Jiu-Yu Li Ren-Kou Xu Hong Zhang. Iron oxides serve as natural anti-acidification agents in highly
weathered soils. J Soils Sediments 2012 12:876–887.

Abstract

Purpose The effect of Fe oxides on the natural acidification of highly weathered soils was investigated to explore the natural acidification process in variable charge soils.

Materials and methods A variety of highly weathered soils with different Fe oxide contents were collected from the tropical and subtropical regions of southern China to investigate the soil acidity status. Electrodialysis experiments were conducted to simulate natural acidification process and promote accelerated acidification in a variety of systems such as relatively less weathered soils mixtures of goethite with montmorillonite or kaolinite an Alfisol a limed Ultisol and Fe oxides coated montmorillonite. The objective was to gather evidence for the occurrence of Fe oxide inhibited natural acidification in highly weathered soils.

Results and discussion Highly weathered soils with free Fe2O3<100 g-kg (17 soils) had an average pH04.64±0.06 while the soils with free Fe2O3>100 g-kg (49 soils) had an average pH05.25±0.04. A significant linear relationship was found between the soil pH and Fe oxide content of these soils. Similar results were obtained in electrodialysis experiments i.e. in soils that underwent accelerated acidification. A negative correlation was found between the Fe oxide content and exchangeable acidity or effective cation exchange capacity respectively. In another set of experiments goethite slowed down acidification in experiments conducted with this Fe oxide and montmorillonite or kaolinite or an Alfisol or a limed Ultisol. The overlapping of the electrical double layers on the positively charged Fe oxide particles and negatively charged minerals may have caused the release and subsequent leaching of the base cations but inhibited the production of exchangeable acidity cations. In addition when montmorillonite or Fe oxide-coated montmorillonite were electrodialyzed in another set of experiments exchangeable acidity of the former was much greater than that of the latter suggesting that the positively charged Fe oxide coatings on montmorillonite have partially neutralized the permanent negative charge on montmorillonite surfaces decreasing exchangeable acidity.

Conclusions Fe oxides may function as natural “anti-acidification” agents through electric double-layer overlapping and coating of phylliosilicates in highly weathered soils.

Yang Song Fang Wang Yongrong Bian Yinping Zhang Xin Jiang. Chlorobenzenes and organochlorinated pesticides in vegetable soils from an industrial site China. Journal of Environmental Sciences 2012 24(3): 362–368.

Abstract

Organochlorinated compounds are ubiquitous contaminants in the environment especially in industrial sites. The objective of the work was to investigate whether a vegetable field near an industrial site is safe for vegetable production. The residues of chlorobenzenes (CBs) hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in a vegetable field which was near a chemical plant in China were characterized. Point estimate quotient was used for ecological risk assessment of the investigated site. The results showed that all CBs except monochlorobenzene (MCB) were detected in soils. The total concentrations of ∑CBs ranged from 71.06 to 716.57 ng-g with a mean concentration of 434.93 ng-g. The main components of CBs in soil samples were dichlorobenzenes (DCBs) trichlorobenzenes (TCBs) and tetrachlorobenzenes (TeCBs) while for single congeners 124-TCB had the highest concentration which ranged from 13.21 to 210.35 ng-g with a mean concentration of 111.89 ng-g. Residues of hexachlorobenzene (HCB) in soil samples ranged from 0.9 to 11.79 ng-g significantly lower than ∑DCB ∑TCB and ∑TeCB. Concentrations of ∑HCHs and ∑DDTs in soils ranged from 11.32 to 55.24 ng-g and from 195.63 to 465.58 ng-g respectively of which the main components were a-HCH and pp‘-dichlorodiphenyldichloroethylene (pp‘-DDE). Ecological risk assessment for the investigated site showed that the most potential risks were from TCBs and TeCBs based on the hazard quotients. The higher residues of CBs and DDTs compared to the target values and the higher than 1 hazard quotients indicated that this area is not safe for vegetable production and thus soil remediation is needed.

J Min W Shi G Xing D Powlson & Z Zhu. Nitrous oxide emissions from vegetables grown in a polytunnel treated with high rates of applied nitrogen fertilizers in Southern China. Soil Use and Management 2012 28: 70–77.

Abstract

Soils under intensive agricultural practices such as those for growing vegetables in plastic greenhouses are an important anthropogenic source of nitrous oxide (N2O). Nitrous oxide emissions and measures to mitigate them through fertilizer N management have been less frequently studied than open field systems. The objectives of this study were to measure N2O emissions from vegetables under greenhouse conditions in Southern China and to investigate the effect of reducing the amount of applied synthetic N fertilizer compared with local practice. Results indicate that the average N2O-N flux during the growth of four vegetables (tomato cucumber celery and a second tomato crop) was 117.4 ± 9 lg N⁄m2 ⁄ h and the annual emission rate was 8.1 ± 0.6 kg ⁄N⁄ ha for local farms. Temperature was important with much lower emissions during the celery-growing season when soil and air temperatures were frequently <10 C. Nitrous oxide emissions from the greenhouse vegetables were seven times greater than from the rice–wheat system in the same area and soils. Reducing the amount of applied synthetic N fertilizer by 40% relative to local farmers’ normal usage could reduce annual cumulative N2O emissions by 33% without any impact on crop yields.

Guang-Zhong Han Gan-Lin Zhang Zi-Tong Gong and Gai-Fen Wang. Pedotransfer Functions for Estimating Soil Bulk Density in China. Soil Sci 2012 177: 158-164.

Abstract

Soil bulk density (BD) which can be measured by several labor-intensive procedures is frequently missing from soil databases. However it is an essential parameter in many calculations and models and pedotransfer functions (PTFs) can be developed to estimate it. In this article the predictive accuracy of 19 published PTFs was evaluated using soil data sets from China. In addition exploratory stepwise regression models were proposed and validated. The data used in model development were legacy data from various sources and were divided randomly into two sets: a training set for model development with 75% of the data and a validation set for model validation with 25% of the data. The results show that existing models developed by Alexander (1980) (P1) Manrique and Jones (1991) (P7) and Périé and Ouimet (2008) (N6) respectively produced relatively accurate predictions. However the first two models were inappropriate for soils containing a large amount of soil organic carbon. The exploratory model (Model 1) indicated that soil organic matter organic matter^0.5 total nitrogen and clay were the four most important factors in BD prediction. The exploratory model and its simplified version (Model 3) had higher prediction accuracies than previously published PTFs. The results show that parameters tailored to the current data improved prediction accuracy for the nonlinear model (Model 2). Compared with the exploratory model (Model 1) its simplified version and the nonlinear model with only one variable had good prediction accuracies as demonstrated by validation.

Xuezheng Shi Wentai Zhang Biao Huang and Dongsheng Yu. Soil Information Acquisition and Monitoring in the Anthropocene of a Changing World. Soil Horizons 2012 53(2): doi: 10.2136-sh12-01-0001

Abstract

Social demands have boosted the development of soil science. According to different social demands soil science shouldered varied specific tasks in different time or countries. In the Anthropocene era human activities have already become the sixth soil-forming factor in addition to the natural factors. Soil scientists should not only focus on soil attributes but also place emphasis on the studies dealing with human activities driven by social demands. This article addresses three areas in which more focus is required to build a new “anthropedology” subject: (i) theory and methodology for acquiring information on soil change induced by anthropogenic factors; (ii) major factors controlling anthropogenic soil change; and (iii) building a universal soil classification system an old yet unresolved question. In conclusion soils have been more strongly affected by new types of human activities than ever before. Under intensive anthropogenic influences processes of soil change are accelerated. Soil scientists should not ignore soil changes by human activities in such a rapidly changing world in order for the development of soil science to meet the social demands.

Yanjiang Cai Weixin Ding Jiafa Luo. Spatial variation of nitrous oxide emission between interrow soil and interrow plus row soil in a long-term maize cultivated sandy loam soil. Geoderma 2012 181–182: 2–10.

Abstract

There is a high spatial variation in N2O emission fromagricultural fields and N2O emissions from fields cultivated with stalk-crops was generally measured in the interrow area. The aim of this study was to evaluate the difference in seasonal N2O emissions between interrow soil and interrow+row soil and to understand the effect of different fertilizers on N2O emissions in a maize-cultivated sandy loam soil in the North China Plain. The experiment included five treatments: organic manure (OM) half-organic manure N plus half fertilizer N (HOM) fertilizer NPK (NPK) fertilizer NK (NK) and control (CK). CumulativeN2O emission frominterrow+rowsoil during the maize growth season was 0.84–1.22 kg N ha−1 with an average of 0.98 kg N ha−1 in the N-fertilized treatments significantly higher than the 0.30–0.49 kg N ha−1 from interrow soil. However no significant difference was observed in the CK treatment. Themeasurement in interrow soil underestimated N2O emissions by 44–67%. This difference mainly occurred at the two peak emission periods following fertilizer application probably due to discrepancy in soil denitrification potential. Manure application more efficiently increased difference in N2O emission between interrow soil and interrow+row soil than inorganic N fertilizer application. The higher NO3 − concentration did not induce larger N2O emission from interrow soil in the NK treatment than in the NPK treatment but did frominterrow+row soil resulting in greater difference in N2O emission between interrowsoil and interrow+rowsoil. It is suggested that measuring N2O emission solely frominterrowsoil could underestimate seasonal N2O emissions and partly mask the effect of N fertilizer application rates on N2O emission in a maize-cultivated soil in the North China Plain.

Jia Deng Zaixing Zhou Xunhua Zheng Chunyan Liu Zhisheng Yao Baohua Xie Feng Cui Shenghui Han Jianguo Zhu. Annual emissions of nitrous oxide and nitric oxide from rice-wheat rotation and vegetable fields: a case study in the Tai-Lake region China. Plant Soil 2012 DOI 10.1007-s11104-012-1223-6.

Abstract

Background and aims Knowledge on nitrous oxide (N2O) and nitric oxide (NO) emissions from typical cropping systems in the Tai-Lake region is important for estimating regional inventory and proposing effective N2O and NO mitigation options. This study aimed at a) characterizing the seasonal and annual emissions of both gases from the major cropping systems and b) determining their direct emission factors (EFds) as the key parameters for inventory compilation.

Methods Measurements of N2O and NO emissions were conducted year-round in the Tai-Lake region using a static opaque chamber method. The measurements involved a typical rice-wheat rotation ecosystem and a vegetable field. The two types of croplands were subjected to both a fertilized treatment and a control treatment without nitrogen addition. In the rice-wheat ecosystem N2O emissions were measured throughout an entire year-round rotation spanning from June 2003 to June 2004 whereas NO emissions were measured only during the non-rice period. In the vegetable field both N2O and NO emissions were measured from November 2003 to November 2004.

Results During the investigation period the average cumulative N2O and NO emissions under the fertilized conditions amounted to 3.80 and 0.80 (during the nonrice period for NO) kg Nha−1 respectively in the ricewheat field and 20.81 and 47.13 kg N ha−1 respectively in the vegetable field. The average total N2O and NO emissions under the control conditions were 1.39 and 0.29 (during the non-rice period for NO) kg Nha−1 respectively in the rice−wheat rotation and 2.98 and 0.80 kg N ha−1 respectively in the vegetable field. The direct emission factor (EFd which is defined as the loss rate of applied nitrogen via N2O or NO emissions in the current season or year) of N2O was annually determined to be 0.56 % in the ricewheat field while the seasonal EFd of NO was
0.34 % during the non-rice period of the rotation cycle. In the vegetable field the seasonal EFds of N2O and NO varied from 0.15 % to 14.50 % and 0.80 % to 28.21 % respectively among different crop seasons; and the annual EFds were 1.38 % and 3.59 % respectively.

Conclusions This study suggests that conventional vegetable fields associated with intensive synthetic nitrogen application as well as addition of manure slurry may substantially contribute to the regional N2O and NO emissions though they account for a relatively small portion of the farmlands in the Tai-Lake region. However further studies to be conducted at multiple field sites with conventional vegetable and rice-based fields are needed to test this conclusion.

    3月27日上午，农业部副部长张桃林一行在中国水产科学院张显良院长、农业部科教司石燕泉副司长及江西省和鹰潭市有关领导的陪同下，考察调研了鹰潭农田生态系统国家野外科学观测研究站。陪同调研考察的地方领导有江西省政协副主席李华栋、江西省政协常委毛慧忠、江西省农业厅副厅长马岩波以及中共鹰潭市委书记陈兴超、鹰潭市市长钟志生等。

    首先，土壤所副所长蔡立主持了座谈会，并回顾了红壤生态实验站的建设历程和主要成果，随后红壤生态站站长孙波汇报了红壤站的主要研究方向、科研进展及十二五发展规划，鹰潭市钟志生市长介绍了红壤站与地方在农业综合开发和农村发展方面的合作情况。

    张桃林副部长在讲话中充分肯定了红壤站所取得的成绩，并就红壤站的进一步发展提出了指导性意见。他指出红壤站要继续夯实研究基础，注重发展形成自身的优势与特色，在定位上要瞄准农业资源与生态环境领域的前沿学科发展方向，要继续扎根江西、面向南方，加强基地建设与技术成果的转移转化，以红壤站为农业科研与生产结合的突破口，发展成为江西省农业科研与科技推广的前沿阵地，并通过联合开放加强与农业公益性教学科研单位的合作，进一步提升地方农业科技的研发和推广水平。他殷切希望红壤站在新的历史时期继承和发扬优良传统，以人为本，以科技人才为核心，开创实验站发展的新局面。

    座谈会结束后，张桃林副部长视察了站内分析测试中心和各类长期定位试验，并就农业废弃物安全阈值、秸秆还田技术、生物有机肥、生物碳等问题与相关科研人员进行了具体的探讨，提出了产业化推广的要求。

Yang Song Fang Wang Yongrong Bian Fredrick Orori Kengara Mingyun Jia Zubin Xie Xin Jiang. Bioavailability assessment of hexachlorobenzene in soil as affected by wheat straw biochar. Journal of Hazardous Materials 2012 217– 218: 391– 397.

Abstract

Biochar incorporation with soil could increase sorption of organic contaminants thereby reducing their bioavailability. In this study the effects of wheat straw biochar on the sorption dissipation and bioavailability of hexachlorobenzene (HCB) a typical persistent organic pollutant (POP) were investigated in laboratory experiments. We observed that HCB sorption by biochar was 42 times higher than that by soil and the sorption isotherm was linear for the concentration range studied. Biochar amendments reduced HCB dissipation volatilization and earthworm (Eisenia foetida) uptake of HCB from soil. Hydroxypropylcyclodextrin extraction correlated better with the earthworm bioassay than butanol extraction of HCB in biochar-amended soil. The results of both chemical extraction and earthworm bioassay indicate that biochar amendment of soil resulted in a rapid reduction in the bioavailability of HCB even for the 0.1% biochar application rate. This suggested that wheat straw biochar could potentially be used in immobilizing POPs in contaminated sites.