Nitrogen (total and 15N) uptake by barley and wheat under two irrigation regimes’

Nitrogen (total and ¹⁵N) uptake by barley (Hordeum vulgare L., cv. ‘Walfajr') and wheat (Triticum aestivum L., cv. ‘Karaj I') plants subjected to water stress were studied at the College of Agriculture, University of Tehran Experimental Farm located in the city of Karaj, Iran. The treatments consisted of two irrigation intervals, 7 days (control) and 14 days (stress). The plants were at the reproductive stage of growth at the start of the ¹⁵N treatment. Nitrogen (¹⁵N) was applied to 1m x 1m plots selected at the center of the 2.5m x 2.5m main plots. The ¹⁵N was provided to plants by adding 250 mg ¹³N as (NH₄)₂SO₄ (5.1 Atom % ¹⁵N) dissolved in water to each plot. The ¹⁵N treatment period continued for 48 hours. The plants were harvested at 6‐hour intervals during the ¹⁵N treatment period. After each harvest, the straw and the grains were separated, oven dried at 65°C and dry weights were recorded. Plant materials were ground in a Wiley Mill to pass through a 2mm sieve for chemical analysis. Total N was measured by an Auto‐Analyzer after Kjeldahl digestion, and ¹⁵N was measured using a mass spectrometer.

Nitrogen (total‐N and ¹⁵N) content of both plant species decreased under stress, with wheat appearing more severely affected than barley. However, nitrogen concentration was slightly higher for the stressed plants as compared with the controls. This pattern was essentially similar for both plants.     

N Cycle, N Flow Trends in Japan, and Strategies for Reducing N2O Emission and NO3^- Pollution

To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO3^- pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO3^- pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth‘s biosphere.     

浅析兴国县农田N,P,K养分现状及对策

选择第二次土壤普查取样点为背景,在原取样点再次取样分析,同时收集全县有关农田养收支状况进行对比,结果表明,农田养分来源钾氮供应以有机肥和化肥基本各占一半,而磷素供应基本上以化肥为主,农田氮素基本平衡,磷素略有孕余,钾素则明显亏缺。１７年间农田养分状况有增有减,其中速效钾下降３１．９％,ＰＨ下降近１个单位。为此,特提出调整农田养分现状的对策：一是调整化肥结构,协调氮磷钾施肥比例;二是增施有机肥料,重     

土壤NO,N2O产生的水,氧气效应

测定了水和氧气对壤反硝化气体（ＮＯ和Ｎ２Ｏ）形成的影响。在低温条件下，ＮＯ是培育土壤的主要终产物；然而在较湿状态下，Ｎ２Ｏ相对量增加，布鲁克斯顿粘土（简称Ｂ土）产生的ＮＯ和Ｎ２Ｏ总量随土壤含水量提高而增加，而福克期砂壤（简称Ｆ土）含水量为１５％时，ＮＯ和Ｎ２Ｏ总量最高。含水量较高的福克斯砂壤土中，ＮＯ和Ｎ２Ｏ减少很可能是由于Ｎ２Ｏ还原成Ｎ２所致。土壤反硝化气体的存留时间随含水量提高而增长。进一步促     

Composition of total, neutral, and phospholipids in Mapará (Hypophthalmus sp.) from the Brazilian Amazonian area

Ten lots of mapará (Hypophthalmus sp.), captured from the Amazon River, Brazil, were analyzed for their lipid content and fatty acid composition. This knowledge would allow for the development of adequate processing methods and the formulation of therapeutic diets. Separation into neutral and phospholipids was accomplished by silica-gel column chromatography. Fat from the muscular tissue and from the orbital cavity of the mapará was analyzed by high-resolution gas chromatography-mass spectrometry in two different seasonal periods. There were high levels of saturated and monounsaturated fatty acids in the total and neutral lipid with the principal components 16:0, 18:1omega9, 18:0, 16:1omega7, 14:0, 18:3omega3, and 18:1omega7 in both seasons. In the phospholipids there was a high level of polyunsaturated fatty acids, including primarily 16:0, 18:1omega9, 18:0, 16:1omega7, 22:6omega3, 20:4omega6, 18:3omega3, and 20:5omega3. The ratio omega3/omega6 was the same in the muscular tissue and in the orbital cavity, in both seasonal periods. The muscle tissue could be used in diets that need high levels of polyunsaturated fatty acids, but use of the head to produce an omega3 fatty-acid-rich oil still requires greater study with respect to its economic viability.     

不同肥力黄绵土在施肥条件下的土壤供N,P能力和N,P肥的效应

经过６年长期施用不同肥料定位试验，使其同一土壤形成肥力上的差异，在此土壤上，进行盆栽试验，分析和研究了不同基础肥力土壤供肥能力，以及施用Ｎ、Ｐ肥的增产效应和作物吸Ｎ、Ｐ量的反映。结果表明，基础肥力以施ＭＮＰ肥土壤供Ｎ、Ｐ能力最强，其次为施ＭＰ肥处理，单施Ｎ肥土壤供Ｎ、Ｐ能力最差。     

黄土高原坝控小流域土壤C,N,P计量特征解析

研究采集了陕西绥德王茂庄流域埝堰沟流域内沟壁裸露地、荒草地及耕地3种利用类型的土壤及坝地沉积泥沙,分析了小流域土壤及沉积泥沙中的碳(C)、氮(N)、磷(P)的化学计量特征,结合泥沙量与降雨侵蚀力的阶段性变化,对流域侵蚀环境进行反演。结果表明:(1)坝控流域内土壤C,N,P含量均值分别为3.36g/kg,0.35g/kg,0.68g/kg,C∶N,C∶P,N∶P均值分别是9.30,5.75,0.60,低于全国平均水平;坝地泥沙的C,N,P含量均值分别为1.76g/kg,0.20g/kg,0.55g/kg,坝地养分未表现出富集效应,研究区土壤的C∶N,C∶P,N∶P比值反映出土壤矿化速度较快但氮素缺乏,限制植物生长;(2)C∶P在不同土地利用类型土壤间、土壤与沉积泥沙中均有显著差异,因此可作为泥沙对土地利用类型变化响应的敏感指标;(3)根据泥沙量的累积距平趋势变化曲线可以将流域侵蚀历史划分为4个阶段,结合降雨侵蚀力及C∶P值与泥沙量的回归关系,分析了不同阶段降雨和土地利用变化对侵蚀泥沙的贡献。     

Estimating total Pb,Cd, and Zn in contaminated soils from NH4HCO3‐DTPA‐extractable levels

Abstract

Twenty‐six garden soils from Aspen, Colorado, contaminated with old silver mine dumps, were extracted with diethylenetriamine pentaacetic acid (DTPA) and NH₄HCO₃‐DTPA (AB‐DTPA). Total soil digests (HNO₃‐HClO₄‐HF) were carried out on 21 highly contaminated soils. All soil extracts and digests were analyzed for Pb, Cd, and Zn using inductively‐coupled plasma atomic emission spectrometry (ICPS). Linear regression equations for DTPA versus AB‐DTPA values gave 0.96, 0.99 and 0.99 “r”; values for Pb, Cd, and Zn, respectively. Linear regression equations for total Pb, Cd, and Zn levels versus their respective AB‐DTPA extractable levels were developed with “r”; values of 0.92, 0.93, and 0.89, respectively. It was concluded that AB‐DTPA test can be used to screen soils contaminated with the above‐mentioned elements.     

Concentrations of total nitrogen in squash,cucumber and melon in relation to growth,and to a piper‐steenbjerg effect

Abstract

Squash (Cucurbita pepo), cucumber (Cucranis sativus), and sweet melon (Cucumis dudain) were grown in sand cultures with N supply concentrations as the variable. For several reasons, total‐N values were found to be less satisfactory than NO ‐N for the purpose of determining the critical nitrogen concentration for maximum growth. Concentrations of total‐N in mature petioles were higher in plants severely deficient in N than in less deficient plants, characteristic of a Piper‐Steenbjerg effect.     

四川盆地紫色土N,P损失载体及其影响因子

农业面源污染对环境的压力越来越大,已引起国内外广泛重视。利用人工降雨装置模拟3种不同强度的降雨,采用模拟径流小区研究了雨强及耕作措施对紫色土N,P损失量及载体的影响。结果表明:在耕作方式相同时,雨强越大,地表径流量越大,地下径流量减少,总径流量增加,不利于土壤保蓄雨水和含水量的提高。在相同雨强条件下,平作的地表径流量最大,土壤侵蚀也最剧烈。横坡垄作在中小雨强条件下控制地表径流和侵蚀的效果非常明显,但在大雨强条件下,控制径流和泥沙的效果减弱;横坡垄作有增加地下径流和N流失量的趋势。在本试验条件下,有约1%的化肥N(速效N)被雨水淋洗出土体并排放到环境中;而速效P的流失量只占化肥P的3/10000~10/10000,流失量很微小。紫色土坡耕地P流失载体是泥沙,流失量更易受雨强的影响,要控制P流失,首先应防止土壤侵蚀;横坡垄作能有效控制土壤侵蚀,因此,也能较好控制P流失。紫色土坡耕地N流失载体在雨强较小时是径流,径流中又以壤中流为主,要控制N流失,首先必须控制壤中流;传统横坡垄作会加大壤中流量,也就加大了N流失。全面控制紫色土的N,P损失,必须采用控蚀耕作、增厚土层、提升土壤有机质等措施。     

巢湖流域河水中N,P盐分组成特征分析

我国５大淡水湖之一的巢湖目前正面丰严重的水环境污染与水体的富营养化,通过对巢湖流域自然,经济,社会系统的全面分析,考察了巢湖流域人湖河流河水中氮,磷的形态组成,应用对应分析技术,研究了湖各主要人湖河流河水中N,P营养盐分输入特征,为巢湖水环境污染与水体富营养化的控制提供了科学依据。     

Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an Amazonian fruit

The fruit of Arazá (Eugenia stipitata McVaugh) native to the Colombian Amazon is considered a potentially economically valuable fruit for the Andean economy due to its novel and unique taste. The fruit has an intense yellow color, but its chemical composition and properties have not been well studied. Here we report the identification and quantitation of carotenoids in the ripe fruit using high performance liquid chromatography (HPLC) with photodiode array detector (PDA) and atmospheric pressure chemical ionization (APcI) mass spectrometry (MS/MS). The qualitative carotenoid profile of the fruit according to maturity stage was also observed. Furthermore, antioxidant activity of the peel and pulp were assessed using the ferric reducing ability of plasma (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods, in addition to chemical indexes and total phenolic content. Multiple carotenoids were identified in the peel and pulp including four xanthophylls (free and esterified as their mono and diesters) and two carotenes. One of the xanthophylls was tentatively identified as zeinoxanthin, while the others were identified as lutein, zeaxanthin, and β-cryptoxanthin. Carotenes included α-carotene and β-carotene. The total carotenoid content was significantly higher in the peel (2484 ± 421 μg/100 g FW) than in the pulp (806 ± 348 μg/100 g FW) with lutein, β-cryptoxanthin, and zeinoxanthin as the major carotenoid components. The unique carotenoid composition of this fruit can differentiate it from other carotenoid-rich fruits and perhaps be useful in authentication procedures. Overall, results from this study suggest that Colombian Arazá may be a good edible source of carotenoids important in retinal health as well as carotenoids with provitamin A activity. Therefore, Arazá fruit can be used as a nutraceutical ingredient and in production of functional foods in the Colombian diet.     

Semi‐micro determination of total phosphorus in soils,sediments, and organic materials: A simplified perchloric acid digestion procedure

Abstract

A semi‐micro modification of perchloric acid digestion method for the determination of total P in soils, sediments, and organic materials is described. Samples are digested for 30 minutes with nitric acid at 115 °C and then for 2 hours with perchloric acid at 170 °C in an aluminum heating block. After dilution, samples are hydrolyzed at 100 °C for 1 hour in order to decompose pyrophosphate, and the liberated orthophosphate is determined without a neutralization step by the phosphomolybdate blue method of Murphy and Riley (1962). Comparability with the method of Sommers and Nelson (1972) is demonstrated using nine samples of different types. The same reaction conditions of digestion and color development as in the determination of total P in waters (Kopá?ek and Hejzlar, 1993) enable a comparable estimate of total P in solid and water samples in complex environmental studies.     

ARE ORGANIC N FERTILIZING STRATEGIES ABLE TO IMPROVE LETTUCE YIELD,USE OF NITROGEN AND N STATUS?

Despite the importance of fertilizing practices in the crop yield improvement, nitrogen (N) utilization, and N status, their management by farmers is still rather empirical, especially when new organic materials are applied. Therefore, the aim of this research was to study the possible bio-products (anaerobic digestates and on-farm compost) applications and to evaluate their effects on lettuce performance, N efficiency and soil properties. The plant and soil N indicators were also investigated to reduce the N supply in lettuce production. To accomplish these objectives a three-year field experiment was carried out comparing the following N fertilization strategies: organic, with anaerobic digestates, based on stabilized wine distillery wastewater (SAD) and not stabilized wine distillery wastewater (NSAD) and on-farm compost, based on olive pomace compost (OPC); mineral (MIN), with ammonium sulfate and ammonium nitrate; mineral-organic, with a slow N release commercial fertilizer (CORG). All treatments received 140 kg N ha^?1 and they were compared with an unfertilized control (CONTR). The organic material application increased the marketable yield of 25.6, 20.3 and 10.1% for SAD, NSAD, and OPC treatments, respectively, in comparison with the CONTR. No significant reduction was found for both anaerobic digestates in respect to conventional fertilizers, while the OPC application significantly decreased the crop yield compared to MIN and CORG treatments. Moreover, the marketable head weight showed no significant difference among MIN, CORG, and SAD treatments, while a significant reduction of the weight was observed for NSAD and OPC. These findings highlighted the importance of organic fertilizer choice to sustain lettuce yield. The anaerobic digestates also enhanced head weight of 18.9 and 11.9% for SAD and NSAD, respectively, compared to CONTR, pointing out that the by-products application could be a valid agricultural practice to provide nutrients. Besides, no significant difference in N utilization parameters was found between SAD, MIN and CORG, indicating the effectiveness of the stabilized wine wastewater. Among the plant and soil N indicators tested, our results suggested that the leaves green index and nitrate contents in the leafstalks not only were the most reliable methods for evaluating N status, but they also offered potential advantages of both an easier sampling and a higher positive correlation with lettuce performance. Finally, since the agro-industrial residues did not significantly increase the soil potentially toxic elements level, the findings of this research pointed out that the organic materials can be usefully applied, at least in the short-term period.     

50 Jahre organische und mineralische Düngung: Humusgehalte,N‐Ausnutzung und N‐Bilanzen

Nach Umbruch einer Naturwiese wurden während 48 Jahren zehn organische und mineralische Düngungsverfahren geprüft. Der Wechsel von der futterbaulichen zur ackerbaulichen Nutzung hatte bei allen Verfahren ein Absinken des Humusgehaltes von 2,3% auf 1,4–2,1% zur Folge. Bei regelmässiger Stallmistdüngung und bei mineralischer Düngung stabilisierte sich der Humusgehalt nach ca. 35 Jahren auf einem neuen Niveau bei etwa 1,4 bis 1,6%. Bei der Düngung mit Klärschlamm oder Torf stellte sich nach 48 Jahren noch kein neues Gleichgewicht ein. Sowohl die ausreichende mineralische wie auch die organische Düngung förderte die Menge und Aktivität der Bodenmikroorganismen. Die pflanzenbauliche Ausnutzung des Stickstoffs (N) von organischen Düngern betrug während der gesamten Versuchsdauer meist nur 10–30%. Die N‐Ausnutzung mineralischer Dünger dagegen stieg von 20–70% auf 50–80%. Dies gibt einen Hinweis auf ein erhöhtes Umweltgefährdungspotential organischer Dünger. Unter Berücksichtigung der abnehmenden Humusgehalte deuten auch die N‐Bilanzen auf eine erhöhte Umweltgefahrdung organischer Düngung.     

不同水分梯度下小叶章地上构件C,N,P含量动态分析

通过野外调查分析,研究了波动水文情势下,不同水分梯度带小叶章地上构件C,N,P含量动态。结果表明,各构件TC含量随时间波动变化,常年积水带大于无常年积水带;TN和TP含量,总体随水分的增加而减小,且生长季内含量逐渐下降;3种元素含量总体均为叶片含量高于茎和鞘。构件C/N常年积水和无常年积水两种情况下随水分增加呈现不同变化规律;C/P随水分的增加及生长过程的推进而增大;N/P总体随水分的增加而增大,生长季内均呈先增加后减小的波动变化。随水分的增加,小叶章质量下降;生长季初期,各水分梯度带小叶章生长均受N限制,而后期无常年积水区生长受N限制,深度积水区则受P限制。     

科尔沁沙地半固定沙丘不同坡位土壤C,N特征

[目的]研究沙丘不同坡位土壤碳氮的分布特征,旨在探索沙丘不同坡位植被演替机制。[方法]选取高于5m的半固定沙丘,沿主要风向于坡底、坡中、坡顶和背风坡设置样点,对土壤容重、土壤总有机碳含量和土壤总氮含量进行测定,并计算碳氮比、碳氮密度和碳氮储量。[结果](1)不同坡位土壤碳含量均随深度增加显著降低,主要变异层发生在0—40cm层。不同坡位土壤碳含量在30—40cm层和60—100cm层存在差异。(2)氮含量与容重在不同坡位和不同深度均不存在显著差异性,碳氮比在坡底和坡顶存在显著的垂直差异性,背风坡60—100cm层土壤碳氮比显著高于其它坡位。(3)各坡位土壤碳密度随深度增加显著下降。30—40cm层土壤碳密度存在显著的坡位差异,而土壤氮密度的垂直差异和坡位间差异均不显著。(4)半固定沙丘土壤碳氮储量分别为716.89和94.14kg/m2,不同坡位差异性不显著;碳储量的构成在4种坡位差异较大,而各坡位不同深度土壤氮储量对总储量的贡献差异较小。[结论]科尔沁沙地半固定沙丘土壤碳氮含量与密度不同坡位的差异较小,同时各坡位的碳氮均存在显著的垂直差异性,尤其在30—40cm层,变异程度较大,这可能与该层植物根系分布有关。     

Deficiency of N,P, K,Ca, Mg,or Fe Mineral Nutrients in Narcissus cv. “Garden Giant”

Narcissus cv. “Garden Giant” bulbs were grown in N, P, K, Ca, Mg, or Fe-deficient solutions and compared with bulbs grown in the control solution containing all these nutrients. Plants were sampled at 4 stages: (I) at planting, (II) at sprouting, (III) after flower senescence and/or after visible deficiency symptoms developed, and (IV) at lifting. Observation of visible deficiency symptoms showed that leaves of narcissus displayed chlorosis in the —N, —Mg, and —Fe treatments, while roots were most susceptible to Ca-deficient conditions. Root tips in the —Ca treatment showed brown in followed by root rot. In the —N treatment, shoot growth was markedly retarded and leaves were small and yellow. On the other hand, visible deficiency symptoms were not evident in the —P treatment except for early senescence. K deficiency symptoms were also not evident. Narcissus flowers were not affected by the mineral deficiencies and mineral contents in full-bloom flowers were not different between samples.

In the control plants, there was a large accumulation of N in the roots at sprouting and the content decreased thereafter. Large amounts of K accumulated in roots more than in any other organs. On the other hand the Ca content was high in the tunic and Ca in the scales was hardly mobilized thoughout the growth period. A large proportion of each element eventually accumulated in new inner scales whereas only a small fraction in the old outer scales. The -N, -Ca, and -Mg treatments severely depressed dry matter accumulation, unlike the -P, -K, and -Fe treatments. The -N treatment did not affect the concentration of other minerals, but the -P treatment tended to decrease N, K, Ca, and Mg concentrations. On the other hand, the -K treatment increased Ca and Mg concentrations. -Ca caused an increase in Mg concentration and -Mg raised Ca concentration. These results may be due to compensation effects of cation absorption for the maintenance of the cation/anion balance.     

施硒对苦荞N,P,K营养元素和土壤有效养分含量的影响

采用盆栽试验研究土壤施硒对不同生长期苦荞N,P,K营养元素和土壤有效养分含量的影响.结果表明,除80 d的Se0.5处理外.施硒增加了苦养茎的N含量,茎的P含量在60 d时除Se0.5处理外均显著降,40 d和80 d时均显著增加,施硒均降低苦荞全生育期茎的K含量.40 d时,叶的N,P含量降低,K含量在施硒≤1.5mg/kg范围升高0.46～0.8个百分点;60 d时,叶的N,P含量在低浓度硒时降低.高浓度硒时升高,K含量除Se0.5处理外均显著降低;80 d时叶的N,P含量除Se2.0处理外均降低,施硒各处理叶的K含量显著降低.花的N含量除Se0.5处理外均高于不施硒处理,P含量均不同程度降低,K含量显著提高.除Se0.5处理外,子粒的N,P,K均有所提高.施硒对速效氮的影响因硒水平和苦养生育期各异,土壤有效磷、钾含量均随外源硒浓度的增加而增高.     

Differing N status and N retention processes of soils under old-growth lowland forest in Eastern Amazonia,Caxiuanã, Brazil

Indirect evidence of the nitrogen (N) status of tropical forests strongly suggests that in heavily weathered soils under old-growth lowland tropical forests nitrogen is in relative excess. However, within the lowland forests of the Amazon basin, there is substantial evidence that soil texture influences soil NH₄⁺ and NO₃^? concentrations and hence possibly N availability and retention in the soil. Here, we evaluate the soil N status of two heavily weathered soils which contrast in texture (sandy versus clay Oxisol). Using ¹⁵N pool dilution, we quantified gross rates of soil N cycling and retention. We also measured the δ¹⁵N signatures from the litter layer down to 50-cm depth mineral soil and calculated the overall ¹⁵N enrichment factor (ε) for each soil type. The clay soil showed high gross N mineralization and nitrification rates and a high overall ¹⁵N enrichment factor, signifying high N losses. The sandy soil had low gross rates of N cycling and ¹⁵N enrichment factor, manifesting a conservative soil N cycling. Faster turnover rates of NH₄⁺ compared to NO₃^? indicated that NH₄⁺ cycles faster through microorganisms than NO₃^?, possibly contributing to better retention of NH₄⁺ than NO₃^?. However this was opposite to abiotic retention processes, which showed higher conversion of NO₃^? to the organic N pool than NH₄⁺. Our combined results suggest that clay Oxisol in Amazonian forest have higher N availability than sandy Oxisol, which will have important consequences for changes in soil N cycling and losses when projected increase in anthropogenic N deposition will occur.