不同芹菜浮床对富营养化水体净化效果研究

采用EVA地板垫和陶粒为浮床载体种植芹菜,研究芹菜在富营养化水体的生长状况及芹菜浮床对水体营养物质的净化效果.结果表明,2种浮床种植方式下芹菜的成活率均为100％.陶粒浮床上生长的芹菜与EVA浮床上生长的芹菜相比,根冠比和含水率分别降低了26.32％和0.91％,而含氮率和含磷率提高了18.35％和22.92％,芹菜生长状态更佳.芹菜-EVA浮床和芹菜-陶粒浮床系统对富营养化水体中的氮磷有较好的净化效果,其中TN、NH4+-N和NO3-N的去除率分别达到73.88％和86.82％、94.07％和95.27％、95％和94.34％;TP的去除率分别达到89.46％和94.56％.种植芹菜的浮床载体选用陶粒可以改善芹菜的生长品质和提高净化效果.因此,芹菜和陶粒可以作为栽培植物和浮床载体在植物浮床技术应用中推广.     

立体式生态浮床中植物在水体净化中的效果分析

分析了水污染处理技术中生态浮床的重要作用,简单对立体式生态浮床进行说明,从立体式生态浮床去除富营养物质的原理及效果得出,立体式生态浮床中植物组合的重要性。通过分析多个实验结果,对比得出水体去除效果较好的优势植株,也从多角度说明了植物选取的方法及注意事项。     

生态浮床在治理污染水体中的应用

由于人类的活动使得河流和湖泊的水体水质日益恶化,生态浮床技术已被用于水体的污染治理和生态修复。介绍了生态浮床含义、分类、构造、工作机理、影响因素及其在污染水体治理中的应用,并指出生态浮床技术在我国污染水体治理中有广泛的应用前景。     

生态浮床的应用现状及前景

探讨了人工生态浮床的净化水质的机理,传统生态浮床和组合式生态浮床的特点,生态浮床因其具有不占用耕地、区域美化效果好、经济价值突出和修复作用持久等优点而被广泛采用。总结了人工浮床在富营养化水体中的净化效果、人工浮床中植物选择、人工填料引入强化水体净化效果和其他方面的应用现状。同时指出了人工浮床技术在资源化方面的研究、人工浮床技术领域的基质研究和生态浮床模型的研究3个方面的应用前景。可以为生态浮床的发展和应用研究提供一定的参考。     

人工浮床及其在污染水体治理中应用进展

对人工浮床的分类、构造及其工作原理进行了介绍,并对人工浮床在我国污染水体治理中的应用情况进行了概述.     

生态浮床的应用及进展

生态浮床作为一种新型富营养化水体修复技术,因具有可操作性强、运行成本低、易维护、生态风险小、景观效果好等优点,已得到广泛研究和应用。但影响该技术的因素也较多,主要包括温度、浮床水生植物选型、水体污染程度等。目前该技术仍然存在一些亟需解决的问题,如被修复水体对浮床植物的选型要求、浮床植物的回收处理、浮床载体的选择等。     

组合型生态浮床处理富营养化景观水体研究

为探索高效处理富营养化景观水体的生态浮床,本文用再力花和沸石组建成组合型生态浮床,研究其对富营养化景观水体的净化效果。结果表明,该组合型生态浮床对化学需氧量(COD)、总氮(TN)、氨氮(NH_4~+-N)和总磷(TP)的去除率分别达到82.04%、80.74%、85.51%和85.07%,均明显高于基质对照组和植物对照组。组合型生态浮床中的水体细菌繁殖速度及植物的生物量明显优于植物对照组,可见在组合型生态浮床中,沸石对植物的生长及微生物的生长繁殖具有较好的促进作用。再力花根系吸收、沸石吸附及微生物的分解吸收三者协同作用,对污染物的去除效果要优于单一系统。该研究结果对治理富营养化景观水体具有一定的现实指导意义。     

不同组合复合浮床对微污染水体的修复研究

研究了以竹制填料和美人蕉构建的复合生态浮床在不同空间组合方式与曝气方式下对微污染水体的净化效果.结果表明,在水力停留时间为12h和气水体积比3∶1环境下,填料和浮床3种组合方式对微污染水体的污染物有良好的净化效果,组间差异显著.上部浮床下部填料的组合方式对浊度的平均去除率为84％,氨氮平均去除率为63％,明显高于其它2种组合方式;而对于COD和总磷的去除效果方面,前端填料后端浮床,且曝气集中在填料端的组合方式较另外两种组合方式有明显的优势,平均去除率分别为46％和50％.     

生态浮床对富营养化水体修复作用的研究

为了验证生态浮床对富营养化水体的修复能力,构建了两个容积各8.28m3的模拟水池,其中一池中放入面积为4m2的浮床,另一池为空白对照,两池中同样放入2.7m3的富营养化河水。比较两池在静态状况下和三种不同水力停留时间下对CODMn、TN和TP三个水质指标的去除效率。实验结果表明：浮床对CODMn、TN和TP均具有明显的去除效果,在静态期浮床池对CODMn、TN和TP的净去除率分别达到了16.9%、50.3%和50%。在动态实验中,随着水力停留时间的缩短,去除率有所降低,但当水力停留时间为最短的4.5d时,浮床对CODMn、TN、TP的净去除率仍达到了9.4%、39.8%和36.6%,达到了国家规定的地表水Ⅲ类水质要求。由此可知,水体富营养化现象通过生态浮床的净化明显能够得到改善。     

多级人工生态系统净化景观水体的研究

以景观水体为处理对象,构建了植物浮床生态箱-植物浮床生态箱-人工湿地-沉水植物生态箱多级人工生态系统,在系统中引入了多种植物、鱼类、螺蛳、虾等物种,且该系统在循环流方式下运行,系统的平均水力停留时间为2d,模拟景现水体4．2d被系统交换一次。试验结果表明,系统迭到稳定运行之后,景观水体池中,     

Are Partial Nutrient Balances Suitable to Evaluate Nutrient Sustainability of Land use Systems? Results from a Case Study in Central Sulawesi,Indonesia

Nutrient input–output balances are often used as indicators for the sustainability of land use systems. In a case study on plot scale in Central Sulawesi, Indonesia, we measured nutrient input–output balances of natural rainforest and two unfertilized land use systems (maize, and coffee/cacao agroforestry). These are the two major land use systems on converted rainforest sites in this part of Sulawesi. We wanted to test if (a) plant nutrient balances are negative, (b) which pathway is most important for losses of plant nutrients, and (c) if partial plant nutrient balances are suitable to evaluate sustainability of the land use systems. We measured nutrient inputs by precipitation and nutrient outputs by harvest export and leaching. We selected two locations, the first was situated on a fertile Cambisol developed on alluvial sediment soil, and the second on a less fertile Cambisol developed on weathered phyllite substrate. Nutrient losses through leaching were higher on sites with higher soil fertility. Nutrient balances in natural forest on fertile soils were negative for N, Ca, K and Mg. Inputs of P by precipitation and outputs by leaching were below detection limit. On less fertile soils, leaching of N and K in natural forest was lower than inputs by precipitation. As net nutrient losses were highest in agroforestry, followed by maize and natural forest stands, forest conversion into agricultural land will result in increased nutrient losses. Main output pathway of N, P and K was harvest, whereas main output pathway for Ca and Mg was through leaching. The annual losses of nutrients we measured were higher than in comparable studies on nutrient poor soils; however losses were only small fractions of available nutrient stocks. Our results showed negative partial nutrient balances in both agricultural systems. Nutrient balances in this study were more influenced by native soil fertility than by land use. Because we found indirect evidence that some nutrient pathways, which were not measured, may have significantly changed the overall balance (biological N fixation, weathering), we conclude that partial nutrient balances are no good indicators for sustainability of land use systems.     

Nutrient uptake of iron,zinc, magnesium,and copper in transgenic maize (<Emphasis Type="Italic">Zea mays</Emphasis>) as affected by rotation systems and N application rates

Understanding the interaction of macro- and micronutrients is a prerequisite to targeting nutrient balance in crop production. A 3-year field study was conducted to determine mineral nutrient uptake of maize hybrids with N fertilizer application under different rotation systems. The experiment was arranged in a split-plot design with rotation [maize-alfalfa (MA), maize-soybean (MS), and continuous maize (MM)] by N rate (0, 50, 100 and 150 kg N ha^?1) as the mainplot and hybrid as the subplot. Two additional treatments (200 and 250 kg N ha^?1) were tested in MM. Maize plant total Mg, Zn, and Cu content were in the order: MA?>?MS?>?MM. Plant Fe uptake was the lowest in MA and not affected by N input. The increased Cu uptake with increasing N rates indicated the synergism of these two nutrients, whereas dilution effects of N application on stover Zn and Mg concentrations were recorded. Rotation systems and N rates interactively affected nutrient harvest index and internal efficiency of Zn, Mg, Fe, and Cu. Relationships of plant N with Cu and Mg concentrations, and N with Zn, Mg, and Cu content at the V6 stage were established, but they were not necessarily preserved at maturity due to the progressive synergistic and dilution effects. The findings of nutrient uptake of Cu, Zn, Mg and Fe and their relationships with N nutrition in maize with stacked transgenic traits are important for developing best management practices to achieve concurrent improvements in nutrient use efficiency and crop productivity.     

Decomposition of organic amendment and nutrient release under the zai technique in the Sahel

In the West African Sahel, farmers use the zai technique to reclaim degraded cropland. Although the nutrients released by the decomposition of the amendments are central to the success of the technique, little is known regarding the impact of the zai pits on the decomposition process and whether the nutrient release is synchronized with plant requirements. The decomposition of millet stalks and cattle manure applied in zai pits or at the soil surface was studied in Niger using litterbags, under controlled irrigation on-station in 1999 and on-farm in 1999 and 2000 at two locations (Damari and Kakassi) with contrasting soils. In addition, a satellite trial was conducted in 2000 on-farm at the same locations to study the relative contribution of termites to manure decomposition. Only at Damari did termite presence enhance manure decomposition, by a factor three for surface placement compared to the zai pits. At Damari, zai pits enhanced the decomposition when termite activity was suppressed. Whereas manure decomposition proceeded two to three times faster than that of millet stalks at Damari, the type of amendment had no effect on decomposition rate at Kakassi. Nutrient release followed the trend of organic amendment decomposition except for K. When applied prior to the rainy season, nutrient release rate of organic amendments strongly exceeded plant nutrient uptake, which could lead to important leaching losses during the first 4–6 weeks after sowing, especially for N and to a lesser extent for K. However, at harvest, total nutrient absorption by plants was generally higher than the total amount released. The results indicate a highly site-specific response of amendment decomposition to zai and the need for a better timing of amendment application to reduce potential leaching losses, possibly through a split application.     

Estimation of phosphorus and potassium concentrations in Bermudagrass

Equations were developed to estimate concentrations of phosphorus and potassium for Coastal bermudagrass [Cynodon dactylon, (L.) Pers.] as related to applied nutrient level and harvest interval. Data from several field studies were used in the analysis. Estimates from these agronomic studies agreed with data from fertilizer and waste application for several locations. Concentrations of phosphorus and potassium decreased linearly with harvest interval (up to 6 weeks) and increased exponentially with nutrient level. This information should be relevant to crop production and environmental quality.     

Fertilization response and nutrient diagnosis in peach palm (Bactris gasipaes): a review

Peach palm (Bactris gasipaes Kunth) is a relatively new food crop with great potential for the humid tropics. Native to tropical America, it is commercially grown to produce hearts-of-palm and, to a lesser extent, an edible fruit. Peach palm is well adapted to nutrient poor, acid soils, and is cultivated in Brazil and Costa Rica on highly weathered soils with low pH, high aluminum saturation and, often, low organic matter content. Fertilization trials on peach palm have shown significant responses to applied nitrogen while the response to other nutrients such as phosphorus has been less frequent. Additional research, however, is necessary to determine soil and foliar nutrient critical levels and to address questions concerning peach palm growth responses to nutrient additions varying in time and space. Recycled nutrients likely contribute significantly to peach palm nutrition because plant residues are produced in considerable amounts and can decompose rapidly in commercial peach palm plantation in humid environments where cut leaves and stems are left in the field following harvest. On the other hand, nutrient exports from the system are relatively small (e.g., 4.8–6.4 kg P ha^-1yr^-1, 28–32.3 kg N ha^-1 yr^-1, 31–45.2 kg K ha^-1 yr^-1). As for most perennial tree crops, diagnosis of nutrient deficiencies in peach palm is less clear than in annual crops because of factors such as nutrient cycling, internal retranslocation, stand age, foliage age and position within the crown, and seasonal and climatic variations. Some studies on peach palm have examined variation in nutrient content within leaves and plants, and among plants as well, but the sensitivity of different plant tissues to reflect changes in nutrient uptake and response to nutrient additions should be investigated in controlled field experiments.     

Farm‐scale assessment of maize–pigeonpea productivity in Northern Tanzania

Little is known about productivity of smallholder maize–pigeonpea intercropping systems in sub-Saharan Africa. We conducted a survey of 277 farm households in Northern Tanzania to assess socio-economic factors, field management characteristics, and their association with productivity of maize–pigeonpea intercrops. On each farm, crop assessments were focused on a field that the farmer identified as most important for food supply. Variables associated with yields were evaluated using linear regression and regression classification. Biomass production ranged between 1.0 and 16.6 for maize, and between 0.2 and 11.9 t ha^?1 for pigeonpea (at maize harvest). The corresponding grain yields ranged between 0.1 and 9.5 for maize, and between 0.1 and 2.1 t ha^?1 for pigeonpea. Plant density at harvest, number of years the field had been cultivated, slope, weeding, soil fertility class, fertiliser and manure use were significantly associated with variation in maize grain yield, with interactions among the factors. Fields on flat and gentle slopes with plant density above 24,000 ha^?1 had 28% extra yields when fertiliser was applied, while less than 24,000 plants ha^?1 yielded 16% extra yield when manure was applied. Plant density at harvest was the key factor associated with pigeonpea yield; fields with densities above 24,000 plants ha^?1 yielded an average of 1.4 t ha^?1, while less than 24,000 plants ha^?1 yielded 0.5 t ha^?1. We conclude that performance of intercrops can be enhanced through application of organic and inorganic nutrient sources, and agronomic interventions including weeding, implementing soil conservation measures on steep slopes and optimising plant density.

     

Silicon Affects Nutrient Content and Ratios of Wetland Plants

Purpose

The main objective of this study is to enhance our knowledge about the interplay between the plant Si content and the plant nutrient content as well as the nutrient stoichiometry for a broad range of submerged and emergent wetland plants.

Methods

We investigated the carbon, nitrogen, phosphorus and silicon content of 16 species (10 submerged and 6 emergent) along a transect within the Biebrza river (Poland) at 10 locations for the years 2006 and 2007. In addition, the relationships between silicon and carbon, nitrogen and phosphorus content as well as the calculated nutrient ratios (C/N, C/P and N/P) were analyzed.

Results

We found evidence for a significant relation of Si to major nutrients carbon and nitrogen (negative correlation) and phosphorus (positive correlation) within wetland plants. Our results show that especially submerged plants are able to substitute carbon compounds in a significant share by silicon compounds. Nitrogen however is partially substituted by Si for emergent plants. This change in plant nutrient content in turn alters the nutrient stoichiometry of C : N : P.

Conclusion

Our data is the first showing a possible important effect of plant Si content on plant nutrition and nutrient cycling in wetlands. Plant Si has to be considered in plant ecology, physiology and biogeochemistry of wetland plants, because of its effects on the plant nutrient state. Furthermore, Si may also possibly affect the carbon and nutrient turnover via altered plant nutrient content and subsequently via litter decomposition.

     

Effects of organic wastes digestion for biogas production on mineral nutrient availability of biogas effluents

Organic farming systems are characterized by the strong regulation of the import of nutrients into the farming system to replace nutrient losses via sold products. In the present study mineral nutrient flows and balances of P, K and magnesium (Mg) were analysed for a mixed organic cropping system with dairy husbandry and for a stockless organic farming system. Also the influence of biogas digestion of farmyard residues (stable wastes, crop residues, etc.) as well as the effect of the import of substrates for biogas digestion on plant mineral nutrient uptake and farmgate nutrient balances was analysed. The objectives of the current study were; (1) to study the effects of anaerobic digestion of cattle manure and crop residues on plant mineral nutrient uptake; and (2) to model nutrient flows and balances related to the input of different kind of substrates for biogas digestion at the farmgate. Results indicated that slurry digestion did not influence plant P and K uptake. Import of single allowed substrates for digestion would lead to large imbalances in nutrient inputs compared to withdrawals. Most of the suited substrates for biogas digestion were associated with large K surpluses and insufficient P returns in comparison to mineral nutrient outputs via sold animal and plant products.     

"绿生源"高效植物营养液的研制及其应用

通过对蔬菜和花卉的试验表明,“绿生源”高效植物营养液对促进作物生长发育、增强光合作用、提高植株的抗逆性等方面,均有明显作用。