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1 Korean Journal of Environmental Agriculture Korean J Environ Agric (2013) Online ISSN: Vol. 32, No. 4, pp Print ISSN: Research Article Open Access 간척지논토양의염농도가메탄배출에미치는영향 임창현, 1 김상윤, 1 정승탁, 1 김건엽, 2** 김필주 1,3* 1 경상대학교응용생명과학부, 2 농촌진흥청국립농업과학원, 3 경상대학교농업생명과학연구원 Effect of Salt Concentration on Methane Emission in a Coastal Reclaimed Paddy Soil Condition: Pot Test Chang-Hyun Lim, 1 Sang-Yoon Kim, 1 Seung-Tak Jeong, 1 Gun-Yeob Kim 2** and Pil-Joo Kim 1,3,* ( 1 Division of Applied Life Science, Gyeongsang National University, Jinju, , South Korea, 2 National Academy of Agricultural Science, RDA, 3 Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, , South Korea) Received: 5 September 2013 / Revised: 26 September 2013 / Accepted: 7 October 2013 c 2013 The Korean Society of Environmental Agriculture This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract BACKGROUND: Salt accumulation in coastal reclaimed soil can decrease plant growth and productivity, which could lead to considerable variation of methane(ch 4 ) emission in a rice paddy. The objective of this study was to evaluate the effect of salt concentration on CH 4 emission in a coastal reclaimed soil. METHODS AND RESULTS: The effect of salt concentration on CH 4 emission and rice growth characteristics was studied by pot test, which packed by reclaimed paddy soils collected from Galsa, Hadong, Gyeongnam province. Electrical conductivity(ec) of each treatment was controlled by 0.98, 2.25, 5.05 and 9.48 ds/m and CH 4 emission was characterized a week interval by closed chamber method during rice cultivation. The CH 4 emission rate was significantly decreased with increase of salt accumulation, but total CH 4 flux in EC 5.50 ds/m treatment was lower than those of EC 9.48 ds/m treatment. It seems because of higher content of water soluble SO 4 2- in EC 5.50 ds/m treatment than those of EC 9.48 ds/m treatment. Rice growth and grain yield were significantly decreased with increase of salt accumulation. Soil properties, especially EC and ph were negatively correlated with CH 4 flux, while rice growth characteristics like plant height and tiller number show significantly positive correlation with CH 4 flux. CONCLUSION(S): Conclusively, salt accumulation significantly decreased CH 4 flux in a rice paddy, which could be useful information for evaluating CH 4 flux in reclaimed area in Korea. Key words: CH 4 emission, Reclaimed soil, Salt accumulation * 교신저자 (corresponding author), Phone: ; Fax: ; pjkim@gnu.ac.kr ** 공동교신저자 (co-corresponding author), Phone: ; Fax: ; gykim1024@korea.kr 서론 메탄 (CH 4) 은이산화탄소 (CO 2) 와더불어주요온난화가스로서지구전체온실가스배출량의약 20 % 이상을차지하고있다 (IPCC, 2007). 대기중메탄농도는약 1.7 ppmv로서 (Le Mer and Roger, 2001) 1800년대를기준으로연간 252

2 Effect of Salt Concentration on Methane Emission in a Coastal Reclaimed Paddy Soil Condition: Pot Test % 가량증가해오고있으며 (Conrad, 2007), 이산화탄소의약 25배에달하는지구온난화잠재능 (Global warming potential, GWP) 때문에매우중요한온실가스로알려져있다 (Blake and Rowland, 1988; Rodhe, 1990; Minami and Neue 1994). 전체메탄배출량의약 70 % 는인위적활동 (Anthropogenic activity) 에의해발생되는것으로추정되며, 지구전체메탄배출량의약 5-29 % 에해당하는 Tg/yr 이벼재배과정에서배출되고있어수도작논은주요한메탄배출원으로간주되고있다 (Le Mer and Roger, 2001). 최근국내에서는 1960년이후부터감소되고있는농업용지의확충을위한대책으로간척사업을진행해오고있으며, 상당부분의간척지가벼재배를위한농경지로서활용되고있다 ( 한국농어촌공사보고서, 2009). 간척농경지는일반농경지와다르게토양내염농도가매우높아일반농경지에비해높은 ph를가지고있을뿐만아니라, 다른양이온에비해칼슘의함량이상대적으로낮아이온의불균형이존재하는것으로알려져있다. 토양내경반층이형성되어용적밀도가높고공극률이낮아토양의물리성또한매우불량하여벼생육및수량그리고미질등이일반농경지에비해감소되는것으로알려져있다 (Jung and Ryu, 2005). 수도작논에서배출되는약 % 의메탄은벼의통기조직 (Arenchyma channel) 을통하여대기중으로배출되며 (Cicerone and Shetter, 1981; Holzapfel-Pschorn and Seiler, 1986; Holzapfel-Pschorn et al., 1986; Wassmann et al., 1996; Wassmann and Aulakh, 2000), 벼생육은메탄배출량을조절하는주요한인자로서보고된바있다 (Ali et al., 2009; Kim et al., 2012, 2013). 간척지수도작논의염농도에따른메탄배출특성이크게다를것으로판단되어지나, 이에대한연구는아주드물게이루어지고있는실정이다. 메탄발생은메탄생성균 (Methanogens) 과메탄산화균 (Methanotrophs) 의활동도에영향을받으며, Patel 과 Roth (1977) 는토양내 NaCl과같은염의축적이메탄생성균의생장과메탄생성을억제시킬수있으며, Balttlet 등 (1987) 또한토양내염농도의증가가메탄발생량을유의하게감소시키는것으로보고된바있다. 하지만현재까지상당부분의연구가비농경지에서이루어지거나, 특정미생물만을분리하여 in vitro 상에서주로이루어졌기때문에실제농경지에서염농도가메탄배출량에미치는영향에대한정확한평가는이루어지지않고있는실정이며특히국내에서는이에관한연구가거의전무한편이다. 본연구에서는간척지내서로다른염농도가메탄배출량에미치는영향을평가하기위하여, 염농도가다른간척지논토양을선발하여메탄배출량을평가함과동시에토양의화학성및벼의생육특성을 pot 실험을통하여조사하였다. 재료및방법 조사대상토양선발본연구를위한공시토양으로경상남도하동군금성면갈사리에위치한갈사간척지의토양을선정하였다. 갈사간척지는경남하동군금산면가덕리, 갈사리고포리일대에위치한간척지로서, 총면적은약 651 ha로약 403 ha가개답되어 1994년부터본격적으로답상태영농에이용되어져왔으며, 갈사간척지의평균적인토양이화학성은일반적인간척지논토양의특성과비슷하였다 (Koo et al., 1998). 실험전갈사간척지 16개지점에서토양을채취하여토양의이화학적특성분석을실시하였다. 채취된간척지논토양에서염농도에따른메탄발생차이를평가하기위하여분석된토양들은염농도에따라크게네가지로분류하였다. 간척지토양과비교를위한저염도 (Low, EC 0.98 ds/m), 보통염도 (Medium, EC 2.25 ds/m) 토양과간척지토양인고염도 (High, EC 5.05 ds/m), 초고염도 (Very high, EC 9.48 ds/m) 로나누어토양을선발하였으며, 이때선발된네지역의토양의이화학적특성은 Table 1과같다. Table 1. Chemical properties of the selected soils before the experiment Soil properties Salt accumulation level Low Medium High Very high Electrical conductivity (ds/m) ph (1:5 with H 2O) Organic matter (g/kg) Exchangeable cations (cmol + /kg) K Ca Mg Na Water soluble Fe (mg/kg) Water soluble SO 2-4 (mg/kg) Sodium adsorption ratio (SAR) 분석방법상의차이는있으나저염도와보통염도를제외한고염도와초고염도의경우 U.S. Soil Salinity Laboratory Staff의염류집적지기준인 EC 4.0 ds/m의기준을초과하는것으로보아상당량의염류를포함하고있음을알수있었다. 상대적으로조사토양내 SAR 값은 13 이하로나트륨자체에의한작물생육의장해나토양의물리성을불량하게만들가능성은그리높지않은것으로판단되었다. 따라서본토양에서염농도가메탄배출량에미치는효과를검증하기에적합한토양으로판단되었다.

3 254 LIM et al. 포트실험 간척농경지에서염농도에따른메탄발생특성을조사하기위하여포트실험을실시하였다. 실험대상으로선정된토양은채취후자연건조후사분 (<10 mm) 한후벼재배를위한포트실험에사용되었다. 사분된토양 13.5 kg을 Wagner pot(1/2000 a size) 25 cm 높이까지가비중 1.2 g/cm 3 의조건으로충진한후토양에유기물원으로서분쇄볏짚 5 Mg/ha 비율로처리하였다. 농촌진흥청표준시비량을근거로하여이앙 1일전기비로 50 kg N/ha( 요소 ), 45 kg P 2O 5/ha( 용과린 ), 40 kg K 2O /ha( 염화가리 ) 로전층시비하였으며, 벼는조생종품종인오대벼 (Oryza sativa L.) 를공시작물로선택하여각포트당 3포기를손이앙하였다. 1차추비 ( 분얼비 ) 는이앙 2주일후질소를 20 kg/ha를처리하였으며, 2차추비 ( 수비 ) 는이앙 2개월후 ( 출수 15일전 ) 에질소와가리을각각 20, 17 kg/ha를처리하였다 (RDA, 1999). 실험포트는무작위로배치되었으며, 모든처리구는 3반복으로하여실험을수행하였다. 생육기간동안약 5 7 cm 높이로물수위를유지하였으며, 벼수확을위하여수확약 1달전에배수를실시하였으며, 이앙후 106일이경과된후수확을실시하였다. 메탄가스채취및정량분석가스시료채취는이전연구에서사용된방법을기준으로벼재배기간동안일주일에 1회, 메탄발생량이가장많은오후 2 3시사이에실시하였다 (Lim et al., 2011). 주 1회가스시료채취는당일의날씨와같은환경에영향을받을수있어한계점이있을수있으나, 일반적으로통용되는방법이며본실험은포트실험으로필드실험에비해외부환경이잘통제되었다. 벼재배기간중벼를통해발생되는메탄가스는폐쇄형챔버법 (Closed chamber method, Rolston, 1986) 을이용하여시료를채취하였으며, 원통형아크릴챔버내부에공기를혼합하기위해 64 cm 2 (8 cm 8 cm) 사이즈의소형팬을설치하여시료의균질성을확보하였다. 메탄포집시간은 30분동안실시하였으며 50 ml 주사기를이용해채취하였다. 이때챔버내부와토양의온도를각각측정하였다. 메탄가스는가스크로마토그래피 (Shimadzu, GC-2010, Tokyo) 를이용하여측정하였으며, 이때 Packed Porapak NQ column( mesh) 을이용하였으며, 검출기는불꽃이온화검출기 (Flame ionization detector, FID) 를사용하여분석하였다. 이때분석조건은컬럼 80, 주입구 100, 검출기 110 로설정하였으며, 운반가스로헬륨 (He) 을연소가스로수소 (H 2) 를이용하였다. 재배기간중포트로부터배출되는메탄배출량은아래의식을이용하여계산하였다 (Rolston, 1986). F = ρ. V/A.Δc/Δt.273/T F: 단위시간당메탄배출량 (mg/m 2 /hr) ρ: 메탄가스의밀도 0.714(mg/cm 3 ) A: 챔버표면적 ( 가로 (m) 세로 (m):m 2 ) V: 챔버부피 (A h:m 3 ) Δc: 시료채취전후의농도차 (nl/cm 3 ) Δt: 시료채취시간 (hr) T: 273+ 측정시간중평균온도 ( ). 재배기간중발생된총메탄발생량은 Singh 등 (1999) 이도입한식을이용하여도출하였다. 총메탄발생량 (Seasonal CH 4 flux) = Σ n i (R i D i) Seasonal flux: 재배기간중발생된총메탄발생량 (CH 4 g/m 2 ) R i: i번째샘플링기간내일메탄발생량 (g/m 2 /day) D i: i번째기간내샘플링간격일수 n: 샘플링간격 토양의이화학적특성조사벼재배기간중에토양의산화환원전위 (Eh) 를조사하였으며토양면으로부터약 5cm 깊이에백금전극 (Platinum electrode) 을설치하여산화환원전위측정기 (Eh meter, PRN-41, DKK-TOA Corporation) 를이용하여측정하였다. 시험전공시토양과수확후채취된토양은자연건조후사분 (<2 mm) 하여화학성분석에이용하였다. 토양의 ph와 EC는토양과물을 1:5 비율로침출후산도측정기 (ph meter, Orion 3 star, Thermo Electron Corporation) 와전기전도도측정기 (EC meter, Orion 150A +, hermo Electron Corporation) 로각각측정하였다. 치환성양이온은 1N NH 4OAc로침출후 ICP-OES(Inductively coupled plasma-optical emission spectrophotometer Perkin Elmer Model OPTIMA 4300DV, Shelton Connecticut USA) 를이용하여측정하였다. 유기물은 Tyurin 법을이용하여측정하였다 (RDA, 1988). 토양용액중의 Ca 2+ 와 Mg 2+ 에대한농도비를이용하여 SAR(Sodium adsorption ratio) 을다음과같이계산하였다 (Sposito and Mattigod, 1997). 통계분석 염농도에따른토양의화학성과메탄배출량은 SAS software(sas Institute Inc., 1995) 를이용하여 One-way ANOVA 방식으로처리효과를비교하였으며, 처리효과가인정될경우최소유의차 (Least significant difference, LSD) 를이용하여처리구간의평균값을비교하였다. 결과및고찰 염농도에따른메탄배출특성염농도가다른논토양으로부터벼재배기간중메탄배출량변화를조사한결과, 벼이앙후시간이경과함에따라토양의환원조건발달과벼생육이증진되면서메탄배출량은크게증가하는경향을보였다 (Fig. 1). 특히대부분의메탄은벼생육초기인이앙후 13 44일사이에서집중적으로발생되는것으로조사되었다. 일반적으로수도작논에서메탄의배

4 Effect of Salt Concentration on Methane Emission in a Coastal Reclaimed Paddy Soil Condition: Pot Test 255 CH 4 emission rate (mg/m 2 /hr) Eh (mv) CH 4 Eh Days after transplanting EC 0.98 ds/m EC 2.25 ds/m EC 5.05 ds/m EC 9.48 ds/m Fig. 1. Changes of CH 4 emission rates and soil Eh values at different levels of salt accumulated soils during rice cultivation. 출특성은유수형성기부터출수기사이인생육중반부에메탄배출이가장왕성하게이루어진다 (Ali et al. 2008, 2009; Lee et al. 2010). 이러한결과는토양의온도상승과메탄생성균의생장에적합한환원상태발달 (Eh vale -200 mv 이하 ) (Adhya et al., 1994; Takai, 1961; Garica et al., 2000), 벼생육에따른근권삼출물 (root exudate) 생성량증대로인한가급태유기물 (labile organic carbon) 의공급증가 (Bouwman, 1991; Wassmann et al., 1993), 벼식물체생육증대에의한메탄전이율증대 (Mariko et al., 1991) 등이메탄배출량증가의주요원인으로해석되고있다. 하지만본연구에서는이전연구결과와는다르게생육초기에다량의메탄이배출되는경향을확인하였다. 이러한결과는토양내볏짚시용으로인한다량의유기물이벼생육초기에공급됨에따라 methanogen 활성이크게증가된것으로판단되며, 이에따라벼생육초반부에메탄배출량이크게증가된것으로판단된다. 염농도에따른메탄배출은대부분의처리구에서염농도와는관계없이비슷한경향을보였으나, 저염도와보통염도에서의초기메탄배출량이고염도와초고염도에비하여더욱높게나타났다. Patel 과 Roth(1977) 의연구에의하면토양내높은염의농도가메탄생성균의성장과메탄생성을억제하는것으로보고하였으며, 본연구에서도벼생육초기에상대적으로더높게유지되었던염농도가고염도와초고염도 처리구의메탄배출량감소에큰영향을준것으로판단된다 (Fig. 2). 그러나이앙후 44일경과후염농도와관계없이메탄배출량은대부분감소하는경향을보였다. 이는담수를통한염용탈의증가및식물체를통한흡수량의증가로인한염농도의희석효과때문에메탄배출량이대부분의처리구에서큰차이를보이지않았던것으로판단된다. 이앙후 70 일경과후벼등숙을위하여배수를실시한결과토양산화환원전위는급격히증가하는경향을보였으며, 그이후의메탄배출은대부분의처리구에서관찰되지않았다. 염농도처리구별총메탄배출량 (Fig. 3) 은저염도와보통염도에서각각 93과 92 g/m 2 로가장높았으며, 고염도와초고염도에서총메탄발생량은각각 50과 58 g/m 2 로보통농도에비해약 % 낮은것으로조사되었다. Balttlet 등 (1987) 은토양내염농도의증가가메탄발생량을유의한수준으로감소시킬수있는것으로보고하였다. 하지만본연구에서는고염도처리구에서오히려총메탄배출량이초고염도처리구보다다소낮았다. 이는고염도처리구의공시토양에서초고염도처리구에비해높았던수용성황산염 (water soluble SO 4) 함량으로인해황환원균 (Sulfate reducer) 의활성이더욱증대된것으로보이며 (Table 1), 결과적으로동일한기질 (H 2 와 CH 3COOH) 을두고경쟁하는메탄생성균의활성을저감시켜고염도처리구의메탄배출량이초고염도처리구에비해다소낮게나타난것으로판단된다 (Hori et al., 1990; Ranjan et al., 2009). ph(1:5) Electrical conductivity(ds/m) ph EC Days after rice transplanting EC 0.98 ds/m EC 2.25 ds/m EC 5.05 ds/m EC 9.48 ds/m Fig. 2. Changes of phs and electrical conductivities (EC) of the percolated waters from the potted soils with different levels of salt accumulation during rice cultivation.

5 256 LIM et al. Total CH 4 flux(g/m 2 ) Grain yield (Mg/ha) Total flux Grain yield Y=1.13X X , R 2 =0.898 * Y=0.059X X+8.92, R 2 =0.999 *** Electrical conductivity(ds/m) Fig. 3. Total CH 4 fluxes and grain yields at different levels of salt accumulated soils during rice cultivation. 특히염농도와메탄산화균의활성은고도의부의상관관계가성립하는것으로조사된바있으며 (Singh et al. 2010), 간척지내다량으로존재하는황산염과암모늄이온 (NH + 4 ) 같은염의존재는 EC의증가를초래할뿐아니라, 메탄산화균과암모니아산화균 (Ammonium oxidazing bacteria) 의경쟁을유발시켜메탄의산화능을크게감소시킬수있다 (Bodelier and Laanbroek, 2004). 본연구결과를통해높은염농도는메탄생성균의활성을감소시켜실제메탄배출량을크게감소시킨것으로판단되며, 메탄산화균의활성증진효과에따른메탄배출량감소효과는거의없었던것으로평가된다. 침출수및토양의화학적특성벼재배기간중염농도별토양의침출수내 EC 변화를조사한결과 (Fig. 2), 염농도와관계없이전체처리구에서비슷한경향을보였으며전반적으로벼생육초기에가장높았다가벼의생육증가에따라서서히감소하는경향을보였다. 특히토양내염농도가높은처리구일수록침출수에서더높은 EC를나타내었다. Hanna 등 (2011) 은염의함량과메탄발생은높은역의상관관계가성립하는것으로보고하였으며, 본연구에서도동일하게염농도와메탄발생은고도의역의상관관계가성립되는것으로조사되었다 (Table 3). 염농도의 지속효과를확인하기위해공시토양과수확후토양의염농도를메탄배출량과각각상관관계를분석해본결과공시토양에서만높은상관관계가확인이되었으며수확후토양과는유의한상관관계를나타내지않았다. 이결과를통해벼재배기간중염농도는메탄배출량에영향을주는것으로판단되며, 특히초기메탄배출량감소에큰영향을주는것으로평가된다. 하지만벼생육후반부부터토양내염희석효과에의해그영향성이다소감소되는것으로보이나여전히메탄배출량에영향을주는중요한인자로서평가되었다. 벼재배기간중토양침출수의 ph 변화 (Fig. 2) 를조사한결과전체처리구에서염농도에관계없이비슷한경향의변화를보였으나, 고염도와초고염도처리구에서더높은 ph 증가를보였다. 벼생육초기에 ph가 로각처리구가비슷한경향을보였으나, 이앙후 30일이후부터고염도와초고염도처리구에서저염도와보통염도에비해 ph가 범위까지높았다. 이에반해저염도와중간염도처리구는벼재배기간전반적으로 ph가중성범위로유지되는것을확인할수있었다. 일반적으로메탄생성균은중성범위에서최적의활성을보이며 (Garcia et al., 2000), 토양내 ph에아주민감하게반응하는것으로알려져있다 (Wang et al., 1993). 고염도와초고염도처리구에서높았던 ph가메탄생성균의활성감소에영향을준것으로판단되며, 총메탄배출량과도고도의부의상관관계가있는것으로보아메탄배출량감소에도큰영향을준것으로보인다. 벼생육및수량특성수확후염농도에따른벼의생육및수량을조사한결과 (Table 2), 초장 (plant height), 분얼수 (tiller number per hill), 수당입수 (number of grains per panicle), 볏짚수량 (straw yield), 천립중 (1000 grain weight) 및등숙율 (ripened grains) 등은염의농도가높아짐에따라전반적으로감소되는경향을보였다. 일반적으로논토양에서벼재배과정중메탄배출량은토양의특성뿐만아니라벼식물체요인에의해서도크게영향을받는것으로알려져있다. 벼이앙초기토양내유기물분해되는과정중메탄이과량생성되어토양으로부터직접배출되는것과, 식물의생육이증대되면서통기조직 (aerenchyma channel) 의발달로식물을통해배출량이증대되면서메탄배출량증가가발생되는것으로알려져있다. 이때문에논토양에서벼를재배하는과정중메탄배출량의 90 % 이상이벼의통기조직을통해배출되고나머지 10 % 내외가토양으로부터단순확산에의해배출되는것으로알려져있다. 일반적으로벼의지상부의생육관련인자가메탄배출량과고도의정의상관관계가있다고알려져있으며 (Kim et al., 2012; Ali et al., 2009), 본연구에서도벼생육관련인자와고도의정의상관관계가있는것으로조사되었다 (Table 3). 특히높은염의농도로인한벼생육악화가벼재배기간중메탄배출량감소에영향을준것으로판단된다.

6 Effect of Salt Concentration on Methane Emission in a Coastal Reclaimed Paddy Soil Condition: Pot Test 257 Table 2. Chemical properties of the surface soils (0-15cm) and Characteristics of rice growth and yields in the potted soils packed with different levels of salt accumulation at rice harvesting stage Parameters Soil properties Salt accumulation level Low Medium High Very high LSD 0.05 Electrical conductivity (ds/m) ph (1:5 with H 2O) Exchangeable cations (cmol + /kg) K Ca Mg Na Water soluble Fe (mg/kg) Water soluble SO 2-4 (mg/kg) Sodium adsorption ratio (SAR) Growth and yield properties Plant height (cm) Tiller number per hill Number of grains per panicle grain weight (g) Ripened grains (%) Straw yield (Mg/ha) Table 3. Correlation between total CH 4 flux and soil and plant growth characteristics at rice harvesting stage Parameter Correlation coefficient (r) Before rice transplanting After rice harvesting Soil properties Electrical conductivity * ph ** * Exchangeable K *** ** Exchangeable Ca ** *** Exchangeable Mg * ** Exchangeable Na ** * Water soluble Fe ** Water soluble SO *** Sodium adsorption ratio (SAR) * Growth and yield properties Grain yield Straw yield Plant height Tiller number per hill Number of grains per panicle * * 정조수량 (Fig. 3) 은수량구성요소와마찬가지로토양내염농도가높아질수록유의하게감소하는것으로조사되었다. 예를들어, 저염도의경우 7.8 Mg/ha 로서일반적인벼수량과큰차이를보이지않았으나, 토양내염도가보통, 고염 도, 초고염도순으로높아짐에따라 6.2, 3.8, 2.2 Mg/ha 로토양내염의농도가높아질수록저염도대비생산량이 % 감소하는것으로조사되었다. 이는고염도처리구의높은염농도가식물의수분흡수를방해해벼의생육에불리한

7 258 LIM et al. 영향을미쳤기때문으로판단된다 (U.S. Salinity Laboratory Staff, 1954). 본연구에서토양의화학성, 벼의생육특성및수량구성요소와메탄발생간의상관관계를조사한결과 (Table 3), 벼의생육및수량특성에비해토양의화학적인특성이메탄발생에더욱많은영향을미치는것으로조사되었다. 특히토양에서치환성칼륨, 칼슘, 나트륨, 수용성철, 수용성황산염의함량은총메탄배출량과고도의부의상관관계가있는것으로평가되었다. 일반적으로토양내전자수용체 (Fe 3+, Mn 4+, SO 2-4, NO - 3 ) 가존재할경우산화환원전위의감소에다소영향을줄수있으며, 이는결국메탄생성단계로이어지는전자의흐름을차단시켜메탄생성량을큰폭으로억제시킬수있다 (Conrad, 2007). 실제벼재배과정중전자수용체로서규산질비료 (10 Mg/ha) 를활용하여메탄배출량을무처리대비약 28 % 까지저감가능한것으로이미보고된바있다 (Ali et al., 2008). 간척지토양은일반토양에비해다량의수용성철 ( mg/kg) 과황산염 ( mg/kg) 을포함하고있으며 (Lim et al., 2011), 상대적으로전자수용체 (Electron acceptor) 의농도가메탄배출량의감소에유의한영향을준것으로판단된다. 하지만본연구에서는수용성철의경우메탄배출량과부의상관관계를나타내지않았는데, 이는아마도상대적으로높았던황산염에의해그효과가다소낮아진것으로판단된다. 토양내과다한이온이존재할경우높은 EC 문제를야기시킬뿐아니라벼재배기간중메탄생성균의활성과벼의생육을억제시켜총메탄배출량을감소시킨것으로판단된다. 특히초기의높은염농도가메탄배출량감소에큰영향을준것으로평가되며, 담수이후염의상당부분이용탈되어없어지면서그효과가점차감소된것으로판단된다. 요약 간척지논토양에서염농도에따른메탄배출특성을조사하기위하여포트실험을실시한결과, 염농도의증가는메탄배출량감소와벼생육및수량성악화에영향을주는것으로조사되었다. 벼재배기간중높은 EC와 ph로인한메탄생성균의활성감소와벼생육악화에따른메탄배출량감소가주요원인으로평가되었다. 토양의 EC와 ph는총메탄배출량과고도의부의상관관계를나타내었으며, 벼생육 ( 초장및분얼 ) 과는정의상관관계를나타내었다. 하지만주로높은 EC에의한메탄저감효과는벼의생육초기에대부분나타났으며, 생육후기로갈수록염의희석효과에의하여저감효과가크게감소되는것으로확인하였다. 본연구의결과를통하여간척지논토양의염농도가메탄배출량에감소에큰영향을줄수있는것으로평가되며, 간척지논토양에서메탄배출량평가또는예측에좋은자료로활용될수있을것으로판단된다. Acknowledgement This work was carried out with the support of Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ009315) Rural Development Administration, Republic of Korea. References Adhya, T.K., Rath, K., Rao, P.K., Das, S.N., Parida, K.M., Sethunathan, D.C., Methane emission from flooded rice fields under irrigated conditions, Biol. Fertil. Soils. 18, Ali, M.A., Lee, C.H., Lee, Y.B., Kim, P.J., Silicate fertilization in no-tillage rice farming for mitigation of methane emission and increasing rice productivity, Agric. Ecosyst. Environ. 132, Ali, M.A., Oh, J.H., Kim, P.J., Evaluation of silicate iron slag amendment on reducing methane emission from flood water rice farming, Agric. Ecosyst. Environ. 128, Balttlet, K.B., Bartlett, D.S., Harriss R.C., Sebacher, D.I., Methane emissions along a salt marsh salinity gradient, Biogeochem. 4, Blake, E.R., Rowland, F.S., Continuing worldwide increase in tropospheric methane, Science 239, Bodelier, L.E., Laanbroek, J., Nitrogen as a regulatory factor of methane oxidation in soils and sediments, FEMS Microbiol. Ecol. 47, Bouwman, A.F., Agronomic aspects of wetland rice cultivation and associated methane emissions, Biogeochem. 15, Cicerone, R.J., Shetter, J.D., 1981 Sources of atmospheric methane: Measurements in rice paddies and a discussion, J. Geophys. Res. 86, Conrad, R., Microbial ecology of methanogens and methanotrophs, Adv. Agron. 96, Garica, J.L., Patel B.K.C., Ollivier, B., Taxonomic, phylogenetic and ecological diversity of methanogenic archea, Anaerobe 6, Hanna, J., Brian, A., J. Patrick, 2011.Salinity influence on methane emissions from tidal marches, Soc. Wet. Sci. 31, Holzapfel-Pschorn, A., Conrad, R., Seiler, W., Effects of vegetation on the emission of methane from submerged paddy soil, Plant and Soil 92, Holzapfel-Pschorn, A., Seiler, W., Methane emission during a cultivation period from an Italian rice paddy, J. Geophys. Res. 91,

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<30335FB1E8BBF3C0B12E687770> Korean Journal of Environmental Agriculture Korean J Environ Agric (2011) Online ISSN: 2233-4173 Vol. 30, No. 3, pp. 243-251 http://dx.doi.org/10.5338/kjea.2011.30.3.243 Print ISSN: 1225-3537 간척지논토양개량제로서석고처리가메탄배출량저감에미치는영향