Suppression of NHSubscript3/Subscript and NSu

Authors: Kwang Seop Kim Man Park Choong Lyeal Choi Dong Hoon Lee Young Jin Seo Chan Yong Kim Jong Su Kim SeokIn Yun HeeMyong Ro Sridhar Komarneni

Publish Date: 2011/01/18

Volume: 11, Issue: 3, Pages: 416-422

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Abstract

A large amount of nitrogen N fertilizers has been broadcasted over soil surface for reliable crop production Unfortunately the broadcasted N vulnerable to volatilization and leaching can lead to serious environmental problems As a new approach to mitigate N loss of broadcasted fertilizers massive intercalation of urea into montmorillonite MMT was recently proposed to innovatively enhance the urea use efficiency This study focuses on demonstrating the behaviors of the urea intercalated into MMT in soilsA eutectic Ca07/Mg03urea6Cl2 complex was intercalated into MMT at a weight ratio of complex/MMT of 10 the resulting product was referred to as Ca/MgUCM Behaviors of broadcasted urea were examined on both bare and planted soils Soil ureaN ammonium and nitrate were analyzed using a spectrophotometer after extraction of the soil by 2 M KCl solution Ammonia emitted from the soil was collected by a closeddynamic air flow method and NH3 concentration was determined by titration with a standard 0005 M H2SO4 In particular urea labeled with 5 15N atom was used in evaluating N uptake Emission of N2O was evaluated by collecting all the gases from the soil using a PVC columnA dramatic difference between the ureabroadcasted and Ca/MgUCMbroadcasted soils was found in ammonia emission A peak emission rate decreased from 385 N mg m−2 h−1 of the ureabroadcasted soil to 283 N mg m−2 h−1 of the Ca/MgUCMbroadcasted soil This remarkable suppression of the initial ammonia emission could be explained by the events such as delayed urea hydrolysis dissolution of ammonia into soil waters especially water adsorbed on MMT adsorption of ammonia by MMT and delivery of urea molecules into inner soils through deintercalation and diffusion Uptake amounts of total N and 15N by whole perilla plants were substantially increased by Ca/MgUCM broadcasting compared with urea broadcasting The intercalation also suppressed N2O emission noticeably At the same dosage of urea Ca/MgUCM broadcasting led to an increase in dry weight of kale shoot by 38 compared with urea broadcastingThis study has successfully demonstrated that the urea intercalation led to considerable suppression of both ammonia and N2O emissions compared to that with ureabroadcasted soils but without any noticeable effects on fast effectiveness of urea in the former Thus clayintercalated urea as a fast effective fertilizer is expected to greatly contribute to mitigation of ammonia and N2O emissions along with green and sustainable crop production

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