S. D. KIMURA YAN Xiao-Yuan R. HATANO A. HAYAKAWA K. KOHYAMA TI Chao-Pu DENG Mei-Hua M. HOJITO S. ITAHASHI K. KURAMOCHI CAI Zu-Cong and M. SAITO. Influence of Agricultural Activity on Nitrogen Budget in Chinese and Japanese Watersheds. Pedosphere 2012 22(2): 137–151.

Abstract

To analyze the effect of agricultural activity on nitrogen (N) budget at the watershed scale a comparative study was conducted at two Japanese watersheds the Shibetsu River watershed (SRW) and Upper-Naka River watershed (UNRW) and one Chinese watershed the Jurong Reservoir watershed (JRW). The total area and the proportion of agricultural area (in parentheses) of the watersheds were 685 (51%) 1 299 (21%) and 46 km² (55%) for SRW UNRW and JRW respectively. The main agricultural land use in SRW was forage grassland while paddy fields occupied the highest proportion of cropland in UNRW (11% of total area) and JRW (31% of total area). The farmland surplus N was 61 48 and 205 kg N ha⁻¹ year⁻¹ for SRW UNRW and JRW respectively. The total input and output for the whole watershed were 89 and 76 83 and 61 and 353 and 176 kg N ha⁻¹ year⁻¹ for SRW UNRW and JRW respectively. The proportion of discharged N to net anthropogenic N input was 31% 37% and 1.7% for SRW UNRW and JRW respectively. The two watersheds in Japan showed similar proportions of discharged N to those of previous reports while the watershed in China (JRW) showed a totally different characteristic compared to previous studies. The high N input in JRW did not increase the amount of discharged N at the outlet of the watershed due to high proportions of paddy fields and water bodies which was an underestimated N sink at the landscape scale.

GAN Lei PENG Xin-Hua S. PETH and R. HORN. Effects of Grazing Intensity on Soil Water Regime and Flux in Inner Mongolia Grassland China. Pedosphere 2012 22(2): 165–177.

Abstract

In the past few decades the increase in grazing intensity has led to soil degradation and desertification in Inner Mongolia grassland China due to population growth and shift in the socio-economic system. Two sites with different grazing intensities continuous grazing site (CG) with 1.2 sheep ha⁻¹ year⁻¹ and heavy grazing site (HG) with 2.0 sheep ha⁻¹ year⁻¹ were investigated at the Inner Mongolia Grassland Ecosystem Research Station (43° 37′ 50″ N 116° 42′ 18″ E) situated in the northern China to i) characterize the temporal distribution of soil water content along soil profile; and ii) quantify the water fluxes as affected by grazing intensity. Soil water content was monitored by time domain reflectometry (TDR) probes. Soil water retention curves were determined by pressure membrane extractor furthermore processed by RETC (RETention Curve) software. Soil matric potential plant available water and water flux were calculated using these data. Both sites showed an identical seasonal soil water dynamics within four defined hydraulic periods: 1) wetting transition coincided with a dramatic water increase due to snow and frozen soil thawing from March to April; 2) wet summer rainfall in accordance with plant growth from May to September; 3) drying transition a decrease of soil water from October to November due to rainfall limit; and 4) dry winter freezing from December to next February. Heavy grazing largely reduced soil water content by 43%–48% and plant available water by 46%–61% as compared to the CG site. During growing season net water flux was nearly similar between HG (242 mm) and CG (223 mm) sites between 5 and 20 cm depths. However between 20 and 40 cm depths the upward flux was more pronounced at HG site than at CG site indicating that water was depleted by root uptake at HG site but stored at CG site. In semi-arid grassland ecosystem grazing intensity can affect soil water regime and flux particularly in the growing season.

Deli Tong Renkou Xu. Effects of urea and (NH4)2SO4 on nitrification and acidification of Ultisols from Southern China. Journal of Environmental Sciences 2012 24(4): 682–689.

Abstract

The mechanisms for the effects of ammonium-based fertilizers on soil acidification in subtropical regions are not well understood. Two Ultisols collected from cropland and a tea garden in Anhui and Jiangxi Provinces in subtropical southern China respectively were used to study the effects of urea and (NH₄)₂SO₄ on the nitrification and acidification of soils with incubation experiments. Nitrification occurred at very low pH with no N fertilizer added and led to lowering of the soil pH by 0.53 and 0.30 units for the soils from Jiangxi and Anhui respectively. Addition of urea accelerated nitrification and soil acidification in both Ultisols; while nitrification was inhibited by the addition of (NH₄)₂SO₄ and greater input of (NH₄)₂SO₄ led to greater inhibition of nitrification. Ammonia-oxidizing bacteria (AOB) played an important role in nitrification in cropland soil under acidic conditions. Addition of urea increased the soil pH at the early stages of incubation due to hydrolysis and stimulated the increase in the AOB population and thus accelerated nitrification and soil acidification. At the end of incubation the pH of Ultisol from Jiangxi had decreased by 1.25 1.54 and 1.84 units compared to maximum values for the treatments with 150 300 and 400 mg-kg of urea-N added respectively; the corresponding figures were 0.95 1.25 and 1.69 for the Ultisol from Anhui. However addition of (NH₄)₂SO₄ inhibited the increase in the AOB population and thus inhibited nitrification and soil acidification. Soil pH for the treatments with 300 and 400 mg-kg of (NH₄)₂SO₄-N remained almost constant during the incubation. AOB played an important role in nitrification of the cropland soil under acidic conditions. Addition of urea stimulated the increase in the AOB population and thus accelerated nitrification and soil acidification; while addition of (NH₄)₂SO₄ inhibited the increase in the AOB population and thus inhibited nitrification.

Yunxia Wang Lianxin Yang Yan Han Jianguo Zhu Kazuhiko Kobayashic Haoye Tang Yulong Wang. The impact of elevated tropospheric ozone on grain quality of hybrid rice: A free-air gas concentration enrichment (FACE) experiment. Field Crops Research 2012 129: 81–89.

Abstract

Rising tropospheric ozone concentration is currently the most important air pollutant which suppresses plant growth and thus results in yield loss of agronomic crops. However little is known about ozone effects on grain quality of crops. Using a free-air gas concentration enrichment (FACE) facility for ozone fumigation in paddy rice (Oryza Sativa L.) a Chinese hybrid indica cultivar Shanyou 63 was exposed to either ambient or elevated ozone concentration (ca 23.5% above ambient) for two consecutive growth seasons from 2007 to 2008. Harvested grain samples were subjected to various quality tests. In both seasons the brown milled and head rice yield all reduced by elevated ozone concentration with this reduction being greater in 2008 (17–22%) than in 2007 (8–19%). Ozone elevation caused small but significant decrease in brown rice percentage but greatly increased head rice percentage by 8.8%. Chalky grain percentage increased (5.8%) due to ozone elevation while chalkiness area and chalkiness degree remaining unchanged. Although the amylose concentration of rice grains was marginally reduced starch pasting properties demonstrated that grains in elevated ozone concentration had lower breakdown (7.7%) and higher setback value (25.2%) and gelatinization temperature (0.9 °C) than those grown in ambient conditions. Nutrition evaluation indicated that ozone exposure tended to increase the concentrations of protein and all mineral elements analyzed (i.e. K Mg Ca Fe Zn Mn and Cu) but the contents of protein and mineral elements in harvested grains were unchanged or reduced. For most traits of grain quality the year effect was significant however its interaction with ozone was not detected. Our results suggested that long-term exposure to ozone-enriched atmospheres projected in the coming a few decades not only caused serious reductions in yield but also tended to produce the deleterious effects upon grain quality of hybrid Shanyou 63 in terms of appearance and eating-cooking quality.

Gong W ; Yan XY ; Wang JY .The effect of chemical fertilizer on soil organic carbon renewal and CO₂ emission-a pot experiment with maize. Plant and Soil 2012 353 85-94 (IF 2.773 农林科学，一区）

摘要

Background and Aims Previous studies have clearly shown substantial increases of soil organic carbon (SOC) in agricultural soils of Yellow River reaches. Those soils did not receive organic fertilizer input but did receive chemical fertilizer inputs. Thus to investigate the hypothesis that the observed SOC increases were driven by chemical fertilizer additions a maize pot experiment was conducted using a Fluvisol that developed under C-3 vegetation in the Yellow River reaches.

Methods Using the natural C-13 abundance method we calculated the SOC renewal ratio (C-renewal) and separated total soil organic carbon (TOC) into maize-derived soil organic carbon (SOCmaize) and original soil organic carbon (SOCoriginal). Carbon dioxide fluxes and microbial biomass carbon (MBC) were determined by closed chamber method and fumigation-extraction method respectively. The experiment included five treatments: (1) NPK: application of chemical fertilizer NPK; (2) NP application of chemical fertilizer NP; (3) PK: application of chemical fertilizer PK; (4) NK application of chemical fertilizer NK; and (5) CK: unfertilized control.

Results Fertilization increased maize biomass (including grain straw and root) TOC C-renewal SOCmaize maize-derived carbon (MDC: including SOCmaize and root and stubble biomass carbon) and MBC and these values among the treatments ranked NPK>NP>PK>NK>CK. The C-renewal was 5.548.50% across the treatments. Fertilization also increased soil CO2 emission (including root respiration and SOCoriginal decomposition) while the SOCoriginal decomposition during the maize growing season only amounted to 74.0-93.4 and 33.5-46.1% of SOCmaize and MDC among the treatments respectively. Thus input was larger than export and led to SOC increase. Maize grain and straw biomass were positively and significantly correlated with soil delta C-13 TOC C-renewal SOCmaize MDC and MBC.

Conclusions The study suggests that chemical fertilizer application could increase C-renewal by increasing crop-derived C and accelerating original SOC decomposition and that as long as a certain level of crop yield or aboveground biomass can be achieved application of chemical fertilizer alone can maintain or increase SOC level in Fluvisol in the Yellow River reaches.

    为深切缅怀著名土壤学家、我国现代土壤学与植物营养化学的奠基人之一、原中国土壤学会理事长李庆逵先生，牢记他为我国农业和土壤科学发展所作出的突出贡献，传承他的高尚品德和精神风范，南京土壤研究所于4月20日上午隆重举行了“李庆逵先生诞辰100周年”纪念大会。江苏省人大常委会、九三学社江苏省委、中国科学院南京分院、中国科学院亚热带农业生态研究所等单位有关领导，李庆逵先生的亲属，南京土壤研究所全体职工、老同志、研究生及有关人士200余人出席了大会。

    党委书记林先贵主持大会并致辞。他说，李庆逵先生毕生致力于我国土壤科学事业，学术上的精深造诣、科研上的卓著功绩与他的优秀品格交相辉映，是我们后人学习的榜样。我们精心举办纪念活动，不仅仅是缅怀他的丰功伟绩，更为重要的是继承他的科学精神，从他身上汲取科学和道德的力量。

    随后，南京土壤研究所所长沈仁芳向与会人员介绍了李庆逵先生的生平及突出贡献。他指出，李庆逵先生把一生献给了我国土壤科学事业和国民经济建设，取得了辉煌的成就。一是在学术上取得了累累硕果，25岁时编写了中国第一本《土壤分析法》，长期从事红壤研究和开发利用并取得了系统性理论与实践成果，开创了对磷、钾、微量元素的系统研究并推动了我国科学施肥的进程；二是为国民经济建设提供了科学指导，突破了天然橡胶林栽培线的禁区并推移到北纬18-24度，推动了我国磷矿粉的农业利用，创造了碳酸氢铵造粒及深施技术；三是为南京土壤研究所和中国土壤学会的创建与发展作出了突出贡献，创立发展了多个土壤科学分支学科，培养了一大批学科带头人，凝聚了土壤学界同仁共同把我国土壤科学推上了国际舞台；四是积极开展参政议政和社会活动，利用自己的专长参与社会事务管理、服务经济社会发展。沈仁芳所长号召大家谨记李庆逵先生为土壤所的发展和中国土壤科学事业的进步作出的突出贡献，传承和弘扬他热爱科学、淡泊名利、求实创新、诲人不倦的优良品德和高尚情操，奋力拚搏、开拓进取，为“创新2020”的深入实施和土壤科学事业的创新发展贡献智慧和力量。

    江苏省人大常委会仇中文秘书长、南京分院周健民院长、亚热带农业生态所王克林所长、老一辈土壤学家代表赵其国院士、李庆逵先生的学生曹志洪研究员、中青年科技工作者代表施卫明研究员、青年学生代表郭淼同学、李庆逵先生的儿子李定钊先生等先后发表感言，从不同方面回顾了李庆逵先生为我国土壤科学发展和国民经济建设，以及为南京土壤研究所的创建和发展所作出的巨大贡献。各位代表对李庆逵先生在不同阶段、不同方面的深情回忆和精彩描述，使全体与会人员对李庆逵先生传奇的一生有了一个清晰的脉络，对他光辉的形象有了一个全面的认识，李庆逵先生不仅是一位杰出的学者，还是一位优秀的园丁、一位优秀的管理者和建设者，他的贡献不仅在于他的科研成果及担任的职务，更在于他为人师表及提携后人的高尚风范、为中国土壤科学进行科学谋划及凝聚土壤学界参与国家建设和社会事务管理的宏大气魄。随后，所领导向李庆逵先生的家属赠送了由一张张珍贵历史照片汇成的精美生动的纪念画册。

    大会最后，林先贵书记总结说，在中共中央开展创先争优活动之际，对李庆逵先生的追思具有更加重要的意义。李庆逵先生三次获得江苏省劳动模范光荣称号，以及“新中国成立60年模范‘三农’人物”光荣称号，他就是我们身边的先进，是我们学习的楷模，创先争优的一面旗帜。在新的历史时期，我们要学习他热爱祖国、无私奉献的优秀品德，淡泊名利、潜心致研的高尚风范，脚踏实地、敢于创新的科学精神，凝聚人心、识才育人的优良作风，牢记他为南京土壤研究所的发展和我国土壤科学事业的进步作出的突出贡献，坚定理想信念，坚持创新科技、服务国家、造福人民，同心同德、奋力拚搏，推动土壤科学事业开创新的局面，以优异成绩迎接党的十八大胜利召开。

    大会结束后，与会人员还观看了李庆逵先生诞辰一百周年图片展，再次怀念他的音容笑貌、缅怀他的丰功伟绩。

    据悉，李庆逵先生诞辰一百周年纪念大会是系列纪念活动之一，南京土壤研究所还于近期征文并编印了“《土壤园地》纪念专刊”，组织开展了以“追忆李老英姿，再现先驱风采”为主题的图片展和以“传承先辈精神，成就土壤英才”为主题的新老科技工作者交流会，李庆逵先生生前活动过的单位、同仁和学生及有关人士纷纷来函、提供资料、撰写纪念文章等，精心描绘李庆逵先生一生中的点点滴滴，深刻表达对李庆逵先生的无限敬仰和思念。

实验室主任沈仁芳介绍李庆逵先生生平及突出贡献

Xiao-Lin Sun Yu-Guo Zhao Hui-Li Wang Lin Yang Cheng-Zhi Qin A-Xing Zhu Gan-Lin Zhang Tao Pei Bao-Lin Li. Sensitivity of digital soil maps based on FCM to the fuzzy exponent and the number of clusters. Geoderma 2012 171-172: 24–34.

Abstract

Fuzzy c-means clustering (FCM) has been used frequently in digital soil mapping. One of the key issues in applying FCM is the determination of the appropriate classification parameters of the fuzzy exponent (m) and the number of clusters (c). To determine the optimal selection of appropriate m and c values in this study we first used two simulated datasets to demonstrate the sensitivity of three commonly used validity functions to m and c. These two simulated datasets contained overlapping clusters and hierarchical clusters respectively. The three studied validity functions were fuzzy performance index (FPI) compactness and separation (S) and a derivative of the objective function with respect to the fuzzy exponent (−[(δJE-δm)c0.5]). Then a case study mapping soil organic matter (SOM) based on memberships from FCM clustering terrain attributes was conducted to investigate the sensitivity of soil maps to m and c. The results of the study on the simulated datasets showed that the three validity functions were sensitive in differing degrees to the structures of the clustered datasets under a wide range of m but the sensitivities and the range of mwere different for different validity functions and depended on the clustered datasets. The results from the case study of the soil mapping showed that soil maps based on FCM clustering were sensitive to m and c but only the spatial variations of SOM presented on the maps were significantly sensitive to c. Furthermore mapping accuracy was slightly sensitive to m and c. It is concluded that there was a range of optimal m over which digital soil maps did not change very much but this was not certain for c given that the spatial variation presented on the maps changed significantly with c.

Anna Yang Junli Hu Xiangui Lin Anning Zhu Junhua Wang Jue Dai Ming Hung Wong. Arbuscular mycorrhizal fungal community structure and diversity in response to 3-year conservation tillage management in a sandy loam soil in North China. J Soils Sediments 2012 12:835–843.

Abstract

Purpose Modern agricultural science has greatly reduced the use of tillage. Monitoring conservation versus conventional tillage effects on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to investigate the effects of conservation tillage on the spore community structure and the diversity of soil arbuscular mycorrhizal (AM) fungi and to find out the main factors that influence these parameters.

Materials and methods A long-term field experiment established in a sandy loam soil in Northern China has received continuous tillage management treatments for 3 years including conventional tillage (CT) no tillage (NT) and alternating tillage (AT). Topsoil samples (0–15 cm) from four individual
plots per treatment were collected for the analysis of chemical properties and fungal parameters. AM fungal spores were isolated using the wet-sieving method and identified to species level based on morphology by light microscopy. The community structure and the diversity of AM fungi were evaluated using the following parameters: spore density relative abundance species richness Shannon–Wiener index (H′) evenness (E) and Simpson’s index (D). Jaccard index (J) of similarity was calculated to compare AM fungal species composition under different treatments.

Results and discussion Twenty-eight species of AM fungi within four genera Glomus Acaulospora Scutellospora and Entrophospora were recovered from the 12 plots within the three tillage management treatments. Higher spore density species richness and species diversity (H′ E and D) of AM fungi were observed in the two conservation tillage treatments and the redundancy analysis showed that the species richness significantly correlated to soil organic carbon content (P<0.05). The positive effects of NT and AT on the species richness were very close while the AT had relatively greater beneficial impacts on the spore density and the evenness of AM fungi compared to the NT. The lowest Jaccard index (J) of similarity in species composition was also observed between the AT and CT treatments.

Conclusions Soil organic carbon the spore density and species richness and diversity of AM fungi increased in the two conservation tillage treatments. The species richness of AM fungi significantly correlated to soil organic carbon content (P<0.05). Compared with the CT treatment the AT rather than the NT significantly increased the spore density and the evenness of AM fungi (P<0.05). Thus alternating tillage practice may be more beneficial to agroecosystem in this region.