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1 ISSN Korean J. Sci. Fert. 45(6), (2012) 보문 Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River Doug-Young Chung, Hyejin Kim, Misuk Park, and Sang-Eun Lee 1 * Dept. of Bio-environmental Chemistry, College of Agriculture and Life Sciences, Chungnam National University, Daejeon , Korea 1 Dept. of Plant Resources Sciences, Hankyung National University, Ansung , Korea The total area of a reclaimed tidal soil distributed on the south-west coast is approximately 156,600 ha, and the soil contains high contents of sand and silt as well as highly saline. Most of the reclaimed tidal soils are used as a paddy due to bad permeability and high groundwater table, resulting in easy accumulation of salts on the soil surface by capillary rise. Therefore, resalinization may occur because of rise of groundwater table after desalinization. The researches related to the reclaimed tidal soil mainly focused on desalinazation while most of the researches completed were limited to yields of crop based on desalinazation. ph of old reclaimed tidal soil is neutral or less than 7 while that of newly developed reclaimed tidal soils is greater than 7, that cause N-fertilizer to be volatile as ammonia. Thus, the physical and chemical properties should be investigated to be used as an arable upland instead of a paddy soil due to change in government policy. We need to develop measures to make soils grow crops normally by identifying problems related to reclaimed tidal soils. Key words: Reclaimed Tidal, Resalization, Saline 서 언 우리나라의식량자급률은 50% 내외로낮고곡물자급률은사료부문을포함하여도 26% 로매우낮은수준이나우리나라의농경지는산업화에따른타용도전용등으로 98년이후매년평균 15천 ha 씩급속히감소되고있는추세에있다 (2009 Yearbook of MAF). 따라서식량의안정적공급을위한기본적인농경지의확보가필요하며이러한상황에서간척지는식량의안정적공급을위한경지면적을확보한다는면에있어그의의가크다. 우리나라의서남해안은내부간석지의면적이넓어짧은방조제를축조하여넓은땅을개발할수있다. 우리나라의서남해안총간척자원은 81 만ha로이중개발가능면적은 51 만 9천ha이고 (1995, KRCC), 간척사업추진현황을살펴보면총대상면적이 156,603 ha 중준공한면적은약 97,000 ha 이다. 한편연도별개발현황을살펴보면 1945 년이전총개발면적은약 40,877 ha 이며 1946 년이후총 1628 개소에서간척지개발이실시되었다. 이중정부가시행한지구수는 186 개소약 3558ha이고민간주도로약 1442 개소총면적약 40200ha 정도가개발된되었다 (KRCC, 2002; NHAES, 2002). 현재국내간척지는염농도가높고모래와미사가많고지하수위가높아배수가불량하고표토에염분집적이쉬울 접수 : 수리 : * 연락저자 : Phone: selee@hknu.ac.kr 뿐만아니라제염을실시한후다시지하수상승등에의한재염화가발생하고있다 (Ryu, 2009). 국립식량과학원간척지농업과에서남양간척지에대해조사한바에따르면초기염농도가약 1.6% ( 약 25 ds m -1 ) 인미사질양토 ( 표토 ) 와미사질식양토 ( 심토 ) 를자연강우를이용하여벼재배임계농도인염농도 0.3% ( 약 4.7 ds m -1 ) 로낮추는데소요된제염시간을살펴보면표토 (0~10 cm) 의경우는약 40 년그리고심토 (60~120 cm) 는약 90 년이소요된다. 한편계화도포승통의경우영농후약 50 년의시간이지났음에도불구하고벼재배임계농도인염농도 0.3% ( 약 4.7 ds m -1 ) 보다높은 0.44% 정도로조사되었으며광활과문포통의경우영농후 20 년정도시간이지난후부터벼재배임계농도인염농도 0.3% 이하로감소되는것으로보고되었다. 따라서계화도간척지의경우세사양토 사양토의경우약 20 년, 그리고미사질양토의경우 33 년내지약 50 년정도소요되는것으로추정된다. 그러므로간척지를효율적으로활용하기위한간척지토양의조기숙전화기술이개발되어야한다. 국내간척지토양의이화학특성우리나라의간척지토양통은모두 47 개로논토양 5개유형, 밭토양 2개유형으로분류하며 47 개토양통중논토양은 40 개로보통답 15개, 사질답 6개, 습답 8개, 염해답 8개, 특이산성답 3개토양통으로구분되고, 밭토양은 7개토양통으로보통전 1개, 사질전 6개토양통으로구분한다 (Ryu, 2008) 년도에완성

2 Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River 1223 Fig. 1. Change in salt concentration based on cultivated period at Poseung series in Gyehwa island (right) and desalinization period for each soil layer at Namyang reclaimed tidal land under natural precipitation (left). Table 1. General information of the reclaimed tidal land developed since Year of completion Location series - Osan Junbook Hwapo Jinbong, Gwanghal, Daehang, Seopo Daeya Howhyun Buyong 1960 Mimyon Oksuh Gyehwa Imhae Industrial site Gunsan, Gwanghal, Gyehwa Moonpo Moonpo Yumpo Layer Depth cm particle distribution Sand Silt Clay texture A SiL B SiL B SiL C SiL A SiCL B SiCL C SiCL C SiCL A SiL C SiL A SiL C SiL C SiL A SiL C SiL A SiL C SL C LS A SiL C SL Groundwater table cm A SL - < < < 100 한화포와진봉, 대창등의간척지로부터최근완성된새만금간척지의토양통은전북, 부용, 만경, 문포, 염포통이주를이루며 A층은 25cm 이내로토성은미사질양토, 미사질식양토, 그리고일부지역은사질양토로조사되었다. 그리고지하수위위치는모두지표면으로부터 100cm 이내에존재하는것으로조사되었다 (Table 1). 그리고화학성을비교하여 (Table 2) 보면간척지토양통이토양의이화학성에영향을미치는것으로판단되며 1920 년이전개발간척지는토층분화가생성된반면 1930 년대이후개발된간척지는대부분표층에해당하는 A층하부에층이존재하는것으로조사되었다 (NHAES, 2002).

1224 Doug-Young Chung, Hyejin Kim, Misuk Park, and Sang-Eun Lee Table 2. Chemical properties of the reclaimed tidal soils developed since 1920.

3 1224 Doug-Young Chung, Hyejin Kim, Misuk Park, and Sang-Eun Lee Table 2. Chemical properties of the reclaimed tidal soils developed since Year of completion Location series - Osan Junbook Hwapo Jinbong, Gwanghal, Daehang, Seopo Daeya Howhyun Buyong 1960 Mimyon Oksuh Gyehwa Imhae Ind. site Hwapo, Gunsan, Gwanghal, Gyehwa Moonpo Moonpo Yumpo Layer Depth ph EC OM TN Av.P 2O 5 Ex.cations K Ca Mg Na CEC cm 1:5 ds m -1 g kg -1 mg kg cmol + kg A B B C A B C C A C A C C A C A C C A C A 간척지토양의이화학특성새만금간척지는전북옥 구군옥서면을중심으로금강, 만경강, 동진강하구갯벌을개발한간척지로새만금간척지내에존재하는토양통은문포, 염포, 광활, 포승, 만경통총 5개의토양통이카테나를이루고있다 (Ryu, 2008). 새만금지역의 A 또는 Ap층의깊이는 20 cm 이내이며대부분하부에 C층이바로연결돼있다 (Fig. 2). Yang(2008) 이조사한새만금문포, 염포, 광활통의년간지하수위변동조사결과를살펴보면문포통의지하수위는봄철에가장높고여름보다가을에지하수위는최저약 71 cm 로낮아지고반면염포와광활통은봄보다가을철에지하수위가낮아지며반면최대지하수위는여름에 18 cm 와 11 cm 로지표면가까이까지상승되는것으로발표하였다. 그리고 Ryu(2008) 가조사한토양통별토양의토성은미사질양토~ 미사질식양토로배수등급은약간불량~ 불량~ 매우불량한토양으로벼재배에는큰문제가없으나밭작물 Fig. 2. Catena and ground-water levels of soil series at the Saemangum reclaimed tidal land area (Ryu, 2010). 재배에는토양배수등의문제로적합하지못하다 (Ryu, 2008). 또한지하수위에따라토양의형태및토색이상이하며지하수의영향으로기층은심히환원되어토색이청회색내지암회색을나타내고액화상태이며토양중반문은

Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River 1225 거의형성되어있지않다. 작토및심토층은각각회갈색, 암회색을나타내고, 농적갈색의 Mn 반문을포함하는무구조이다 (Fig. 3).

4), 내륙에서부터태안, 광포, 복천 ( 또는전북 ), 그리고포승통의순서로토양통이배열돼있다 (Lee, 2008). 그리고각각의토양통별깊이에따른토성을살펴보면표층은사질양토 (SL) 또는미사질식양토 (SiCL) 가혼재하며심층은사질양토와양토 (SL/L) 가혼재하며전북과포승통은미사질양토와미사질식양토 (SiL/SiC) 가혼재하는상태로조사되었다 (Table 3).

4 Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River 1225 거의형성되어있지않다. 작토및심토층은각각회갈색, 암회색을나타내고, 농적갈색의 Mn 반문을포함하는무구조이다 (Fig. 3). 한편계절별지하수위지점에서의염류농도를살펴보면 (Table 3) 조사된토양통모두여름에가장높고봄과가을은유사한것으로조사되었다 (Yang, 2008). 한편한국농어촌공사가 2009 년개발한영산강간척지 III 지구토양조사결과를살펴보면총 5개의토양통으로구성되어있으며 (Fig. 4), 내륙에서부터태안, 광포, 복천 ( 또는전북 ), 그리고포승통의순서로토양통이배열돼있다 (Lee, 2008). 그리고각각의토양통별깊이에따른토성을살펴보면표층은사질양토 (SL) 또는미사질식양토 (SiCL) 가혼재하며심층은사질양토와양토 (SL/L) 가혼재하며전북과포승통은미사질양토와미사질식양토 (SiL/SiC) 가혼재하는상태로조사되었다 (Table 3). 특히내륙에위치하는태안통의 경우기반층의경우모래 (S) 와함께자갈이함께혼재하는상태로조사되었다. 배수특성은소택지로존재하는포승과복천통이매우불량 (Bad) 한것으로조사되었다 (Jung, 2008; NHAES. 2002). 그리고 Fig. 5에서보는바와같이영산호 III 지구간척지토양은지하수위에따라기층은심히환원되어토색이청회색내지암회색을나타내고액화상태이며토양중반문은거의형성되지않은 (non-mottle) 토양의구조와토색의특성을보이며작토및심토층은각각회갈색, 암회색을나타내고, 농적갈색의 Mn- 반문을포함하며무구조이다 (Lee, 2008). 이와같이토양의형태적특성에큰영향을미치는지하수위는 45~95 cm 범위로포승통은 50 cm 정도로높다 (Lee, 2008). 그리고표토의토성은사양토또는미사질양토로조사되었으며심층은사양토, 미사질양토또는양토로조사되었다. 한편기층은자갈이많은사양토부터심층 Fig. 3. Status of ground-water table and soil profiles for soil series at the Saemangum reclaimed tidal area (NHAES. 2002). Table 3. Depth and salt content at the level of ground-water-water table measured at the soil series of Moonpo, Yumpo, and Kwanghal at Saemangum reclaimed tidal area. Ground-water table Salt content of Ground-water series Spring Summer Fall Spring Summer Fall cm % Moonpo Yumpo Gwanghal Fig. 4. Distribution of soil series (left) and salt contents of surface soils (right) at Youngsan-river reclaimed tidal area.

5 1226 Doug-Young Chung, Hyejin Kim, Misuk Park, and Sang-Eun Lee Fig. 5. profiles of the soil series at the Youngsan-river reclaimed tidal soils. Table 5. Chemical and physical properties of a reclaimed tidal soils in Saemangum area. series Hasa Yumpo Moonpo Gwanghal Horizon Depth ph EC OM Ex. cation particle distribution Ca Mg Na K Sand Silt Clay cm 1:5 ds m -1 % cmol kg % texture AP 0~ S C1 13~ S AP 0~ SL C1g 10~ LS AP1 0~ S AP2 8~ S C1g 18~ S AP1g 0~ SiL AP2g 12~ SiL C1g 22~ SiL 과같은사양토, 미사질양토, 또는양토의토성을가지고있는것으로조사되었다 (NHAES. 2002). 간척지토양의토양입자분포특성을살펴보면새만금지역의광활통의경우지표면 30 cm 이내에서는미사함량이 50% 이상존재하며다음모래가약 40%, 그리고점토가 10% 이하로존재하고있다 (Park, 2008). 따라서점토크기에가까운미사함량이증가할수록토양내공극의크기는감소하여배수가불량해진다. 그리고토양에가해지는질소공급원인요소전환에영향을미치는토양 ph 는염포통과포승통을제외한나머지토양통모두에서 7 이상알카리토양으로조사되었다. 그리고염류농도는조사된모든토양통에서 4 ds m -1 이상으로작물체가자라는데부적합한것으로판단된다. 그리고 A 또는 Ap 층의입도분포를살펴보면점토함량은광활통의경우 8.5% 가최대로조사되었다 (Table 4). 한편 KRCC(2010) 가영산강간척지 III 지구토양을대상으로조사한결과를살펴보면조사대상지모두토양 ph 는 7 이상이며 EC는작물이자라기에부적합한 8 ds m -1 이상으로조사되었다 (Table 6). 그리고논토양으로활용하고있는영산강 Ⅱ-1지구토양통에속하는여수통, 포리통, 그리고금진통간척지토양의화학적특성을살펴보면 (Jung, 2008a,b; Lee, 2008a) 표토의 ph 는 5.6 이하로약산성에속하며유기물함량은일반관행논보다다소높으나인산함량은일반농경지토양보다매우낮은최대 42 mg kg -1 이었다 (Table 6). Ryu(2008) 발표한바에따르면간척년대별토양물리성변화를살펴보면새만금지역의광활, 염포, 그리고문포통심토의용적밀도와경도그리고포장수분함량은간척년대가경과할수록조립질인광활, 염포, 그리고문포통은낮아지는경향이나반면세립질토양인포승통과포두통은증가하였다 (Table 8). 영산강간척지시험포장의토양깊이별토양경도를조사한결과한빛뜰 ( 태안통 ) 감자재배포장을제외한모든포장에서깊이 15cm 이하부터토양경도가식물뿌리침투신장의한계범위인 2 kg cm -2 를초과하는것으로조사되었다 (Fig. 6). Chung(2012) 이새만금광활통과영산강태안통토양에서조사한용적밀도, 토양경도, 그리고포화수리전도측정결

6 Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River 1227 Table 6. Chemical and physical properties of a reclaimed tidal soils in Youngsan-river reclaimed tidal area (KRCC, 2010). Ex. Name of Field ph EC CEC OM Avail. P 2O 5 K Ca Mg ds m -1 cmol + kg -1 % mg kg cmol + kg Hanbit Samho Jangsoo Maebong Others Table 7. Chemical and physical properties of a reclaimed tidal soils in Youngsan-river reclaimed tidal area (KRCC, 2010). series ph OM P 2O 5 CEC Ex.cation K Ca Mg Na 1:5 g kg -1 mg kg -1 cmol c kg cmol c kg Yeosu Pori Gumjin Table 8. Changes in bulk density and soil hardness for soils series of Kwanghal, Yumpo, and Moonpo at Saemangum area during five years after completion of reclamation. Bulk density hardness series 1 st yr 5 th yr 1 st yr 5 th yr g cm mm Kwanghal Yumpo Moonpo Fig. 6. hardness measured at the reclaimed tidal area of Youngsan-river. 과를살펴보면일반관행농경지와유사하게경반층에해당하는 25 cm 깊이에서용적밀도가최대치로조사되었으며이지점에서토양경도도식물의뿌리생육에저해하는 18 mm 이상으로조사되었다 (Gerard, 1982). 또한포화수리전도도도 0-25cm 깊이에서는 0.63 과 0.51 cm 이나 25-55cm 깊이에서는거의투수가되지않거나 0.11 로급격히감소하는경향을보였다. 간척지토양은토양의단면조사에서도알수있듯이매우 높은용적밀도를가지고있으며일반적으로투수성이매우불량하다고알려져있다. 용적밀도에따른간척지토양의투수성변화를조사한결과용적밀도별초기 K는용적밀도 1.30 g cm -3 토주에서 0.68 공극수량 (pore volume) 용출후 0.10 cm hr -1 을나타내었고, 용적밀도 1.35 g cm -3 토주에서 0.38 공극수량용출후 0.06 cm hr -1 을나타내었으며, 용적밀도 1.40 g cm -3 토주에서는 0.29 공극수량용출후 0.04 cm hr -1 를나타내었다. 또한용적밀도 1.45 g cm -3 에서는 0.24 공극수량용출후 0.06 cm hr -1 를나타내었고용적밀도 1.50 g cm -3 에서는 0.11 공극수량용출후 0.02 cm hr -1 을나타내었다. 그러나시간이경과함에따라투수성은크게저하되어용적밀도에관계없이투수가되지않아결국 K 값은 0을나타내는특성을보였다 (Chung, 2012). 이는치환성 Na + 함량이높은간척지토양에전해질농도가낮은일반용수를담수하면토양의점토입자가분산되고분산된점토는공극수와함께중력에의해하향이동하다가미세한공극의막힘이발생하여 K가감소되고결국투수가정지되는것으로판단된다 (Dawidowski and Koolen, 1987). 간척지토양은 NaCl의영향으로토성에비하여액성한계

7 1228 Doug-Young Chung, Hyejin Kim, Misuk Park, and Sang-Eun Lee Table 9. physical properties and saturate hydraulic conductivity of Gwanghal series and Taean series. depth Bulk density hardness K sat Remarks cm g cm -3 mm cm hr ( )* ( )* ( ) indicates the value measured at the Youngsan-river Table 10. mechanical properties of Kwanghal series. Category Depth Period of reclamation (yr) r (n=13) Cole surface Subsurface Atterberg limits (%) Liquid limit Plastic limit Plastic index surface Subsurface surface Subsurface surface Subsurface 와소성지수가높다. Cole 값은점토함량, 유기물함량, Atterberg limits 와는정의관계이나수분함량과는부의상관성을가지고있다. Kim (2008) 발표한바에따르면새만금광활통토양의액성한계와소성한계, 그리고소성지수는액성한계가표토보다심토에서약간높으며부의상관성을나타내는것은심토의점토함량이높은것이원인으로추정된다. 한편광활통은 33 년차부터경반층이생성되었다 (Table 10). Summary 간척지토양은일반적으로매우높은염농도를가지고있으며염고농도의염특히, 높은 Na + 농도는점토의분산을일으키고토양의공극을감소시켜토양의공기와수분의유통을악화시키고고농도의염은생리적가뭄 (physiological drought) 의한가지형태인낮은수분퍼텐셜을발생시켜서수분과양분의흡수를어렵게한다. 따라서간척지를효율적으로활용하기위해서는간척지토양에대한제염이선행되어야한다. 이러한제염효과를증진시키기위해서는상기에서살펴본바와같이물리성개선을통하여토양의화학성을개선시켜야한다. 본조사를기준으로한간척지토양개선은물리성중물질의이동을용이하게하는심층토내토양압밀층개선이우선되어야할것으로판단한다. 그리고높은지하수위에의한모세관상승에동반한재염화를방지하기위한토양관리방안이필요하다. 따라서최종적으로간척지의효과적재염 (Resalization) 방지와제염 (Desalinazation) 방안에대한토질역학적측면에서연구가추진되어야한다. Acknowledgement This work was carried out with the support of Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ008516) Rural Development Administration, Republic of Korea. References Chung, D.Y Unpublished data Dawidowski1, J.B. and A.J. Koolen Changes of soil water suction, conductivity and dry strength during deformation of wet undisturbed samples. Till. Res. 9: Gerard, C.J. P. Sexton, and G. Shaw Physical Factors Influencing Strength and Root Growth. Agron. J. 74: Jung, J.H series of a reclaimed tidal soil-bogchung series. Jung, J.H. 2008a. series of a reclaimed tidal soil-yeosu series. Jung, J.H. 2008b. series of a reclaimed tidal soil-pori series. daum.net/viny9364/ Kim, T.G Changes of physical and chemical properties of a reclaimed tidal soils with reclamation ages.

8 Characteristics of a Reclaimed Tidal for Effective Resalization at Saemangum and Youngsan-River KRCC Status of Reclamation Project Progress KRCC KRCC Status of Reclamation Project Progress KRCC KRCC Report of soil characteristics for Youngsan-river reclaimed tidal area. KRCC Lee, D.G. 2008a. series of a reclaimed tidal soil-gumjin series. daum.net/viny9364/ Lee, G.H characteristics of reclaimed tidal area at the Youngsan- river. MAF Food, Agricultural, Forestry and Fisheries Statistical Yearbook NHAES Agriculture in a reclaimed tidal soils in Korea. RDA. Park, K. H Characteristics of soils for a reclaimed tidal soils at Gyehwa area-chemical and physical properties. Ryu, J.H Classification of reclaimed tidal soils. viny9364/ RDA. Ryu, J.H Problems in a newly reclaimed tidal soil. viny9364/ Ryu, J.H Ph. D. Thesis. Chungnam National University. Yang, C.H Changes in groundwater table in a reclaimed tidal soils at Saemangum.

조사보고서 완본(최종인쇄본).hwp

조사보고서 완본(최종인쇄본).hwp 뉴질랜드 농업투자환경조사보고서 ( 주 ) 제이앤드에이 Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ Ÿ 2.3) Waipara Limestone Vineyard Estate 토양특성 [표 2-7] Waipara Limestone Vineyard Estate 부지 토양 특성 유효