• 한국환경생태학회지
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• 제16권3호
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• pp.249-260
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• 2002

서울과 같은 대도시의 농경지는 인간의 간섭이 끊임없이 이루어지는 준자연지역으로 생산성보다는 도시의 생물다양성보존 및 경관다양성을 통한 일반시민의 자연체험이라는 측면에서 관리.보호될 필요가 있다. 그러나 도시지역의 농경지는 개발용지로 토지이용이 전환되어 급속히 감소하고 있다. 본 연구에서는 서울시를 대상으로 농경지 패취의 시간변화에 따른 토지이용변화를 살펴보고 서울시 비오톱유형도에 근거한 농경지 패취를 분석하여 서울지역 농경지의 경관생태학적 구조와 특성을 파악하고, 이러한 분석결과를 토대로 생물다양성 증진을 위한 농경지 관리모델을 구상하는데 그 목적이 있다.

• 한국토양비료학회지
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• 제42권4호
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• pp.249-256
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• 2009

오리농업재배가 이뤄지고 있는 소유역 하류에 위치한 자연습지가 오리농업시 유출되는 영양염류 부하량 저감에 미치는 영향을 평가하였다. 오리농업재배가 이뤄지고 있는 소유역은 논면적이 61.9ha로서 총 논면적의 74%에서 오리농업재배가 이뤄지고 있었으며 하류에 위치한 자연습지의 면적은 5.9ha를 차지하고 있었다. 재배기간 중 오리농업이 이뤄지고 있는 논물의 영양염류 함량을 조사한 결과 T-N 13.7, $T-P2.5kg\;ha^{-1}$로 나타났는데, 이는 동일기간 중 관행재배에 비해 1.2~2.5배 높은 결과였다. 하류에 위치한 자연습지의 우점초생은 갈대, 줄, 고마리 등이었으며, 이들 식생이 함유하고 있는 영양염류량은 T-N 761 kg, T-P103 kg으로서 오리재배논으로부터 유출되는 영양염류 부하량의 94%와 79%에 해당되는 양이었다. 이와 같은 연구결과를 볼 때, 오리재배농업단지 하류에 습지를 유지하는 것은 오리농업 재배시 발생할 수 있는 영양염류 부하량을 저감시킬 수 있는 하나의 방법이 될 수 있으리라 생각된다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.8-9
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• 2017

Soybean yield has been low and unstable in Japan and other areas in East Asia, despite long history of cultivation. This is contrasting with consistent increase of yield in North and South America. This presentation tries to describe perspective of breaking stagnation of soybean yield in East Asia, considering the factors of the different yields between regions. Large amount of rainfall with occasional dry-spell in the summer is a nature of monsoon climate and as frequently stated excess water is the factor of low and unstable soybean yield. For example, there exists a great deal of field-to-field variation in yield of 'Tanbaguro' soybean, which is reputed for high market value and thus cultivated intensively and this results in low average yield. According to our field survey, a major portion of yield variation occurs in early growth period. Soybean production on drained paddy fields is also vulnerable to drought stress after flowering. An analysis at the above study site demonstrated a substantial field-to-field variation of canopy transpiration activity in the mid-summer, but the variation of pod-set was not as large as that of early growth. As frequently mentioned by the contest winners of good practice farming, avoidance of excess water problem in the early growth period is of greatest importance. A series of technological development took place in Japan in crop management for stable crop establishment and growth, that includes seed-bed preparation with ridge and/or chisel ploughing, adjustment of seed moisture content, seed treatment with mancozeb+metalaxyl and the water table control system, FOEAS. A unique success is seen in the tidal swamp area in South Sumatra with the Saturated Soil Culture (SSC), which is for managing acidity problem of pyrite soils. In 2016, an average yield of $2.4tha^{-1}$ was recorded for a 450 ha area with SSC (Ghulamahdi 2017, personal communication). This is a sort of raised bed culture and thus the moisture condition is kept markedly stable during growth period. For genetic control, too, many attempts are on-going for better emergence and plant growth after emergence under excess water. There seems to exist two aspects of excess water resistance, one related to phytophthora resistance and the other with better growth under excess water. The improvement for the latter is particularly challenging and genomic approach is expected to be effectively utilized. The crop model simulation would estimate/evaluate the impact of environmental and genetic factors. But comprehensive crop models for soybean are mainly for cultivations on upland fields and crop response to excess water is not fully accounted for. A soybean model for production on drained paddy fields under monsoon climate is demanded to coordinate technological development under changing climate. We recently recognized that the yield potential of recent US cultivars is greater than that of Japanese cultivars and this also may be responsible for different yield trends. Cultivar comparisons proved that higher yields are associated with greater biomass production specifically during early seed filling, in which high and well sustained activity of leaf gas exchange is related. In fact, the leaf stomatal conductance is considered to have been improved during last a couple of decades in the USA through selections for high yield in several crop species. It is suspected that priority to product quality of soybean as food crop, especially large seed size in Japan, did not allow efficient improvement of productivity. We also recently found a substantial variation of yielding performance under an environment of Indonesia among divergent cultivars from tropical and temperate regions through in a part biomass productivity. Gas exchange activity again seems to be involved. Unlike in North America where transpiration adjustment is considered necessary to avoid terminal drought, under the monsoon climate with wet summer plants with higher activity of gas exchange than current level might be advantageous. In order to explore higher or better-adjusted canopy function, the methodological development is demanded for canopy-level evaluation of transpiration activity. The stagnation of soybean yield would be broken through controlling variable water environment and breeding efforts to improve the quality-oriented cultivars for stable and high yield.