Meta-analysis data quantifying nitrous oxides emissions from Chinese vegetable production (original) (raw)
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Re-assessing nitrous oxide emissions from croplands across Mainland China
Agriculture, Ecosystems & Environment, 2018
Reliable quantification of nitrous oxide emission is a key to assessing efficiency of use and environmental impacts of N fertilizers in crop production. In this study, N2O emission and yield were quantified with a database of 853 field measurements in 104 reported studies and a regression model was fitted to the associated environmental attributes and management practices from China's croplands. The fitted emission model explained 48% of the variance in N2O emissions as a function of fertilizer rate, crop type, temperature, soil clay content, and the interaction between N rate and fertilizer type. With all other variables fixed, N2O emissions were lower with rice than with legumes and then other upland crops, lower with organic fertilizers than with mineral fertilizers. We used the subset of the dataset for rice-covering a full range of different typical water regimes, and estimated emissions from China's rice cultivation to be 31.1 Gg N2O-N per year. The fitted yield model explained 35% of the variance in crop yield as a function of fertilizer rate, temperature, crop type, and soil clay content. Finally, the empirical models for N2O emission and crop yield were coupled to explore the optimum N rates (N rate with minimum N2O emission per unit yield) for combinations of crop and fertilizer types. Consequently, the optimum N application rate ranged between 100 kg N ha-1 and 190 kg N ha-1 respectively with organic and mineral fertilizers, and different crop types. This study therefore improved on existing empirical methods to estimate N2O emissions from China's croplands and suggests how N rate may be optimized for different crops, fertilizers and site conditions.
Korean Journal of Environmental Agriculture, 2012
BACKGROUND: Generally, nitrogen (N) fertilization higher than the recommended dose is applied during vegetable cultivation to increase productivity. But higher N fertilization also increases the concentrations of nitrate ions and nitrous oxide in soil. In this experiment, the impact of N fertilization was studied on nitrous oxide (N 2 O) emission to standardize the optimum fertilization level for minimizing N 2 O emission as well as increasing crop productivity. Herein, we developed N 2 O emission inventory for upland soil region during red pepper and Chinese milk vetch cultivation. METHODS AND RESULTS: Nitrogen fertilizers were applied at different rates to study their effect on N 2 O emission during red pepper and Chinese milk vetch cultivation. The gas samples were collected by static closed chamber method and N 2 O concentration was measured by gas chromatography. The total N 2 O flux was steadily increased due to increasing N fertilization level, though the overall pattern of N 2 O emission dynamics was same. Application of N fertilization higher than the recommended dose increased the values of both seasonal N 2 O flux (94.5% for Chinese cabbage and 30.7% for red pepper) and N 2 O emission per unit crop yield (77.9% for Chinese cabbage and 23.2% for red pepper). Nitrous oxide inventory revealed that the N 2 O emission due to unit amount of N application from short-duration vegetable field in fall (autumn) season (6.36 kg/ ha) was almost 70% higher than that during summer season. CONCLUSION: Application of excess N-fertilizers increased seasonal N 2 O flux especially the N 2 O flux per unit yield during both Chinese cabbage and red pepper cultivation. This suggested that the higher N fertilization than the recommended dose actually facilitates N 2 O emission than boosting plant productivity. The N 2 O inventory for upland farming in temperate region like Korea revealed that N 2 O flux due to unit amount of N-fertilizer application for Chinese cabbage in fall (autumn) season was comparatively higher than that of summer vegetables like red pepper. Therefore, the judicious N fertilization following recommended dose is required to suppress N 2 O emission with high vegetable productivity in upland soils.
Atmospheric Environment, 2009
In China, vegetable croplands are characterized by intensive fertilization and cultivation, which produce significant nitrogenous gases to the atmosphere. In this study, nitric oxides (NO X ) and nitrous oxide (N 2 O) emissions from the croplands cultivated with three typical vegetables had been measured in Yangtze River Delta of China from September 2 to December 16, 2006. The NO fluxes varied in the ranges of 1.6-182.4, 1.4-2901 and 0.5-487 ng Nm À2 s À1 with averages of 33.8 AE 44.2, 360 AE 590 and 76 AE 112 (mean AE SD) ngNm À2 s À1 for cabbage, garlic, and radish fields (n ¼ 88), respectively. N 2 O fluxes from the three vegetable fields were found to occur in pulses and significantly promoted by tillage with average values of 5.8, 8.8, and 4.3 ng Nm À2 h À1 for cabbage, garlic, and radish crops, respectively. Influence of vegetables canopy on the NO emission was investigated and quantified. It was found that on cloudy days the canopy can only shield NO emission from croplands soil while on sunny days it cannot only prevent NO emission but also assimilate NO through the open leaves stomas. Multiple linear regression analysis indicated that soil temperature was the most important factor in controlling NO emission, followed by fertilizer amount and gravimetric soil water content. About 1.2%, 11.56% and 2.56% of applied fertilizers N were emitted as NO-N and N 2 O-N from the cabbage, garlic and radish plots, respectively. Crown
2010
There is increasing concern that agricultural intensification in China has greatly increased N 2 O emissions due to rapidly increased fertilizer use. By linking a spatial database of precipitation, synthetic fertilizer N input, cropping rotation and area via GIS, a precipitation-rectified emission factor of N 2 O for upland croplands and water regime-specific emission factors for irrigated rice paddies were adopted to estimate annual synthetic fertilizer N-induced direct N 2 O emissions (FIE-N 2 O) from Chinese croplands during 1980-2000. Annual FIE-N 2 O was estimated to be 115.7 Gg N 2 O-N year À1 in the 1980s and 210.5 Gg N 2 O-N year À1 in the 1990s, with an annual increasing rate of 9.14 Gg N 2 O-N year À1 over the period 1980-2000. Upland croplands contributed most to the national total of FIE-N 2 O, accounting for 79% in 1980 and 92% in 2000. Approximately 65% of the FIE-N 2 O emitted in eastern and southern central China. Please cite this article in press as: Zou, J., et al., Estimates of synthetic fertilizer N-induced direct nitrous oxide emission from Chinese croplands during
Fertilizer-induced emission factors and background emissions of N 2O from vegetable fields in China
Atmospheric Environment, 2011
The estimation of nitrous oxide (N 2 O) emissions based on specific cropping systems is important for accurate national N 2 O budgets. Intensively managed vegetable cultivation is responsible for large N 2 O emissions in mainland China. However, little information can be obtained on the nationwide estimation of direct N 2 O emissions from vegetable fields. Estimates of fertilizer-induced direct N 2 O emissions from vegetable fields in mainland China were thus obtained by compiling and analyzing reported data in peerreviewed journals and research reports. The results indicated that the seasonal N 2 O emissions from vegetable fields significantly increased with nitrogen (N) fertilizer application (p < 0.0001). According to the ordinary least squares (OLS) model, the fertilizer-induced emission factor (EF) and background emissions of N 2 O were estimated to be 0.55 AE 0.05% and 1.067 AE 0.277 kg N ha À1 yr À1 , respectively. The EF was reduced and the background emission of N 2 O increased when the measurement duration was prolonged from 100 d to >100 and 200 d. Comparable results were obtained by the maximum likelihood (ML) model, with an EF of 0.49 AE 0.06% and background N 2 O emissions of 1.228 AE 0.189 kg N ha À1 yr À1 . Based on the OLS-derived parameters, the fertilizer-induced direct emissions and background emissions of N 2 O were estimated to be 66.95 Gg N and 19.63 Gg N, respectively, in 2009, and the annual N 2 O emissions were much higher in the provinces of Shandong, Henan, Hebei and Sichuan. The estimated N 2 O emissions from vegetable fields accounted for 21.4% of the total direct N 2 O emissions from Chinese croplands, with large uncertainties. Therefore, the EF and background emissions of N 2 O for each cropping system, particularly for intensively managed vegetable fields, should be specifically determined for accurate national N 2 O inventories.
Meta‐analysis of yield and nitrous oxide outcomes for nitrogen management in agriculture
Global Change Biology
Nitrogen (N) is an essential nutrient in crop production that supports current and future human population. With the advent of the "Green Revolution" in the 1960s, crop yields-especially for cerealsincreased substantially to support rising global food demand. This increased production was made possible through the introduction of high yielding crop varieties, accompanied by the availability and
Environmental Science & Technology, 2019
Updating and refining the N2O emission factors (N2O-EF) is vital to reduce the uncertainty in estimates of direct N 2 O emissions. Based on a database with 1151 field measurements across China, the N2O-EFs were established via three approaches including the maximum likelihood method, a linear regression with intercept, and a linear regression with the intercept set to 0 using 70% of the observations. The remaining 30% of the observations were then used to evaluate the predicted N2O-EFs. The third method had the highest R 2 of 0.39 and the best model efficiency of 0.38 with no significant bias, showing the best calculation efficiency. The results showed that the N2O-EFs varied with agro-regions, crops, and management patterns. The agro-regions of Huang-Huai-Hai and Yangtze River had the higher N2O-EFs in maize and wheat seasons than other regions, and the highest N2O-EFs of 0.66~0.92% in rice season was found in the South and Southwest agro-regions. Both fertilizer types and water regimes had the remarkable effects on N2O-EFs. Based on the best estimation by the selected method, direct N2O emissions from China's crop cultivation were estimated to be 194 Gg N2O-N with a 95% confidence interval of 180-208 Gg N2O-N in the year 2016.
2002
To identify the key soil parameters influencing N 2 O emission from the wheat-growing season, an outdoor pot experiment with a total of 18 fertilized Chinese soils planted with wheat was conducted in Nanjing, China during the 2000/2001 wheat-growing season. Average seasonal N 2 O-N emission for all 18 soils was 610 mg m -2 , ranging from 193 to 1,204 mg m -2 , approximately a 6.2fold difference between the maximum and the minimum. Correlation analysis indicated that the seasonal N 2 O emission was negatively correlated with soil organic C (r 2 =0.5567, P<0.001), soil total N (r 2 =0.4684, P<0.01) and the C:N ratio (r 2 =0.4530, P<0.01), respectively. A positive dependence of N 2 O emission on the soil pH (r 2 =0.3525, P<0.01) was also observed. No clear relationships existed between N 2 O emission and soil texture, soil trace elements of Fe, Cu and Mg, and above-ground biomass of the wheat crop at harvest. A further investigation suggested that the seasonal N 2 O-N emission (E, mg m -2 ) can be quantitatively explained by E=1005-34.2SOC+4.1S a (R 2 =0.7703, n=18, P=0.0000). SOC and S a represent the soil organic C (g kg -1 ) and available S (mg kg -1 ), respectively.
Direct and indirect nitrous oxide emissions from agricultural soils, 1990-2003
… document on the …, 2007
Direct and indirect nitrous oxide emissions from agricultural soils, 1990-2003 Background document on the calculation method for the Dutch National Inventory Report Since 2005 the Dutch method to calculate the nitrous oxide emissions from agricultural soils has fully complied with the Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidelines. In order to meet the commitments of the Convention on Climate Change and the Kyoto Protocol, nitrous oxide emissions have to be reported annually in the Dutch National Inventory Report (NIR). Countries are encouraged to use country-specific data rather than the default values provided by the IPCC. This report describes the calculation schemes and data sources used for nitrous oxide emissions from agricultural soils in the Netherlands. The nitrous oxide emissions, which contribute to the greenhouse effect, occur due to nitrification and denitrification processes. They include direct emissions from agricultural soils due to the application of animal manure and fertilizer nitrogen and the manure production in the meadow. Also included are indirect emissions resulting from the subsequent leaching of nitrate to ground water and surface waters, and from deposition of ammonia that had volatilized as a result of agricultural activities. Before 2005 indirect emissions in the Netherlands were calculated using a method that did not compare well with IPCC definitions and categories. The elaborate explanation here should facilitate reviewing by experts. Finally, the report also presents an overview of the nitrous oxide emissions from agricultural soils and the underlying data used in the 1990-2003 period.