施肥对黑土农田土壤全碳、微生物量碳及土壤酶活性的影响

通过对吉林省德惠市中层黑土农田6年定位施肥试验研究表明,施有机肥、秸秆还田+有机肥、秸秆还田+化肥和半量有机肥+化肥处理较单施化肥、未施肥和休闲裸地处理提高了土壤全碳、全氮含量,降低了土壤碳氮比。对玉米播前、抽穗期和收获期土壤微生物量碳测定表明,抽穗期土壤微生物量碳最高,处理间差异显著,且不同采样时期的土壤微生物量碳与土壤全碳含量之间呈高度正相关。对土壤酶活性研究表明,施有机肥较单施化肥、未施肥和休闲裸地处理显著地提高了土壤脲酶、转化酶和过氧化氢酶活性;单施化肥处理对土壤转化酶和过氧化氢酶具有一定的抑制作用;而有机肥、秸秆和化肥之间的配合施用处理的土壤酶活性表现不一致。相关分析显示土壤微生物量碳与土壤酶活性呈显著或极显著正相关。该研究结果表明,长期向中层黑土农田增施有机物,不仅提高了土壤全碳和土壤微生物量碳的含量,而且也提高土壤酶活性,有利于提高土壤养分转化效率,可使黑土质量向健康方向发展。     

长期施肥对黑土、棕壤微生物量的影响

以公主岭黑土长期定位试验和中科院沈阳生态试验站棕壤长期试验为平台,对不同施肥处理土壤微生物量碳、氮含量的变化及其与土壤有机碳、全氮的关系进行研究。结果表明,长期不同施肥处理黑土和棕壤微生物量碳、氮含量不同,大小依次为有机肥配施化肥>有机肥>化肥>不施肥,其中有机肥配施化肥处理可以显著提高土壤微生物量碳、氮。微生物量碳、氮含量与土壤有机碳、全氮含量之间具有极显著的正相关关系。同时,有机肥配施化肥处理能够显著增加土壤微生物商。     

长期不同施肥对茶园土壤碳氮磷构成的影响

从浙西茶区采集了34个茶园表层土壤,按施肥模式分为施用有机肥+化肥、单施化肥和不施肥等3组茶园,用化学分析方法研究了长期不同施肥下茶园土壤碳、氮、磷库的变化特点。结果表明,3组施肥模式之间的茶园土壤p H和有机碳含量差异不明显;单施化肥或有机肥+化肥的茶园土壤全磷、全氮和有效磷含量明显高于不施肥茶园;全磷与全碳的比例(P/C)和全氮与全碳的比例(N/C):化肥有机肥+化肥不施肥;施用有机肥+化肥土壤的有机质结合态磷比例明显高于单施化肥和不施肥土壤,单施化肥土壤的钙结合态磷的比例明显高于施有机肥+化肥和不施肥土壤,不施肥土壤的闭蓄态磷的比例高于施有机肥+化肥和单施化肥土壤;单施化肥土壤具有较高的NO3--N/NH4+-N比和无机氮含量;施用有机肥+化肥土壤有较高比例的颗粒态有机碳、活性有机碳和微生物生物量碳。基于19项分析指标应用主成分分析方法对研究的34个土壤进行聚类的结果也表明,土壤之间碳、氮、磷库组成的差异主要与施肥模式有关。施用有机肥+化肥的茶园土壤养分较为协调。     

长期施用生物有机肥对土壤肥力及微生物生物量碳的影响

为了研究施用生物有机肥(EM堆肥,即有效微生物制剂 堆肥)对土壤肥力及微生物生物量碳的影响,进行了7年的施用15t/hm2.a有机肥、施用7.5t/hm2.a有机肥(包括EM堆肥、EM鸡粪肥和传统有机肥)、施用化肥和对照处理的田间试验。结果表明:长期施用生物有机肥的土壤肥力明显提高。随着生物有机肥用量的提高,碱性土壤的pH值逐渐降低,土壤有机质、全N、碱解氮、有效磷、速效钾、微生物生物量碳含量增加,与有机肥施用量呈显著正相关。施用化肥可一定程度提高土壤有机质、全N和有效养分含量,但作用不明显。施肥对土壤肥力和微生物量碳的影响趋势是:EM堆肥>传统堆肥>化肥>对照。土壤微生物量碳与土壤有机质、全N、碱解氮、有效磷、速效钾含量呈显著正相关,可以作为施肥过程中土壤质量变化的生物学指标。     

长期培肥对农田黑土土壤微生物量碳、氮的影响

以黑龙江省农科院"黑土肥力与肥效长期定位试验"的农田黑土为研究对象,探讨了长期不同施肥处理对土壤微生物量碳、氮动态变化的影响。研究结果表明,与不施肥、单施化肥、单施有机肥处理相比,化肥配施有机肥能显著增加大豆各生育期土壤微生物量C、N,促进土壤微生物量显著增长,增强了农田黑土土壤有机质、全氮含量,有利于培肥农田黑土。     

不同施肥处理对长期不施肥区稻田土壤微生物生态特性的影响

采用室内恒温培养方法,研究了不同施肥处理对水稻长期肥料试验中不施肥区（CK）和全肥区（NPK）土壤酶活性及微生物群落结构的变化。结果表明,施肥处理（单施化肥、施猪粪和施秸杆）可以显著提高土壤的微生物量碳以及脲酶、酸性磷酸酶的活性,施用有机肥的效果明显大于单施化肥; 有机肥在无肥区（CK）的施用效果与在全肥区（NPK）的效果接近。PLFA分析表明,施肥使无肥区（CK）土壤微生物群落结构发生了显著的变化,施用有机肥显著增加了土壤微生物群落结构的多样性。与不施肥和单施化肥相比,施有机肥主要增加了细菌和真菌的特征脂肪酸如不饱和脂肪酸、环状脂肪酸cy19∶0等的相对含量,而降低了放线菌标记性脂肪酸10Me18∶0的相对含量。     

有机肥和化肥长期施用对土壤活性有机氮组分及酶活性的影响

本文以中国农业科学院山东禹城长期定位施肥试验为平台,研究了长期施用有机肥和化肥26年后对土壤活性氮库不同组分［颗粒有机氮（POM-N）、 可溶性有机氮（DON）、 微生物量氮（SMBN）及轻组有机氮（LFOM-N）］及土壤酶活性的影响。结果表明,与不施肥相比,长期施肥显著提高了土壤全氮、 颗粒有机氮、 可溶性有机氮、 微生物量氮以及轻组有机氮的含量,长期施有机肥效果好于化肥,施用高量有机肥效果好于施用常量有机肥。常量施用量下,50%有机肥和50%化肥配施处理其土壤全氮和活性有机氮库各组分含量与高量化肥处理的相当。长期施化肥处理土壤全氮及活性有机氮库各组分含量随施肥量的增加而显著增高。POM-N对土壤全氮的贡献率最高,且明显受施肥方式的影响,LFOM-N对土壤全氮的贡献率不随施肥方式的改变而变化。长期施肥处理土壤脲酶、 碱性磷酸酶和蔗糖酶活性显著增加,它们之间及与土壤全氮、 速效磷及有机碳含量间呈现显著或极显著相关性,脲酶活性与土壤各活性氮组分间也存在显著或极显著相关性; 但长期施肥后土壤过氧化氢酶的活性低于不施肥     

有机肥替代部分化肥对马铃薯根际土壤微生物群落功能多样性的影响

长期过量施用化肥使农田的土壤微生物区系和生物活性受到极大破坏,作物产量对化肥养分的依赖性越来越强。本文采用大田试验和Biolog生态板法技术相结合的方法,研究了有机肥(普通有机肥-OF,生物有机肥-BIO)替代部分化肥(CF)对马铃薯收获期根际土壤微生物群落功能多样性的影响。结果表明,25℃培养144 h后,收获期马铃薯根际土壤微生物代谢活性以T8处理(60%CF+BOF6000 kg hm-2)最大为0.848,T2处理(100%CF)最小为0.467,单施化肥降低了根际土壤的微生物代谢活性,低于不施肥的对照处理40.52%;生物有机肥替代部分化肥处理的Shannon、Mc Intosh丰富度指数、均匀度指数以及Simpson指数均高于普通有机肥替代化肥的处理,说明施用生物有机肥比普通有机肥更能提高马铃薯根际土壤的微生物活性和多样性;8个处理的主要利用碳源均为羧酸类物质和糖类物质,表明以糖类和羧酸为营养物质的微生物在马铃薯收获期的根际土壤中占主导位置;主成分分析结果显示,生物有机肥比普通有机肥更有利于土壤微生物活性的提高。生物有机肥替代部分化肥可以提高马铃薯根际土壤微生物群落功能多样性。     

长期有机无机配施下烤烟-玉米轮作优化土壤微生物活化无机磷

采集遵义市15年长期施肥定位试验的土壤,包括撂荒地（对照）、烤烟连作—单施化肥、烤烟连作—化肥有机肥配施、烤烟玉米轮作—单施化肥和烤烟玉米轮作—化肥有机肥配施等处理,通过土壤悬浊液与培养液混合培养技术、微生物高通量测序及常规分析,研究长期施肥对土壤无机磷活化的影响。结果表明,烤烟玉米轮作、施用有机肥和撂荒地的土壤可培养微生物（细菌、真菌、放线菌和无机磷细菌）数量增多,种群多样性增加,说明土壤生态环境改善。将土壤悬浊液接种至微生物培养液中,培养期间混合液中的有效磷含量以烤烟玉米轮作高于烤烟连作,化肥有机肥配施和撂荒地高于单施化肥,其中以烤烟玉米轮作—化肥有机肥配施最高,烤烟连作—单施化肥最低,说明合理种植和科学施肥有益于土壤无机磷的活化,在遵义烟区提倡烤烟玉米轮作—化肥有机肥配施很有必要。在混合液中,氢离子与溶解钙磷、有机酸与溶解铁磷和铝磷显著相关。与溶磷微生物的纯培养技术相比,土壤悬浊液培养既能反映微生物的溶磷特征,又更接近土壤微生物菌群复杂的溶磷状况。在供试土壤微生物中,存在柠檬酸合酶、蛋白葡萄糖脱氢酶和苹果酸合酶等的合成通路,处理间的差异可从分子生物学角度解释合理轮作和化肥有机肥配施促进土壤无机磷活化的原因。     

有机肥替代部分化肥对土壤肥力和微生物特征的影响

采用有机肥替代30%化肥(I)、常规化学施肥(N)和不施加任何肥料(CK)三种处理进行田间试验,探讨三种施肥处理对玉米产量、土壤可培养微生物和土壤养分的影响。结果表明,有机肥替代30%化肥显著提高玉米的株高、双穗率、地上部分生物量、产量和土壤养分的容量和供应强度。玉米拔节期有机肥替代30%化肥显著增加了可培养细菌和固氮菌的数量,表明添加有机肥有利于土壤养分转化和土壤氮素的补充,而化肥处理显著提高了可培养氨化细菌的菌群数量,表明施加化肥的土壤对氮素的固持能力差,造成氮素外排,污染环境。相关性分析结果显示,土壤可培养真菌、细菌、氨化细菌和固氮菌与土壤全氮、有效磷、有效钾和有机质均显著正相关,而可培养放线菌数量与土壤养分均负相关;聚类分析和主成份分析结果表明,不同施肥方式下土壤养分和土壤微生物类群及数量随玉米生育期的完成而逐渐趋同化,揭示定期补肥的必要性和土壤微生物具有可指示土壤肥力的作用。     

有机无机肥配施对烟叶化学成分和品质的影响

通过饼肥与化肥不同比例配施研究得出,河南烟区中等肥力的褐土上以50%芝麻饼肥氮 50%化肥氮处理与单施化肥相比,提高了下、中、上3个部位烟叶饱和脂肪酸相对含量,降低了不饱和脂肪酸含量,表现为豆蔻酸和月桂酸相对含量增加,而亚麻酸和亚油酸含量降低。中部叶、上部叶石油醚提取物含量也得到提高,烟叶糖碱比适宜,化学成分较协调,烟叶品质得到改善,并缩小了不同部位间质量差异。     

Biological and chemical stability of garlic-derived allicin

This study verifies the instability of garlic ( Allium sativum L.)-derived allyl 2-propenylthiosulfinate (allicin) in various aqueous and ethanolic solutions as well as in vegetable oil through chemical and biological analyses performed simultaneously. Crushed fresh garlic cloves generated antibacterial activity and chemically detectable allicin, a major antibacterial principle, and both declined on a daily basis in aqueous and ethanolic solutions at room temperature, showing biological and chemical half-lives of about 6 and 11 days, respectively. Allicin was more stable in 20% alcohol than in water, but surprisingly unstable in vegetable oil, with an activity half-life 0.8 h, as estimated from its antibacterial activity toward Escherichia coli, and a chemical half-life of 3.1 h, based on chromatographic quantification. In alcoholic and aqueous extracts, the biological half-life of allicin tended to be longer than the chemical one, suggesting the occurrence of bioactive compounds other than allicin in the extracts.     

Radioactivity and chemical characteristics of Alberta phosphogypsum

Gypsum based by-products of phosphate fertilizer production, termed phosphogypsum (PG), are stockpiled at numerous locations worldwide. Although dominated by gypsum, PG contains accessory minerals, trace elements, and radionuclides. This study was conducted to characterize the composition and pore water chemistry of PG samples from a plant site in southern Alberta, Canada. Pore water chemistry was studied by equilibrating PG with deionized water for 80 days; the aqueous phase was then analyzed for dissolved constituents. The PG samples had pH levels of 4.0 or lower and contained gypsum and minor amounts of quartz, phosphate rock and sodium feldspar. The PG was elevated in total content of Ag, Au, Ca, Cd, P, S, Se, Sr, U and some of the light rare earth elements and Y relative to shale. Average ²²⁶Ra activity, determined by the radon emanation method, was 890 Bq kg^?1. Activity of ²¹²Pb, in equilibrium with ²²⁸Th, was 5.8 Bq kg^?1. Pore water concentrations of As, Cd, Cr, Cu, Fe, Mn, Na, NO₃ ^?-N, Se, SO₄ ^2?-S, and Zn exceeded drinking water standards in some PG samples. Although closer to flue gas desulfurization sludge in mineralogy, the pore water chemistry of PG is more like that of some fly ashes.     

The biological and chemical variability of yacon

This paper focuses on the biological and chemical variability of four yacon (Smallanthus sonchifolius) accessions cultivated under field conditions. Significant variations in tuber shape, weight, content of oligofructans, as well as in leaf isozymes, phenolics, and relative DNA contents were found. Accessions 6 and 88 were the most productive (up to 3.01 and 3.74 kg/plant); accession 48 was the most balanced from the yield aspect in three vegetative periods. A significantly higher content of beta-(2-->1) oligofructans was noted in accessions 48 and 88 as compared to 6 and 60. No difference in sucrose, glucose, and fructose level was observed. Only accession 6 exhibited separate acid phosphatase and esterase isoforms. Accessions 6 and 60 had the highest content of phenolics, and accession 88 had the lowest relative DNA content. Large yacon intraspecific variation may be useful in future detailed research as a good background for breeding, growing, and utilization in industrial processing.     

牡丹花红色素理化性质研究

目前牡丹主要是用于观赏,其综合加工技术没有突破。为了为牡丹花保鲜、护色和色素加工提供理论支持,该文对从牡丹红色品种洛阳红中提取的牡丹红色素进行理化性质研究。结果显示:牡丹红色素水溶性好,颜色随pH值变化而变化。pH值小于3时比较稳定,最大吸收波长为526.5 nm。在酸性条件下该色素对光、热有很好的稳定性;耐氧化性和还原性较差;Zn²⁺、Mg²⁺、Fe²⁺、K⁺、Cu²⁺、Ca²⁺离子对牡丹花红色素的稳定性影响不大,但Sn²⁺、Fe³⁺离子可使色素溶液变色,稳定性差。     

Botanical origin and chemical composition of Brazilian propolis

Brazilian propolis has been classified into 12 groups based on physicochemical characteristics: five in the southern Brazil group (group 3), one in the southeastern Brazil group (group 12), and six in the northeastern Brazil group (group 6). The plant origins of these groups were investigated using reversed-phase high-performance thin-layer chromatography (RPHPTLC), reversed-phase high-performance liquid chromatography (RPHPLC), and gas chromatography-mass spectrometry (GC-MS). It was concluded that the origins of propolis group 3, group 6, and group 12 are resins of the poplar tree, Hyptis divaricata, and Baccharis dracunculifolia, respectively.     

长期有机无机肥配施对稻田土壤基本理化性状的影响

通过湖南省7个土壤肥力与肥效监测长期定位试验,研究了有机无机肥配施对稻田耕层土壤基本理化性状的影响.结果表明,(1)长期有机无机肥配施可以促进土壤有机碳及活性有机碳的积累,降低土壤容重,提高孔隙度特别是通气孔隙度,促进水稳性大团聚体(WSA)的形成,提高阳离子交换量(CEC),高量有机肥效果优于中量有机肥.(2)有机肥使初始pH为5.20～7.8的土壤pH调节到5.6左右.(3)土壤有机碳(TOC)、热水可提取碳(HWC)与容重呈显著负相关(p＜0.05),与孔隙度、水稳性团聚体、CEC呈显著正相关(p＜0.05).有机无机肥配施有利于土壤有机碳和活性有机碳的积累,因而能使土壤变得疏松,透气性、保水保肥能力都得到增强.     

Decomposition in soil and chemical characteristics of pollen

The input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo‐ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C‐to‐N ratios and large water‐soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16°C an amount of C equivalent to 22–26% of the added pollen C was lost as CO₂ within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water‐soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid‐state ¹³C nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl‐ and methyl‐C region (0–45 p.p.m.) indicative of aliphatic compounds, the O‐alkyl‐C (60–90 p.p.m.) and the acetal‐ and ketal‐C region (90–110 p.p.m.) indicative of polysaccharides, and the carbonyl‐C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N‐alkyl‐C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.     

Sampling and preparation of sample for chemical examination

Sampling and methods for reducing a laboratory sample to a test sample are discussed, with particular emphasis on sampling peanuts for aflatoxin analysis as a practical example. The only way to control the total error in the analysis of this heterogeneous product is to take and to analyze many and large samples.