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1.
硫氰酸钾-邻菲啰啉-吐温-20分光光度法测定植物中的铁 总被引：1，自引：0，他引：1
何斌 《植物营养与肥料学报》1997,3(1):66-71
本文研究了在吐温-20存在下，于硝酸介质中，铁（Ⅲ）与硫氰酸钾和邻菲啉的显色反应房件。结果表明，所形成的红色配合物的最大吸收波长为518nm，表观摩尔吸光系数为2.06104Lmol-1cm-1，铁（Ⅲ）含量在0～50g范围内服从比耳定律。本法具有操作简便，选择性高，重复性好等优点，可不经分离和掩蔽，直接用于植物中铁的测定，结果满意。 相似文献
2.
华北平原小麦-玉米农田生态系统服务评价 总被引：8，自引：1，他引：7
本研究于2006 年和2007 年在中国科学院栾城农业生态系统试验站田间试验基础上, 评价了华北平原小麦-玉米农田的初级产品生产、气体调节、土壤有机质累积、水调节和氮素转化等5 项生态系统服务。研究表明, 华北平原小麦-玉米农田初级产品量包括籽粒产量5.04~5.71 t·hm-2·a-1(小麦)和6.69~8.24t·hm-2·a-1(玉米), 秸秆量8.58~9.72 t·hm-2·a-1(小麦)和6.97~8.58 t·hm-2·a-1 (玉米); 农田气体调节包括释放O2 24.99~28.64 t·hm-2·a-1, 固定CO2 34.23~39.22 t·hm-2·a-1, 排放N2O 0.72~1.13 kg·hm-2·a-1, 吸收CH4 3.39~5.70 kg·hm-2·a-1; 农田耕层土壤有机质累积量为1.13~2.39 t·hm-2·a-1; 水资源消耗量为2 890~3 830 m3·hm-2·a-1; 农田土壤氮素几乎都处于亏缺状态, 变化范围为-107.73~5.33 kg(N)·hm-2·a-1, 不施氮肥农田亏缺较多。综合评价发现, 小麦-玉米农田提供生态服务的经济价值为5.48~6.25 万元·hm-2·a-1, 是粮食生产价值的3 倍左右。氮肥施用对农田生态系统服务及其产生福利的影响较为复杂, 这主要是由于施加氮肥明显增加了氮素转化功能导致的经济损失, 而同时可能会增加初级产品生产、气体调节中作物固定CO2 和释放O2 功能的经济价值。尽管目前有关生态系统服务评价研究主要关注生态系统产生的正效应, 但仍有必要对农田产生的负效应做出评价, 以便客观看待农田生态系统价值, 正确认识农田生态系统对人类福利的影响。 相似文献
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4.
Hydraulic Resistance and Capacitance in the Soil-Plant System 总被引：1，自引：0，他引：1
In this paper, the hydraulic resistances and capacitances were evaluated. based on the development of non-(?) model of water flow in the soil-plant system and the simulating experiment work.The results show that the mean hydraulic resistance in the soil-plant system is 6.79×109 MPa·S·m-3; the mean hydraulic capacitance in the system is 5.2×107m3·MPa-1. In the components of hydraulic capacitance in the system, the capacitance in soil (81.8×10-6m3·MPa ) is the biggest and its variability with suii water potential is extremely strong, the capacitance in plant (5.3×10-7m3·MPa-1) is much smaller than that in soil, and the capacitance in shoots (15.5×10-7m3·2MPa-1) is bigger than that in roots (8.4×10-7m3·2MPa-1). An interesting result is that the capacitance in plant is almost equivalent to that in the soil-plant system. 相似文献
5.
华北平原氮肥周年深施对冬小麦-夏玉米轮作体系土壤氨挥发的影响 总被引：1，自引：0，他引：1
氮肥深施能有效减少土壤氨挥发,然而目前国内外关于小麦-玉米轮作体系氮肥深施缺乏周年系统性研究。本试验于2018年10月—2019年10月在中国科学院栾城农业生态系统试验站小麦-玉米轮作农田进行,利用动态箱法研究不同深施模式氨挥发损失率、氨挥发特征,旨在探讨冬小麦-夏玉米轮作体系下土壤氨排放对氮肥深施的响应,为减少农业源氨排放和优化农田施肥提供理论依据。试验设置5个处理：不施肥（CK）、常规肥料表施（T1）、缓释肥表施（T2）、缓释肥基追肥分层深施（T3）、缓释肥一次性分层深施（T4）。结果表明：氨挥发主要发生在玉米追肥季,占全年氨挥发量的84.84%;T1、T2、T3和T4处理的周年氨挥发累积量分别为22.75 kg·hm-2、6.17 kg·hm-2、2.25 kg·hm-2和0.55 kg·hm-2,分别占总施肥量的4.86%、1.32%、0.48%和0.13%。与常规肥料表施（T1）相比,缓释肥处理（T2、T3和T4）分别降低72.88%、90.11%和97.32%的氨挥发损失;一次性深施处理（T4）能避开土壤氨高挥发期,周年氨挥发累积量与不施肥处理（0.43 kg·hm-2）没有显著差异,且显著低于表施处理。CK、T1、T2、T3和T4全年产量分别为8.31 t·hm-2、13.20 t·hm-2、12.66 t·hm-2、14.42 t·hm-2和14.22 t·hm-2;与常规肥料表施（T1）相比,缓释肥深施（T3和T4）均可提高作物产量,分别增产9.25%和7.75%。而缓释肥表施（T2）产量略有降低。综合考虑土壤氨排放和作物产量,缓释肥表施（T2）可以显著降低土壤氨挥发,但是作物产量不稳定;而氮肥深施（T3、T4）能在保证作物高产的基础上显著降低土壤氨排放,是一种高效、简便、环境友好的施肥方式。 相似文献
6.
何斌 《广西农业生物科学》1996,(4)
本文研究了在乙醇存在下，铁（Ⅲ）与铬天青Ｓ和溴化十六烷基三甲铵的高灵敏显色反应。在ｐＨ５．１～６．８的乙酸－乙酸铵缓冲介质中，配合物吸光度最大且稳定，最大吸收波长为６４６ｎｍ，表观摩尔吸光系数为２．４２×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，铁（Ⅲ）量在０～０．１４ｍｇ·Ｌ－１范围内遵守比耳定律。在氟化钠的存在下，方法具有良好的选择性，直接应用于水样中微量铁的测定，结果满意，相对标准偏差＜５．２％，回收率在９５．６％～１０２．４％之间 相似文献
7.
三波长分光光度法测定土壤中可溶态稀土总量 总被引：7，自引：0，他引：7
偶氮氯膦Ⅲ是测定稀土总量的灵敏试剂,已广泛地应用于铸铁、低合金钢中稀土总量的测定。罗庆尧等[1]研究并提出了稀土—偶氮氯膦Ⅲ—溴化十六烷基三甲基铵三元络合物体系在强酸条件下测定稀土总量的方法,该法具有更高的灵敏度和选择性,已用于合金钢中微量稀土总量的直接光度测定。 相似文献
8.
以向日葵为试验植物,用营养液培养的方法,研究不同浓度重碳酸盐对向日葵缺铁的适应性反应机理的影响。结果表明,在营养液中添加重碳酸盐使铁高效植物根系还原螯合态铁(FeBDDHA)的能力大大降低,当重碳酸盐添加量为0.8 cmolL-1时,木质部伤流液中放射性铁含量由对照的493μmolL-1降到234μmolL-1,幼叶中放射性铁含量也从对照的7.4 mgg-1干物质降到2.0 mgg-1干物质。 相似文献
9.
GFP标记的植物促生菌B96-Ⅱ-gfp的定殖能力研究 总被引：1，自引：0，他引：1
采用绿色荧光蛋白基因标记技术研究了植物促生菌B96-Ⅱ的标记菌B96-Ⅱ-gfp在盆栽黄瓜土壤中的时间、空间定殖动态以及在黄瓜植株上的分布。研究表明: B96-Ⅱ-gfp在土壤中具有持久的定殖能力, 接种180 d时在自然土和黄瓜枯萎菌病土中的定殖数量分别为2.7×104 cfu·g-1和6.6×104 cfu·g-1, 360 d时在土壤中仍可检测到B96-Ⅱ-gfp的存在。B96-Ⅱ-gfp可在盆栽植株生长土壤的表层(0~4 cm)、中层(4~8 cm)和底层(8~12 cm)定殖, 定殖数量随土壤深度的增加而增加。此外, B96-Ⅱ-gfp还可在黄瓜的根、茎和叶上定殖, 根部定殖的数量(7.2×104 cfu·g-1)显著高于茎部和叶部定殖的数量; 黄瓜植株体内定殖的数量多于体表定殖的数量。对土壤中可培养的3大微生物类群影响的研究表明: B96-Ⅱ-gfp对土壤中真菌数量具有显著抑制作用, 而对细菌和放线菌数量则没有明显影响。防病促生试验表明: B96-Ⅱ-gfp可增加黄瓜株高、鲜重和干重, 对黄瓜枯萎病有一定的防治效果, 且与未标记菌株B96-Ⅱ的防病促生作用无显著差异。 相似文献
10.
为了解九龙坡花椒种植区土壤养分状况及该区地形因子、土壤肥力因子与花椒产量的关系,为科学合理制定花椒高效施肥措施提供理论依据,本研究采用田间调查研究和室内分析的方法,研究了九龙坡花椒种植区低、中、高产区的海拔、坡度及土壤pH、有机质、大量微量元素含量和交换性能的变化特征,及其与花椒产量的关系。研究结果表明：九龙坡花椒普遍种植于200~500 m海拔范围,高产区集中在300 m左右的海拔;从低产区到高产区坡度略有增加,但未达显著水平。土壤均属酸性土,pH<6.5。土壤肥力总体属高水平范围,但各养分因子差异很大,其中土壤阳离子交换量（CEC）、有效磷、有效钙、有效镁、有效铁、有效锰、有效铜、有效锌含量丰富,分别为27.2 cmol（+）·kg-1、35.2 mg·kg-1、3 289.8 mg·kg-1、271.8 mg·kg-1、48.6 mg·kg-1、62.1 mg·kg-1、1.5 mg·kg-1、4.5 mg·kg-1;有机质、碱解氮、速效钾、交换性酸属适中水平,分别为19.1 mg·kg-1、114.9 mg·kg-1、107.0 mg·kg-1、8.1 cmol（+）·kg-1;水溶性硼缺乏,为0.28 mg·kg-1。相关分析表明花椒产量与有效钙、CEC、pH、有效锰、水溶性硼呈显著正相关;通径分析结果表明有效钙、CEC、交换性酸、有效铜、有效铁、有效锌是影响花椒产量的主要因子,逐步回归分析构建了有效钙（X6）与花椒产量（Y）的最优回归线性方程：Y=11.693+0.003X6。综上所述,九龙坡花椒种植区土壤养分失衡较为严重,施肥应注重养分的平衡,增施有机肥,改善土壤理化性状,治理土壤酸化。 相似文献
11.
两种基因型豌豆根系质外体铁的积累与消耗 总被引：1，自引：0，他引：1
采用两种基因型豌豆,在水培条件下研究了根系质外体铁的积累和利用。结果发现供铁后短时间内豌豆根系质外体铁就大量积累,铁效率不同的豌豆基因型根系质外体铁的积累量没有明显差异,根系质外体铁的利用速率与根系缺铁适应性反应强弱有关。 相似文献
12.
In the northern highlands of Ethiopia, establishment of exclosures to restore degraded communal grazing lands has been practiced for the past three decades. However, empirical data on the effectiveness of exclosures in restoring degraded soils are lacking. We investigated the influence of exclosure age on degree of restoration of degraded soil and identified easily measurable biophysical and management‐related factors that can be used to predict soil nutrient restoration. We selected replicated (n = 3) 5‐, 10‐, 15‐, and 20‐year‐old exclosures and paired each exclosure with samples from adjacent communal grazing lands. All exclosures showed higher total soil nitrogen (N), available phosphorus (P), and cation exchange capacity than the communal grazing lands. The differences varied between 2·4 (±0·61) and 6·9 (±1·85) Mg ha−1 for the total N stock and from 17 (±3) to 39 (±7) kg ha−1 for the available P stock. The differences in N and P increased with exclosure age. In exclosures, much of the variability in soil N (R2 = 0·64) and P (R2 = 0·71) stocks were explained by a combination of annual average precipitation, woody biomass, and exclosure age. Precipitation and vegetation canopy cover also explained much of the variability in soil N (R2 = 0·74) and P (R2 = 0·52) stocks in communal grazing lands. Converting degraded communal grazing lands into exclosures is a viable option to restore degraded soils. Our results also confirm that the possibility to predict the changes in soil nutrient content after exclosure establishment using regression models is based on field measurements. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
13.
Phosphate extracted by ion-exchange resins in the chloride and sodium forms from a deep river-gravel soil under widely varying conditions is always from the isotopically exchangeable or‘labile’ pool. At any reaction time, a constant fraction of this pool is desorbed by the chloride form of the anion-exchange resin alone, irrespective of the pH and phosphate manuring of the soil. If, however, a sodium: cation exchange resin is included, increasing fractions of the‘labile pool’ are desorbed with decreasing soil acidity. Phosphate desorption by the anion-exchange resin alone and with the cation exchange resin is shown to be‘particle-diffusion’ controlled in the anion exchange resin and neither a‘chemical reaction’ nor a‘film-diffusion’ mechanism. Over the pH range 4·5–8·5, values between 4·8 and 0·9 × 10-9 cm2 sec-1 were calculated for the interdiffusion coefficient of the phosphate: chloride exchange process in the resin. The isotopically exchangeable phosphate in the soils seems to behave like sparingly soluble or weakly dissociating compounds towards ion-exchange resins and its rate of desorption depends on the nature and composition of the resins. 相似文献
14.
Sibaway Bakari Mwango Balthazar Michael Msanya Peter W. Mtakwa Didas N. Kimaro Jozef Deckers Jean Poesen 《Land Degradation \u0026amp; Development》2016,27(4):1266-1275
Soil erosion is a major threat to food security in rural areas of Africa. Field experiments were conducted from 2011 to 2014 in Majulai and Migambo villages with contrasting climatic conditions in Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of mulching in reducing soil erosion and restoring soil fertility for productivity of maize (Zea mays) and beans (Phaseolus vulgaris) under miraba, a unique indigenous soil conservation measure in the area. Soil loss was significantly higher (p < 0·05) under miraba sole than under miraba with mulching, for example, 35 versus 20 and 13 versus 8 Mg ha−1 y−1 for Majulai and Migambo villages, respectively, in 2012. Soil fertility status was significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, for example, 0·35 versus 0·25% total N, 37 versus 22 mg kg−1 P and 0·6 versus 0·2 cmol(+) kg−1 K for the Majulai village; and 0·46 versus 0·38 total N, 17·2 versus 10·2 mg kg−1 P and 0·50 versus 0·2 cmol(+) kg−1 K for the Migambo village. Maize and bean yields (Mg ha−1) were significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, 2·0 versus 1·3 for maize and 0·9 versus 0·8 for beans in Majulai; and 3·8 versus 2·6 for maize and 1·0 versus 0·8 for beans in the Migambo village in 2012. This implies that Tughutu mulching is more effective in improving crop yield than Tithonia, although both could potentially protect the arable land from degradation caused by water erosion under miraba. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
15.
A calcareous organic soil was extracted by shaking with Na+-resin suspended in 0·2M acetyl acetone at pH 8·3. Fractionation of the fulvic acid on Sephadex G 25 gave (a) a high molecular-weight component which contained inositol tetraand hexa-phosphates and a sugar phosphate; (b) low molecular-weight components which included the mono-, di-, and triphosphate esters of inositol and two sugar phosphates, but no free inositol phosphates. Inositol phosphates and sugar phosphates accounted for 30·2 per cent and 16·6 per cent of the soil organic P respectively. Our evidence indicates that these phosphate esters exist in an organic complex. 相似文献
16.
偶氮氯膦Ⅰ(简称CPA Ⅰ)作为光度显色剂最初应用于测定铀和镤[4,5],后又用于测定镉、铜、锆、钍、镧和钇[3],近年则被应用于测定镁[1,2].但应用于测定钙,尚未见国内外报道.本文研究了Ca-CPA Ⅰ络合物的形成条件、组成和稳定常数,应用于土壤水溶性钙镁的连续测定,获得了较满意的结果. 相似文献
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18.
S. Yan‐Gui L. Xin‐Rong C. Ying‐Wu Z. Zhi‐Shan L. Yan 《Land Degradation \u0026amp; Development》2013,24(4):342-349
Enhanced carbon fixation in soil crusts may facilitate the restoration of damaged ecosystems, but this requires greater knowledge of carbon fixation patterns and mechanisms. We measured the net photosynthetic rate (Pn) and estimated annual carbon fixation (ACF) in cyanobacterial–algal crusts after desert fixation in the Tengger Desert, northwestern China. The accumulated carbon fixation since the establishment of a restoration site was also calculated. In addition, stepwise regression analysis was used to study the relation between Pn and ACF and the physicochemical properties of crusts. Results showed that Pn was significantly higher at a more established 51‐year‐old restoration site (1·57 µmol m−2 s−1) than at a younger 15‐year‐old site (0·92 µmol m−2 s−1). The ACF also increased significantly with restoration time, but in two temporal phases, a slower ACF phase between 15 and 26 years of restoration (0·28–0·7 gC m−2 y−1) and a high ACF phase after 43–51 years of restoration (3·3 gC m−2 y−1). Stepwise regression analysis revealed that Pn was significantly correlated with chlorophyll a and crust cover, whereas ACF was only correlated with crust cover. Accumulated carbon fixation increased from 2·9 gC m−2 after 15 years to 35·4 gC m−2 at 51 years following establishment of the restoration site. The accumulated carbon fixation was positively correlated with soil organic carbon content. This study demonstrated that carbon fixation by cyanobacterial–algal crusts increased progressively after desert fixation. Artificial measures, like the establishment of these restoration zones, can facilitate the colonization and development of biological soil crusts and are an effective biological tool for desert soil restoration. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
19.
R. A. G. RAWSON 《European Journal of Soil Science》1969,20(2):325-335
A new method is described for determining the surface area of soils and clays by adsorbing ethylene glycol vapour under continuous evacuation at c. 10-2 cm of mercury. The adsorption of a monolayer of ethylene glycol is inferred from the dynamics of pressure changes in the adsorption chamber. The time at which monolayer adsorption is evaluated is proportional to the total weight of ethylene glycol required to form a monolayer on all samples in the adsorption chamber. This period ranged from 30 to 75 minutes when from 0·39 to 1·56 g of glycol was adsorbed in the experiments. A single 0·75 g sample of Wyoming bentonite required 0·195 & glycol. 相似文献
20.
D. J. GREENWOOD 《European Journal of Soil Science》1970,21(2):314-329
Theory predicts that in the aqueous phase of aerobic soils carbon dioxide concentration/distance gradients are 1·35 times as large as those for oxygen. Because of differences in solubility, the partial pressure/distance gradients of carbon dioxide should be less than one-twentieth of the gradients of oxygen partial pressure. Experiments were carried out to test this prediction. In some experiments oxygen partial pressures were measured directly by means of a micro-electrode and carbon dioxide indirectly by methods involving microelectrode determinations of specific conductance in agar-CaCO3 gel. Measurements were made in models of water-saturated soil consisting of yeast cells embedded in agar-CaCO3 gel, around plant roots in agar-CaCO3 gel and within water-saturated soil. Oxygen partial pressures fell by 5–15 per cent of an atmosphere over distances of 0·2–0·4 cm whereas carbon dioxide partial pressures increased by less than 0·3 per cent of an atmosphere over the same distance. In other experiments different thicknesses of water-saturated soil were incubated with their upper surfaces exposed to air. The mean oxygen partial pressure fell by 7–13 per cent of an atmosphere with increasing the thickness from 0·2 to 0·4 cm whereas the carbon dioxide partial pressure never increased by more than 0·2 per cent of an atmosphere. Both sets of evidence confirm the theoretical prediction. It is concluded that the partial pressure of carbon dioxide in the aqueous phase of soils containing no oxygen-free zones, would never, even at the surfaces of roots, be more than 1 per cent of atmosphere greater than in the gas phase. 相似文献