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 ha -1)]. 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.
Ethephon is one of the chemical stimulator of crop growth that is also considered as a structural analogue of coenzyme M (CoM), having a promising potential for methanogenic inhibitor. However, the effect of ethephon application on greenhouse gas (GHG) emissions under rice cultivation has not been studied yet. In this pot experiment, different levels of ethephon (0, 2.5, 5 and 10 mg L -1 ) were applied at the presence or absence of manure compost as an organic amendment to study its effect on GHGs emissions in particular CH4 and rice productivity during the cultivation. Application of ethephon effectively suppressed CH4 emissions in particular the initial periods (ca. 3 weeks) right after the application as compared with control soil during rice cultivation, but did not significantly affect N2O emissions. In addition, the maximum CH4 reduction (82% reduction over control) was found at 10 mg L -1 ethephon application right after its addition for 3 weeks during rice cultivation. Rice productivity and yield properties were mainly affected by ethephon application, enhancing ripened grains and number of grains per panicle. Soil properties were not influenced by ethephon application except for available phosphate, which is probably due to enhanced root growth in rhizosphere soils. Conclusively, ethephon could be a new and pioneering amendment for reducing CH4 emission in particular at the initial 3 weeks after the application without increasing other GHG emissions and enhancing rice productivity in paddy soils.
Nitrogen (N) is one of the most important elements in agriculture. However, excessive fertilization may cause serious global environmental issues including increasing greenhouse gases (GHGs) in agricultural environments. Combination of organic and inorganic fertilizations may enhance nutrient holding capacity and productivity, mitigation potential N losses during cultivation. However, these effects remain unclear. We investigated GHGs emissions, their intensity (GHGI), soil characteristics, and productivity in a maize filed under different N fertilization regimes with equivalent N rate including NPK (urea), Compost (compost), NPK+ Compost (urea and compost) except control (no fertilizer). Inorganic fertilizations significantly stimulated N 2 O emission as compared to the control. Compost and NPK+Compost treatments effectively mitigated N 2 O emissions by ca. 50% as compared to NPK treatment (0.8 g m -2 ). CO 2 and CH 4 emissions were not mainly influenced or negligible by N fertilizations during cultivation. Overall soil qualities were improved by compost and NPK+Compost applications including extractable NH 4 + -N and CEC. The GHGI, a sustainable indicator, was lowest in NPK+Compost treatment, suggesting the promising N management practice. Conclusively, combined amendments of inorganic and organic fertilizers could be a better way to reduce potential N losses and increase productivity and soil quality in maize cultivated soils.
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 (Q 10 value) via soil incubation were evaluated. Total carbon content in pepper soil showed highest (28.7 g kg -1 ) and followed by pumpkin (23.9 g kg -1 ), cucumber (17.6 g kg -1 ), and Korean melon (11.8 g kg -1 ). Highest Q 10 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 -1 ), and followed by pumpkin (18.0 g kg -1 ), cucumber (14.6 g kg -1 ), and Korean melon (9.9 g kg -1 ), 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.
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