interactions between cations and clay particles in paddy soil of Yellow-brown soil based on Wien effect

      2012, 49(4):716-724. DOI: 10.11766/trxb201106070204

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      Abstract:Paddy soil derived from yellow-brown soil, rich in organic matter, was used to extract clay particles < 2 μm, half of which was deprived of organic matter, and then prepared into samples saturated with Na+,K+,NH4+,Ca2+, Cd2+ and La3+ cations, separately. Effects of organic matter (OM) on interactions between cations and soil clay particles were investigated with the aid of the suspension Wien effect. It was found that threshold electrical conductivity was higher in the suspensions of original soil than in the suspensions of OM-removed soils. In all the suspensions, except for Na+ -saturated one, the rate increasing electrical conductivity of the OM-removed soil suspensions with field strength in the range > 50~100 kV cm-1 was apparently higher than that of the original soil suspensions. OM increased the mean free binding energies of all the cations other than Na+, with the effect being the most significant on Ca2+, about 0.57 kJmol-1, and being the least on Cd2+, around 0.03 kJmol-1. In all the soil suspensions, binding energies of various cations followed the sequence of Na+ < K+ ≈ NH4+ < Ca2+ ≈ Cd2+ < La3+.OM reduced the mean free adsorption energies of all the cations except Na+. The effect was significant for NH4+ at field strengths > 70 kV cm-1, for K+, Ca2+ and Cd2+ at field strengths > 50 kV cm-1 and for La3+ at field strengths > 70 kV cm-1, and the difference got more obvious with increasing field strength. OM made it more difficult for cations adsorbed on clay particles to get released into the solution. Stripping intensities of the cations except Na+ were distinctly higher in the suspension of OM-removed soil than in the suspension of original soil, with the difference △Is following the order of K+ < NH4+ < La3+< Ca2+ < Cd2+, which indicated that OM made Cd2+ adsorbed on clay particles most difficultly strip off. In Na+ and K+ saturated soil clay particles, OM made zeta potential move towards positivity by 40 mV, but in clay particles saturated with NH4+,Ca2+,Cd2+and La3+, towards negativity by 17 ~ 36 mV.

    • Movement and transformation of phosphorus in fertilizer microsites in a fluvo-aquic soil

      2012, 49(4):725-730. DOI: 10.11766/trxb201104190141

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      Abstract:Movement and transformation of phosphorus (P) in fertilizer microsites in fluvo-aquic soil were studied through an indoor incubation experiment using soil columns. Results show that fertilizer P did not move far, only 8~14 mm, after 7 and 28 days of transportation. Most of the applied P was fixed by the soil within the radius of 0~2 mm of the site of fertilizer placement. The concentrations of water-extractable P, acid-extractable P and available P decreased rapidly with the increase in distance from the site, showing an exponential curve. P movement occurred mainly within the first 7 days after application and most of the P that moved into the soil was fixed by the soil through adsorption. P application rate significantly affected the movements of various fractions of P within the fertilizer microsite, whereas duration of the incubation had significant effect only on the movement of water-extractable P.

    • Effects of nitrogen fertilization and root separation on agronomic traits of intercropping soybean, quantity of microorganisms and activity of enzymes in soybean rhizosphere

      2012, 49(4):731-739. DOI: 10.11766/trxb201110080379

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      Abstract:A pot experiment using the root separation technique was carried out to study effect of root interaction in soybean maize intercropping with or without N fertilization. Results of the experiment show that the chlorophyll content of soybean was higher in Treatment NS (No separation) than in Treatment PS (partially separated with nylon net) and Treatment FS (fully separated) at all the growth stages with or without N fertilization. N fertilization was better at improving agronomic traits of the soybean, such as plant height, node number of the main stem, effective branches, pods per plabt and 100-seed weight, than mere intercropping (without N fertilization), and root interaction between the two interplanted crops played a significant(p<0.05) role only in improving pods per plant and 100-seed weight of the soybean. The treatments of root separation underground also demonstrated that the root interaction improved economic and biological yields of the soybean, but the effect was not significant than that of N fertilization. Intercropping and N fertilization could not only increase the populations of bacteria, fungi, actinincrease and nitrogen-fixing bacteria, but also enhanced the activities of urease, phosphatase, invertase and protease. Correlation analysis revealed that the populations of bacteria, fungi, actinincrease, and nitrogen-fixing bacteria and the activities of urease, phosphatase, invertase and protease, were all significant (p<0.05) and markedly significant (p<0.01) related to chlorophyll content of soybean and economic and biological yields of soybean per plant. All the findings demonstrate that root interaction between interplanted crops plays an important role in improving soil micro-ecoenvironment, increasing the population of microorganisms and the activity of enzymes in the soil, and raising economic and biological yields of the crops.

    • Effect of long-term land use on fractionation and profile distribution of organic nitrogen in aquic brown soil

      2012, 49(4):740-747. DOI: 10.11766/trxb201106280239

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      Abstract:Contents of fractions of organic nitrogen ( N ) in the soil profiles of fields that had been under different land uses (paddy field, upland and forestland) for 16 years were determined with the Bremner method. Results show that non-acidolysable N was the dominant fraction of organic nitrogen in all the three soils (0~60 cm in depth), and the contents of acidolysable total N and acidolysable soil organic nitrogen fractions and their proportions to total N were, on the whole, the highest in surface soil (0 ~ 20 cm). The content of acidolysable total N in 0 ~ 60 cm soil layer and contents of various acidolysable organic N fractions in 0 ~ 40 cm soil layer decreased with soil depth, but the proportions of acidolysable total N and various acidolysable organic N fractions to total N in 0 ~ 60 cm soil layer did not show any obvious regulations. Within the same soil depth, the paddy soil and the upland soil showed a similar regularity in contents of acidolysable total N and acidolysable soil organic nitrogen fractions and their proportions to total N, that is, unknown N > ammonia N > amino acid N > amino sugar N, while the forest soil, did not show any obvious regularity in this aspect. Compared with paddy soil, upland soil and forest soil were more likely to increase the contents and their proportions to total N of acidolysable total N, acidolysable ammonia N, amino acid N and amino sugar N in the surface soil layer. In upland soil, the increase in acidolysable ammonia N was more significant, while in forest soil, the increase in acidolysable amino acid N and acidolysable amino sugar N was As a whole, when paddy field was turned into forest land, the increase in eadily decomposable acidolysable N was the most significant, thus indicating that its potential of increasing soil N supply is the highest.

    • Effects of n application on n content and n uptake by crops in soils under different long-term fertilization managements in wheat-maize rotation system

      2012, 49(4):748-757. DOI: 10.11766/trxb201107120257

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      Abstract:The microplot method was used to compare soils under different long-term (19 years) fertilization treatments i.e. NF (no fertilizer); NPK (inorganic NPK fertilizer) and MNPK (manure plus inorganic NPK fertilizer) in retention, crop uptake, and leaching of applied N. Results show that application of N significantly increased mineral N in the soil of Treatment NF, but had no such effect in the soils of Treatments NPK and MNPK. However, it increased soil microbial biomass N (SMBN) by 4.3 and 0.8 times in the soils of Treatments NPK and MNPK at the elongating stage of wheat, but did not in the soil of Treatment NF. From the elongating stage to the flowering stage, soil microbial biomass N in the soils of Treatments NPK and MNPK dropped by 51% and 56%. In Treatments NPK and MNPK, the crop of wheat used up 36% and 45%, respectively, of applied N, while in Treatment NF, wheat rarely absorbed any of the applied N, of which 34% was used up by the subsequent maize. By the time when wheat was harvested more than 50% of the applied N had been leached into the soil layers below 30 cm in Treatment NF, and a significant portion into the 30~50 cm soil layer in Treatment NPK, but little down the soil profile in Treatment MNPK. The findings demonstrate that long-term combined application of manure and NPK is an effective way of fertilization management that could strengthen N buffer capacity of the soil, harmonize the relationship between soil N retention and crop N uptake demand, improve N use efficiency and minimize the risk of environment pollution.

    • Distribution and mineralization rate of Phosphorus in different polluted rivers in Taihu basin

      2012, 49(4):758-763. DOI: 10.11766/trxb201111260469

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      Abstract:Water samples were collected for phosphorus (P) analysis in the rivers polluted with farming (Type-A), fishery (Type-B) and domestic sewage (Type-C) in Taihu Basin, China. The results show that the total phosphorus (TP), the total dissolved phosphorus (TDP) and the soluble reactive phosphorus (SRP) are slightly higher for Type-B river than Type-A river, but much lower than Type-C river. On the contrary, enzymatically hydrolysable phosphorus (EHP) in Type-A river is the highest with a maximum value of 0.11 mg L-1 in high-water period, and is the lowest for Type-C. Laboratory analysis reveals that mineralization rate of organophosphorus is significantly higher for Type-A and –B rivers than that for Type-C, especially in high-water period with a maximum value of 1.437 nmol L-1 min-1. EHP is found to be positively related to mineralization rate, and organo-phosphorus has a regeneration period of 3~7 days in Type-A and -B rivers versus the 9.1 days in Type-C river. Overall, the distribution and mineralization rate of P are river-type dependent. The major TP contributed from domestic sewage, while the phosphorus contributed from farming and fishery is more readily available to plants in Taihu Lake.

    • Lignin in buried ancient paddy soils at Chuodun site

      2012, 49(4):764-772. DOI: 10.11766/trxb201105050171

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      Abstract:In order to know the resource, preservation and development of lignin, a useful biomarker of SOM (soil organic matter), samples of lignin extracted from the buried ancient paddy soil at Chuodun ruin site, China were analyzed with the CuO oxidation method for its characteristics and catabolites of phenolic acids. The buried ancient paddy soils was identified to be more than 6 000 years old and confirmed with the archaeological method. Results showed that the total lignin-derived phenols in that soil ranged from 0.004 to 0.035 mg kg-1, decreasing with the depth and was obviously lower than those in the modern paddy soils (0.27~0.34 mg kg-1), but no significant difference was found between buried paddy soils that had been planted with rice or without rice. The composition of oxidized phenols in the soil with S-to-V and C-to-V ratios being 0.40~1.55 and 0.15~0.89, respectively, demonstrates that non-woody angiosperms once grew in the soil; between ancient soils with rice or without rice, no significantl difference was found in S-to-V and C-to-V, suggesting that it is not easy to distinguish origin of organic matter of the same kind in the buried soils based on characteristics of lignin. Lignin carbon accounted only for a small portion of the SOC in buried ancient paddy soils, indicating lignin is not so preservable as usually expected in the soil.

    • Application of microplate colorimetric method in determining actvities of polyphenol oxidase and β-glucosidase in soil

      2012, 49(4):773-779. DOI: 10.11766/trxb201108010287

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      Abstract:The microplate colorimetric method has the potential of fast batch-determining activity of soil enzymes. However, so far in China, nothing has been reported on use of this method in measuring activities of lignin-and-cellulose-decomposing enzymes, i.e. polyphenol oxidase (PPO) and β-glucosidase (BG), in the soil and in studying their sensitivity to temperature (EQ10). In this study, based on optimized acidity of the buffer solution, duration of the incubation and buffer/sample ratio of the slurry, the microplate colorimetric method was used to measure activities of the two enzymes in soils under two different farming systems, i.e. consecutive cropping of cotton and alfalfa-switchgrass rotation, and their sensitivity to temperature, and furthermore, its value to the study of soil enzymes was assessed. Results demonstrate that pH 7 of the buffer solution, 2 hours of the incubation and 20:1 of the ratio were the optimal parameters for the test, satisfying both the requirements for batch-analysis and accuracy of the analysis. No significant different was observed between the two cropping systems in soil PPO activity. However, BG activity was much higher in the soil under rotation than under consecutive cropping of cotton. Nevertheless, the two enzymes became more active with rising temperature. The EQ10 values of BG and PPO did not vary much with cultivation systems. It is, thus, concluded that the microplate technique can be used as a routine analytic technique to measure quite rapidly a number of soils and enzymes at the same time in the study of enzymes. Meanwhile, it is necessary to adjust some major parameters properly for use of the microplate method in light of properties of the soil samples.

    • Effects of shading level and fertilization on the yield and quality of Lycoris radiata cut flower

      2012, 49(4):780-787. DOI: 10.11766/trxb201106280241

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      Abstract:A field experiment designed to have different organic/inorganic combinations in fertilization and 4 levels of shading was carried out to study effects of fertilization and shading on yield and quality of cut flower of Lycoris radiata. Results show that shading and fertilization significantly affected yield of the cut flower yield. Proper shading (30%, 65%) could improve yield and quality of the cut flower, and a higher level (90%) of shading could also have a little effect in improving the yield and quality of Lycoris radiata cut flower in summer high in temperature and solar irradiation. Application of a certain amount of organic fertilizer could increase the yield of Lycoris radiata cut flower, but had no significant effect on quality of the cut flower. The treatment with 1.3 kg of pig manure only was the highest in yield in the experiment. Application of inorganic fertilizer could prolong scape of the flower, increase the number of flower per scape, and enlarge the scape in diameter and base diameter, but do nothing on yield of the flower in this study. However, increased application of P did not have any significant effect on improving quality of the cut flower. Treatment A2B2C1 (combining the three factors, shading, application of organic fertilizer and application of inorganic fertilizer) was highest in high in this study, averaging 25.6 cut flowers per plot and 85.57% in blossom rate. However, sharp variation was observed between the treatments in quality parameters of Lycoris radiate cut flower, which demonstrates that proper combination of inorganic fertilizer and organic manure in fertilization plus proper shading can increase yield of the cutflower of Lycoris radiate and improve its quality.

    • Effects of magnetic tracer for soil erosion on physiological characteristics, yield and quality of Chinese cabbage

      2012, 49(4):788-795. DOI: 10.11766/trxb201108230314

      Abstract (2210) HTML (0) PDF 1.54 M (1270) Comment (0) Favorites

      Abstract:In order to determine effects of the magnetic tracer for soil erosion on Chinese cabbage, a field experiment was carried out, with the cabbage exposed to the tracers different in concentration (1%, 3%, 5% and 10%). Results show that in all the four treatments, leaf length, leaf width, root length and yield of the plant were all increased significantly. In Treatments 3% and 5%, the tracer improved plant height, chlorophyll content (p<0.05), net photosynthetic rate and transpiration rate as well. The tracer inhibited SOD (Superoxide dismutase) activity in leaves of the plant, but stimulated the activity in roots significantly (p<0.05), however, its effect on POD (peroxidase) in the plant was just the opposite and its effect on CAT (catalase) activity little. In plants exposed to low concentrations of the tracers, POD activity and CAT activity both remained high in leaves and roots. The tracer also caused increase in MDA (malondialdehyde) content significantly (p<0.05) in seedling leaves, but decrease in content of soluble sugar, though not significant. When higher than 5%, the tracer significantly decreased vitamin C in the plant (p<0.05), but when lower than 3%, it improved quality of the plant effectively. In a word, the tracer low in concentration promotes growth of Chinese cabbage, but when high in concentration, it displays an opposite effect on the plant.

    • >Reviews and Comments
    • Biochar and its relation to humus carbon in soil: a short review

      2012, 49(4):796-802. DOI: 10.11766/trxb201111210460

      Abstract (3901) HTML (0) PDF 680.86 K (1680) Comment (0) Favorites

      Abstract:For the past few years, whether there is any genealogical relationship between biochar C (BcC) and humus carbon (HC) has been a hot spot in both pedology and geochemistry and a scientific issue for urgent solution. BcC is a kind of carbon-contained material, transformed from bioactive organic matter in an environment high in temperature and low in or free of oxygen, while humus is a kind of carbon-contained polymeric compound formed as a product of microorganisms decomposing dead plants or animals in soil. This review covered works done by foreign and domestic researchers on the relationship between BcC and HC in the recent 20 years, especially the recent 10 years. The researches available suggested that BcC could be transformed into HC by microorganisms. But the work on paths of the transformation and comparison between BcC and HC in physical, chemical and biological feature is still insufficient. Advantages and disadvantages were analyzed of a variety of methods, such as chemical oxidation, molecule marker analysis, hydropyrolysis, thermo-chemical oxidation, UV-oxidation, and nuclear magnetic resonance (NMR), used in quantitative analysis of BcC. Detailed introduction was presented to the application of scanning electron microscopy (SEM), elementary analysis (EA), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), Pyrolysis-Gas chromatography-Mass spectroscopy(Py-GC-MS)and NMR to structural characterization of BcC. Feasibilities were also elaborated of exploring comparison in structure and transformation between BcC and HC.

    • Review of remediation of POPs contaminated sites with soil washing method

      2012, 49(4):803-814. DOI: 10.11766/trxb201105040165

      Abstract (3310) HTML (0) PDF 1.58 M (2200) Comment (0) Favorites

      Abstract:Soil washing is one of the most used physical and chemical methods in remediation of POPs contaminated sites. This method refers to the process of washing the contaminated soil in depth with an object-specific kind of washing solution; pooling the solution for separation of the pollutants; recycling the purified solution for reuse; and safely disposing the pollutants. Owing to differences in position of soil washing at the contaminated site, type of the washing solution and way of the washing, soil washing varies in type, like multi-step washing, washing aided with ultrasound waves, electricity-powered washing, chemical washing, etc., which can be selected for use site-specifically to enhance effectiveness of the washing. Efficiency of the remediation is obviously affected by a number of factors, such as soil texture, properties of contaminants, properties of the solution, optimal conditions for soil washing and reuse efficiency of the solution. Problems with the soil washing method, orientation of the research in future and its application are also discussed. Considering the scope of its application and cost factors, soil washing is considered a suitable technology in line with the actual status of POPs contaminated sites in China, and may have some prospect of extensive application.

    • Methane emission and mitigation strategies in animal manure management system

      2012, 49(4):815-823. DOI: 10.11766/trxb201110240408

      Abstract (2840) HTML (0) PDF 1001.05 K (1757) Comment (0) Favorites

      Abstract:Methane, produced from decomposition of livestock manure under anaerobic conditions, contributes significantly to anthropogenic CH4 emission to the atmosphere. The expansion of the scale of livestock breeding will lead to a continuing increase in CH4 emission. To achieve utilization of manure as resource and mitigation of CH4 emission, it is urgent to introduce the concept of “animal manure management system”, and investigate characteristics of the production and emission of CH4 in the system and its mitigation strategies. Therefore, the current review began with an introduction to structure of the manure management system, elaborated CH4 production in the system and factors affecting CH4 emissions. It also discussed emission-calculating methods, and summarized advancements in the study on CH4 emissions from manure management system at home and abroad. At the end, optimized manure management models compatible to the current scale of livestock breeding in China and strategies based on improvement of management technology for mitigation of CH4 emissions were suggested.

    • >Research Notes
    • Prediction of coastal saline soil salinity based on VIS-NIR reflectance spectroscopy

      2012, 49(4):824-829. DOI: 10.11766/trxb201108310329

      Abstract (3035) HTML (0) PDF 1.22 M (1497) Comment (0) Favorites

      Abstract:

    • Characteristics and sources of polycyclic aromatic hydrocarbons in soils different in land use in Zhanjiang city

      2012, 49(4):830-834. DOI: 10.11766/trxb201105180179

      Abstract (2534) HTML (0) PDF 1.23 M (1305) Comment (0) Favorites

      Abstract:

    • Effects of water-saving irrigation on soil salt distribution and soil microflora in saline soil

      2012, 49(4):835-840. DOI: 10.11766/trxb201110110387

      Abstract (2565) HTML (0) PDF 1.27 M (1261) Comment (0) Favorites

      Abstract:

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