ZHANG Xiao-Yan ZHANG Guang-Bin JI Yang MA Jing XU Hua and CAI Zu-Cong. Straw Application Altered CH4 Emission Concentration and 13C-Isotopic Signature of Dissolved CH4 in a Rice Field. Pedosphere 2012 22(1): 13–21.

Abstract

CH₄ emission and the concentration of dissolved CH₄ in soil solution and floodwater in a rice field and their stable carbon isotopic signatures as affected by straw application were investigated in 2009 in a field experiment at Jurong Jiangsu Province China. Straw application increased CH₄ emission and CH₄ concentration in the soil solution and floodwater. A positive seasonal correlation was also observed in the variation between CH₄ flux and CH₄ concentration in soil solution. The seasonal total CH₄ emission (51.6 g CH₄ m⁻²) in Treatment WS (straw applied) was about 168% higher than that in Treatment CK (without straw). The emitted CH₄ and CH₄ in soil solution were initially relatively enriched then depleted and finally enriched again in ¹³C in both treatments while CH₄ in floodwater became isotopically heavier. The carbon isotopic signature of emitted CH₄ and CH₄ in floodwater averaged around −62‰ and −45‰ for both treatments respectively and was not significantly influenced by the application of straw. However straw application caused the CH₄ in soil solution to be significantly depleted in ¹³C during the middle of the rice season and the mean δ¹³C value was lower in WS (−57.5‰) than in CK (−49.9‰). Calculation from the isotopic data showed that straw application increased the fraction of CH₄ oxidized causing no significant difference in the δ¹³C value of the emitted CH₄ between the two treatments.

LI Yan CHEN Ying-Long LI Min LIN Xian-Gui and LIU Run-Jin. Effects of Arbuscular Mycorrhizal Fungi Communities on Soil Quality and the Growth of Cucumber Seedlings in a Greenhouse Soil of Continuously Planting Cucumber. Pedosphere 2012 22(1): 79–87.

Abstract

A pot experiment was performed to determine the effects of arbuscular mycorrhizal fungi (AMF) communities on soil properties and the growth of cucumber seedlings in a degraded soil that had been used for continuous cucumber monoculture in a greenhouse for 15 years. In the experiment AMF communities (created by combining various AMF species that were found to be dominant in natural farm soil) were inoculated into the degraded soil and then the soil was planted with cucumber. Inoculation with AMF communities did not affect soil pH but increased soil aggregate stability and decreased the concentrations of salt ions and electrical conductivity (EC) in the soil. Inoculation with AMF communities increased the numbers of culturable bacteria and actinomycetes but reduced the number of fungi. AMF communities increased plant growth soluble sugar content chlorophyll content and root activity compared to non-mycorrhizal or a single AMF species treatments. Improvements of soil quality and plant growth were greatest with the following two communities: Glomus etunicatum + G. mosseae + Gigaspora margarita + Acaulospora lacunosa and G. aggregatum + G. etunicatum + G. mosseae + G. versiforme + G. margarita + A. lacunosa. The results suggested that certain AMF communities could substantially improve the quality of degraded soil.

Xin Hong Liu Wei Ming Shi Sheng Zhou Masaaki Hosomi. Improved Capillary Electrophoresis Method with a New Buffer for the Determination of Major Cations in Soil Extracts. Communications in Soil Science and Plant Analysis 2012 43:788–798.

Abstract

Determination of major cations in soil extracts is important for soil research. This study introduced a new buffer system (Buf-I) for capillary-zone electrophoresis (CZE) for the detection of major cations in soil. The Buf-I system achieved baseline separation of major cations with a wider detection range in less time and with better reproducibility than the old buffer system (Buf-M). Storage stability and running stability experiments showed that the running current of Buf-I was also more stable and the relative standard deviation (RSD%) was significantly less than those of Buf-M. The recovery (91.13–107.64%) by Buf-I was better than that (78.38–103.87%) by Buf-M. The results by Buf-I method were highly consistent with traditional analysis techniques (with a correlation of 0.9963). Therefore we conclude that the new Buf-I system is more stable and accurate than the old Buf-M system and is especially suitable to determine major cations in soil extract.

Shi-Peng Yu Jing-Song Yang Guang-Ming Liu Rong-Jiang Yao Xiang-Ping Wang. Multiple time scale characteristics of rainfall and its impact on soil salinization in the typical easily salinized area in Huang-Huai-Hai Plain China. Stoch Environ Res Risk Assess 2012 26: 983–992.

Abstract

On the basis of monthly rainfall data over 50 years we analyzed temporal properties of annual and seasonal rainfall variability by using and comparing two kinds of continuous wavelet transforms. Furthermore we deduced its impacts on soil salinization in the area of Huang-Huai-Hai Plain China. Results showed that the annual rainfall collected by the studied area showed a decreasing trend during period 1960–2009 at a climatic tendency rate of 14.43 mm-10 years. The Morlet wavelet is better at capturing local feature of rainfall oscillatory behaviors at fine time scales and the Mexican Hat wavelet is better at revealing global feature of rainfall period. Combining Wavelet transform with wavelet power spectrum and its confidence test we found the 8-year dominant period of annual rainfall and the 5- 6- 10- and 12-year dominant periods of seasonal rainfall respectively. The annual and seasonal rainfall trends in the near future and their impacts on soil salinization are deduced based on the rainfall dominant periods and the prominent correlation between rainfall and soil salinity changes. The annual rainfall will still be in a relatively low period in the subsequent year after 2009 and then revert to a relatively high period during 2011–2014. The subsequent summer variability of rainfall may be helpful for reducing the soil salinization while the opposite trends of spring and autumn rainfall variability may aggravate the soil salinization. This suggests sustainable irrigation and drainage measures to prevent soil salinization in this area.

    由中国科学院南京土壤研究所、土壤与农业可持续发展国家重点实验室主持，中国农业大学、华南农业大学、华中农业大学、西南大学、湖南省土壤肥料研究所、南京农业大学等单位共同承担的公益性行业（农业）科研专项经费项目“钾肥高效利用与替代技术研究”启动会于2012年2月19日在南京顺利召开。农业部科技教育司产业处张振华处长、王迎春博士，种植业管理司耕肥处许发辉处长，科技发展中心技术合作处郑戈处长，咨询专家中科院土壤所朱兆良院士、谢建昌研究员、中国农科院农业资源与区划所金继运研究员、全国农业技术推广中心土肥处李荣处长、南京农业大学徐国华教授、中化化肥钾肥事业部郭强副总经理、江苏省农林厅土肥站徐茂站长，以及主持单位和各协作单位代表等近50位专家学者出席了本次会议。
    会议由土壤与农业可持续发展国家重点实验室主任沈仁芳研究员主持并致辞。他代表项目主持单位对农业部、财政部对项目的支持以及对各协作单位的努力表示感谢，对各位专家和各参会课题骨干成员表示欢迎，并代表项目牵头单位表示将对项目的实施提供强有力的支持。项目首席专家周健民研究员为咨询专家颁发了聘书，并向与会代表介绍了本项目的立项背景和意义，及项目的研究内容、任务分配等，着重强调了项目执行过程中要求掌握的原则和相关注意事项。农业部张振华处长、许发辉处长和郑戈处长分别就项目的定位、实施和经费管理等方面提出了要求和建议。随后，各课题负责人详细汇报了各自的研究目标、内容和规划，咨询专家认真听取并给出了中肯的意见和建议。最后，周健民做了会议总结，要求各协作单位按专家的建议认真细致地修改各自的任务书，强调细化任务与总项目目标的衔接，要求大家加强交流、齐心协力，高质量完成目标任务。
    该项目以我国华北、华中、长三角、华南、西南的农作区为研究区域，通过对农田土壤钾素供应潜力和钾资源利用潜力进行综合评估，对我国钾肥需求做出合理预测。以粮食作物、大田经济作物、果树和蔬菜等四大类主要作物为研究对象，对试区主要作物钾肥高效施用与钾资源高效利用配套技术进行筛选与改进、技术研发、集成和模式构建、大面积示范，为我国钾肥的高效利用和减轻钾肥供应对国际市场的依赖提供有效的技术手段，为我国钾肥产业发展和调控规划提供政策决策和技术支持，同时培养一批高水平的研究队伍，为我国钾肥高效利用技术研发的长期发展奠定基础。

Ren-kou Xu An-zhen Zhao Jin-hua Yuan Jun Jiang. pH buffering capacity of acid soils from tropical and subtropical regions of China as influenced by incorporation of crop straw biochars. J Soils Sediments 2012 12:494–502.

Abstract

Purpose The key factors influencing pH buffering capacity of acid soils from tropical and subtropical regions and effects of soil evolution and incorporation of biochars on pH buffering capacity were investigated to develop suitable methods to increase pH buffering capacity of acid soils.

Materials and methods A total of 24 acid soils collected from southern China were used. The pH buffering capacity was determined using acid–base titration. The values of pH buffering capacity were obtained from the slope of titration curves of acid or alkali additions plotted against pH in the pH range 4.0–7.0. Two biochars were prepared from straws of peanut and canola using a low temperature pyrolysis method. After incubation of three acid soils pH buffering capacity was then determined.

Results and discussion pH buffering capacity had a range of 9.1–32.1 mmol kg–1 pH–1 for 18 acid soils from tropical and subtropical regions of China. The pH buffering capacity was highly correlated (R200.707) with soil cation exchange capacity (CEC) measured with ammonium acetate method at pH 7.0 and decreased with soil evolution due to the decreased CEC. Incorporation of biochars at rates equivalent to 72 and 120 t ha−1 increased soil pH buffering capacity due to the CEC contained in the biochars. Incorporation of peanut straw char which itself contained more CEC and alkalinity induced more increase in soil CEC and thus greater increase in pH buffering capacity compared with canola straw char. At 5% of peanut straw char added soil CEC increased by 80.2% 51.3% and 82.8% for Ultisol from Liuzhou Oxisol from Chengmai and Ultisol from Kunlun respectively and by 19.8% 19.6% and 32.8% with 5% of canola straw char added respectively; and correspondingly for these soils the pH buffering capacity increased by 73.6% 92.0% and 123.2% with peanut straw char added; and by 31.3% 25.6% and 52.3% with canola straw char added respectively. Protonation-deprotonation of oxygen-containing functional groups of biochars was the main mechanism for the increase of pH buffering capacity of acid soils with the incorporation of biochars.

Conclusions CEC was a key factor determining pH buffering capacity of acid soils from tropical and subtropical regions of China. Decreased CEC and content of 2:1-type clay minerals during evolution of tropical soils led to decreased pH buffering capacity. Incorporation of biochars generated from crop straws did not only ameliorate soil acidity but also increased soil pH buffering capacity.

Junxiang Jia Liying Sun Xianwang Kong Xiaoyuan Yan Zhengqin Xiong. Annual N2O and CH4 emissions from intensively managed vegetable fields in Nanjing China. Soil Science and Plant Nutrition 2012 58: 91—103.

Abstract

Nitrous oxide (N2O) and methane (CH4) emissions were monitored from an intensive vegetable production region with four typical consecutive rotations and a bare fallow in Nanjing China from 2009 to 2010. The four consecutive rotations were established as follows: Celery (Apium graveolens dulce L.)—Tung choy (Ipomoea aquatica Forsk L.)—Baby bok choy (Brassica rapa Chinensis L.)—Amaranth (Amaranthus mangostanus L.) (C-T-Bb-A) Choy sum (Brassica rapa Chinensis L.)—Celery—Tung choy—Bok choy (Brassica rapa Chinensis L.) (Cs-C-T-Bc) Garland chrysanthemum (Chrysanthemum coronarium L.)—Tung choy—Bok choy (G-T-Bc) and Celery—Choy sum—Lettuce (Lactuca sativa L.)—Bok choy (C-Cs-L-Bc). Annual cumulative N2O emissions were 237.718.3 137.28.5 100.97.5 56.410.6 and 29.23.7 kgNha1 from the G-T-Bc C-T-Bb-A Cs-C-T-Bc C-Cs-L-Bc rotation fields and the bare fallow respectively. Cumulative N2O emissions from the rotation fields except the C-Cs-L-Bc rotation were significantly higher than that from the bare fallow. Annual cumulative CH4 emissions were 9.03.5 13.91.5 18.81.2 12.13.8 and 16.13.5 kgCha1 from the bare fallow C-T-Bb-A Cs-C-T-Bc G-TBc and C-Cs-L-Bc respectively and they did not show significant differences among systems. The annual N2O emission factor averaged 2.6% ranging from 1.2% to 5.0% and was higher than the current IPCC default value (1.0%). Total N fertilizer application rate explained 35.5% of annual N2O emissions. N2O emissions from intensively managed vegetable fields were characterized by high fluxes and emission factors that varied with cropping systems. Frequent year-round monitoring of N2O fluxes from intensively managed vegetable fields is essential for better constraint of the national N2O budget.

Zhou Xin-Bin Huang Jian-Guo Zhou Yong-xiang and Shi Wei-Ming. Genotypic variation of rape in phosphorus uptake from sparingly soluble phosphate and its active mechanism. African Journal of Biotechnology 2012 11(13): 3061-3069.

Abstract

Phosphorus deficiency is one of the most growth-limiting factors in soils in various parts of the world. Two rape cultivars which differed in Phosphorus (P) uptake from Fe-P (FePO4·4H2O) and Al-P (AlPO4) were investigated to elucidate the contributions of root morphology and organic acids exudation to P uptake by rape from iron phosphate and aluminum phosphate. By solution culture and sand culture experiments the activation capacity of insoluble Fe-P and Al-P of organic acids secreted by different rape genotypes roots was studied. The results show that two rape cultivars has significant genotypic variations in both plant dry weight and P uptake per plant when supplied with Fe-P and Al-P as the P source. When supplied with sparingly soluble phosphate (Fe-P and Al-P) the root length surface area and number of roots tips of genotype HG (phosphorus efficient rape) were significantly higher than genotype LG (phosphorus inefficient rape). The rape grew better in Al-P treatment than Fe-P treatment. Root exudates of rape has certain ability to activate insoluble P and it had better activation capacity of insoluble Fe-P under the condition of P stress than normal supply of P. Hence the large differences show traits for more phosphorus efficient plants between in the tested rape genotypes. The genotype HG showed increased P acquisition from the Al-P and Fe-P than the genotype LG. This opens the possibility to breed for more P uptake-efficient varieties as a way to bring more sparingly soluble soil P into cycling in crop production.

    全球稻田面积约1.5亿公顷，75%处于淹水状态。厌氧环境使得水稻土含有丰富的小分子有机酸。通过代谢这些物质，微生物驱动着稻田土壤生物地球化学循环过程。甲酸是稻田有机质降解过程中重要中间产物之一，但水稻土中甲酸代谢微生物及其生态功能却鲜有报道。实验室林先贵研究员团队通过稳定性同位素核酸探针技术，利用13C标记的甲酸培育水稻土，让微生物“吃掉”甲酸的13C；再利用超高速密度梯度离心对土壤总DNA进行分层，获得甲酸代谢微生物13C-DNA；借助实时定量PCR技术、指纹图谱技术和系统发育分析，清楚表明13C-甲酸被土壤梭菌和紫色非硫细菌利用。前者可利用甲酸为电子供体促进水稻土中硫酸盐和铁还原过程；紫色非硫细菌是首次原位条件下被发现可在黑暗中有机异养生长。这些结果不仅仅揭示了水稻土中甲酸代谢微生物，更扩展了我们对甲酸在生物地球化学循环过程中重要性的认知，为全面理解微生物驱动下的土壤养分循环过程及其调控机制提供了重要科学依据。该成果发表在Soil Science Society of America Journal上，并选为研究亮点在美国农作物科学协会(Crop Science Society of America)创办的CSA (Crops Soils Agronomy) news magazine的2012年2月刊上报道。

Youzhi Feng Xiangui Lin* Zhongjun Jia and Jianguo Zhu. Identification of Formate-Metabolizing Bacteria in Paddy Soil by DNA-Based Stable Isotope Probing. Soil Science Society of America Journal 2012 76(1): 121-129.