东北黑土旱田改稻田对土壤团聚体微生物群落功能多样性的影响

为了解东北黑土旱田改种稻田后土壤团聚体中微生物群落功能多样性的变化,将东北黑土旱田(种植玉米为主)改种为稻田(简称“旱改稻”),采用Biolog-Eco微平板技术,研究了“旱改稻”后不同粒径土壤团聚体微生物的多样性指数以及其对碳源利用能力的变化。结果表明,“旱改稻”显著增加了黑土土壤水稳性微团聚体数量,增加了不同粒径土壤团聚体内有机碳(SOC)的含量。旱田和稻田不同粒径土壤团聚体内的土壤微生物群落平均颜色变化率(AWCD)表现为旱田淤泥+粘土>旱田大团聚体>旱田微团聚体>稻田大团聚体>稻田淤泥+粘土>稻田微团聚体。“旱改稻”明显降低了各粒径土壤团聚体微生物的多样性指数以及碳源利用能力,尤其对氨基酸与碳水化合物最为明显。主成分分析结果表明,旱田和稻田不同粒径土壤团聚体微生物群落功能多样性差异显著。综上,“旱改稻”明显改变了黑土土壤团聚体微生物群落功能多样性,降低了以碳源为底物的土壤微生物代谢活性。本研究结果为东北黑土区土壤可持续利用提供了理论参考。     

红壤恢复林地微团聚体形成与稳定的影响机制研究进展

微团聚体是土壤团粒结构的基本组成单元,较大团聚体具有更强的稳定性,其形成与稳定对于土壤有机碳的长期吸存起着决定性作用。目前关于微团聚体形成与稳定性的研究多专注于农业土壤,红壤侵蚀地植被恢复后土壤团聚体稳定性、有机碳分布及微生物群落特征研究也主要集中在大团聚体上,而土壤微团聚体的动态变化及其主要影响因素尚不明确,对于其内在机制更缺乏了解。通过总结土壤微团聚体的形成过程及稳定性,综述了凋落物、根系和菌根对土壤微团聚体形成与稳定的影响,阐述了土壤微团聚体内微生物群落、化学结合态有机碳及有机碳结构是土壤有机碳稳定的重要机制,并提出了未来微团聚体研究方向,以期揭示红壤侵蚀退化地森林恢复过程中微团聚体形成和稳定的生物化学机制,从而为深入阐明有机质—土壤团聚结构—微生物—化学耦合作用和森林土壤碳吸存机制提供参考。     

三种南方典型水稻土长期试验下有机碳积累机制研究Ⅱ.团聚体内有机碳的化学结合机制

在对我国南方3种典型的水稻土有机碳团聚体分布研究的基础上,对用低能量超声波分散法分离得到的团聚体颗粒组进一步进行有机碳键合形态分析,考察不同键合态有机碳在不同粒径团聚体的分布,由此探讨这些水稻土中有机碳积累中物理作用基础上的化学机制。结果表明:钙键合态有机碳(Ca-SOC)多分布于2 000～200μm的粗团聚体颗粒组中,且在紫色水稻土中含量最高(达到9 g kg-1左右),而红壤性水稻土中最低(不到3 g kg-1);相反,铁铝键合态有机碳(Fe(Al)-SOC)趋向于在细团聚体颗粒组集中,是<2μm颗粒组中有机碳的优势组分,且以红壤性水稻土中最高(介于20～30 g kg-1之间),紫色水稻土中最低(仅为10 g kg-1左右),这与该团聚体颗粒组中铁铝氧化物的含量分布相吻合。统计分析表明,易氧化态碳(LOC)占有机碳(SOC)的比值与Ca-SOC占SOC的比值表现为正相关关系,而与Fe(Al)-SOC占SOC的比值表现为反相关关系。直径为2 000～200μm的粗团聚体中的Ca-SOC和Fe(Al)-SOC对长期不同耕作和施肥的响应最为敏感,良好的耕作施肥下水稻土有机碳的积累主要表现为Fe(Al)-SOC的增加。氧化铁铝的含量与SOC和LOC的含量之间存在一定的依变关系,说明这些土壤发生的无机组成分在有机碳的保护与稳定中发挥着重要作用,并且以红壤性水稻土粗团聚体中的氧化铁铝对有机碳的保护作用最强。由此看来,团聚体更新中物理保护的有机碳在细团聚体形成中进一步与氧化铁铝的键合可能是这些水稻土中有机碳稳定的重要机制。     

长期施肥对旱地红壤微团聚体磷素有效性的影响

【目的】土壤微团聚体是磷素储存与周转的重要载体,明确长期施肥下旱地红壤微团聚体中赋存磷素的形态及其生物有效性,为磷肥的高效合理施用提供理论依据。【方法】以位于鹰潭农田生态系统国家野外科学观测研究站院内的长期肥料定位试验(1988～2014)为依托,分别以有机无机配施区的1/2 NPK(CK)、低量NPK+稻秆(RS)与低量NPK+猪厩肥(PM)处理及无机肥区的NK与NPK处理的旱地红壤为研究材料,采用水分散-吸管法逐级提取了土壤中0.25～0.05 mm、0.05～0.01 mm、0.01～0.005 mm与<0.005 mm粒级微团聚体,对比分析了各粒级微团聚体中全磷、有效磷及磷活化系数的变化差异。基于土壤磷素分级结果,分析了旱地红壤中大小粒级微团聚体中极有效磷、中等有效磷及非有效磷对长期施肥的响应。借助于结构方程模型探讨了微团聚体中各形态磷、磷活化系数、颗粒组成、有机质、铁铝氧化物等因子与有效磷的互应关系。【结果】长期配施猪粪可以显著增加旱地红壤各粒级微团聚体中全磷、有效磷、磷活化系数及极有效磷、中等有效磷及非有效磷的含量,且<0.005 mm粒级微团聚体中的各组分磷增...     

长期施肥与地下水位对红壤性水稻土微团聚体及其分形特征的影响

以1982年开始的长期定位试验红壤性水稻土为材料,采用野外采样与室内分析的方法,对耕层土壤微团聚体组成进行分析,以探究长期施肥(高量有机肥+化肥(2/3 OM)、常量有机肥+化肥(1/3 OM)、单施化肥(NPK))和地下水位(20 cm、80cm)对红壤性水稻土微团聚体分布、分形维数及特征微团聚体的影响。结果表明:长期施肥土壤2～0.25 mm团聚体含量表现为2/3 OM 1/3 OM NPK,而微团聚体含量均表现为2/3 OM 1/3 OM NPK;且有机肥处理的土壤团聚状况和团聚度均高于NPK处理,分散系数、分散率、RMD(0.02 mm/(2～0.02) mm微团聚体比值)和微团聚体分形维数则表现相反。不同地下水位的2～0.25 mm团聚体含量表现为20 cm地下水位高于80 cm地下水位,而0.25 mm微团聚体含量相反;同时团聚状况、团聚度表现为20 cm地下水位高于80 cm地下水位,分散率、分散系数、RMD和微团聚体分形维数则相反。相关分析表明,2～0.25mm团聚体含量与总有机碳、易氧化有机碳、轻组有机碳、络合态铁和络合态铝含量极显著正相关,与游离氧化铁含量极显著负相关,而0.05～0.02 mm、0.02～0.002 mm和0.002 mm微团聚体含量与以上指标的相关关系相反。微团聚体分形维数和RMD均与2～0.25 mm团聚体、全N、总有机碳、易氧化有机碳、轻组有机碳、络合态铁、络合态铝的含量呈显著或极显著负相关,与0.05 mm各粒级微团聚体和游离氧化铁含量呈极显著正相关;表明RMD可作为评价红壤性水稻土肥力的综合指标。     

不同林地类型土壤团聚体稳定性与铁铝氧化物的关系

[目的]探究浙江省凤阳山保护区内土壤铁铝氧化物对土壤团聚体稳定性的影响机理,为该区恢复与保护土壤资源提供理论依据。[方法]以浙江省凤阳山保护区内黄棕壤地带4种林分类型(阔叶混交林、针阔混交林、杉木林、竹林)为对象,测定不同土层(0—10cm,10—20cm,20—30cm)水稳定性团聚体粒径分布以及不同形态的铁铝氧化物含量,分析各形态铁铝氧化物含量对土壤团聚体稳定性的影响。[结果](1)4种林分类型土壤团聚体水稳性大团聚体(0.25mm)含量均在90%以上,水稳定性大团聚体含量和平均质量直径(MWD)均表现为:杉木林针阔混交林阔叶混交林竹林。(2)不同形态铁铝氧化物含量大小整体上表现为:游离态氧化铁Fe_d游离态氧化铝Ald无定形氧化铁Fe_o无定形氧化铝Alo络合态氧化铁Fe_p络合态氧化铝Al_p,各形态的氧化铁含量随土层加深均增加。(3)增强回归树BRT分析结果显示,对土壤团聚体MWD影响最大的是Al_p,贡献率为43.6%;其次是Ald(23.5%)和Fe_d(19.5%);Fe_o(6.9%),Alo(4%)及Fe_p(2.4%)的影响程度较小。[结论]Al_p,Ald和Fe_d能促进土壤团聚体稳定,络合态氧化铝Al_p对土壤团聚体稳定性的促进作用大于游离态铁铝氧化物Ald和Fe_d。     

长期施肥条件下红壤有机碳化学结构与团聚体稳定性的关系

[目的]红壤普遍存在团聚体结构较差和有机碳含量较低的问题,土壤有机碳是影响土壤团聚体结构的重要指标,但以往研究主要关注有机碳含量与团聚体的相关关系,而对有机碳的化学结构如何调控团聚体结构则缺乏深入研究.[方法]依托始于1986年的红壤旱地长期施肥试验,选取不施肥(CK)、施用氮磷肥(NP)、施用氮磷钾肥(NPK)、施用...     

玉米间作大豆、萝卜对红壤不同粒径水稳性团聚体碳氮分布的影响

为了探讨不同种植模式对红壤水稳性团聚体粒径分布以及不同粒级团聚体中有机碳、氮含量,土壤微生物量碳、氮含量的影响,选择大豆、萝卜与玉米间作及3种作物的单作进行田间试验,在作物成熟期采样,进行样品测定。结果表明:在玉米-大豆(玉//豆)、玉米-萝卜(玉//萝)、玉米单作(玉单)、大豆单作(豆单)、萝卜单作(萝单)处理中,大团聚体(> 0.25 mm)的百分含量明显高于微团聚体(<0.25 mm),其中以大团聚体中粒径为0.25~2 mm的百分含量最高且显著高于其余两种粒径,大团聚体百分含量表现为:玉//豆>玉//萝>玉单>萝单>豆单,微团聚体则与其相反。团聚体粒径中的有机碳含量表现为0.25~2 mm粒径最高、<0.25 mm粒径次之、>2 mm粒径含量最少、玉米大豆间作含量最高、玉米单作含量最低。团聚体粒级中全氮含量与有机碳分布一致,但单作的全氮含量高于间作。有机碳与全氮的C/N为间作高于单作,>2 mm粒径C/N高于其余两种粒径。微生物量碳、氮在团聚体粒径中的分布趋势一致,都表现为间作模式高于单作模式,大团聚体中的含量高于微团聚体。微生物量碳、氮的C/N为单作模式高于间作模式,微团聚体大于大团聚体。与单作相比,间作能提高土壤中水稳性大团聚体的含量,增加大团聚体粒径内的有机碳、氮及微生物量碳、氮的含量。     

侵蚀程度对红壤团聚体分布及养分含量的影响

[目的]探讨不同侵蚀程度下红壤团聚体和养分的变化规律,为侵蚀红壤的肥力提升和合理开发利用提供理论依据。[方法]将红壤表层按照不同深度剥离来模拟不同土壤侵蚀程度,比较分析不同侵蚀程度下团聚体稳定性、有机质和各养分的变化规律及其相互关系。[结果]各侵蚀程度红壤团聚体干筛粒级分布规律大体相似,以≥2mm粒级团聚体为优势粒级,与无明显侵蚀土壤相比,强烈侵蚀土壤≥2mm水稳性团聚体含量降低近1/3;随着土壤侵蚀程度增加,土壤碳、氮、磷等养分含量均表现出逐渐减少的规律,其中强烈侵蚀土壤有机质、全氮和全磷含量减少了30%左右,碱解氮含量减少了近50%,速效磷含量减少了80%以上。相关分析表明,土壤有机质、全氮、全磷、碱解氮含量均与≥2 mm团聚体含量、WSA,MWD和GMD值具有较好的正相关性(p0.05),与D和PAD值呈负相关。[结论]不同侵蚀程度对红壤团聚体分布及养分含量有一定影响,可通过增加有机肥来改善侵蚀红壤结构,提高土壤肥力。     

土地利用变化对土壤团聚体微生物量碳的影响

对福建省建瓯市山地红壤的天然林、人工林、次生林和园地等4种典型土地利用方式的不同土层(0-10cm,10-20 cm)土壤团聚体微生物量碳进行研究.结果表明:除茶园外,不同土地利用方式均表现出随着团聚体粒径增大,单位土壤微生物量碳增加的趋势.天然林转变为其他土地利用方式后,团聚体微生物量碳和单位土壤团聚体微生物量碳分别平均下降了18.66%～51.82%和21.20%～50.05%,但不同土地利用土壤团聚体微生物量碳的下降幅度小于土壤有机碳.土壤团聚体微生物商在本区域未表现出一定规律性.因此亚热带山地红壤内天然林转变为人工林、次生林和园地会导致土壤团聚体微生物量碳含量下降,但其能否作为表达土地利用变化敏感性指标,还需进一步斟酌.     

Chemistry, biochemistry, nutrition, and microbiology of lysinoalanine, lanthionine, and histidinoalanine in food and other proteins

Heat and alkali treatments of foods, widely used in food processing, result in the formation of dehydro and cross-linked amino acids such as dehydroalanine, methyldehydroalanine, beta-aminoalanine, lysinoalanine (LAL), ornithinoalanine, histidinoalanine (HAL), phenylethylaminoalanine, lanthionine (LAN), and methyl-lanthionine present in proteins and are frequently accompanied by concurrent racemization of L-amino acid isomers to D-analogues. The mechanism of LAL formation is a two-step process: first, hydroxide ion-catalyzed elimination of H(2)S from cystine and H(2)O, phosphate, and glycosidic moieties from serine residues to yield a dehydroalanine intermediate; second, reaction of the double bond of dehydroalanine with the epsilon-NH(2) group of lysine to form LAL. Analogous elimination-addition reactions are postulated to produce the other unusual amino acids. Processing conditions that favor these transformations include high pH, temperature, and exposure time. Factors that minimize LAL formation include the presence of SH-containing amino acids, sodium sulfite, ammonia, biogenic amines, ascorbic acid, citric acid, malic acid, and glucose; dephosphorylation of O-phosphoryl esters; and acylation of epsilon-NH(2) groups of lysine. The presence of LAL residues along a protein chain decreases digestibility and nutritional quality in rodents and primates but enhances nutritional quality in ruminants. LAL has a strong affinity for copper and other metal ions and is reported to induce enlargement of nuclei of rats and mice but not of primate kidney cells. LAL, LAN, and HAL also occur naturally in certain peptide and protein antibiotics (cinnamycin, duramycin, epidermin, nisin, and subtilin) and in body organs and tissues (aorta, bone, collagen, dentin, and eye cataracts), where their formation may be a function of the aging process. These findings are not only of theoretical interest but also have practical implications for nutrition, food safety, and health. Further research needs are suggested for each of these categories. These overlapping aspects are discussed in terms of general concepts for a better understanding of the impact of LAL and related compounds in the diet. Such an understanding can lead to improvement in food quality and safety, nutrition, microbiology, and human health.     

Detection, accumulation, distribution, and depletion of furaltadone and nifursol residues in poultry muscle, liver, and gizzard

Nitrofurans were broadly used as an extremely effective veterinary antibiotic especially in pig and poultry production farms. Because of fears of the carcinogenic effects on humans, the nitrofurans were banned from use in livestock production in many countries, including the European Union. The present study examines the accumulation, distribution, and depletion of furaltadone and nifursol and of their tissue-bound metabolites [3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ) and 3,5-dinitro-salicylic acid hydrazine (DNSAH), respectively, in poultry edible tissues (muscle, liver, and gizzards) following administration to chickens of therapeutic and subtherapeutic concentrations of both compounds. Nitrofurans determination was performed by high-performance liquid chromatography-diode array detection and liquid chromatography-tandem mass spectrometry, respectively, for feeds and for poultry tissues. Furaltadone and nifursol, in very low concentrations, were found in samples of muscle, liver, and chicken's gizzard collected from slaughtered animals after 5 weeks of treatment and no withdrawal time period. When a withdrawal time period of 3 weeks was respected, no detectable nitrofuran parent compounds was observed in all of the studied matrices. For AMOZ, concentrations of 270 μg/kg in meat, 80 μg/kg in liver, and 331 μg/kg in gizzard were determined after administration of a medicated feed with furaltadone (132 mg/kg), 3 weeks after withdrawal of treatment. For DNSAH, the concentration values obtained are much lower than those observed for AMOZ. For meat, liver, and gizzard, DNSAH concentrations of 2.5, 6.4, and 10.3 μg/kg, respectively, were determined, after administration of a medicated feed with nifursol (98 mg/kg), 3 weeks after withdrawal of treatment. The gizzard could be considered a selected matrix for nitrofuran residues evaluation in poultry, due to its capacity of retaining either nitrofuran parent compounds or metabolites in higher concentrations, regardless of the administered dose or of the respected withdrawal time period.     

Growth and Ca,Mg, K,and P uptake by triticale,wheat, and rye at four al levels

This study was conducted to determine relationships between Al toxicity and mineral uptake of triticale (X Triticosecale, Wittmack), wheat (Triticum aestivum L.), and rye (Secale cereale L.). Two culti‐vars of each species were grown in 1/5‐strength Steinberg solution with 0, 3, 6, or 12 ppm Al added. The solutions were adjusted to pH 4.8 at transplanting and were not adjusted thereafter. The plants were grown in a growth chamber for 19 days before harvesting to determine nutrient solution pH, dry weights, and Al, Ca, Mg, K, and P levels in plants. Increasing Al concentration reduced the final pH of solutions. The addition of 12 ppm Al severely reduced the growth and increased Al concentration of plant tops. The Al levels in roots generally increased with increments of added Al up to 6 ppm. Increasing Al decreased the uptake of Ca, Mg, and P by plant tops more than that of K. Regression analyses indicated that Al toxicity was associated with increasing K/Ca + Mg equivalent ratios and decreasing P concentration in plant tops. Differences between species were: higher Al concentration in rye than wheat with 6 and 12 ppm Al, higher translocation of Ca from roots to tops in wheat than in rye and Mg in triticale and wheat than rye; K/Ca + Mg equivalent ratios associated with 50% reduction in top growth followed the order: triticales > tolerant wheat > sensitive wheat > rye. Differences in mineral uptake associated with Al toxicity in wheat were more indicative of differential Al sensitivity in wheat than in triticale and rye which have higher internal Al tolerance.     

Grain Yield,Quality, and Nutrient Concentrations of Feed,Food, and Malt Barley

Barley (Hordeum vulgare L.) is a cereal grown for animal feed, human consumption, and malting. Nutrient concentrations are important as they provide information regarding the dietary values of barley consumed by animals or human beings. In addition, grain nutrient removal may be useful for refining fertilizer recommendations. A study was conducted in 2015 and 2016 investigating the cultivar effects on grain yield, quality, and grain nutrient concentrations and removal under irrigated conditions for two-row barley cultivars. Adjunct and feed cultivars produced the highest yields compared with the all-malt and food cultivars. Specific quality and nutrient values were greater than or equal to in the food cultivar compared to the malt or feed cultivars. Variations in nutrient concentrations were measured among the adjunct and all-malt cultivars, which could potentially affect the malting and brewing qualities. Grain yield, quality, nutrient concentrations and nutrient removal varied among cultivars grown under identical environmental conditions, which may influence end-use.     

Phytotoxicity of cobalt,vanadium, titanium,silver, and chromium

Abstract

The phytotoxicity of five nonessential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Cobalt was one of the more mobile of the five trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10^‐5 M) and 142 (with 10^‐4 M) μg Co/g dry weight in leaves resulted in severe chlorosis. Vanadium as 10^‐4 M vanadate resulted in smaller plants but not in chlorosis. Leaf, stem, and root V, respectively, were 13, 8, and 881 μg/g dry weight. Titanium was somewhat mobile with considerable yield decrease at 10^‐4 M; leaf, stem, and root Ti concentrations, respectively, were 202, 48, and 2420 μg/g. Symptoms were chlorosis, necrotic spots on leaves, and stunting. Silver was very lethal at 10^‐4 M AgNO₃; at 10^‐5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem, and root concentrations of Ag for this treatment, respectively, were 5.8, 5.1, and 1760 μg/g dry weight. Plants grown with 10^‐5 N Cr₂O₇ were decreased in yield by about 25% with or without EDTA (ethylenediamine tetraacetic acid) while the same level of Cr₂(SO₄)₃ was essentially without effect. For the two salts, the leaf, stem, root concentrations for Cr, respectively were 2.2 and 1.3, 0.7 and 0. 7, and 140 and 104 μg/g. Most of the trace metals studied here had interactions in the uptake and/or distribution of other elements.     

Occurrence, sensory impact, formation, and fate of damascenone in grapes, wines, and other foods and beverages

Among plant-derived odorants, damascenone is one of the most ubiquitous, sometimes occurring as an apparent natural product but more commonly occurring in processed foodstuffs and beverages. It has been widely reported as a component of alcoholic beverages, particularly of wines made from the grape Vitis vinifera . Although damascenone has one of the lowest ortho- and retronasal detection thresholds of any odorant, its contribution to the sensory properties of most products remains poorly understood. Damascenone can be formed by acid-catalyzed hydrolyses of plant-derived apocarotenoids, in both aglycon and glycoconjugated forms. These reactions can account for the formation of damascenone in some, but not all, products. In wine, damascenone can also be subject to degradation processes, particularly by reaction with sulfur dioxide.     

Total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone

The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.     

Tillage,lime, and poultry litter effects on soil zinc,manganese, and copper

Abstract

Long‐term no‐tillage has profound effects on soil properties which can affect the availability of plant nutrient elements. The objectives were to study the effects of tillage and lime treatments on soil pH and extractable soil micronutrients where poultry litter was used as a nitrogen (N) source. Surface soil samples were taken in the spring and fall for two years from a long‐term tillage experiment that had been in place for nine years. There were two tillage treatments [conventional (CT) and no‐tillage (NT)] and six lime/ gypsum treatments (control, 8,960 kg gypsum ha^‐1 every fourth year, 4,480 kg lime ha^‐1 every fourth year, and three treatments of 8,960 kg lime ha^‐1 in a four‐year period divided by application times into 1, 2, and 4 treatments per year). Poultry litter was applied each year of the two‐year experiment at a rate of 8.96 Mg ha^‐1 on a dry weight basis. The crop was corn (Zea maize L.). Soil samples were analyzed for pH and Mehlich‐1 zinc (Zn), manganese (Mn), and copper (Cu). Soil pH was higher for NT than CT and was higher in the spring than in the fall. Lime rates resulted in soil pH increases, but showed less difference for CT than NT. The three 8,960 kg ha^‐1 per four yr treatments caused an interaction in that for CT the pH increased more for 2,240 kg ha^‐1each year than for 8,960 kg ha^‐1 every fourth year and the opposite was true for NT. Extractable Zn, Mn, and Cu all responded to this interaction being lower for the higher pH plots. Extractable Zn was higher for NT possibly due to high Zn from the poultry litter and non‐incorporation for NT. Extractable Cu was lower for NT as expected from the soil pH, whereas extractable Mn was not affected by tillage. Extractable Zn and Cu both increased over time due to inputs from the poultry litter. Neither extractable Zn nor Mn responded to increasing lime rates, however Cu decreased with increasing lime rate. Extractable Cu was influenced mainly by soil pH differences due to tillage and lime. Extractable Zn was influenced much more by tillage and from inputs by the poultry litter and not as much by pH differences. Extractable Mn was the least responsive to tillage and lime treatments of the three micronutrients studied.     

Phytotoxicity and some interactions of the essential trace metals iron,manganese, molybdenum,zinc, copper,and boron

Abstract

The essential trace elements Fe, Mn, Zn, Cu, and B in high concentrations can produce phytotoxicities. Iron toxicity resulted from 5 × 10^‐4 M and 10^‐3 M FeSO₄, but not from equivalent amounts of FeEDDHA (ferric ethylenediamine di (o‐hydroxyphenylacetic acid) ). Leaf concentrations in bush beans of 465 μg Mn/g, 291 μg B/g, and 321 μg Zn/g all on the dry weight basis resulted in 27%, 45%, and 34% reduction in yields of leaves, respectively. Zinc was concentrated in roots while Mn and B concentrated in leaves. Solution concentrations of MnS0₄ of 10^‐3 and 10^‐2 M depressed leaf yields of bush beans by 63% and 83%, respectively, with 5140 and 10780 μg Mn/g dry weight of leaves. Copper concentrations were simultaneously increased and those of Ca were decreased. Bush bean plants grown in Yolo loam soil with 200 μg Cu/g soil had a depression in leaf yield of 26% (with 28. 8 μg Cu/g leaf); plants failed to grow with 500 μg Cu/g soil. A level of 10^‐3 M H₂MoO₄ was toxic to bush beans grown in solution culture. Leaves, stems, and roots, respectively, contained 710, and 1054, and 5920 μg Mo/g dry weight.     

Dry Matter,Nitrogen, Phosphorous,and Potassium Partitioning,Accumulation, and Use Efficiency in Transgenic Cotton-Based Cropping Systems

A better understanding of the fate of nutrients in transgenic cotton (Gossypium hirsutum L.) fields will improve nutrient efficiencies, will optimize crop growth and development, and may help to enhance soil quality. A study was made to evaluate and quantify the effect of cropping system [sole cotton and groundnut (Arachis hypogaea) intercropping with transgenic cotton] and nitrogen (N) management [control (0N), 100% recommended dose of nitrogen (RDN) through urea, substitution of 25% RDN through farmyard manure (FYM), and substitution of 50% RDN through FYM] on dry matter (DM) and nutrient partitioning and accumulation by transgenic cotton and groundnut at New Delhi during 2006–2007. Soil and plant samples were collected and analyzed at 60, 90, and 120 days after sowing and at harvest. Results revealed that intercropping of groundnut with cotton did not significantly affect DM and nutrient partitioning in cotton, but residual soil fertility in terms of potassium permanganate (KMnO₄) N showed an improvement in contrast to Olsen's P and ammonium acetate (NH₄OAc)–exchangeable K over sole cotton. At harvest, of total DM assimilated, leaves constituted 10–20%, stem 50%, and reproductive parts of cotton accounted for the rest. For each kilogram of seed cotton produced, the crop assimilated 61 g of N, of which 23 g was partitioned to harvested seed cotton. Substitution of 25% RDN through FYM, being on par with 100% RDN through urea, recorded greater DM, nutrient uptake in different parts of cotton, agronomic N-use efficiency (9.5 kg seed cotton kg N^?1), and apparent N recovery (83.3%) over 50% RDN substitution through FYM and control. The control, being on par with 50% RDN substitution through FYM, recorded significantly greater DM and nutrient uptake by intercropped groundnut over other treatments. Apparent N and potassium (K) balance at the end of study was negative in all treatments; however, the actual change in KMnO₄ N was positive in all the treatments except control. Our study suggests that intercropping of groundnut with transgenic cotton and substitution of 25% dose of N through FYM is sustainable in tropical countries.