Tracking nitrogen losses in a greenhouse crop rotation experiment in North China using the EU-Rotate_N simulation model

Vegetable production in China is associated with high inputs of nitrogen, posing a risk of losses to the environment. Organic matter mineralisation is a considerable source of nitrogen (N) which is hard to quantify. In a two-year greenhouse cucumber experiment with different N treatments in North China, non-observed pathways of the N cycle were estimated using the EU-Rotate_N simulation model. EU-Rotate_N was calibrated against crop dry matter and soil moisture data to predict crop N uptake, soil mineral N contents, N mineralisation and N loss. Crop N uptake (Modelling Efficiencies (ME) between 0.80 and 0.92) and soil mineral N contents in different soil layers (ME between 0.24 and 0.74) were satisfactorily simulated by the model for all N treatments except for the traditional N management. The model predicted high N mineralisation rates and N leaching losses, suggesting that previously published estimates of N leaching for these production systems strongly underestimated the mineralisation of N from organic matter.     

Modeling transport and fate of nitrogen from urea applied to a near-trench paddy field

A simple but comprehensive model is developed to quantify N losses from urea applied to a near-trench paddy field, considering all the N-transformations such as urea hydrolysis, volatilization, nitrification, denitrification, and all the important transportations like runoff, lateral seepage, vertical leaching and crop uptake. Seasonal average data of field observations for three crop seasons were used for model calibration and validation, which showed that ammonia volatilization accounted for 26.5-29.4% of the applied N and N uptake by crop occupied 38.2-44.8%, while N losses via surface runoff, vertical leaching and lateral seepage varied from 5.6-7.7%, 4.0-4.9% to 5.0-5.3% of the applied N, respectively. These observed results were well predicted by our model, indicating that the model performed effectively at quantifying N losses via individual processes in a wide range of urea application rates and benefit for developing water and fertilizer management strategies for near-trench paddy fields.     

An integrative analysis of the role of atmospheric deposition and land management practices on nitrogen in the US agricultural sector

Additions of anthropogenic nitrogen (N) compounds constitute one of the major classes of air pollutants of significance to human health and the environment. Reliance on wet deposition measurements alone can lead to considerable underestimates (by 40-60%) of the total (wet + dry) atmospheric N deposition. In addition, wet deposition of N are about 20% of the levels that are lost due to volatilization (primarily ammonia). Nevertheless, in the agricultural sectors of the Mississippi River basins, farm management practices, and recycling of N within cropping systems clearly outweigh the contributions of atmospheric deposition. As opposed to native vegetation and forests, there are no records of the negative effects of atmospheric N deposition on crop yield. Similarly, field studies on the interactions of atmospheric N compounds with the incidence and spread of pathogens does not permit any generalizations. Nitrogen applied as fertilizer affects disease probably more by its effect on the plant growth than by its effects on pathogens. In contrast, atmospheric nitrogen dioxide appears to be a stimulant of aphid performance. Under conditions of heavy weed infestation, N fertilization stimulates weed growth and competitiveness, rather than crop yield.     

Methane and nitrous oxide emissions from an irrigated rice of North India

Upland rice was grown in the kharif season (June-September) under irrigated condition in New Delhi, India (28 degree 40'N and 77 degree 12'E) to monitor CH4 and N2O emission, as influenced by fertilizer urea, ammonium sulphate and potassium nitrate alone (at 120 kg ha-1) and mixed with dicyandiamide (DCD), added at 10% of applied N. The experimental soil was a typic ustochrept (Inceptisol), clay loam, in which rice (Oryza sativa L., var. Pusa-169, duration: 120-125 days) was grown and CH4 and N2O was monitored for 105 days by closed chamber method, starting from the 5 days and 1 day after transplanting, respectively. Methane fluxes had a considerable temporal variation (CV=52-77%) and ranged from 0.05 (ammonium sulphate) to 3.77 mg m-2 h-1 (urea). There was a significant increase in the CH4 emission on the application of fertilizers while addition of DCD with fertilizers reduced emissions. Total CH4 emission (105 days) ranged from 24.5 to 37.2 kg ha-1. Nitrous oxide fluxes were much lower than CH4 fluxes and had ranged from 0.18 to 100.5 g m-2 h-1 with very high temporal variation (CV=69-143%). Total seasonal N2O emission from different treatments ranged from 0.037 to 0.186 kg ha-1 which was a N loss of 0.10-0.12% of applied N. All the fertilizers significantly increased seasonal N2O emission while application of DCD reduced N2O emissions significantly in the range of 10-53%.     

Effects of air quality on foliar injury, growth, yield, and quality of muskmelon

An evaluation of the effects of ambient ozone (O3) on muskmelon was conducted with the use of open-top chambers (OTCs). 'Superstar' muskmelons grown in charcoal-filtered (CF) chambers compared to those grown in nonfiltered (NF) chambers showed significant differences in the severity of visible foliar O3 injury. Furthermore, plants grown in NF conditions had significantly less (21.3%) marketable fruit weight and fewer (20.9%) marketable fruit number than those from CF chambers. No differences were found in early biomass production, leaf area, or number of nodes after 3 weeks of exposure to treatment conditions. Ambient O3 did not affect soluble solids content of mature fresh fruit nor foliage fresh weight at final harvest. Results indicate that ambient concentrations of O3 in southwestern Indiana caused significant foliar injury and yield loss to muskmelons.     

添加氮损失抑制剂对蓝藻泥堆肥质量的影响

对脱水蓝藻进行大型生产性堆肥实验。研究堆肥过程中,氮损失抑制剂过磷酸钙的添加对堆肥物料各类理化性质的影响。研究结果表明,过磷酸钙加入的处理组与未加过磷酸钙的对照组堆制37 d后堆肥物料均可腐熟,且堆肥肥效均符合NY525-2002的相关要求。添加过磷酸钙处理组有机质含量为490 g/kg,全N、全P和全K含量分别为20.75、10.02和11.32 g/kg,总养分含量达到9.77%,堆肥品质明显优于对照处理。同时,在微生物的作用下,对照组中微囊藻毒素MC-RR与微囊藻毒素MC-LR去除率分别达到89.8%与78.3%。值得一提的是,添加过磷酸钙后,MC-RR和MC-LR的去除率得到进一步提高,分别达到了92.96%和100%,较好地保证了蓝藻堆肥农用的安全性,为脱水蓝藻好氧堆肥化提供了可行性依据。     

Growth and lead accumulation by the grasses Vetiveria zizanioides and Thysanolaena maxima in lead-contaminated soil amended with pig manure and fertilizer: a glasshouse study

Bo Ngam lead mine soils contain high concentrations of lead (up 1% total Pb) and low amounts of organic matter and major nutrients (N, P, K). A glasshouse study was conducted to compare growth performance, metal tolerance and metal uptake by two grasses, Thysanolaena maxima (Roxb.) O. Kuntze and four ecotypes of Vetiveria zizanioides (L.) Nash, syn. Chrysopogon zizanioides (L.) Roberty (three from Thailand: Surat Thani, Songkhla and Kamphaeng Phet, and one from Sri Lanka) and to study the effects of pig manure (20% and 40% w/w) and inorganic fertilizer (75 and 150 mg kg(-1)) amendments to this lead mine soil. The results showed that both T. maxima and V. zizanioides (Surat Thani and Songkhla) could tolerate high Pb concentrations in soil (10750 mg kg(-1)) and had very good growth performance. Application of pig manure increased electrical conductivity (EC) and reduced DTPA-extractable Pb concentration in the soils. Pig manure application improved the growth of vetiver, especially at 20%, application dosage. Vetiver had the highest biomass. T. maxima could not tolerate high EC values. The uptake by roots and transport of Pb to shoots of both species was reduced when soils were amended with pig manure. Application of inorganic fertilizer did not improve growth of vetiver but did improve that of T. maxima. Fertilizer application did not have any great influence on the Pb uptake in vetiver while T. maxima took up more Pb as a result of the fertilizer enhancing its biomass yield. Both species transported low Pb concentrations to shoots (8.3-179 mg kg(-1)) and accumulated higher concentrations in roots (107-911 mg kg(-1)). In summary, both species may be species well suited for phytostabilization in tropical lead mine areas.     

Effects of elevated CO2 nitrogen supply and tropospheric ozone on spring wheat. I. Growth and yield

Spring wheat (Triticum aestivum L. cv. Minaret) was exposed to three CO(2) levels, in combination with two nitrogen fertilizer levels and two levels of tropospheric ozone, from sowing to ripening in open-top chambers. Three additional nitrogen fertilizer treatments were carried out at the lowest and the highest CO(2) level, respectively. Plants were harvested at growth stages 31, 65 and 93 and separated into up to eight fractions to gain information about biomass partitioning. CO(2) enrichment (263 microl litre(-1) above ambient levels) drastically increased biomass of organs serving as long-term carbohydrate pools. Peduncle weight increased by 92%, stem weight by 73% and flag leaf sheath weight by 59% at growth stage 65. Average increase in shoot biomass due to CO(2) enrichment amounted to 51% at growth stage 65 and 36% at final harvest. Average yield increase was 34%. Elevated nitrogen application was most effective on biomass of green tissues. Yield was increased by 30% when nitrogen application was increased from 150 to 270 kg N ha(-1). Significant interactions were observed between CO(2) enrichment and nitrogen application. Yield increase due to CO(2) ranged from 23% at 120 kg N to 47% at 330 kg N. Triticum aestivum cv. Minaret was not very responsive to ozone at 1.5 times ambient levels. 1000 grain weight was slightly decreased, which was compensated by an increased number of grains.     

Fate of nitrogen during composting of chicken litter

Chicken litter (a mixture of chicken manure, wood shavings, waste feed, and feathers) was composted in forced-aeration piles to understand the changes and losses of nitrogen (N) during composting. During the composting process, the chemical [different N fractions, organic matter (OM), organic carbon (C), and C:N ratio], physical, and microbial properties of the chicken litter were examined. Cumulative losses and mass balances of N and organic matter were also quantified to determine actual losses during composting. The changes in total N concentration of the chicken litter piles were essentially equal to those of the organic N. The inorganic N concentrations were low, and that organic N was the major nitrogenous constituent. The ammonium (NH(4)(+))-N concentration decreased dramatically during first 35 days of composting. However, the rapid decrease in NH(4)(+)-N during composting did not coincide with a rapid increase in (NO(3)(-)+NO(2)(-))-N concentration. The concentration of (NO(3)(-)+NO(2)(-))-N was very low (<0.5 g kg(-1)) at day 0, and this level remained unchanged during the first 35 days of composting suggesting that N was lost during composting. Losses of N in this composting process were governed mainly by volatilization of ammonia (NH(3)) as the pile temperatures were high and the pH values were above 7. The narrow C:N ratio (<20:1) have also contributed to losses of N in the chicken litter. The OM and total organic C mass decreased with composting time. About 42 kg of the organic C was converted to CO(2). On the other hand, 18 kg was lost during composting. This loss was more than half (59%) of the initial N mass of the piles. Such a finding demonstrates that composting reduced the value of the chicken litter as N fertilizer. However, the composted chicken contained a more humified (stabilized) OM compared with the uncomposted chicken litter, which would enhance its value as a soil conditioner.     

Plant uptake of phosphorus and nitrogen recycled from synthetic source-separated urine

Urine contains about 50 % of the phosphorus (P) and about 90 % of the nitrogen (N) excreted by humans and is therefore an interesting substrate for nutrient recovery. Source-separated urine can be used to precipitate struvite or, through a newly developed technology, nitrified urine fertilizer (NUF). In this study, we prepared ³³P radioisotope- and stable ¹⁵N isotope-labeled synthetic NUF (SNUF) and struvite using synthetic urine and determined P and N uptake by greenhouse-grown ryegrass (Lolium multiflorum var. Gemini) fertilized with these products. The P and N in the urine-based fertilizers were as readily plant-available in a slightly acidic soil as the P and N in reference mineral fertilizers. The ryegrass crop recovered 26 % of P applied with both urine-based fertilizers and 72 and 75 % of N applied as struvite and SNUF, respectively. Thus, NUF and urine-derived struvite are valuable N and P recycling fertilizers.     

Cadmium uptake by tobacco as affected by liming, N form, and year of cultivation

Tobacco is able to accumulate cadmium and reduction of cadmium content can reduce health hazards to smokers. Soil pH and form of N fertilizers are among the factors affecting Cd uptake by tobacco. This hypothesis was tested in an acid soil in northern Greece by a four year field experiment. The variability of Cd uptake by tobacco was attributed to the variation of soil Cd availability as affected by soil pH. Liming with 3000 kg Ca(OH)(2) ha(-1) increased soil pH by 0.8 units and decreased extractable with DTPA soil and leaf Cd by 40% and 35%, respectively. The ammonium fertilizer caused the opposite, but weaker, effects. Liming reduced soil Cd more in the ammonium treatment than in nitrate or combined N treatments. The year of cultivation strongly affected soil and leaf Cd. Four years after tobacco cultivation, soil pH was reduced by 0.5 units, whereas soil and leaf Cd reduction was more than 60% in the limed treatments. Liming affected Cd uptake only in the first three years of cultivation.     

Surface runoff and nitrogen (N) loss in a bamboo (Phyllostachys pubescens) forest under different fertilization regimes

Nitrogen (N) losses from agricultural fields have been extensively studied. In contrast, surface runoff and N losses have rarely been considered for bamboo forests that are widespread in regions such as southern China. The thriving of bamboo industries has led to increasing fertilizer use in bamboo forests. In this study, we evaluated surface runoff and N losses in runoff following different fertilization treatments under field conditions in a bamboo (Phyllostachys pubescens) forest in the catchment of Lake Taihu in Jiangsu, China. Under three different fertilization regimes, i.e., control, site-specific nutrient management (SSNM), and farmer's fertilization practice (FFP), the water runoff rate amounted to 356, 361, and 342 m³?ha^?1 and accounted for 1.91, 1.98, and 1.85 % of the water input, respectively, from June 2009 to May 2010. The total N losses via surface runoff ranged from 1.2 to 1.8 kg?ha^?1. Compared with FFP, the SSNM treatment reduced total nitrogen (TN) and dissolved nitrogen (DN) losses by 31 and 34 %, respectively. The results also showed that variations in N losses depended mainly on runoff fluxes, not N concentrations. Runoff samples collected from all treatments throughout the year showed TN concentrations greater than 0.35 mg?L^?1, with the mean TN concentration in the runoff from the FFP treatment reaching 8.97 mg?L^?1. The loss of NO₃ ^?–N was greater than the loss of NH₄ ⁺–N. The total loss of dissolved organic nitrogen (DON) reached 23–41 % of the corresponding DN. Therefore, DON is likely the main N species in runoff from bamboo forests and should be emphasized in the assessment and management of N losses in bamboo forest.     

黄浦江上游蔬菜田氮素流失规律测坑研究

通过测坑试验,研究了黄浦江上游蔬菜田渗漏水中氮素的变化动态和流失规律。结果表明,蔬菜田渗漏水中氮素以NO3^--N为主,NO3^--N作为氮素在土壤中流失的主要形态将成为施用氮肥造成地下水污染的重要来源;施用精制有机肥或粗猪粪代替部分化学氮肥有利于减少蔬菜田渗漏水中氮素的流失。     

Influence of activated charcoal amendment to contaminated soil on dieldrin and nutrient uptake by cucumbers

Activated charcoal (AC) amendments have been suggested as a promising, cost-effective method to immobilize organic contaminants in soil. We performed pot experiments over two years with cucumber (Cucumis sativus L.) grown in agricultural soil with 0.07 mg kg^?1 of weathered dieldrin and 0, 200, 400, and 800 mg AC per kg soil. Dieldrin fresh weight concentrations in cucumber fruits were significantly reduced from 0.012 to an average of 0.004 mg kg^?1, and total uptake from 2 to 1 μg in the 800 mg kg^?1 AC treatment compared to the untreated soil. The treatment effects differed considerably between the two years, due to different meteorological conditions. AC soil treatments did neither affect the availability of nutrients to the cucumber plants nor their yield (total fruit wet weight per pot). Thus, some important prerequisites for the successful application of AC amendments to immobilize organic pollutants in agricultural soils can be considered fulfilled.     

A nitrogen budget of the Changjiang river catchment

Based on 1997-1998 field investigations in the Changjiang river mouth, rain sampling from the river's upper reaches to the mouth, historical data, and relevant literature, the various sources of Total Nitrogen (TN) and Dissolved Inorganic Nitrogen (DIN) in the Changjiang river catchment and N transport in the Changjiang river mouth were estimated. The export fluxes of various form of N were mainly controlled by the river runoff, and the export fluxes of NO3-N, DIN and TN in 1998 (an especially heavy flood year) were 1438 10(3) tonnes (t) yr(-1) or 795.1 kg km(-2) yr(-1), 1746 10(3) t yr(-1) or 965.4 kg km(-2) yr(-1) and 2849 10(3) t yr(-1) or 1575.3 kg km(-2) yr(-1), respectively. The TN and DIN in the Changjiang river came mainly from precipitation, agricultural nonpoint sources, N lost from fertilizer and soil, and point sources of industrial waste and residential sewage discharge, which were about 56.2% and 62.3%, 15.4% and 18.5%, 17.1% and 14.4%, respectively, of the N outflow at the Changjiang river mouth; maximum transport being in the middle reaches.     

The European nitrogen case

The N budget for Europe (excluding the former Soviet Union) indicates that the 3 principal driving forces of the acceleration of the European N cycle are fertilizer production (14 Mt (mill. tonnes) N yr-1), fossil fuel combustion and other industry (3.3 Mt N yr-1) and import of N in various products (7.6 Mt N yr-1). The various leaks of reactive N species from European food, energy and industrial production systems are estimated and their effects on human health and terrestrial and aquatic ecosystems are assessed. Future European environmental policy measures to close the N cycle and to reduce leaks of reactive N can best focus on the three major driving forces, taking into consideration the possible consequences in the N cascade. Critical loads may be useful tools in determining N-emission ceilings and developing integrated policies for regulating N flows such as fertilizer use and imports and N levels.     

Assessing the impact of Cross Compliance measures on nitrogen fluxes from European farmlands with DNDC-EUROPE

We investigated the effects of the agricultural Cross Compliance measures for European cultivated lands, focusing on nitrogen (N) fluxes from corn fields. Four scenarios have been designed according to some conservation farming practices, namely no-till, max manure, catch crop and N splitting. Results indicated that (1) in the no-till scenario the N₂O fluxes are decreased during the first simulated years, with a return to default fluxes in following years; no-till particularly decreased N₂O emission in the dryer and colder simulation spatial units (HSMUs); (2) the no-till and the N splitting scenarios slightly increased the N surplus because of a decrease in plant uptake; (3) introducing a rotation with alfalfa decreased the N leaching in the corn crops following the catch crops; and (4) the application of fertilizer and manure during the cold and wet seasons led to an increase of N leaching.     

Use of precision agriculture technology to investigate spatial variability in nitrogen yields in cut grassland

Spatial variability in N uptake and utilisation by swards within uniformly managed field units could be responsible for a significant proportion of the NH3, N2O, NO3- and NOx (NO and NO2) 'pollutants' generated by agriculture and released to the environment. An investigation was commenced, therefore, to quantify, map and explain the spatial variability in sward N yield in a 'large' silage field and to assess the potential for managing this variability using some of the latest precision agriculture technology. Sward dry matter (DM) and N yields were predicted from the results of plant tissue analyses using mathematical models. Sward N yields were found to vary greatly across the field seemingly because of differences in net soil N mineralisation, but the pattern of variability appeared to remain constant with time. Conventional soil analysis of a range of soil chemical and physical properties, however, failed to explain this variability. It was concluded that the N-yield distribution map might be used in place of soil analysis as the basis for varying the rates of N application to different parts of the field with the twin objectives of maximising fertiliser use efficiency and minimising N emissions to air and water.     

The influence of organic amendment and nickel pollution on tomato fruit yield and quality

The effects of organic fertilization (sludge application) and/or different levels of Ni pollution on tomato fruit yield, quality, nutrition, and Ni accumulation were investigated. The mass loading of sewage sludge solids used in this study for the amendment of a calcareous soil with low organic matter content was 2% (w/w). A control with no sewage sludge amendment was also included (S). Nickel was added to the sludge amended soil at 0, 60, 120 and 240 mg kg-1 concentrations. Sewage sludge addition to the calcareous soil significantly increased fruit yield but did not adversely affect the quality and nutritional status of the tomato fruit. The results demonstrated that sewage sludge could be successfully used as a horticultural fertilizer. Only the highest addition rate of Ni (240 mg kg-1) to an organic amended calcareous soil had negative effects on fruit yield and quality, and caused a Ni accumulation in fruit that could be considered as a hazard for human health. Thus, no toxic problems will be encountered in tomato fruit due to Ni pollution provided the total Ni (soil Ni plus Ni incorporated with sludge amendment) concentration is kept below the maximum concentration of Ni allowed for agricultural alkaline soils in Spain (112 mg Ni kg-1).     

Responses of bean (Phaseolus vulgaris L. cv. Pros) to chronic ozone exposure at two levels of atmospheric ammonia

Plants of bean (Phaseolus vulgaris cv. Pros) were exposed to a range of O3 concentrations up to 70 nl litre(-1) for 9 h day(-1) in the presence (45 nl litre(-1)) and absence (21 nl litre(-1)) of enhanced NH3 in 12 open-top chambers. Treatment effects on visible injury, growth and yield were assessed after 49 (intermediate harvest) and 62 days of exposure (final harvest). The proportion of leaves with visible injury at final harvest increased with increasing concentrations of O3. Enhanced NH3 did not cause any symptoms and did not affect injury by O3. The estimated seasonal mean concentration corresponding with 5% injury was circa 23 nl litre(-1) O3. Biomass production and green pod yield decreased with increasing concentrations of O3 and were generally stimulated by enhanced NH3 at both harvests. Adverse effects of O3 on biomass and pod yield did not depend on the NH3 level. Relative yield response to increasing 9-h daily mean O3 concentrations was nonlinear and yield losses of 5 and 10% were calculated to occur at seasonal daytime mean concentrations of 27 and 33 nl litre(-1) O3, respectively. Linear regression showed that the Accumulated exposures Over a Threshold of 30 (AOT30) and 40 nl litre(-1) (AOT40) O3 performed equally well. The estimated accumulated O3 exposures corresponding with a yield loss of 5% were 1600 nl litre(-1) h for AOT30 and 400 nl litre(-1) h for AOT40. The results are discussed in relation to the long-term critical level that is used as a guideline to protect crops against adverse effects by O3.