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71.
Ved Prakash Ranjan Bhattacharyya Govindan Selvakumar Samaresh Kundu Hari Shanker Gupta 《植物养料与土壤学杂志》2007,170(2):224-233
This study aims to examine the effects of long‐term fertilization and cropping on some chemical and microbiological properties of the soil in a 32 y old long‐term fertility experiment at Almora (Himalayan region, India) under rainfed soybean‐wheat rotation. Continuous annual application of recommended doses of chemical fertilizer and 10 Mg ha–1 FYM on fresh‐weight basis (NPK + FYM) to soybean (Glycine max L.) sustained not only higher productivity of soybean and residual wheat (Triticum aestivum L.) crop, but also resulted in build‐up of total soil organic C (SOC), total soil N, P, and K. Concentration of SOC increased by 40% and 70% in the NPK + FYM–treated plots as compared to NPK (43.1 Mg C ha–1) and unfertilized control plots (35.5 Mg C ha–1), respectively. Average annual contribution of C input from soybean was 29% and that from wheat was 24% of the harvestable aboveground biomass yield. Annual gross C input and annual rate of total SOC enrichment from initial soil in the 0–15 cm layer were 4362 and 333 kg C ha–1, respectively, for the plots under NPK + FYM. It was observed that the soils under the unfertilized control, NK and N + FYM treatments, suffered a net annual loss of 5.1, 5.2, and 15.8 kg P ha–1, respectively, whereas the soils under NP, NPK, and NPK + FYM had net annual gains of 25.3, 18.8, and 16.4 kg P ha–1, respectively. There was net negative K balance in all the treatments ranging from 6.9 kg ha–1 y–1 in NK to 82.4 kg ha–1 y–1 in N + FYM–treated plots. The application of NPK + FYM also recorded the highest levels of soil microbial‐biomass C, soil microbial‐biomass N, populations of viable and culturable soil microbes. 相似文献
72.
添加莠去津的土壤中微生物生物量碳、氮、磷对外源有机无机物质的动态响应 总被引:1,自引:4,他引:1
研究了添加有机、无机营养物质对外加除草剂莠去津土壤(每1g土中含莠去津10mg/)中微生物生物量碳、氮和磷的动态变化过程。研究结果表明,在整个培养过程中,仅加莠去津的土壤中微生物生物量碳、氮、磷的含量均显著降低,与对照相比,分别平均降低了13.5%,10.1%,20.0%。但是,施用有机、无机营养物质的处理,土壤微生物生物量碳、氮、磷的含量均显著增加。不同处理对微生物生物量碳、氮的含量影响程度依次为:腐熟猪粪>紫云英>水稻秸秆腐熟猪粪>N、P肥配施>单施N肥>单施P肥。而对微生物生物量磷含量的影响则为:腐熟猪粪>N、P肥配施>紫云英>单施N肥>单施P肥>水稻秸秆。 相似文献
73.
贵州西部喀斯特石漠化地区退耕弃荒地土壤氮素变异特征 总被引:6,自引:3,他引:6
研究以贵州西部喀斯特石漠化地区退耕弃荒地土壤为研究对象,在保证自然因素相对一致的条件下,根据退耕年限的不同和有无梯化过程,采集土壤样品进行全氮及氮素形态的化学分析。结果表明,该区域土壤有机质、全氮及各形态氮素含量呈现先降后升的趋势。根据此结论,并结合该区域性水热同期的先天条件,认为在贵州西部喀斯特石漠化地区土壤氮素肥力的自然修复是存在可能的。 相似文献
74.
采用淹水密闭培养-间歇淋洗法,研究了有机肥(猪粪和牛粪)与化肥(尿素)氮以不同比例配施后对水稻土铵态氮释放特征的影响。结果表明:与单施100%尿素处理相比,培养到28 d,配施有机肥处理(除80%尿素氮配施20%牛粪氮、70%尿素氮配施30%牛粪氮和50%尿素氮配施30%牛粪氮处理)显著降低土壤铵态氮的累积释放量,且随有机肥配施比例的增加降幅增大,降低幅度为5.78%~41.20%(P0.05);培养28~90 d,配施有机肥处理(50%尿素氮配施30%牛粪氮处理除外)的土壤铵态氮释放量显著提高;至培养90 d,50%尿素氮配施50%猪粪氮和80%尿素氮配施20%牛粪氮处理的土壤铵态氮累积释放量显著高于单施100%尿素处理,提高幅度分别为4.81%和9.32%(P0.05)。培养结束时,氮素减施20%(单施80%尿素氮、50%尿素氮配施30%猪粪氮和50%尿素氮配施30%牛粪氮)处理的土壤铵态氮累积释放量与单施100%尿素处理无显著差异。本研究表明,50%尿素氮配施30%猪粪氮既可以降低土壤铵态氮前期释放速率,又可以增加水稻土持续稳定的供氮能力,对减少氮肥损失维持作物生产具有重要意义。 相似文献
75.
76.
Background River and lake sediments constitute complex and difficult analytical samples. On the other hand, sediments play a fundamental
role in the distribution of toxic compounds in aquatic systems and in the evaluation of the current state and the course of
changes taking place in the environment.
Among elements present in the environment in trace concentrations, but having well-elaborated toxic properties, one of most
dangerous is arsenic. The element occurs in the environment in several chemical forms, predominant are inorganic forms of
As(V) and As(III), and methylated forms such as monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA).
Objectives Reported herein are experiments, which were undertaken with the aim of examining the dynamics of arsenic sorption in sediments
and its dependence on speciation of the element and the pH in the environment. Simultaneously, influence of organic matter
content and chemical composition of the sediments on As sorption, were investigated.
Methods Sediment samples (upper 10 cm layer) were collected from three sites located in the vicinity of Cracow:
Using XRD and IR methods, mineral composition of sediments was analysed. Concentrations of iron, manganese, aluminium and
arsenic as well as organic matter content in solid samples were analysed.
Sorption experiment 100 g of dry sediment sample was placed in a 400 ml volume glass beaker. 300 ml of arsenic containing solution was poured
into the beaker. Every 30 min (total experiment time span equalled 7 to 7.5 hours), 0.5 ml of the suspension’ (the beaker
content was constantly mixed) was collected and centrifuged, and the concentration of arsenic was determined in the supernatant.
In the series of experiments, solution contained about 0.05 μg/ml of arsenic in organic (DMAA) and inorganic forms, at different
pH values — 3, 5, 7 and 9.
Results and Discussion Examined sediments of Vistula river and Dobczyce Lake were characterised by relatively high concentrations of arsenic, iron,
manganese and aluminium.Rudawa river. At pH 3, the concentration of inorganic As in solution decreased from an initial value of 0.049 μg/ml to 0.012 μg/ml in
7.5 hours time. The same decreasing tendency was found at pH 5 (initial value 0.046 μg/ml, after 7.5 hours - 0.015 μg/ml).
Less distinct sorption effects were noted at pH 7 and 9.
Vistula river. At all pH values, a very significant decrease of inorganic As concentration up to 80% of the initial value, as well as a
short time of achieving an equilibrium state (1 – 2.5 hours), was found.
Dobczyce lake. Inorganic As was distinctly accumulated in sediments at pH 3 (decrease of As concentration in solution from 0.052 to 0.007
μg/ml after 7.5 hours of the experiment) and at pH 5. At pH 7, about 40% of As was accumulated in sediments (solution As concentration
decrease from 0.050 to 0.030). Only 20% of As adsorbed on sediments at pH 9.Very weak accumulation of organic form of As (DMAA)
was found in all examined sediments at pH 3 and 5. At higher pH values no sorption was registered.
Conclusions The following facts were established:
Recommendations The presented method of analysis of As sorption in sediments and results visualization (based on a newly defined coefficient)
provides a useful tool for the characterization of sorptive properties of sediments and may be used for other compounds as
well. Crucial, functional information — how much of a given element may be accumulated in sediments at a certain pH — is obtained
without digestion of the sediment sample, in an experiment taking less than one day. 相似文献
• | Rudawa river — 37 km long river, flowing mainly through the suburban area; |
• | Vistula river — heavily contaminated, main Polish river; |
• | Dobczyce reservoir — artificial reservoir on Raba river, total capacity of 125,000,000 m3, supplying about 60% of drinking water to the city of Cracow. |
• | inorganic form of arsenic was effectively accumulated in all analysed sediments; |
• | inorganic As sorption in sediments strongly depended on pH — for sediments of Rudawa river and Dobczyce lake, the highest sorption was found at pH 3, and a decrease of accumulated As was noted with an increase of pH (at pH 9, the lowest amount of As was immobilised in sediments); in the case of Vistula river sediments, a reverse tendency was found; |
• | organic form of arsenic (DMAA) was accumulated only at pH 3 in all sediments and less significantly at pH 5 (Vistula river sediments); no sorption of that form of As was found in the other sediment samples; |
• | state of equilibrium (no change in inorganic As concentration in liquid medium) was achieved in 1 hour for Vistula river sediments, after about 2 hours for Rudawa river and after about 4 hours for Dobczyce lake sediments. |
77.
研究了黄土类土对不同浓度外源As的缓冲性及其随平衡时间、污染物浓度的动态变化规律;阐明了黄土类土对As的缓冲速率与平衡时间的关系;确定了黄土类土对As的缓冲动力学方程,为更准确的评价黄土类土对As的污染-净化能力提供依据。 相似文献
78.
79.
连续分期配施有机肥对棉花超高产及土壤肥力的影响 总被引:5,自引:0,他引:5
1997~ 1 999年定位施肥试验表明 ,在施N量为 592 5~ 60 0 0kg·hm- 2 (N∶P2 O3∶K2 O =1∶0 5∶0 6) ,有机肥N、P2 O5、K2 O分别占 1 0 0 %~ 1 2 4%、 50 3 %~ 51 0 %和 50 0 %的条件下 ,随着分期配施有机肥年限的增加 ,棉花果节数、结铃数、结铃率和皮棉产量均得到明显的提高 ,铃重和衣分也略有增加 ,土壤肥力也得了改善和提高。创棉花 2 2 50kg·hm- 2 高产 ,要求连续分期配施有机肥 2年以上 ,棉花六成铃区成铃比例皆在 1 0 %以上。 相似文献
80.
添加尿素和无机盐土对秸秆厌氧消化的影响 总被引:2,自引:2,他引:0
向厌氧消化体系加入外源添加剂是一种有效且简单的用于提高产气效率的方法。为了解决秸秆厌氧消化原料转化率低、易酸化、厌氧消化时间长等问题,该文选取尿素和无机盐土作为秸秆厌氧消化的添加剂,研究比较不同添加量对玉米秸秆厌氧消化过程产气特性、发酵环境、微生物活性以及物能转化效率的影响。结果表明,对于出现酸化问题且甲烷菌活性较低的厌氧消化系统,添加尿素和无机盐土有利于缓解酸化并促进微生物生长繁殖,三磷酸腺苷(ATP)峰值时的微生物数量可增加2.76×1011-5.31×1011个/L。添加一定量的尿素和无机盐土可使产气高峰提前,添加10%的无机盐土处理组与纯秸秆处理相比,产气高峰可提前4d;但酸化也会削弱尿素和无机盐土对产甲烷过程的促进作用,添加量越大,削弱效果越显著。研究结果可为秸秆厌氧消化的工程应用提供参考。 相似文献