Effect of irrigation scheduling on grain yield and nitrogen use efficiency of irrigated wheat at Kadawa and Bakura,northern Nigeria

In this study the interaction of applied N with different irrigation schedules on grain yields and N use efficiency of wheat was investigated in two Inceptisols of the Nigerian savanna during 1978–80. Irrigation intervals ranged from 7 to 28 days at Kadawa and 5 to 10 days at Bakura while the N rates varied from 0 to 200 kg per ha. Both grain yield and N uptake increased significantly with increasing N rates at both the locations. The magnitude of increase in yield and N uptake decreased substantially when the irrigation interval became longer. This interaction was very pronounced at Bakura where the soil is highly porous, excessively drained and extremely poor in moisture retention capacity. Longer irrigation intervals produced grains with slightly higher N content but the difference was not significant. Higher N rates and fewer irrigations gave lower fertilizer N recovery.     

城市污泥慢速热解过程中氮的转化规律

利用热重-质谱联用(TG-MS)技术研究城市污泥慢速热解特性及含氮气体产物的生成规律,同时利用原位红外光谱仪实时检测固体表面官能团的变化。研究结果表明:初沉污泥在500℃之前热解已基本完成,二沉污泥由于添加了矿物质盐类,在700℃左右仍有一个较大的失重峰;二沉污泥热解过程HCN和NH₃总生成量均小于初沉污泥,即二沉污泥所加矿物质抑制了HCN和NH₃释放;但温度大于400℃时所加矿物质对HNCO生成具有一定促进作用;污泥中蛋白质热分解会产生环酰胺类物质、含氮杂环化合物和腈类物质,并最终转化为HCN,这是污泥热解过程中HCN的主要来源;400℃以下NH₃主要来自铵盐分解和HCN转化,蛋白质热分解对于NH₃生成贡献很小;400℃以上基本检测不到NH₃生成,即较高温度下挥发分二次反应对NH₃生成几乎没有影响;300~480℃,污泥中木质素裂解产生了大量含氧自由基,促使HCN转化为N₂O,HNCO则最终转化成了NO。     

Nitrogen mineralization in soils amended with composted olive mill sludge

The disposal of olive mill wastewater (OMW) is a critical pollution problem, especially in Mediterranean countries. OMW is produced at a rate of ca. 2 1 kg^-1 of olives. OMW has a biochemical oxygen demand (BOD) of 35–48 g kg^-1. The evaporation of OMW in ponds produces large amounts of sludge (OMWS), which after being dried can be used as organic fertilizer or amendment, either directly or co-composted with agricultural by-products. The present paper deals with the use of a compost of dried sludge of OMW and other agricultural by-products – olive mill wastewater sludge compost (OMWSC) – to amend for three consecutive years two typical soils of southern Spain: a Typic Xeropsamment, S1 (CaCO₃ 86 g kg^-1; OM 1.4 g kg^-1; sandy soil) and a Typic Xerorthent, S2 (CaCO₃ 270 g kg^-1; OM 5.3 g kg^-1; sandy–clay–loam soil). Both soils are poor in organic matter, in total Kjeldahl-N (TKN 347 and 536 mg kg^-1) and in available-P (Olsen P 3.0 and 2.5 mg kg^-1). Mineralization of the organic-N of the OMWSC (OM 106–338 g kg^-1; TKN 7–15 g kg^-1; C/N 12.3–18.9) and of soils treated with OMWSC was studied under laboratory conditions by an aerobic, non-leaching incubation procedure. In both cases, the N-mineralization process was well described by first-order-reaction kinetics, and the potentially mineralizable-N (N₀) and the N-mineralization rate constant (k) estimated from a single first-order equation. Values for N₀ (equivalent to 16% of the N of the compost) and k (0.041 week^-1) indicated that the OMWSC was a mature compost composed mainly of well-humified organic matter, very resistant to mineralization. Soils treated with OMWSC showed increases of the OM, TKN and N₀ contents and of the potential rate of mineralization (N₀ x k), with respect to untreated or mineral fertilized soils. The increases of TKN in soils treated with OMWSC were even higher than expected by the N added together with compost, and attributed to non-symbiotic N fixation. Values of OM, TKN, N₀ and N₀ x k, were higher in S2 than in S1, which can be explained based on the soil properties related to fertility, especially soil texture.     

Conversion of municipal sewage sludge in supercritical water

The conversion of the organic matter of municipal sewage sludge in water under supercritical conditions (T≤750°C; P≤30 MPa) was studied. According to mass-spectrometric data, CO₂, H₂, CH₄, and NH₃ were predominant among volatile conversion products. The kinetic parameters of conversion were determined. It was found that the rate of the process increased with temperature and mainly depended on the interaction of water molecules with sewage sludge carbon T > 600°C.     

包裹型缓／控释肥对冬小麦产量、土壤无机氮和氮肥利用效率的影响

采用超大区田间试验,以不施氮、传统氯素管理方式和优化氮素管理方式为对照,研究冬小麦施用包裹型缓／控释肥（包裹肥料）对产量、土壤无机氮和氮肥利用效率的影响,并对冬小麦施用包裹型缓／控释肥效果进行评价,结果表明：与传统氮素管理方式相比,优化氮素管理方式和包裹肥料处理在分别节省了78％和67％的氮肥的条件下,获得了和传统氮素管理方式相似的冬小麦子粒产量;采用氮素优化管理模式和施用包裹肥料显著降低了土壤无机氮残留和氮素表观损失,从而显著提高了氮肥利用率;与优化氮素管理方式相比,施用包裹肥料可一次性基施,省时省力,提高了经济效益。     

Yield and nitrogen use efficiency of winter wheat with different soil fertility

Nutrient Cycling in Agroecosystems - Both the existing soil fertility and fertilizer application have important influences on crop yield and nitrogen (N) use efficiency, but knowledge about their...     

Relationship between electroultrafiltration (EUF) extractable nitrogen,grain yield,and optimum nitrogen fertilizer rates for winter wheat

The objective of the investigation was to examine whether there exist relationships between the optimum nitrogen fertilizer rate for winter wheat and soil nitrogen fractions extracted by electroultrafiltration (EUF) from autumn samples of the upper soil layer (0–30 cm). Optimum nitrogen fertilizer rates were derived from grain yield curves of field trials carried out with increasing nitrogen fertilizer rates on 19 different sites in 1985/86 and 1986/87. Most soils were luvisols derived from loess, two soils were brown earths and one a pararendzina. Total Nitrogen fertilizer rates were 0, 40, 80, and 120 kg N/ha applied twice before ear emergence. The final nitrogen rate at ear emergence was the same for all treatments, namely 60 kg N/ha.Optimum nitrogen fertilizer rates were derived from the grain yield curve fitted to a modified Mitscherlich equation. The optimum nitrogen fertilizer rates were correlated with the nitrogen fractions extracted by EUF. The regression equation thus obtained showed that NO ₃ ^- , the organic N fraction (EUF Norg), and the EUF Norg-quotient each had a highly significant impact on the optimum nitrogen fertilizer rate. The higher the amounts of EUF-N extracted the lower the optimum nitrogen rate. Substituting the EUF Norg-fraction for total nitrogen concentration in the upper soil layer gave a poorer relationship between the optimum nitrogen fertilizer rate and the soil data. In absolute terms the EUF Norg-fraction had by far the greatest impact on calculating the optimum nitrogen fertilizer rate. The investigation shows that the EUF method is a suitable technique for the determination of available soil nitrogen from which optimum nitrogen fertilizer rates can be derived for winter wheat cultivated under soil and climatic conditions typical for cereal growing areas in central Europe.     

The use of excess activated sludge from municipal sewage treatment works in production of construction ceramics

The composition of a ceramic mixture for production of brick using excess activated sludge from municipal sewage treatment works is developed. The properties of the samples obtained meet the requirements imposed on ceramic construction products. Assessment of the environmental safety of the suggested material was carried out and the efficiency of utilization of activated sludge in production of construction materials was demonstrated. Translated from Steklo i Keramika, No. 5, pp. 31 – 34, May, 1998.     

Comparing different methods of analysing sewage sludge, dewatered sewage sludge and sewage sludge ash

The following article compares different ways of characterising sewage sludge. Against the background of sludge recycling in agriculture as well as treatment with subsequent phosphorus recovery in mind, the article starts by collating and evaluating the levels of phosphorus, heavy metals, chlorine and sulphur in sludge as reported in the literature. Sewage sludge from the sewage treatment plant at Kaditz in Dresden was analysed using standardised and adjusted methods, which produced different results. In the course of this analysis the results were produced by using elemental analysis, atomic absorption spectroscopy, X-ray fluorescence spectroscopy (X-RFA) and ion chromatography (IC). The second part of the article therefore seeks reasons for the differences in the findings and tries to give solution statements. The article closes by calculating transfer coefficients for selected parameters during the incineration process and solid-liquid separation and weighing up the analysis techniques compared. Basically this article will show significant differences in sludge composition and the effects on the specific elements by ashing or mechanical dewatering of the different sludges. An essential attention obtains the analysis by using the X-RFA.     

Agricultural use of sewage sludge and its regulation

Sewage sludge is waste for which the most positive outlet must be sought whilst, at the same time, making use of its qualities. In view of its organic matter and other nutrients content, it may be thought that the best system is to use it for agricultural purposes, although the load of heavy metals it may bear with it proves to be the main obstacle involved. Since it is a heterogeneous material whose composition depends on various factors, the content of such metals in sewage sludge will be highly variable. Thus it becomes necessary to always analyze sewage sludge before directing it towards agricultural use and also to know the heavy metal content of the soil where it is applied already so as to adjust this agronomical practice to the limits as set by current legislation in force. The provisions of law must also be complied with when certain substances deemed toxic or dangerous are present in sewage sludge. The purpose of all this is to prevent possible soil pollution and other kinds of risk involved in accumulation in the food chain.     

污泥水热处理过程中氮元素的迁移转化

采用高温高压反应釜在不同温度下进行了污泥水热实验。主要考察污泥中氮元素在水热过程中的迁移转化以及水热温度的影响,并对水热过程中氮元素的迁移路径进行了系统分析。结果表明,氮元素主要分布在固相和液相产物中,并随着水热温度的升高,分布在液相产物中的氮元素逐渐增加。在水热过程中,污泥中的无机氮形态几乎全部转换为氨氮和硝酸盐氮形态;不稳定性蛋白质氮分解为有机氮和氨氮,有机氮可进一步分解为氨氮;而稳定性蛋白质可转变为吡啶氮、吡咯氮、季氮以及腈氮形态,在较高的水热温度下均可再分解为氨氮。因此,随着水热处理温度的升高,污泥中氮元素逐渐从固相中转移到液相中,在液相产物中主要以有机氮和氨氮形态赋存。     

城市污水生物脱氮除磷技术的研究进展

评述了近年来城市污水生物脱氮除磷技术的研究进展,重点介绍了生物处理的新方法:ANAMMOX–SHARON组合法、好氧同步脱氮除磷法和倒置A2/O法,并比较了各种工艺的优缺点。指出反硝化聚磷技术在倒置A2/O工艺中的应用将成为城市污水同步脱氮除磷研究的一个重要发展方向。     

Simulating water and nitrogen behaviour in soils cropped with winter wheat

The SWATNIT model [26], predicting water and nitrogen transport in cropped soils, was evaluated on experimental data of winter wheat for different N treatments. The experiments were monitored at three different locations on different soil types in the Netherlands. Crop growth was simulated using the SUCROS model [11] which was integrated in the SWATNIT model. Both water and nitrogen stress were incorporated. Except for the soil hydraulic properties, all model parameters were taken from literature. The model performance was evaluated on its capability to predict soil moisture profiles, nitrate and ammonia profiles, the time course of simulated total dry matter production and LAI; and crop N-uptake. Results for the simulations of the soil moisture profile indicate that the soil hydraulic properties did not reflect the actual physical behaviour of the soil with respect to soil moisture. Good agreement is found between the measured and simulated nitrate and ammonia profiles. The simulation of the nitrate content of the top layer at Bouwing was improved by increasing the NH ₄ ⁺ -N-distribution coefficient thereby improving the simulation of the NH ₄ ⁺ -N-content in this layer. Deviations between simulated and measured nitrate concentrations also occurred in the bottom layers (60–100 cm) of the soil profile. The phreatic ground water might influence the nitrate concentrations in the bottom layers. Concerning crop growth modelling, improvements are needed with respect to the partitioning of total dry matter production over the different plant organs in function of the stress, the calculation of the nitrogen stress and the total nitrogen uptake of the crop through a better estimate of the N-demand of the different plant organs.     

The effect of fertilizer placement on nitrogen uptake and yield of wheat and maize in Chinese loess soils

Field trials were carried out to study the fate of¹⁵N-labelled urea applied to summer maize and winter wheat in loess soils in Shaanxi Province, north-west China. In the maize experiment, nitrogen was applied at rates of 0 or 210 kg N ha^–1, either as a surface application, mixed uniformly with the top 0.15 m of soil, or placed in holes 0.1 m deep adjacent to each plant and then covered with soil. In the wheat experiment, nitrogen was applied at rates of 0, 75 or 150 kg N ha^–1, either to the surface, or incorporated by mixing with the top 0.15 m, or placed in a band at 0.15 m depth. Measurements were made of crop N uptake, residual fertilizer N and soil mineral N. The total above-ground dry matter yield of maize varied between 7.6 and 11.9 t ha^–1. The crop recovery of fertilizer N following point placement was 25% of that applied, which was higher than that from the surface application (18%) or incorporation by mixing (18%). The total grain yield of wheat varied between 4.3 and 4.7 t ha^–1. In the surface applications, the recovery of fertilizer-derived nitrogen (25%) was considerably lower than that from the mixing treatments and banded placements (33 and 36%). The fertilizer N application rate had a significant effect on grain and total dry matter yield, as well as on total N uptake and grain N contents. The main mechanism for loss of N appeared to be by ammonia volatilization, rather than leaching. High mineral N concentrations remained in the soil at harvest, following both crops, demonstrating a potential for significant reductions in N application rates without associated loss in yield.     

阿维菌素与城市污泥复合对小麦种苗生长的影响

探讨阿维菌素有机肥与城市污泥复合对小麦种苗生长的影响。采用小麦盆栽种植实验,将城市污泥与阿维菌素有机肥复合施入土壤中,对小麦种子萌发和种苗生长的形态指标进行测定。结果表明,45 g土壤中,阿维菌素的用量为5 g,城市污泥与土壤质量比为20%时,复合肥对小麦种苗的生长最好。对城市污泥的合理化利用具有重要意义。     

市政污泥吸附等温线模型和热力学性质

采用静态重量法测定了市政污泥在30℃、40℃、50℃下的吸附等温线,选用11个常见的数学模型对实验数据进行了拟合并对最佳模型进行了解析,通过净等量吸附热q_st、微分熵ΔS、扩散压力π、净积分焓q_in和净积分熵ΔS_in等指标评价污泥的热力学性质。试验结果表明,在温度恒定时,等温曲线属于Ⅱ型,GAB模型拟合效果最佳,能较好地反映平衡含水量随水分活度的变化。应用Clausius-Clapeyron方程,利用等温线模型计算净等量吸附热和微分熵,随着平衡含水率的增加,净等量吸附热和微分熵明显降低,调和平均温度T_hm与等速温度T_l不等,焓-熵补偿理论成立。在一定的水活度下,扩散压力随温度的升高而减小,在温度恒定的情况下,扩张压力随水分活度增大而升高。净积分焓随平衡含水率的增加而减小,而净积分熵在低平衡含水率时随平衡含水率的增加而减小,在30℃、40℃和50℃时分别达到最小值-75.698J/(K?mol)、-78.987J/(K?mol)和-82.687J/(K?mol),然后呈上升趋势。     

中国南方城市污水厂污泥特性研究及处置对策

采用统计概率分布方法,对中国南方地区中小型污水处理厂的污泥特性、产生原因、处理处置现状进行深入分析,并结合欧盟污泥处理处置现状和未来发展趋势,对中国南方地区污泥处理处置技术的未来发展趋势进行预测,给出应对策略。     

污泥掺烧生物质的重金属排放特性研究

针对城市污泥焚烧面临的重金属污染严重等问题,提出了在城市污泥中掺烧生物质解决重金属污染的新方法,并利用5 k W鼓泡流化床进行试验研究,考查城市污泥掺烧生物质过程中重金属的含量和形态分布特性及燃烧飞灰中重金属的浸出毒性。结果表明:城市污泥掺烧生物质使Cd和As的挥发性降低,Pb、Cu和Cr的挥发性增加,对Hg的挥发性影响很小;城市污泥掺烧麦秆对Zn的挥发性影响不大,掺烧棉秆使Zn的挥发性降低;城市污泥掺烧生物质都使飞灰中Pb、As的形态稳定性降低,使Zn的形态稳定性增加,对Cu、Cr的形态稳定性影响较小;污泥掺烧不同生物质对飞灰中重金属浸出量和浸出率的影响不同,棉秆与麦秆相比更有利于降低飞灰中重金属的浸出量和浸出毒性。     

城市污水污泥焚烧二次污染物控制研究进展

介绍了污泥焚烧技术的现状:它是目前国内外研究最多的处理污泥技术之一,其优势在于处理速度快,减量化程度高,能够利用污泥中的热值。阐述了焚烧过程中产生的重金属、二口恶英、氮氧化物、硫氧化物等的排放限制了污泥焚烧技术的推广和应用,因此对污泥焚烧二次污染控制的研究就显得非常重要。表明了研究污泥焚烧后产生的大量灰渣的处理和利用技术也是污泥焚烧研究的一个重要方面。     

钙镁磷肥复式包膜尿素对冬小麦产量和氮肥效率的影响

通过连续 3年 ( 1999～ 2 0 0 0年 )大田试验 ,研究了钙镁磷肥复式包膜尿素对冬小麦产量、氮效率〔包括 :氮素效率比 ( NER) ,氮吸收效率 ( NUp E) ,氮素使用效率 ( NUE)和氮肥利用效率 ( Nf UE)〕的影响。结果表明 ,钙镁磷肥复式包膜尿素与普通尿素的生物量、籽粒和秸秆量均显著大于对照处理 ;氮素使用效率 ( NUE)和氮肥利用率均显著高于对照。包膜尿素处理的产量和氮效率最高 ,其籽粒、秸秆、生物量平均值比普通尿素处理分别高 9.0 9%～15 .0 6 %、13.11%～ 14 .96 %、11.73%～ 14 .99% ,氮肥利用率高 15～ 16个百分点。在本试验条件下 ,相对于通常氮肥施用量 ( 15 0 kg N/hm2 ) ,少量增加氮肥施用量 (氮肥用量增加 8% )对产量和氮效率 ( NE)没有显著影响 ;而大量增加氮肥施用量 (增加 2 0 % ) ,能明显增加小麦产量、吸氮量和氮肥利用率