Maize production and nitrous oxide emissions from enhanced efficiency nitrogen fertilizers

Nutrient Cycling in Agroecosystems - Enhanced efficiency nitrogen fertilisers (EENFs) attempt to improve nitrogen use efficiency (NUE) by synchronizing nitrogen (N) supply with crop demand to...     

Reducing nitrous oxide emissions and optimizing nitrogen-use efficiency in dryland crop rotations with different nitrogen rates

Recent interests in improving agricultural production while minimizing environmental footprints emphasized the need for research on management strategies that reduce nitrous oxide (N₂O) emissions and increase nitrogen-use efficiency (NUE) of cropping systems. This study aimed to evaluate N₂O emissions, annualized crop grain yield, emission factor, and yield-scaled- and NUE-scaled N₂O emissions under continuous spring wheat (Triticum aestivum L.) (CW) and spring wheat–pea (Pisum sativum L.) (WP) rotations with four N fertilization rates (0, 50, 100, and 150 kg N ha^?1). The N₂O fluxes peaked immediately after N fertilization, intense precipitation, and snowmelt, which accounted for 75–85% of the total annual flux. Cumulative N₂O flux usually increased with increased N fertilization rate in all crop rotations and years. Annualized crop yield and NUE were greater in WP than CW for 0 kg N ha^?1 in all years, but the trend reversed with 100 kg N ha^?1 in 2013 and 2015. Crop yield maximized at 100 kg N ha^?1, but NUE declined linearly with increased N fertilization rate in all crop rotations and years. As N fertilization rate increased, N fertilizer-scaled N₂O flux decreased, but NUE-scaled N₂O flux increased non-linearly in all years, regardless of crop rotations. The yield-scaled N₂O flux decreased from 0 to 50 kg N ha^?1 and then increased with increased N fertilization rate. Because of non-significant difference of N₂O fluxes between 50 and 100 kg N ha^?1, but increased crop yield, N₂O emissions can be minimized while dryland crop yields and NUE can be optimized with 100 kg N ha^?1, regardless of crop rotations.

     

Process-based modelling of nitrous oxide emissions from different nitrogen sources in mown grassland

The process-based Pasture Simulation Model (PaSim 2.5) has been extended to simulate N₂O production and emission from grassland caused by nitrogen inputs from different sources. The model was used to assess the influence of management on N₂O emissions, such as the effect of shifts in the amount and timing of fertilizer application. Model performance has been tested against season-long field measurements at two different field sites. Simulation results agreed favourably with measured N₂O emission and soil air concentrations, except during an extremely wet period at one site when grass growth was very poor. The results of short-term and long-term simulation runs demonstrated the potential of the model to estimate N₂O emission factors under various conditions. During the first growing season, simulated emissions from organic fertilizers were lower than from synthetic fertilizers because more of the nitrogen was used to build up soil organic matter. The relative difference between the fertilizer types became larger with increasing application rate. The difference between fertilizer types was smaller at steady-state when higher soil organic matter content from repeated application of organic fertilizer over time led to enhanced mineralization and N₂O emissions. The dependence of simulated N₂O emissions on N input was close to linear at low, but non-linear at high fertilization rates. Emission factors calculated from the linear part of the curve suggested that the factors used in the current IPCC method underestimate the long-term effects of changes in fertilizer management. Furthermore the simulations show that N₂O emissions caused by nitrogen inputs from the decomposition of harvest losses and from biological fixation in grassland can be considerable and should not be neglected in national emission inventories. This revised version was published online in August 2006 with corrections to the Cover Date.     

Use of polyolefin-coated fertilizers for increasing fertilizer efficiency and reducing nitrate leaching and nitrous oxide emissions

This paper reviews some of the benefits of polyolefin-coated fertilizers (POCFs) with accurate controlled release properties. They are helpful in developing innovative rice farming systems, such as no-till direct seeded rice with single basal fertilization and transplanting of rice seedlings with single basal fertilization. These new cultivation systems can increase fertilizer efficiency and reduce farming costs. The recovery of basal N can be increased from 22–23% with conventional broadcast application of ammonium sulfate or urea to 79% withco-situs application of polyolefin-coated urea. The no-till rice cultivation of transplanting of rice seedlings with single basal application of POCFs decreased the farming cost by 65% as compared to that of the conventional rice cultivation. Theco-situs application of POCFs containing NPK reduced nitrate leaching and nitrous oxide emissions from cultivated soils with heavy fertilization. Since POCFs have various nutrient composition and release types, a variety of application methods to agricultural and horticultural plants are being developed in Japan.     

Closing the global N2O budget: nitrous oxide emissions through the agricultural nitrogen cycle

In 1995 a working group was assembled at the request of OECD/IPCC/IEA to revise the methodology for N₂O from agriculture for the National Greenhouse Gas Inventories Methodology. The basics of the methodology developed to calculate annual country level nitrous oxide (N₂O) emissions from agricultural soils is presented herein. Three sources of N₂O are distinguished in the new methodology: (i) direct emissions from agricultural soils, (ii) emissions from animal production, and (iii) N₂O emissions indirectly induced by agricultural activities. The methodology is a simple approach which requires only input data that are available from FAO databases. The methodology attempts to relate N₂O emissions to the agricultural nitrogen (N) cycle and to systems into which N is transported once it leaves agricultural systems. These estimates are made with the realization that increased utilization of crop nutrients, including N, will be required to meet rapidly growing needs for food and fiber production in our immediate future. Anthropogenic N input into agricultural systems include N from synthetic fertilizer, animal wastes, increased biological N-fixation, cultivation of mineral and organic soils through enhanced organic matter mineralization, and mineralization of crop residue returned to the field. Nitrous oxide may be emitted directly to the atmosphere in agricultural fields, animal confinements or pastoral systems or be transported from agricultural systems into ground and surface waters through surface runoff. Nitrate leaching and runoff and food consumption by humans and introduction into sewage systems transport the N ultimately into surface water (rivers and oceans) where additional N₂O is produced. Ammonia and oxides of N (NO_x) are also emitted from agricultural systems and may be transported off-site and serve to fertilize other systems which leads to enhanced production of N₂O. Eventually, all N that moves through the soil system will be either terminally sequestered in buried sediments or denitrified in aquatic systems. We estimated global N₂O–N emissions for the year 1989, using midpoint emission factors from our methodology and the FAO data for 1989. Direct emissions from agricultural soils totaled 2.1 Tg N, direct emissions from animal production totaled 2.1 Tg N and indirect emissions resulting from agricultural N input into the atmosphere and aquatic systems totaled 2.1 Tg N₂O–N for an annual total of 6.3 Tg N₂O–N. The N₂O input to the atmosphere from agricultural production as a whole has apparently been previously underestimated. These new estimates suggest that the missing N₂O sources discussed in earlier IPCC reports is likely a biogenic (agricultural) one.     

The measurement of nitrous oxide emissions from sewage systems in Belgium

To quantify the nitrous oxide emissions from waste water, an experimental measurement campaign has been set up; waste water was sampled at the collector tubes entering sewage treatment plants and at the settling tanks in these plants. The gas phase developing in the static head space of the water samples was analysed; gas chromatography by means of electron capture detection was the analytical tool by which the nitrous oxide concentration in batch samples of gas was determined. The methodological analysis was based on the concentration/time curves obtained.The formation of nitrous oxide from the waste water matrices is the result of the microbiological denitrification of the organic substrate present; this could be deduced from the response of the nitrous oxide signal to the addition of NaNO₃, NH₄NO₃ and (NH₄)₂SO₄ to the samples. Application of the Lineweaver-Burk kinetic equation for enzyme-catalysed reactions on our results, combined with the yearly mean nitrate concentration and the seasonal mean waste water temperature, enabled us to deduce emission coefficients for the two types of waste water sampled: raw waste water: (4.3 ± 1.0)µg N₂O/gss, settled waste water: (800 ± 180)µg N₂O/gss, where gss stands for gram suspended solids, a water quality parameter continuously monitored in Belgium.     

Nitrogen leaching and indirect nitrous oxide emissions from fertilized croplands in Zimbabwe

Agricultural efforts to end hunger in Africa are hampered by low fertilizer-use-efficiency exposing applied nutrients to losses. This constitutes economic losses and environmental concerns related to leaching and greenhouse gas emissions. The effects of NH₄NO₃ (0, 60 and 120?kg?N?ha^?1) on N uptake, N-leaching and indirect N₂O emissions were studied during three maize (Zea mays L.) cropping seasons on clay (Chromic luvisol) and sandy loam (Haplic lixisol) soils in Zimbabwe. Leaching was measured using lysimeters, while indirect N₂O emissions were calculated from leached N using the emission factor methodology. Results showed accelerated N-leaching (3?C26?kg?ha^?1?season^?1) and N-uptake (10?C92?kg?ha^?1) with N input. Leached N in groundwater had potential to produce emission increments of 0?C94?g N₂O-N?ha^?1?season^?1 on clay soil, and 5?C133?g N₂O-N?ha^?1?season^?1 on sandy loam soil following the application of NH₄NO₃. In view of this short-term response intensive cropping using relatively high N rate may be more appropriate for maize in areas whose soils and climatic conditions are similar to those investigated in this study, compared with using lower N rates or no N over relatively larger areas to attain a targeted food security level.     

Modeling nitrous oxide emissions from tile-drained winter wheat fields in Central France

Modeling nitrous oxide (N₂O) emissions from agricultural soils is still a challenge due to influences of artificial management practices on the complex interactions between soil factors and microbial activities. The aims of this study were to evaluate the process-based DeNitrification-DeComposition (DNDC, version 9.5) model and modified non-linear empirical Nitrous Oxide Emission (NOE_V2) model with weekly N₂O flux measurements at eight sites cropped with winter wheat across a tile-drained landscape (around 30-km²) in Central France. Adjustments of the model default field capacity and wilting point and the optimum crop production were necessary for DNDC95 to better match soil water content and crop biomass yields, respectively. Multiple effects of varying soil water and nitrate contents on the fraction of N₂O emitted through denitrification were added in NOE_V2. DNDC95 and NOE_V2 successfully predicted background N₂O emissions and fertilizer-induced emission peaks at all sites during the experimental period but overestimated the daily fluxes on the sampling dates by 54 and 25 % on average, respectively. Cumulative emissions were slightly overestimated by DNDC95 (4 %) and underestimated by NOE_V2 (15 %). The differences between evaluations of both models for daily and cumulative emissions indicate that low frequency measurements induced uncertainty in model validation. Nonetheless, our validations for soil water content with daily resolution suggest that DNDC95 well represented the effect of tile drainage on soil hydrology. The model overestimated soil ammonium and nitrate contents mostly due to incorrect nitrogen partitioning when urea ammonium nitrate solution was applied. The performance of the model would be improved if DNDC included the canopy interception and foliar nitrogen uptake when liquid fertilizer was sprayed over the crops.     

Measurement of nitrous oxide emissions from two rice-based cropping systems in China

A field experiment was conducted to investigate the effects of winter management and N fertilization on N₂O emission from a double rice-based cropping system. A rice field was either cropped with milk vetch (plot V) or left fallow (plot F) during the winter between rice crops. The milk vetch was incorporated in situ when the plot was prepared for rice transplanting. Then the plots V and F were divided into two sub-plots, which were then fertilized with 276 kg urea-N ha^–1 (referred to as plot VN and plot FN) or not fertilized (referred to as plot VU and plot FU). N₂O emission was measured periodically during the winter season and double rice growing seasons. The average N₂O flux was 11.0 and 18.1 g N m^–2 h^–1 for plot V and plot F, respectively, during winter season. During the early rice growing period, N₂O emission from plot VN averaged 167 g N m^–2 h^–1, which was eight- to fifteen-fold higher than that from the other three treatments (17.8, 21.0 and 10.8 g N m^–2 h^–1 for plots VU, FN, and FU, respectively). During the late rice growing period, the mean N₂O flux was 14.5, 11.1, 12.1 and 9.9 g N m^–2 h^–1 for plots VN, VU, FN and FU, respectively. The annual N₂O emission rates from green manure-double rice and fallow-double rice cropping systems were 3.6 kg N ha^–1 and 1.3 kg N ha^–1, respectively, with synthetic N fertilizer, and were 0.99 kg N ha^–1 and 1.12 kg N ha^–1, respectively, without synthetic N fertilizer. Generally, both green manure N and synthetic fertilizer N contribute to N₂O emission during double rice season.     

The influence of controlled release fertilisers and the form of applied fertiliser nitrogen on nitrous oxide emissions from an andosol

A laboratory experiment was conducted to determine whether applying controlled release nitrogen fertilisers could reduce nitrous oxide emissions from an andosol maintained at different water contents, compared with applying standard nitrogen fertiliser. The effect of the form of N applied (NH₄-N or NO₃-N) was also investigated. Soil was collected from an arable field and sub-samples were treated with controlled release or standard fertiliser, applied at a rate of 200 g N g^–1 dry soil either as NH₄ ⁺ or NO₃ ^–. The soils were maintained at 40%, 55%, 70% or 85% water filled pore space (WFPS) and incubated at 25 °C for 50 days. Gas samples were collected and analysed every 3–4 days and soil samples were analysed on five occasions during the incubation. Emissions of N₂O were much greater from ammonium sulphate than from calcium nitrate fertiliser, indicating that nitrification was the main source of the N₂O. Emissions at 85% WFPS were greater than at the lower water contents in all treatments. The use of controlled release NH₄-N fertilisers reduced and delayed the maximum peak of emissions, but at 55% and 70% WFPS this did not always result in lower total emissions. Emissions from the controlled release NO₃-N fertiliser were very low, but only significantly lower than from standard NO₃-N fertiliser at water contents below 85% WFPS. The results demonstrate that choosing the appropriate form of fertiliser in relation to expected soil moisture could significantly reduce N₂O emissions. Applying the fertiliser in a controlled-release form could further reduce emissions by reducing the length of time that fertiliser nitrogen is present in the soil and available for nitrification or denitrification.     

Simulation of soil nitrogen, nitrous oxide emissions and mitigation scenarios at 3 European cropland sites using the ECOSSE model

The global warming potential of nitrous oxide (N₂O) and its long atmospheric lifetime mean its presence in the atmosphere is of major concern, and that methods are required to measure and reduce emissions. Large spatial and temporal variations means, however, that simple extrapolation of measured data is inappropriate, and that other methods of quantification are required. Although process-based models have been developed to simulate these emissions, they often require a large amount of input data that is not available at a regional scale, making regional and global emission estimates difficult to achieve. The spatial extent of organic soils means that quantification of emissions from these soil types is also required, but will not be achievable using a process-based model that has not been developed to simulate soil water contents above field capacity or organic soils. The ECOSSE model was developed to overcome these limitations, and with a requirement for only input data that is readily available at a regional scale, it can be used to quantify regional emissions and directly inform land-use change decisions. ECOSSE includes the major processes of nitrogen (N) turnover, with material being exchanged between pools of SOM at rates modified by temperature, soil moisture, soil pH and crop cover. Evaluation of its performance at site-scale is presented to demonstrate its ability to adequately simulate soil N contents and N₂O emissions from cropland soils in Europe. Mitigation scenarios and sensitivity analyses are also presented to demonstrate how ECOSSE can be used to estimate the impact of future climate and land-use change on N₂O emissions.     

Developing a country specific method for estimating nitrous oxide emissions from agricultural soils in Canada

Accurate estimates of nitrous oxide (N₂O) emissions from agricultural soils and management factors that influence emissions are necessary to capture the impact of mitigation measures and carry out life cycle analyses aimed at identifying best practices to reduce greenhouse gas emissions. We propose improvements to a country specific method for estimating N₂O emissions from agricultural soils in Canada based on a compilation of soil N₂O flux data from recent published literature. We provide a framework for the development of empirical models that could be applied in regions where similar data and information on N₂O emissions are available. The method considers spatial elements such as soil texture, topography and climate based on a quantitative empirical relationship between synthetic N-induced soil N₂O emission factor (EF) and growing season precipitation (P) {N₂OEF?=?e^{(0.00558P?7.7)}}. Emission factors vary from less than 0.0025 kg N₂O-N kg N^?1 in semi-arid regions of Canada to greater than 0.025 kg N₂O-N kg N^?1 in humid regions. This approach differentiates soil N₂O EFs based on management factors. Specifically, empirical ratio factors are applied for sources of N of 1.0, 0.84, and 0.28 for synthetic N, animal manure N and crop residue N, respectively. Crop type ratio factors where soil N₂O EFs from applied manure- and synthetic-N on perennial crops are approximately 19% of those on annual crops. This proposed approach improves the accuracy of the dominant factors that modulate N₂O emissions from N application to soils.

     

Methane and nitrous oxide emissions from rice and maize production in diversified rice cropping systems

Nutrient Cycling in Agroecosystems - Traditional irrigated double-rice cropping systems have to cope with reduced water availability due to changes of climate and economic conditions. To quantify...     

Growth,grain yield and nitrogen use efficiency of Mediterranean wheat in soils amended with municipal sewage sludge

The application of sewage sludge (SS) to agricultural land can improve soil fertility and physical properties, and enhance crop production. This field study was conducted for two consecutive growing seasons to investigate the influence of SS application on winter wheat growth, grain yield, N accumulation, translocation and use, and on trace elements concentrations in soil and wheat plants under Mediterranean conditions. Treatments consisted of three rates of SS, i.e. 20, 40, and 60 Mg dry weight ha^?1 year^?1, one rate of inorganic fertilizer (IF, 120 kg N ha^?1 year^?1 plus 80 kg P₂O₅ ha^?1 year^?1), and an unamended control. The application of SS resulted in tall plants with high early dry matter and N accumulation similar to or significantly higher than those obtained with IF. The lowest SS application rate resulted in grain yield similar to that obtained with IF. Nitrogen use efficiency (NUE) in SS treatments was mainly determined by uptake efficiency, which decreased with increasing SS application rate. Values of NUE and biomass production efficiency with the lowest SS rate were similar to those obtained with IF. SS application resulted in increased concentrations of total and DTPA-extractable trace elements in the soil after the first year, but concentrations were much lower than the regulation limits. Concentrations of Cu, Mn and Zn in wheat plants did not exceed those obtained with IF. Overall, SS could be considered for use as a fertilizer in wheat production systems in the area, serving also as an alternative method of SS disposal.     

Soil nitrous oxide emissions under different management practices in the semiarid region of the Argentinian Pampas

The aim of this study was to analyze the influence of different crop sequences (soybean-corn and soybean?Csoybean) and tillage systems (no tillage and reduced tillage) on nitrous oxide (N₂O) soil emissions under field conditions. The experiment was carried out in Manfredi, Córdoba province, Argentina on an Entic Haplustoll and N₂O emissions were measured in the field during a year. N₂O fluxes were low during winter, but in late spring it peaked. For fallow, N-NO₃-content was the most important variable to explain N₂O emissions. For growing period water-filled pores was the main variable explaining N₂O emissions. Nitrogen fertilization of corn crop increased N₂O-N emissions, whereas no significant differences were found due to the tillage system. Measured annual N₂O-N emissions were generally lower than those calculated using the methodology proposed by the Intergovernmental Panel on Climate Change.     

水泥窑协同处置高氮危废对氮氧化物排放的影响

结合窑系统运行情况,研究了水泥窑协同处置高氮固危废对氮氧化物排放的影响。结果表明：废有机溶剂(DMAC)为稳定高氮物料,单独入窑对NO_x排放和CO无明显影响;废有机溶剂(DMAC)与碱性铝灰以及酸性蒸馏残渣混合后,稳定有机氮被分解转化为不稳定氮化物,入窑后氮氧化物显著增加,最高达到197.2 mg/m³。铝灰因含丰富的氮化铝,入窑有利于氮氧化物排放,相较于未处置固危废期间最多降低了25.7 mg/m³。水泥窑氮氧化物含量的高低主要受入窑物料氮化物稳定性及其均化发酵程度的影响,为降低氮氧化物的波动,每坑浆渣调配完成后至少均化发酵1周再使用。     

Spatial and temporal scaling of nitrous oxide emissions from the field to the regional scale in Scotland

Nitrous oxide (N₂O) is a powerful greenhouse gas. As the UK government is committed to reducing greenhouse gas emissions, it is important to know not only how much of these gases are released but also where and when. Targeted measurements of emissions in relation to crop growth cycles, soil wetness and fertiliser applications were used to derive annual emission rates for specific combinations of soil type, land management and fertiliser practices. These annual emission rates were then spatially scaled to derive regional figures through the development of a Geographic Information System (GIS) based model framework. Digital soil and land use maps at a scale of 1:25000 for two test areas of approximately 200000 ha each (Lothians and the Ayrshire Basin) were overlain with a climate map within the GIS, deriving unique combinations of soil wetness and land use. The calculated annual emission rates (kg N ha^–1 yr^–1) were then applied to these and multiplied by the total area of each soil/land use type to derive annual emission losses for each area. The annual emission of nitrous oxide from the Lothians was determined as approximately 381000 kg N yr^–1, while the emissions from the Ayrshire Basin were predicted to be 794000 kg N yr^–1. This indicates the increased emissions associated with both the wetter soils of Ayrshire and the greater extent of grazed pasture systems in this area. Due to the detailed scale of the input data, localised areas with large emissions were identified. Abatement strategies would be concentrated on areas of high emissions that include a change to crops with lower emission potential, reducing fertiliser and manure inputs, reducing grazing intensity and improving soil drainage.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1024422604493     

Combined application of organic and inorganic fertilizers mitigates ammonia and nitrous oxide emissions in a maize field

Nutrient Cycling in Agroecosystems - This long-term study used a lysimeter platform to monitor the NH3 and N2O emissions of summer maize resulting from various fertilization treatments in the...