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Yeomyeong Lee,Sieun Lee,Juhee Lee,Seongwoo Choi,Sang Yoon Kim 한국토양비료학회 2020 한국토양비료학회지 Vol.53 No.4
Nitrogen (N) fertilization improves crop growth and productivity, but can cause adverse environmental problems in particular nitrous oxide (N₂O) emissions, requiring reasonable fertilization strategy for a better agroecosystem. Our goal was to understand how different N fertilizations influence greenhouse gas (GHG) emissions (CO₂, CH₄, and N₂O) and global warming potential (GWP), soil properties, and productivity from lettuce (Lactuca sativa) cultivated fields [control (No fertilizer), urea ((NH₂)₂CO), ammonium sulfate ((NH₄)₂SO₄), and compost (10 Mg ㏊<SUP>-1</SUP>)]. Inorganic N fertilizations significantly increased GWP as compared to the control, mainly increasing N₂O emissions. However, CH₄ and CO₂ were not significantly different among all treatments, indicating N₂O emissions were main contributors to be influenced by N fertilizations. Ammonium sulfate showed higher GWP than the urea. However, GWP was lowest in the control, but was not significantly different as compared to the compost. Lettuce yield was significantly enhanced by chemical N fertilizations, showing much greater biomass in ammonium sulfate than the urea. Lettuce yield with the compost was less than with chemical fertilizations, but significantly greater than control. GWP per productivity as an indicator for sustainability was lowest in compost treatment among all treatments mainly due to reduced GHG emissions by less mineralization. Conclusively, compost application could be a sustainable way to mitigate GHG emissions, maintaining soil quality and productivity in upland soils.
Yeomyeong Lee,Seongwoo Choi,Juhee Lee,Hyerin An,Chang Hoon Lee,Pyoung Ho Yi,Seung Tak Jeong,Sang Yoon Kim 한국토양비료학회 2021 한국토양비료학회지 Vol.54 No.4
Enhancing soil carbon sequestration potential is one of the most important strategies to contribute to climate change mitigation. However, basic characteristics of soil organic matter (SOM) distribution and its decomposition rate in soils where fruits and vegetables are cultivated have rarely been investigated though this information is necessary for a better understanding of carbon sequestration. In this study, soil samples were collected from plastic film house fields cultivated for various fruits and vegetables including cucumber, Korean melon, pepper, and pumpkin. Soil chemical properties including characteristics of SOM distribution by chemical oxidizable organic fractions, and their decomposition rates by estimating soil respiration rate (Q10 value) via soil incubation were evaluated. Total carbon content in pepper soil showed highest (28.7 g kg<SUP>-1</SUP>) and followed by pumpkin (23.9 g kg<SUP>-1</SUP>), cucumber (17.6 g kg<SUP>-1</SUP>), and Korean melon (11.8 g kg<SUP>-1</SUP>). Highest Q10 value was observed in pepper cultivated soils (1.65) that could be comparatively sensitive for SOM degradation, and then followed by cucumber (1.42), pumpkin (1.36), and Korean melon (0.82). Labile carbon as easily available form was highest in pepper cultivated soils (20.7 g kg<SUP>-1</SUP>), and followed by pumpkin (18.0 g kg<SUP>-1</SUP>), cucumber (14.6 g kg<SUP>-1</SUP>), and Korean melon (9.9 g kg<SUP>-1</SUP>), showing significantly positive correlations with soil total and labile carbons. Our results provided useful information on SOM distribution and decomposition, which is necessary to manage and thus to further enhance carbon sequestration in soils.
Yeomyeong Lee(이여명),Hyerin An(안혜린),Juhee Lee(이주희),Seongwoo Choi(최성우),Sang Yoon Kim(김상윤) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11
Nitrogen (N) fertilization improves crop yield, but may cause serious environmental problems, increasing ammonia (NH₃) and greenhouse gases (GHGs including CO₂, CH₄ and N₂O) emissions, requiring rational fertilization strategy for a better agroecosystem. Organic fertilizer can improve soil cation exchangeable capacity, which could decrease potential N losses and increase crop yield. However, combined application of organic and inorganic fertilizers was not systematically investigated. Our study investigated NH₃ volatilization, GHGs emissions, their intensity (GHGI), soil properties, and productivity during maize and cabbage cultivation period (two cropping seasons in a year) in upland field. The different treatments were installed with equivalent N rate including NPK (sole inorganic fertilizer as urea), compost (sole compost), NPK+compost (inorganic fertilizer and compost, 50%:50%) except control (no fertilizer). During two cropping periods, total cumulative NH₃ volatilizations were significantly increased with all fertilizations as compared to the control. Compost, NPK+compost applications were effective on mitigating NH₃ emissions during cultivation although the same rate of N was incorporated in all treatment except the control. As compared to NPK treatment, compost (0.83 g m<SUP>-2</SUP>), NPK+compost (0.92 g m<SUP>-2</SUP>) applications effectively mitigated N₂O emissions by ca. 54-59% as compared to NPK treatment (2.0 g m<SUP>-2</SUP>). CO₂ and CH₄ emissions were increased with fertilizations, but there was not significant difference among those treatments. Maize and cabbage productivities significantly increased with N fertilizations, but was highest at NPK which did show significant difference with NPK+compost, improving overall soil quality including soil pH, soil organic matter content, available phosphorus, and CEC etc. The GHGI, a sustainable index, was lowest in NPK+compost treatment (2.54 Mg Mg<SUP>-1</SUP>) followed by control (3.36 Mg Mg<SUP>-1</SUP>) > NPK (3.30 Mg Mg<SUP>-1</SUP>) ≒ compost (3.30 Mg Mg<SUP>-1</SUP>), suggesting the promising N management practice in upland soils. Conclusively, combined amendments of inorganic and organic fertilizers could be a sustainable and promising way to mitigate N losses, greenhouse gas emissions, and to enhance crop productivity and soil quality in maize and cabbage cultivated soils.
Juhee Lee(이주희),Seoungwoo Choi,Yeomyeong Lee,Hyerin An,Sang Yoon Kim 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11
Ammonia (NH₃) volatilization is one of the major nitrogen (N) losses from rice paddies, which leads to low crop productivity lowering N use efficiency as well as deteriorating environmental air quality. Comparing to urea, ammonium sulfate can decrease the soil and water pH, which may reduce NH₃ volatilization loss in rice paddy soils. However, its impact of ammonium sulfate of NH₃ volatilization has been largely unexplored in paddy fields. In this study, the field study was conducted to investigate NH₃ volatilization in rice paddy soils amended with different type of N fertilizers, urea [(NH₂)₂CO], and ammonium sulfate [(NH₄)₂SO₄], at a rate of 0 (PK, control), 45, 90, and 180 kg N ha<SUP>-1</SUP> before the rice transplanting. Moreover, biochemical properties including extractable NH₄<SUP>+</SUP>-N in soils and irrigation water including pH, EC were investigated during cultivation. Application of both N fertilizers significantly increased the amount of NH₃ volatilization as compared to control. NH₃ emissions significantly increased with increasing N application levels, irrespective of types of fertilizers. Ammonium sulfate application effectively reduced NH₃ volatilization, which showed approximately 5 times lower emission than the urea application. In particular, ammonium sulfate application significantly reduced pH at the initial rice cultivation season, but increased EC in irrigation water. Soil NH₄<SUP>+</SUP>-N contents were higher in ammonium sulfate amended soils than the urea applications. This result indicates that more soil NH₄<SUP>+</SUP>-N was released in ammonium sulfate treatment, but NH₃ volatilization was suppressed in the surface water due to its lower pH condition, showing effective reduction of NH₃ emissions. In conclusion, ammonium sulfate application could be considered a promising way to effectively mitigate NH₃ volatilization in rice paddies.