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Nitrogen balance acts an indicator for estimating thresholds of nitrogen input in rice paddies of China
2021
Ding, Wencheng | Xu, Xinpeng | Zhang, Jiajia | Huang, Shaohui | He, Ping | Zhou, Wei
Decision-making related to nitrogen (N) fertilization is a crucial step in agronomic practices because of its direct interactions with agronomic productivity and environmental risk. Here, we hypothesized that soil apparent N balance could be used as an indicator to determine the thresholds of N input through analyzing the responses of the yield and N loss to N balance. Based on the observations from 951 field experiments conducted in rice (Oryza sativa L.) cropping systems of China, we established the relationships between N balance and ammonia (NH₃) volatilization, yield increase ratio, and N application rate, respectively. Dramatical increase of NH₃ volatilizations and stagnant increase of the rice yields were observed when the N surplus exceeded certain levels. Using a piecewise regression method, the seasonal upper limits of N surplus were determined as 44.3 and 90.9 kg N ha⁻¹ under straw-return and straw-removal scenarios, respectively, derived from the responses of NH₃ volatilization, and were determined as 53.0–74.9 and 97.9–112.0 kg N ha⁻¹ under straw-return and straw-removal scenarios, respectively, derived from the maximum-yield consideration. Based on the upper limits of N surplus, the thresholds of N application rate suggested to be applied in single, middle-MLYR, middle-SW, early, and late rice types ranged 179.0–214.9 kg N ha⁻¹ in order to restrict the NH₃ volatilization, and ranged 193.3–249.8 kg N ha⁻¹ in order to achieve the maximum yields. If rice straw was returned to fields, on average, the thresholds of N application rate could be theoretically decreased by 17.5 kg N ha⁻¹. This study provides a robust reference for restricting the N surplus and the synthetic fertilizer N input in rice fields, which will guide yield goals and environmental protection.
Mostrar más [+] Menos [-]Nitrogen budgets in Japan from 2000 to 2015: Decreasing trend of nitrogen loss to the environment and the challenge to further reduce nitrogen waste
2021
Hayashi, Kentaro | Shibata, Hideaki | Oita, Azusa | Nishina, Kazuya | Ito, Akihiko | Katagiri, Kiwamu | Shindo, Junko | Winiwarter, Wilfried
The benefits of the artificial fixation of reactive nitrogen (Nr, nitrogen [N] compounds other than dinitrogen), in the form of N fertilizers and materials are huge, while at the same time posing substantial threats to human and ecosystem health by the release of Nr to the environment. To achieve sustainable N use, Nr loss to the environment must be reduced. An N-budget approach at the national level would allow us to fully grasp the whole picture of Nr loss to the environment through the quantification of important N flows in the country. In this study, the N budgets in Japan were estimated from 2000 to 2015 using available statistics, datasets, and literature. The net N inflow to Japanese human sectors in 2010 was 6180 Gg N yr⁻¹ in total. With 420 Gg N yr⁻¹ accumulating in human settlements, 5760 Gg N yr⁻¹ was released from the human sector, of which 1960 Gg N yr⁻¹ was lost to the environment as Nr (64% to air and 36% to waters), and the remainder assumed as dinitrogen. Nr loss decreased in both atmospheric emissions and loss to terrestrial water over time. The distinct reduction in the atmospheric emissions of nitrogen oxides from transportation, at −4.3% yr⁻¹, was attributed to both emission controls and a decrease in energy consumption. Reductions in runoff and leaching from land as well as the discharge of treated water were found, at −1.0% yr⁻¹ for both. The aging of Japan's population coincided with the reductions in the per capita supply and consumption of food and energy. Future challenges for Japan lie in further reducing N waste and adapting its N flows in international trade to adopt more sustainable options considering the reduced demand due to the aging population.
Mostrar más [+] Menos [-]Enhancement of the denitrification in low C/N condition and its mechanism by a novel isolated Comamonas sp. YSF15
2020
Su, Jun feng | Yang, Shu | Huang, Ting lin | Li, Min | Liu, Jia ran | Yao, Yi xin
A novel denitrifying bacterium YSF15 was isolated from the Lijiahe Reservoir in Xi’an and identified as Comamonas sp. It exhibited excellent nitrogen removal ability under low C/N conditions (C/N = 2.5) and 94.01% of nitrate was removed in 18 h, with no accumulation of nitrite. PCR amplification and nitrogen balance experiments were carried out, showing that 68.92% of initial nitrogen was removed as gas products and the nitrogen removal path was determined to be NO3−-N→NO2−-N→NO→N2O→N2. Scanning electron microscopy and three-dimensional fluorescence spectroscopy were used to track extracellular polymeric substances (EPS). The results show that complete-denitrification under low C/N conditions is associated with EPS, which may provide a reserve carbon source in extreme environments. These findings reveal that Comamonas sp. YSF15 can provide novel basic materials and a theoretical basis for wastewater bioremediation under low C/N conditions.
Mostrar más [+] Menos [-]Quantification of nitrogen transformation and leaching response to agronomic management for maize crop under rainfed and irrigated condition
2020
Srivastava, R.K. | Panda, R.K. | Chakraborty, Arun
Nitrogen (N) plays an important role in agriculture crop production but the increasing application of nitrogen increases the possibilities of groundwater contamination through nitrate leaching. Nitrate leaching is the inevitable part of agriculture production which occurs during nitrogen fertilization. Hence, the quantification of nitrogen fertilizer is required to reduce nitrate leaching. In this study, nitrogen transformation and transport such as ammonium (NH₄⁺) and nitrate (NO3−) at different soil depths and maize crop growth stages were measured during field experiments for two sowing dates (timely and delay) and four N fertilization levels under irrigated (year 2013 and 2014) and rainfed (year 2012 and 2014) conditions for maize crop. NH₄⁺, NO3− and total nitrogen concentrations were measured using spectrophotometer at 410 nm and Kjeldahl method at varying soil depths and maize crop growth stages. Thereafter, nitrogen balance approach was used to estimate the NO3− leaching. Results indicated that NO3− leaching in irrigated condition was higher 109% in N₇₅, 179% in N₁₀₀, and 292% in N₁₂₅ level respectively in comparison to the N₀ level in timely sowing date, while in delayed sowing date, leaching was higher 54% in N₇₅, 123% in N₁₀₀, and 184% in N₁₂₅ level respectively in comparison to N₀ level. In rainfed, the NO3− leaching was higher 30% in N₆₀, 59% in N₈₀, and 99% in N₁₀₀ level respectively in comparison to N₀ level for the timely sowing date, while in delayed sowing, leaching was higher 23% in N₆₀, 44% in N₈₀, and 78% in N₁₀₀ level respectively in comparison to N₀ level. The results indicate that leaching losses were less in timely sowing dates for both rainfed and irrigated maize. The study further reveals that sowing dates combination with N levels could be an effective management strategy to reduce NO3− leaching by minimizing the N fertilization.
Mostrar más [+] Menos [-]Nitrogen balances and leaching in four agricultural catchments in southeastern Norway
1998
Bechmann, M. | Eggestad, H.O. | Vagstad, N. (Jordforsk, Centre for Soil and Environmental Research, N-1432 As (Norway))
Nitrogen efficiency in global animal production
1998
Hoek, K.W. van der (National Institute of Public Health and the Environment (RIVM), PO Box 1, NL-3720 BA Bilthoven (Netherlands))
Regional mass budgets of oxidized and reduced nitrogen and their relative contribution to the nitrogen inputs of sensitive ecosystems
1998
Fowler, D. | Sutton, M.A. | Smith, R.I. | Pitcairn, C.E.R. | Coyle, M. | Campbell, G. | Stedman, J. (Institute of Terrestrial Ecology, Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB (United Kingdom))
Seasonal variability and mitigation options for N2O emissions from differently managed grasslands
1998
Kammann, C. | Grunhage, L. | Muller, C. | Jacobi, S. | Jager, H.J. (Institute for Plant Ecology, University of Giessen, Heinrich-Buff-Ring 38, D-35392 Giessen, Germany)
Feasibility of national nitrogen balances
1998
Slak, M.F. | Commagnac, L. | Lucas, S. (ENITA de Bordeaux, Laboratoire Sols et Paysages (France))
Agricultural nutrient balances as agri-environmental indicators: an OECD perspective
1998
Parris, K. (Directorate for Food, Agriculture and Fisheries, OECD, Paris (France))