Groundwater nitrate in Austria: a case study in Tullnerfeld

Contamination of groundwater from point and non-point sources is one of the major pollution problems. The agricultural community has become keenly aware of the impact of irrigation and fertilization on groundwater quality. In the plains of Austria groundwater is used as a major source of drinking water. In the last few decades nitrate concentrations in groundwater have increased dramatically. Among the various land uses, agriculture is reported to be the main source of groundwater contamination by nitrate. The study presented here was carried out at Tullnerfeld where nitrate levels in groundwater have been reported to be as high as 100 mg l^–1. To assess the contribution of various land uses to nitrate in groundwater, the Institute for Hydraulics and Rural Water-Management has installed facilities for measuring nitrate leaching and percolation under different cropping and management systems. The nitrate from fertilizers was measured using six lysimeters once a week. At the same time the nitrate levels in groundwater were simulated using the physically based model Environmental Policy Integrated Climate (EPIC). This paper gives a brief account of groundwater nitrate in Austria. The case study presented in this paper deals with the qualitative and quantitative aspects of groundwater nitrate by fertilizers and cover crops.     

Determination of nitrogen reduction levels necessary to reach groundwater quality targets in large river basins: the Weser basin case study,Germany

We used the interdisciplinary model network REGFLUD to predict the actual mean nitrate concentration in percolation water at the scale of the Weser river basin (Germany) using an area—differentiated (100 m × 100 m) approach. REGFLUD combines the agro-economic model RAUMIS for estimating nitrogen surpluses and the hydrological models GROWA/DENUZ for assessing the nitrate leaching from the soil. The areas showing predicted nitrate concentrations in percolation water above the EU groundwater quality standard of 50 mg NO₃/l, have been identified as priority areas for implementing nitrogen reduction measures. For these “hot spot” areas a backward modelling approach was used to quantify the maximal permissible nitrogen surplus levels in agriculture to guarantee a mean long-term nitrate concentration in percolation water below 50 mg NO₃/l. Research work will directly support the implementation of the EU-Water Framework Directive in the Weser basin, e.g. by using the maximal permissible nitrogen surplus levels as a framework for the derivation of regionally adapted and hence effective nitrogen reduction measures.     

含硝态氮的国产化肥少了

我国生产的氮肥数量巨大,但含硝态氮的化肥所占比例很小,这不利于化肥的合理施用.铵态氮和硝态氮作为植物的氮源,两者基本上是等效的,要根据作物和土壤条件合理施用.我国应当适当增加含硝态氮化肥的生产.第一,要对硝酸铵进行改性,使之不能再制造炸药;第二,要消除认为用了硝态氮肥就不能生产绿色食品的错误认识.     

Nitrogen inputs in ground and surface waters in the middle Mulde catchment

As the EU Water Framework Directive (WFD) is translated into national legislation, the nitrogen (N) concentration in many rivers will have to be significantly reduced. In order to implement suitable measures, the relevant pathways and input quantities of nitrogen discharge have to be identified. For the Middle Mulde catchment in Saxony, Germany (2,700 km²), a pathway-related model is developed to quantify point and diffuse nitrogen discharges. Calculated N-input via point sources is 2,400 Mg entering the rivers in the study area every year. The main point input representing over 50% of the total is via municipal sewage treatment plants, followed by the industrial direct dischargers and the combined sewer overflows, amounting to approx. 20% (462 Mg and 444 Mg) each. The diffuse nitrogen discharges from the soil zone of the arable land amount to a total of 8,050 Mg per year in the 1980s and 2,815 Mg in the 1990s. The inputs via the groundwater flow make up the main proportion for the 1980s with 5,303 Mg, followed by 1,480 Mg from tile drainage and 1,267 Mg from direct runoff. In the 1990s the nitrogen discharge fell sharply with the considerable fall in the surpluses in the agricultural nitrogen balance after German reunification with 1,934 Mg (groundwater flow), 454 Mg (drainage runoff) and 410 Mg (direct runoff). Sensitivity analyses show that the parameter “total atmospheric deposition” represents the highest uncertainties, because of its uncertain quantification and the high sensitivity of the results to this variable.     

Nitrogen fertilization and nitrate pollution in groundwater in Japan: Present status and measures for sustainable agriculture

During the last two decades, nitrate nitrogen (NO₃-N) concentrations in groundwater in Japan have increased steadily due to the development of intensive agriculture. In some areas, they have reached or even exceeded the unacceptable level for drinking water, 10 mg l^–1. In 2000, the Environment Agency showed that 5.6% (173 of 3,374) tested wells and 4.7% (64 of 1,362) wells used for drinking water exceeded the standard level in 1999. The highest value of NO₃-N in the wells was 100 mg l^–1. Many researches have shown that NO₃-N pollution of groundwater was widely observed in Japan, except the paddy field regions. Farming practices in Kagamigahara city of Gifu prefecture have been typical ones for reducing NO₃-N pollution in groundwater. In the east district of the city, NO₃-N concentration was low in 1966, but reached 27.5 mg l^–1 in June, 1974. The farmers in this district began to reduce the nitrogen fertilizers in carrot cultivation, going from 256 kg N ha^–1 in 1970 to 153 kg N ha^–1 in 1991. The use of controlled release fertilizer increased fertilizer-nitrogen efficiency compared with common compound fertilizer and NO₃-N concentration in the groundwater began to decrease steadily. It was discussed that in order to decrease the NO₃-N pollution of groundwater, it is necessary to refocus not only agricultural technology but also agricultural policy, toward sustainable agriculture and rural development.     

Interaction of ammonium and nitrate nutrition with potassium in wheat

A greenhouse experiment with wheat in 3L pots filled with a sandy loam soil in a factorial design was conducted to determine the effect of potassium on nitrogen utilization. Nitrogen was applied in three NH₄-N/NO₃-N ratios, 0/100, 25/75 and 50/50, at three levels: 0.75, 1.50 and 3.00gN/pot, and potassium was applied at three levels: 0, 0.5 and 1.0gK/pot. The higher levels of nitrate nitrogen with or without potassium reduced dry matter yields drastically, while the same levels of a NH₄-N/NO₃-N mixture of 50/50 with applied potassium reduced yields only slightly. Highest grain yield and total yield were obtained with a 25/75 mixture of ammonium/nitrate nitrogen with added potassium. Potassium addition to soil increased the utilization of nitrogen fertilizers, particularly when the ratio of ammonium to nitrate was increased. The highest uptake of reduced nitrogen was at the highest level of the ammonium to nitrate nitrogen ratio (50/50) when potassium was applied. Tillering was enhanced by an increased ammonium ratio in the nitrogen mixture, and by potassium.     

Field nitrogen budgets and post-harvest soil nitrate as indicators of N leaching to groundwater in a Pacific Northwest dairy grass field

Dairy farms in the U.S. are expected to use farm-field nitrogen (N) budgeting techniques to determine appropriate agronomic manure application rates for crops. As part of nutrient management, post-harvest soil nitrate sampling is often relied upon to indicate the amount of N not used for crop growth during the growing season. A 4–1/2-year study was conducted that quantified the major N inputs, outputs, and residuals (soil and groundwater) at a commercial dairy field overlying a shallow unconfined aquifer in the Pacific Northwest. The purpose of the study was to evaluate the relationships between two indicators, (1) N mass residuals estimated by farm-field N budget and (2) post-harvest soil nitrate residuals, against measured groundwater nitrate-N concentrations following high seasonal recharge. A mass balance mixing-box spreadsheet model that accounts for the hydrogeologic characteristics of the site was used to quantitatively predict the impact of excess farm-field N on underlying shallow groundwater nitrate-N concentrations. Despite intensive sampling of N balance components and post-harvest soil nitrate conditions, the N-budget-predicted groundwater nitrate-N was 37% of the average field-measured early winter groundwater concentration. The post-harvest soil nitrate-predicted groundwater nitrate-N concentration was 140% of that measured in the field. Neither indicator provided a reliable prediction of the groundwater quality response to land application of nutrients using the spreadsheet model in this poorly drained/high water table setting. The mixing-box model provides a basic tool for testing hypothetical nutrient management scenarios in a variety of conditions. However, groundwater nitrate monitoring data are needed to determine actual outcomes.     

我国需增加硝基肥产量,提升硝态氮施肥比例

论述了近年国内外生产和施用的氮肥中所含铵态氮和硝态氮的比例关系。硝态氮肥产量占全球氮肥总产量:世界约14%,欧盟约40%,而我国仅占2%。消费结构比例与产量比例相近。世界最大3家氮肥生产商Yara、Terra和PCS的主要产品为硝铵尿素溶液、硝酸盐等含硝态氮产品,产量和销售量占其氮肥总量的50%以上。加快发展我国硝基肥产业,提高硝态氮肥施用量,对优化我国施肥结构、提高肥料利用率有重要意义。     

铜基材料电催化还原硝酸盐制氨研究进展

人类工农业活动导致环境中硝酸盐浓度升高,利用电催化技术将硝酸盐还原合成氨(NO₃RA)符合“双碳”政策,可达到去除硝酸盐污染和制备氨(NH₃)的双重目的。该文综述了铜(Cu)基材料电催化硝酸盐还原的反应机理,从反应机理角度分析了不同Cu基催化材料优势性能的起源。围绕Cu单原子、单金属Cu、Cu基合金、Cu基氧化物和Cu基金属有机框架材料的大量研究实例,对不同Cu基催化材料催化NO₃RA反应的性能进行归纳总结。通过对Cu基材料催化NO₃RA反应影响因素的分析,针对目前存在的问题展开探讨,以期为未来Cu基催化剂电催化NO₃RA反应的开发与实际应用提供参考。     

提高化肥利用率 发展低碳农业

提高肥料利用率、创新肥料生产技术是发展低碳经济的需要。提高农作物吸收养分能力、测土平衡施肥、开发新型肥料、利用有机废弃资源生产有机肥、加速秸秆应用研究是提高肥料利用率的有效途径,不仅可减轻化肥对环境的污染,而且还可以增强农作物的抗病、抗寒、抗高温的能力,提高农业投入产出比,进而实现农业低碳经济。     

Composting of Disposal Organic Wastes: Resource Recovery for Agricultural Sustainability

One of the major problems of agricultural soils in the tropical regions of the Pacific is the low organic matter content. Because of the hot and humid environment, the soil organic matter (SOM) is minimal due to rapid decomposition. Composted organic material is being applied on agricultural fields as an amendment to provide nutrients and enhance the organic matter content for improving the physical and chemical properties of the cultivated soils. In addition land application of composted material as a fertilizer source effectively disposes of wastes that otherwise are buried in landfills. In our soil program at the University of Guam, we are evaluating the use of organic material as an alternative to synthetic fertilizers. Its goal is to develop management strategies and use available resources for improving crop production while conserving resources and preserving environmental quality. Our case study project is designed to improve soil fertility status by using composted organic wastes and assessing how the nitrogen and other essential nutrients contribute to long-term soil fertility and crop productivity without application of synthetic fertilizers. In our pilot project, compost is produced from wood chips, grinded typhoon debris mixed with animal manure, fish feed, shredded paper and other organic wastes. Mature compost is then applied on the field at the rates of 0, 5, 10 and 20 t/ha as a soil amendment on the eroded cobbly soils of southern Guam. Corn is planted and monitored for growth performance and yield. The effect of land application of composted material on the SOM content and overall soil quality indices are being evaluated in this pilot study.     

Nitrate and phosphorus loss from agricultural land: implications for nonpoint pollution

The impact of agriculture on flood plains and surface water quality has received much attention in temperate countries in recent years. Little attention has been given to loss of nutrients and its impact on the quality of buffer zones and adjacent streams in many tropical environments due to the believe that fertilizer use is still very low compared to temperate countries. This may not be totally true especially in agricultural research stations and University experimental fields where a large amount fertilizers are used continuously for many years. This study was conducted in 2 years (Four seasons) to evaluate the accumulated effect of a long term fertilizer application of an agricultural land on an adjacent stream. Results showed that applied fertilizer significantly contributed to the high levels of nitrate and phosphorus in the stream water. Highest concentration of soil NO₃-N and P were found in 0–15, 15–30 and 30–45 cm soil depths with about 75% reduction in these amounts in the 60–75 cm depth for NO₃-N and 77% reduction at the same depth for soil available phosphorus, the topsoil constituting about 45% of the concentration of the two plant nutrients assessed. There were evident of leaching of basic cations below 15 cm soil depth as indicated in the increased soil pH. There were significantly (P < 0.05) higher soil NO₃-N and P in the dry season relative to the wet season. The long term application of fertilizers to the sandy loam soil significantly contributed to nitrate and phosphate pollution of the stream in excess of the maximum level accepted for potable water. The stream’s pH, temperature, nitrate and phosphate were significantly higher in the dry season. Correlation analyses indicated that agricultural runoffs from the topsoil contributed significantly to the pollution of the stream. There was also positive and significant correlation between the soil nitrate and soil phosphorus at different soil depths, thus indicating that the N and P might have been applied jointly as compound fertilizer and move down the slope through runoff.     

塔式熔体造粒腐植酸长效复合肥料生产技术

针对塔式熔体造粒尿基复合肥料氮含量高,氮素利用率低,采用腐植酸和脲酶抑制剂等研发了一种新型塔式熔体造粒腐植酸长效复合肥料。介绍塔式熔体造粒腐植酸长效复合肥料的原料配方、生产方法、主要技术指标、产品特性。该肥具有提高化学肥料利用率、减轻环境污染、培肥地力、提高农作物产量和提升农产品品质的综合优势,可达到化肥减量增效,绿色环保的要求,值得推广。     

Volatilization of ammonia from urea-ammonium nitrate solutions as influenced by organic and inorganic additives

Fertilizers containing urea can suffer from nitrogen (N) loss through ammonia volatilization, resulting in reduced effectiveness of the fertilizers. The loss of N may be reduced by use of organic or inorganic additives.Laboratory experiments were conducted on surface soil samples (0–15 cm) from two agricultural soils (St. Bernard and Ste. Sophie) to determine the impact of ammonium thiosulfate (ATS), boric acid, and a humic substance from leonardite, on NH₃ losses from surface-applied urea-ammonium nitrate (UAN) solutions. Experiments were carried out using moist soil samples in closed containers. Evolved NH₃ was carried out of the containers and trapped in boric acid solution using an ammonia-free humidified air flow.Total NH₃ losses in these experiments ranged from 12.1 to 21.3% of the N applied. The reduction in NH₃ volatilization (expressed as % of added N) due to additives ranged from 13.6 to 38.5% and 3 to 36.3% in St. Bernard and Ste. Sophie soils, respectively. More NH₃ volatilized from the boric acid or humic treated UAN solutions than from ATS-UAN solutions.Boric acid, ATS, and the humic substance, all significantly reduced urea hydrolysis in both soils in comparison to the untreated UAN solution. Further, the humic substance and boric acid treatment induced significant reduction in NO₃-formation. The results suggest that humic substance and to a lesser extent boric acid may function as urease and/or nitrification inhibitors. ATS treatment, particularly at higher levels increased NO₃-formation in both soils. The reason for this increase in nitrate formation is not clear.     

Source identification of nitrate on Cheju Island, South Korea

Stable isotopes of nitrogen were used to identify sources of nitrate contamination to groundwater on Cheju, a subtropical island off the southernmost tip of the Korean peninsula. The δ¹⁵N ranges of potential animal waste and fertilizer N sources on the island were similar to those previously reported in the USA, Europe, and Africa. A total of 108 soil pore water samples were collected between January and October 1998 from fertilized soils below soybean fields and citrus groves. Low concentrations of nitrate below fertilized soybean fields indicated that it is highly unlikely that these fields contribute significant N to the groundwater problem on Cheju. The low average δ¹⁵N value of +1.9 ± 2.1‰ in pore-water nitrate and the even lower δ¹⁵N values after the fertilizer flush suggest that low levels of mineralized N are released from the bean roots or nodules. Located in the western region, the bean fields received less rainfall than the citrus groves in the southern region. Pore-water below citrus trees contained considerably higher nitrate levels, and the δ¹⁵N values became cyclically enriched after the initial fertilizer flush. Although denitrification can be expected in warm, wet soils high in organic-C content in the southern region of Cheju, it was not supported by pore-water or groundwater chemistry. Isotopic enrichment in soil pore-water is caused primarily by volatilization of ammonium-based fertilizers. Since isotopic fractionation in the soils did not exceed +4‰, source identification was possible. The dominant sources of nitrate contamination to Cheju groundwater were identified as commercial N-fertilizer applications to citrus, and, in the Seogwipo municipality, human or animal wastes.     

Effect of manure quality on nitrate leaching and groundwater pollution in wetland soil under field tomato (Lycopersicon esculentum, Mill var. Heinz) rape (Brassica napus, L var. Giant)

Recent decades have seen an increase in groundwater pollution thought to be a consequence of increasing intensity of land use, primarily through greater use of high N analysis materials as fertilizers. A two-season lysimeter experiment was carried out in a wetland in central Zimbabwe in order to determine the effect of cattle manure quality on (1) NO₃–N concentration in leachate and nitrate leaching (2) dry matter accumulation and uptake of N by tomato and rape crops grown in wetland conditions. Two cattle manure quality types based on N content were used in the experiment. The manure collected from a kraal of the smallholder wetland community was classified as high quality manure (high N, 1.36 % N) while that collected from the adjacent commercial farming area was classified as low quality manure (low N, 0.51 % N). The two manure types were applied in rates of 0, 15, 30 Mg ha^?1. The treatments were arranged in a randomized complete block design with four replicates. When 15 and 30 Mg high and low N manure ha^?1 were applied, the concentration of NO₃–N in leachate exceeded the recommended 10 mg L^?1 concentration in portable water by 15–104 and 53–174 % respectively. The substitution of 15 and 30 Mg of high N manure with 15 and 30 Mg ha^?1 of low N manure reduced total N lost through leaching by 10–43 and 22–69 % respectively. Ground water contamination by nitrate overload can be considerably reduced by application of low N manure to vegetable crops.     

从土壤环境改善和新型肥料研发看食品安全

食品尤其是农产品的安全问题，是我国乃至全世界共同关注的焦点。解决食品安全问题必须从源头抓起。人类食用的大部分食品由农产品转化而来，解决土壤污染、修复土壤生态环境，是解决食品安全重要的源头监控措施。肥料、农药等投入品的合理使用，也是影响食品源头安全的重要因素，新型肥料如腐植酸有机肥料等的研制与开发是保证食品安全的重要措施，具有广阔的市场前景。     

施用氮肥对蔬菜中硝酸盐积累的影响

用硝酸盐快速检测法———改进的镉粉法 ,以小白菜为材料 ,采用田间试验和室外盆栽试验相结合的方法 ,研究了化肥及土壤对蔬菜中硝酸盐含量的影响。结果表明 :蔬菜中硝酸盐的含量依施用氮肥的种类而异 ,磷、钾配施有利于降低NO3 含量 ,且随着土壤中的氮素和有机质含量的增高而增多 ;随着采收期的延长 ,蔬菜中硝酸盐的含量逐渐降低。提出减少蔬菜中硝酸盐含量的有关控制措施 ,为发展无公害蔬菜及绿色食品提供了科学依据     

Alternatives for nitrogen nutrition of crops in tropical agriculture

The development of sustainable agricultural systems for the tropics requires among other technologies, alternatives for nitrogen fertilizers which are often limited in availability for financial reasons and also represent a major source of groundwater and air pollution. There are many new alternatives for the development of agricultural systems which make use of biological processes in soil. Biological nitrogen fixation (BNF), that is, the biological conversion of atmospheric dinitrogen into mineral N, is the most important alternative among them. Examples are given of the impact of various technologies used in Brazil. Soybean, introduced into the country 30 years ago, is now the second most important export crop, reaching 24 million tons annually with no N fertilizer application. Consequently, Brazil today is the country in the world which uses the lowest amounts of nitrogen fertilizers in relation to phosphate. Alternatives for crop rotations and pastures are also discussed. Possibilities of expanding BNF to cereals and other non-legume crops are gaining new credibility due to the identification of endophytic associations with diazotropic bacteria. The definite proof of substantial BNF in sugar cane with N balance and¹⁵N methods in certain genotypes selected under low N fertilizer applications opens up new alternatives for sustainable agriculture and will be the key to viable bio-fuel programmes.