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1.
This study provides a comparative assessment of greenhouse gas (GHG) emissions when converting a reclaimed minesoil that was previously under meadow to miscanthus ( Miscanthus × giganteus ) and maize ( Zea mays L.) land uses in Ohio, USA. Additionally, effluent from an anaerobic digester at rates of 0, 75, 150, and 225 kg N ha −1 rates was also assessed for C and nutrient fertilization. Results from the study show that land use conversion to maize had the highest net release of GHG equivalent of 6·6 Mg CO 2equ ha −1 y −1, on average, across effluent application rates. Under miscanthus land use with no and high effluent application rates, net GHG equivalent on average was 4·3 Mg CO 2equ ha −1 y −1, which was larger when compared with that under the meadow land use (1·6 Mg CO 2equ ha −1 y −1). Miscanthus land use under medium rates of effluent application had similar net GHG equivalent (7·1 Mg CO 2equ ha −1 y −1) to the maize land use. The application of effluent did increase CO 2–C and N 2O–N emissions; but increases in above‐ground–below‐ground biomass production (1·6 Mg C ha −1) in the meadow land use and C input from effluent retained in the soil in the miscanthus and maize land uses offset most of the effluent‐induced GHG equivalent emissions. Contribution of cumulative N 2O–N to GHG equivalent emissions in general was 11% when no effluent was applied and 22% when effluent was applied across land uses. Findings from this study show that land use changes from antecedent meadow to maize and miscanthus during the first year of establishment would result in net increase of GHG emissions. Published 2017. This article is a U.S. Government work and is in the public domain in the USA 相似文献
2.
As global warming intensifies, the soil environment in middle to high latitudes will undergo more extensive and frequent freeze–thaw cycles (FTCs), which will significantly affect the carbon and nitrogen cycles of soil ecosystems and aggravate greenhouse gas (GHG) emissions. Biochar can increase soil organic carbon storage and mitigate climate change. To effectively control GHG emissions, soil supplemented with biochar at different application rates (0%, 2%, 4% and 6% [w/w]) under different numbers of FTCs (0, 3, 6, 9, and 12) was selected as the research object. The soil GHG emission characteristics in different experimental treatments and their relationships with soil physical and chemical properties were determined. Our results showed that N 2O and CO 2 emissions were promoted during FTCs, with values of 3.13–50.37 and 16.22–135.50 μg m −2 h −1, respectively. The order of N 2O and CO 2 emissions with respect to biochar application rate was as follows: 2% > 0% > 4% > 6%. CH 4 emissions were negative during FTCs, varying from −1.62 to −10.59 μg m −2 h −1, and negative CH 4 emissions were promoted by biochar. Correlation analysis showed that N 2O, CO 2 and CH 4 emissions were significantly correlated with pH, soil moisture and soil organic matter (SOM), total nitrogen (TN) and –N contents ( p < .01). The conceptual path model demonstrated that GHG emissions were significantly influenced by FTCs, moisture, SOM and biochar application rate. Our results indicate that the effects of FTCs on GHG emissions were greater than those of biochar application. Biochar application rates of 4% or 6% should be considered in the future to reduce soil GHG emissions in the black soil region of Northeast China. Our results can help provide a theoretical basis and effective strategy to reduce soil GHG emissions during FTCs in seasonally frozen regions. 相似文献
3.
Net greenhouse gas (GHG) source strength for agricultural wetland ecosystems in the Prairie Pothole Region (PPR) is currently unknown. In particular, information is lacking to constrain spatial variability associated with GHG emissions (CH 4, CO 2, and N 2O). GHG fluxes typically vary with edaphic, hydrologic, biologic, and climatic factors. In the PPR, characteristic wetland plant communities integrate hydropedologic factors and may explain some variability associated with trace gas fluxes at ecosystem and landscape scales. We addressed this question for replicate wetland basins located in central North Dakota stratified by hydropedologic vegetation zone on Jul 12 and Aug 3, 2003. Data were collected at the soil-atmosphere interface for six plant zones: deep marsh, shallow marsh, wet meadow, low prairie, pasture, and cropland. Controlling for soil moisture and temperature, CH 4 fluxes varied significantly with zone ( p < 0.05). Highest CH 4 emissions were found near the water in the deep marsh (277,800 μg m − 2 d − 1 CH 4), which declined with distance from water to − 730 μg m − 2 d − 1 CH 4 in the pasture. Carbon dioxide fluxes also varied significantly with zone. Nitrous oxide variability was greater within zones than between zones, with no significant effects of zone, moisture, or temperature. Data were extrapolated for a 205.6 km 2 landscape using a previously developed synoptic classification for PPR plant communities. For this landscape, we found croplands contributed the greatest proportion to the net GHG source strength on Jul 12 (45,700 kg d − 1 GHG-C equivalents) while deep marsh zones contributed the greatest proportion on Aug 3 (26,145 kg d − 1 GHG-C equivalents). This was driven by a 30-fold reduction in cropland N 2O–N emissions between dates. The overall landscape average for each date, weighted by zone, was 462.4 kg km − 2 d − 1 GHG-C equivalents on Jul 12 and 314.3 kg km − 2 d − 1 GHG-C equivalents on Aug 3. Results suggest GHG fluxes vary with hydropedologic soil zone, particularly for CH 4, and provide initial estimates of net GHG emissions for heterogeneous agricultural wetland landscapes. 相似文献
4.
Purpose Land use type is an important factor influencing greenhouse gas emissions from soils, but the mechanisms involved in affecting
potential greenhouse gas (GHG) emissions in different land use systems are poorly understood. Since the northern regions of
Canada and China are characterized by cool growing seasons, GHG emissions under low temperatures are important for our understanding
of how soil temperature affects soil C and N turnover processes and associated greenhouse gas emissions in cool temperate
regions. Therefore, we investigated the effects of temperature on the emission of N 2O, CO 2, and CH 4 from typical forest and grassland soils from China and Canada. 相似文献
5.
Applying biochar to soil is an easy way to sequester carbon in soil, while it might reduce greenhouse gas (GHG) emissions and stimulate plant growth. The effect of charcoal application (0, 1.5, 3.0 and 4.5%) on GHG emission was studied in a wastewater sludge-amended arable soil (Typic Fragiudepts) cultivated with wheat ( Triticum spp. L.) in a greenhouse. The application of charcoal at ≥1.5% reduced the CO 2 emission rate significantly ≥37% compared to unamended soil (135.3 g CO 2 ha −1 day −1) in the first two weeks, while the N 2O emission rate decreased 44% when 4.5% charcoal was added (0.72 g N 2O ha −1 day −1). The cumulative GHG emission over 45 days was 2% lower when 1.5% charcoal, 34% lower when 3.0% charcoal and 39% lower when 4.5% charcoal was applied to the sludge-amended soil cultivated with wheat. Wheat growth was inhibited in the charcoal-amended soil compared to the unamended soil, but not yields after 135 days. It was found that charcoal addition reduced the emissions of N 2O and CO 2, and the cumulative GHG emissions over 45 days, without altering wheat yield. 相似文献
6.
PurposeAnthropogenic-induced greenhouse gas (GHG) emission rates derived from the soil are influenced by long-term nitrogen (N) deposition and N fertilization. However, our understanding of the interplay between increased N load and GHG emissions among soil aggregates is incomplete.Materials and methodsHere, we conducted an incubation experiment to explore the effects of soil aggregate size and N addition on GHG emissions. The soil aggregate samples (0–10 cm) were collected from two 6-year N addition experiment sites with different vegetation types (mixed Korean pine forest vs. broad-leaved forest) in Northeast China. Carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) production were quantified from the soil samples in the laboratory using gas chromatography with 24-h intervals during the incubation (at 20 °C for 168 h with 80 % field water capacity).Results and discussionThe results showed that the GHG emission/uptake rates were significantly higher in the micro-aggregates than in the macro-aggregates due to the higher concentration of soil bio-chemical properties (DOC, MBC, NO3 ?, NH4 +, SOC and TN) in smaller aggregates. For the N addition treatments, the emission/uptake rates of GHG decreased after N addition across aggregate sizes especially in mixed Korean pine forest where CO2 emission was decreased about 30 %. Similar patterns in GHG emission/uptake rates expressed by per soil organic matter basis were observed in response to N addition treatments, indicating that N addition might decrease the decomposability of SOM in mixed Korean pine forest. The global warming potential (GWP) which was mainly contributed by CO2 emission (>98 %) decreased in mixed Korean pine forest after N addition but no changes in broad-leaved forest.ConclusionsThese findings suggest that soil aggregate size is an important factor controlling GHG emissions through mediating the content of substrate resources in temperate forest ecosystems. The inhibitory effect of N addition on the GHG emission/uptake rates depends on the forest type. 相似文献
7.
Background Riparian buffers are primarily implemented for their water quality functions in agroecosystems. Their location in the agricultural landscape allows them to intercept and process pollutants from immediately adjacent agricultural land. Vegetated riparian buffers recycle soil organic matter, which elevates soil carbon (C), which upon processing, processes and releases carbon dioxide (CO 2). The elevated soil C and seasonally anoxic environments associated with riparian buffers promote denitrification and fermentation, further increasing soil CO 2 production. Aim Against this context, a replicated plot-scale experiment was established at North Wyke, UK, to measure the extent of soil CO 2 emissions in permanent pasture served by grass, willow, and woodland riparian buffers, as well as a no-buffer control. Methods Soil CO 2 was measured using the static chamber technique in conjunction with soil and environmental variables between June 2018 and February 2019. Results Cumulative soil CO 2 fluxes were in the descending order: woodland riparian buffer; 11,927.8 ± 1987.9 kg CO 2 ha –1 > no-buffer control; 11,101.3 ± 3700.4 kg CO 2 ha –1 > grass riparian buffer; 10,826.4 ± 2551.8 kg CO 2 ha –1 > upslope pasture; 10,554.6 ± 879.5 kg CO 2 ha –1 > willow riparian buffer; 9294.9 ± 1549.2 5 kg CO 2 ha –1. There was, however, no evidence of significant differences among all treatments of the current study. Conclusions Despite the lack of significant differences, the results from our short-term study show that the woodland riparian buffer had relatively larger soil CO 2 emissions than the remainder of the other riparian buffers and the upslope pasture it serves. Our short-term findings may be useful in developing soil CO 2 mitigation strategies through careful selection of riparian buffer vegetation and may be useful in calibrating mechanistic models for simulating such emissions from similar agro systems. 相似文献
8.
Quantitative information is critical in policy making related to the roles of agriculture in greenhouse gas (GHG) emissions. A Unit Response (UR) curve method was developed in this study for modeling GHG emissions from soil after liquid manure applications. The emission sources (soils and liquid manures) are conceptualized as a set of linear cascaded chambers with equal storage-release coefficients, or two sets of cascaded chambers in parallel, each set having equal storage-release coefficients. The model is based on a two-parameter gamma distribution. Three parameters in this model denote the number of cascaded chambers, the storage-release coefficient, and the multiplier (referring to the total net emissions) added to the gamma distribution function. These parameters can be expressed as functions of site-specific background fluxes without applications of manure/fertilizer. The method was assessed with emissions data from five fields in Washington State. The results showed that at the WSU and Lynden sites, the average excess CH 4 emissions due to manure applications were 0.39 and 0.17 kg CH 4–C ha ? 1, respectively; the average excess CO 2 emissions were 216.50 and 25.20 kg CO 2–C ha ? 1, respectively; and the average excess N 2O were 0.37 and 0.03 kg N 2O–N ha ? 1, respectively. The UR method may fill the gaps between field measurements, simple emission factor (EF) method, and complex process-oriented models. This method has the potential to be used for estimating additional GHG emissions due to manure/fertilizer applications. 相似文献
9.
Purpose The effects of commercial compost fertilizer application on trace gas emissions are not well understood due to a lack of field experiments. The objective of this study was to evaluate the emissions of methane (CH 4) and nitrous oxide (N 2O) along with grain yield from a rice paddy as affected by different organic–inorganic mixed fertilizer (OIMF) treatments. Materials and methods A field experiment was initiated in 2006 with chemical compound fertilizer (CF) and three OIMF amendments including pig manure compost (PMC), Chinese medicine residue compost (CMC), and rapeseed cake compost (RCC), from a rice paddy in southeast China. The emissions of CH 4 and N 2O were simultaneously measured using the static opaque chamber method over the entire rice growing season in 2011. Soil biotic parameters were measured in soil collected after the rice was harvested in 2011. Results and discussion Relative to the control, the OIMF treatments significantly increased CH 4 emissions by 56–99 %, mainly due to exogenous organic substrate input, whereas no difference was observed in the CF treatment. The N 2O emissions were stimulated substantially by an average of 40 % due to nitrogen fertilization compared with the control. Consecutive OIMF application tended to increase the grain yield, making it marginally higher than that of the CF treatment (7 %, P?=?0.06). Compared with the control, the CF treatment slightly decreased the global warming potential and greenhouse gas (GHG) intensity, while they were remarkably increased in the OIMF treatments. Over the 5-year period of 2006–2011, the annual soil carbon sequestration rate was estimated to be 1.19 t C ha ?1 year ?1 for the control and 1.73–1.98 t C ha ?1 year ?1 for the fertilized treatments. Conclusions Our results suggest that despite the beneficial effects of increasing both grain yield and soil organic matter, OIMF application such as PMC, CMC, and RCC may be responsible for increased global warming due mainly to the stimulated CH 4 emissions. This effect should be thus taken into account when balancing agricultural production and GHG mitigation. 相似文献
10.
The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land-use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non-living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no-tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NT SSo), soybean/millet (NT SMi) and maize/sorghum (NT MSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m −2 and 0.5 kg N m −2, 0–0.3-m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NT MSo and 15% lower in the croplands with soybean compared to NV. δ 13C values clearly distinguished between the C-origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile-C (625 g C m −2), microbial-C (70 g C m −2) and microbial-N (5.5 g N m −2), whereas other land uses presented values three times lower. GHG emissions (expressed as C-equivalent) were highest in the NV (1.2 kg m −2 year −1), PA (1.3 kg m −2 year −1) and NT MSo (0.9 kg m −2 year −1) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above- and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions. 相似文献
11.
Background Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated. Aim This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency. Methods After 21 years of annual compost application (100/400 kg N ha –1 year –1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, N min, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated. Results N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha –1 year –1 and 19.5 kg K ha –1 year –1 resulted in 1 mg kg –1 increase in CAL-P and CAL-K over 21 years. Conclusion Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period. 相似文献
12.
We determined N 2O fluxes from an unfertilized control (CON), from a treatment with mineral N‐fertilizer (MIN), from cattle slurry with banded surface application and subsequent incorporation (INC), and from slurry injection (INJ) to silage maize ( Zea mays, L.) on a Haplic Luvisol in southwest Germany. In both years, amount of available N (total N fertilized + N min content before N application) was 210 kg N ha ?1. In the slurry treatment of the 1 st year, 140 kg N ha ?1 were either injected or incorporated, whereas 30 kg N ha ?1 were surface applied to avoid destruction of the maize plants. In the 2 nd year, all fertilizers were applied with one single application. We calculated greenhouse gas emissions (GHG) on field level including direct N 2O emissions (calculated from the measured flux rates), indirect N 2O emissions (NH 3 and induced N 2O emission), net CH 4 fluxes, fuel consumption and pre‐chain emissions from mineral fertilizer. NH 3 losses were measured in the 2 nd year using the Dräger‐Tube Method and estimated for both years. NH 3 emission was highest in the treatment without incorporation. It generally contributed less than 5% of the greenhouse gas (GHG) emission from silage maize cultivation. The mean area‐related N 2O emission, determined with the closed chamber method was 2.8, 4.7, 4.4 and 13.8 kg N 2O‐N ha ?1 y ?1 for CON, MIN, INC, and INJ, respectively. Yield‐related N 2O emission showed the same trend. Across all treatments, direct N 2O emission was the major contributor to GHG with an average of 79%. Trail hose application with immediate incorporation was found to be the optimum management practice for livestock farmers in our study region. 相似文献
13.
In this study, we investigated N 2O emissions from two fields under minimum tillage, cropped with maize (MT maize) and summer oats (MT oats), and a conventionally
tilled field cropped with maize (CT maize). Nitrous oxide losses from the MT maize and MT oats fields (5.27 and 3.64 kg N 2O-N ha −1, respectively) were significantly higher than those from the CT maize field (0.27 kg N 2O-N ha −1) over a period of 1 year. The lower moisture content in CT maize (43% water-filled pore space [WFPS] compared to 60–65%)
probably caused the difference in total N 2O emissions. Denitrification was found to be the major source of N 2O loss. Emission factors calculated from the MT field data were high (0.04) compared to the CT field (0.001). All data were
simulated with the denitrification decomposition model (DNDC). For the CT field, N 2O and N 2O + N 2 emissions were largely overestimated. For the MT fields, there was a better agreement with the total N 2O and N 2O + N 2 emissions, although the N 2O emissions from the MT maize field were underestimated. The simulated N 2O emissions were particularly influenced by fertilization, but several other measured N 2O emission peaks associated with other management practices at higher WFPS were not captured by the model. Several mismatches
between simulated and measured
\text NH4+ {\text{NH}}_4^ + ,
\text NO3- {\text{NO}}_3^ - and WFPS for all fields were observed. These mismatches together with the insensitivity of the DNDC model for increased N 2O emissions at the management practices different from fertilizer application explain the limited similarity between the simulated
and measured N 2O emissions pattern from the MT fields. 相似文献
14.
In-field management practices of corn cob and residue mix (CRM) as a feedstock source for ethanol production can have potential effects on soil greenhouse gas (GHG) emissions. The objective of this study was to investigate the effects of CRM piles, storage in-field, and subsequent removal on soil CO 2 and N 2O emissions. The study was conducted in 2010–2012 at the Iowa State University, Agronomy Research Farm located near Ames, Iowa (42.0°′N; 93.8°′W). The soil type at the site is Canisteo silty clay loam (fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls). The treatments for CRM consisted of control (no CRM applied and no residue removed after harvest), early spring complete removal (CR) of CRM after application of 7.5 cm depth of CRM in the fall, 2.5 cm, and 7.5 cm depth of CRM over two tillage systems of no-till (NT) and conventional tillage (CT) and three N rates (0, 180, and 270 kg N ha −1) of 32% liquid UAN (NH 4NO 3) in a randomized complete block design with split–split arrangements. The findings of the study suggest that soil CO 2 and N 2O emissions were affected by tillage, CRM treatments, and N rates. Most N 2O and CO 2 emissions peaks occurred as soil moisture or temperature increased with increase precipitation or air temperature. However, soil CO 2 emissions were increased as the CRM amount increased. On the other hand, soil N 2O emissions increased with high level of CRM as N rate increased. Also, it was observed that NT with 7.5 cm CRM produced higher CO 2 emissions in drought condition as compared to CT. Additionally, no differences in N 2O emissions were observed due to tillage system. In general, dry soil conditions caused a reduction in both CO 2 and N 2O emissions across all tillage, CRM treatments, and N rates. 相似文献
15.
Background In arid and semiarid countries, grain yield of maize is increasingly impaired by soil salinity. Beside soil amelioration, the development of salt-resistant cultivars is a possibility to enhance crop yield on salt-affected soils. Aims This study aimed at testing yield performance in the field of salt-resistant maize hybrids on a salt-affected soil. In addition, planting density was optimized under the saline conditions. Methods Four salt-resistant maize hybrids ( Zea mays L. SR-05, SR-12, SR-15, and SR-16) were grown under control (EC = 2.0–2.5 dS m −1) and saline (EC = 10.0–12.0 dS m −1) field conditions and compared to the salt-sensitive maize cv. Pioneer-3906. Planting density (5, 8, or 11 plants m −2) was optimized for saline soil conditions for SR-12 and the local hybrid EV-78. Results Yield of Pioneer-3906 was significantly reduced under salinity because of inhibited kernel setting, whereas the SR hybrids showed no decrease in grain yield. Based on grain yield, the optimum planting density was 8 plants m −2 with no further increase with 11 plants m −2. In contrast to SR-12, for cv. EV-78 no increase of harvest index with 8 relative to 5 plants m −2 was observed. Conclusions Vegetative growth of Pioneer-3906 and the SR hybrids was decreased due to Phase-I effects but neither due to water deficiency nor ion toxicity. The experiment corroborated the salt resistance of the SR hybrids under field conditions. Under saline conditions, optimum planting density of salt-resistant cultivars may be higher than under nonsaline conditions when sufficient water supply by artificial irrigation is guaranteed. 相似文献
16.
The development of shrub willow as a bioenergy feedstock contributes to renewable energy portfolios in many countries with temperate climates and marginal croplands. As willow is developed commercially in the US Northeast, there is a need to better understand its impact on water quality and greenhouse gas (GHG) emissions compared to alternative land uses (e.g., corn, hay). We measured the impact of cultivated willow of various ages (2 and 5 years) and management strategies (fertilized vs. unfertilized) compared to corn and hay on water table depth, soil water NO 3 ? and PO 4 3? concentrations, and N 2O, CH 4, and CO 2 fluxes at the soil-atmosphere interface during a drier than normal year in heavy clay soils with marginal agricultural value in upstate New York, USA. Soil water concentrations resulted in higher PO 4 3? in willow and higher NO 3 ? in corn and hay, although willow is unlikely to negatively impact water quality with respect to phosphorus due to shorter periods of hydrologic connectivity in willow and hay than in corn. Gas fluxes varied spatially and temporally with hot moments of CH 4 and N 2O in corn and hay and seasonally variable CO 2 in willow. While CH 4 did not vary between fields, N 2O was higher in corn and hay, and CO 2 in willow, resulting in no net difference between CO 2 equivalent (CH 4, CO 2, and N 2O) emissions between fields. Converting marginal cropland on clay soils from corn or hay to willow left overall GHG emissions unaffected, slightly increased PO 4 3?, and decreased NO 3 ? concentrations in soil water. 相似文献
17.
A high soil nitrogen (N) content in irrigated areas quite often results in environmental problems. Improving the management practices of intensive agriculture can mitigate greenhouse gas (GHG) emissions. This study compared the effect of maize stover incorporation or removal together with different mineral N fertilizer rates (0, 200 and 300 kg N ha ?1) on the emission of nitrous oxide (N 2O) and carbon dioxide (CO 2) on a sprinkler-irrigated maize ( Zea mays L.). The trail was conducted in the Ebro Valley (NE Spain) in a high nitrate-N soil (i.e. 200 g NO 3–N kg ?1). Nitrous oxide and CO 2 emissions were sampled weekly using a semi-static closed chamber and quantified using the photoacoustic technique in 2011 and 2012. Applying sidedress N fertilizer tended to increase N 2O emissions whereas stover incorporation did not have any clear effect. Nitrification was probably the main process leading to N 2O. Denitrification was limited by the low soil moisture content (WFPS <?54%), due to an adequate irrigation management. Emissions ranged from ??0.11 to 0.36% of the N applied, below the IPCC ( 2007) values. Nitrogen fertilization tended to reduce CO 2 emission, but only in 2011. Stover incorporation increased CO 2 emission. Nitrogen use efficiency decreased with increasing mineral fertilizer supply. The application of N in high N soils of the Ebro Valley is not necessary until the soil restores a normal mineral N content, regardless of stover management. This will combine productivity with keeping N 2O and CO 2 emissions under control provided irrigation is adequately managed. Testing soil NO 3 ?–N contents before fertilizing would improve N fertilizer recommendations. 相似文献
18.
PurposeSoil chromium (Cr) pollution has received substantial attention owing to related food chain health risks and possible promotion of greenhouse gas (GHG) emissions. The aim of the present study was to develop a promising remediation technology to alleviate Cr bioavailability and decrease GHG emissions in Cr-polluted paddy soil. Materials and methodsWe investigated the potential role of biochar amendment in decreasing soil CO2, CH4, and N2O emissions, as well in reducing Cr uptake by rice grains at application rates of 0 t ha?1 (CK), 20 t ha?1 (BC20), and 40 t ha?1 (BC40) in Cr-polluted paddy soil in southeastern China. In addition, the soil aggregate size distribution, soil organic carbon (SOC) concentration of soil aggregates, soil available Cr concentration, and rice yield were analyzed after harvesting. Results and discussionBiochar amendment significantly reduced CO2, CH4, and N2O emission fluxes. Compared to CK, total C emissions in the BC20 and BC40 treatments decreased by 9.94% and 17.13% for CO2-C, by 30.46% and 37.10% for CH4-C, and by 34.24% and 37.49% for N2O-N, respectively. Biochar amendment increased the proportion of both the 2000–200 μm and 200–20 μm size fractions in the soil aggregate distribution. Accordingly, the organic carbon concentration of these fractions increased, which increased the total SOC. Moreover, biochar amendment significantly decreased soil available Cr concentration and total Cr content of the rice grains by 33.6% and 14.81% in BC20 and 48.1% and 33.33% in BC40, respectively. Rice yield did not differ significantly between biochar amendment treatment and that of CK. ConclusionsBiochar application reduced GHG emissions in paddy soil, which was attributed to its comprehensive effect on the soil properties, soil microbial community, and soil aggregates, as well as on the mobility of Cr. Overall, the present study demonstrates that biochar has a great potential to enhance soil carbon sequestration while reducing Cr accumulation in rice grains from Cr-polluted rice paddies. 相似文献
19.
Nitrogen amendment followed by flooding irrigation is a general management practice for a wheat–maize rotation in the North China Plain, which may favor nitrification and denitrification. Consequently, high emissions of nitrous oxide (N 2O) and nitric oxide (NO) are hypothesized to occur. To test this hypothesis, we performed year-round field measurements of N 2O and NO fluxes from irrigated wheat–maize fields on a calcareous soil applied with all crop residues using a static, opaque chamber measuring system. To interpret the field data, laboratory experiments using intact soil cores with added carbon (glucose) and nitrogen (nitrate, ammonium) substrates were performed. Our field measurements showed that pulse emissions after fertilization and irrigation/rainfall contributed to 73% and 88% of the annual N 2O and NO emissions, respectively. Soil moisture and mineral nitrogen contents significantly affected the emissions of both gases. Annual emissions from fields fertilized at the conventional rate (600 kg N ha −1 yr −1) totaled 4.0 ± 0.2 and 3.0 ± 0.2 kg N ha −1 yr −1 for N 2O and NO, respectively, while those from unfertilized fields were much lower (0.5 ± 0.02 kg N ha −1 yr −1 and 0.4 ± 0.05 kg N ha −1 yr −1, respectively). Direct emission factors (EF ds) of N 2O and NO for the fertilizer nitrogen were estimated to be 0.59 ± 0.04% and 0.44 ± 0.04%, respectively. By summarizing the results of our study and others, we recommended specific EF ds (N 2O: 0.54 ± 0.09%; NO: 0.45 ± 0.04%) for estimating emissions from irrigated croplands on calcareous soils with organic carbon ranging from 5 to 16 g kg −1. Nitrification dominated the processes driving the emissions of both gases following fertilization. It was evident that insufficient available carbon limited microbial denitrification and thus N 2O emission. This implicates that efforts to enhance carbon sink in calcareous soils likely increase their N 2O emissions. 相似文献
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