Nanjing University of Information Science and Technology

About: Nanjing University of Information Science and Technology is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Precipitation & Aerosol. The organization has 14129 authors who have published 17985 publications receiving 267578 citations. The organization is also known as: Nan Xin Da.

Changes in fertilizer‐induced direct N2O emissions from paddy fields during rice‐growing season in China between 1950s and 1990s

Abstract: Nitrogen fertilizer-induced direct nitrous oxide (N2O) emissions depend on water regimes in paddy fields, such as seasonal continuous flooding (F), flooding‐midseason drainage‐reflooding (F-D-F), and flooding‐midseason drainage‐reflooding‐moist intermittent irrigation but without water logging (F-D-F-M). In order to estimate the changes in direct N2O emission from paddy fields during the rice-growing season in Mainland of China between the 1950s and the 1990s, the country-specific emission factors of N2O-N under different water regimes combined with rice production data were adopted in the present study. Census statistics on rice production showed that water management and nitrogen input regimes have changed in rice paddies since the 1950s. During the 1950s‐ 1970s, about 20‐25% of the rice paddy was continuously waterlogged, and 75‐80% under the water regime of F-D-F. Since the 1980s, about 12‐16%, 77%, and 7‐12% of paddy fields were under the water regimes of F, F-D-F, and F-D-F-M, respectively. Total nitrogen input during the rice-growing season has increased from 87.5kgNha � 1 in the 1950s to 224.6kgNha � 1 in the 1990s. The emission factors of N2O-N were estimated to be 0.02%, 0.42%, and 0.73% for rice paddies under the F, F-D-F, and F-D-F-M water regimes, respectively. Seasonal N2O emissions have increased from 9.6Gg N2O-N each year in the 1950s to 32.3Gg N2O-N in the 1990s, which is accompanied by the increase in rice yield over the period 1950s‐1990s. The uncertainties in N2O estimate were estimated to be 59.8% in the 1950s and 37.5% in the 1990s. In the 1990s, N2O emissions during the ricegrowing season accounted for 8‐11% of the reported annual total of N2O emissions from croplands in China, suggesting that paddy rice development could have contributed to mitigating agricultural N2O emissions in the past decades. However, seasonal N2O emissions would be increased, given that saving-water irrigation and nitrogen inputs are increasingly adopted in rice paddies in China.

Development of biological soil quality indicator system for subtropical China

Abstract: The hilly red soil region of subtropical China is a major rice producing area, where over-exploitation and non-agricultural uses of paddy soils have decreased soil quality and rice productivity. Our objectives were to develop and evaluate a soil quality assessment protocol for Yujiang County in Jiangxi Province. A variety of soil samples, representing the spatial homogeneity in 114 paddy fields, were collected and analyzed for several chemical and physical properties. Pearson correlation analysis between rice yield and the various soil properties was used to identify potential soil quality indicators. Principal component analysis (PCA) was then used to group the indicators into appropriate soil quality factors. A minimum data set (MDS) including soil organic matter, available nitrogen, available phosphorus, slowly available potassium and sand content accounted for 77.9% of the quality variation among soils. A soil quality index (SQI) was calculated using the Integrated Quality Index (IQI) equation. Significant correlation between the SQI and rice yield indicated the index had high biological significance for Jiangxi province and other paddy areas with similar soils.