경사 및 고랑 깊이에 따른 간척지 토양 특성 및 콩 생육 평가 = Assessment of Soil Properties and Soybean Growth in Reclaimed Tideland as Affected by Slope Gradients and Furrow Depths

다국어 초록 (Multilingual Abstract)

Reclaimed tidelands in Korea were developed primarily for paddy rice; however, declining rice consumption and renewed interest in improving national grain self-sufficiency have increased the need to convert these areas to upland crop production. Yet reclaimed tideland soils often exhibit poor drainage and salinity, which reduce yield stability of upland crops and highlight the need for effective drainage-improvement strategies. This study evaluated the effects of slope construction (0°, 3°, and 5°) and furrow depth (25 and 35 cm) on soil properties and soybean (Glycine max L. Merr.) growth and yield over two consecutive growing seasons (2023-2024) in the poorly drained Saemangeum reclaimed tideland, Korea. Volumetric soil water content was continuously monitored at 20 and 40 cm depths using in-situ sensors. Soil pH, electrical conductivity (EC), mineral nitrogen (NH4+-N and NO3--N), organic matter, available phosphorus, microbial biomass carbon, and enzyme activities (β-1,4-glucosidase, BG; β-1,4-N-acetylglucosaminidase, NAG; and acid phosphatase, AP) were analyzed at sowing and at major growth stages (flowering, pod filling, and harvest). Soybean growth and yield components (plant height, aboveground dry weight, leaf number, branch number, pod number, seed number, 100-seed weight, and yield) were assessed at each growth stage. Slope construction exposed subsoil at lower slope positions, which increased soil pH and decreased organic matter and available phosphorus. In 2023 (growing-season rainfall: 1344 mm), slope construction improved surface drainage; however, heavy rainfall early in the season caused severe erosion at upper slope positions and sediment deposition downslope. Soybean growth and yield decreased from the upper to the lower slope positions and were negatively associated with soil water content and pH. To mitigate early-season rainfall damage, the sowing date was shifted to May in 2024, resulting in significantly greater growth up to the flowering stage compared with 2023. Nevertheless, drought and high temperatures during flowering and pod-filling stages reduced yield across all slope and furrow-depth treatments. Redundancy analysis indicated that yield variation in 2024 was more strongly influenced by climatic stress than by soil properties, whereas soil water status and pH were key correlates of yield in 2023. Overall, slope construction alone did not increase soybean yield in sandy reclaimed tidelands, mainly due to erosion-driven soil redistribution and associated deterioration of fertility at lower slope positions. These findings suggest that stable upland crop production in reclaimed tidelands requires integrated adaptive management that combines drainage improvement with soil fertility enhancement, supplemental irrigation, and erosion control.

목차 (Table of Contents)

• 제 1 장 서론 1
• 1.1 연구 배경 1
• 1.2 연구사 3
• 1.3 연구 목적 5
• 제 2 장 재료 및 방법 7
• 2.1 시험지역 및 시험포장 설계 7
• 2.2 토양 모니터링 13
• 2.3 작물 모니터링 18
• 2.4 통계분석 19
• 제 3 장 결과 및 고찰 20
• 3.1 토양 수분함량 변화 20
• 3.2 토양 화학적 특성 변화 27
• 3.3 토양 생물학적 특성 변화 34
• 3.4 콩 생육 변화 39
• 3.5 콩 수량 변화 45
• 제 4 장 종합 결론 50
• 참 고 문 헌 53