• Journal of Korean Society on Water Environment
• /
• v.24 no.2
• /
• pp.185-194
• /
• 2008

There is increased soil erosion potential at highland agricultural crop fields because of its topographic characteristics and site-specific agricultural management practices performed at these areas. The agricultural upland fields are usually located at the sloping areas, resulting in higher soil loss, pesticides, and nutrients in case of torrential rainfall events or typhoon, such as 2002 Rusa and 2003 MaeMi. At the highland agricultural fields, the soil reconditioning have been performed every year to decrease damage by continuous cropping and pests. Also it has been done to increase crop productivity and soil fertility. The increased amounts of soil used for soil reconditioning are increasing over the years, causing significant impacts on water quality at the receiving water bodies. In this study, the field investigation was done to check soil reconditioning status for potato, carrot, and cabbage at the Doam-dam watershed. With these data obtained from the field investigation, the Soil and Water Assesment Tool (SWAT) model was used to simulate the soil loss reduction with environment-friendly and agronomically enough soil reconditioning. The average soil reconditioning depth for potato was 34.3 cm, 48.3 cm for carrot, and 31.2 cm for cabbage at the Doam-dam watershed. These data were used for SWAT model runs. Before the SWAT simulation, the SWAT ArcView GIS Patch, developed by the Kangwon National University, was applied because of proper simulation of soil erosion and sediment yield at the sloping watershed, such as the Doam-dam watershed. With this patch applied, the Coefficient of Determination ($R^2$) value was 0.85 and the Nash-Sutcliffe Model Efficiency (EI) was 0.75 for flow calibration. The $R^2$ value was 0.87 and the EI was 0.85 for flow validation. For sediment simulation, the $R^2$ value was 0.91 and the EI was 0.70, indicating the SWAT model predicts the soil erosion processes and sediment yield at the Doam-dam watershed. With the calibrated and validated SWAT for the Doam-dam watershed, the soil erosion reduction was investigated for potato, carrot, and cabbage. For potato, around 19.3 cm of soil were over applied to the agricultural field, causing 146% of more soil erosion rate, approximately 33.3 cm, causing 146% of more soil erosion for carrot, and approximately 16.2 cm, causing 44% of more soil erosion. The results obtained in this study showed that excessive soil reconditioning are performed at the highland agricultural fields, causing severe muddy water issues and water quality degradation at the Doam-water watershed. The results can be used to develop soil reconditioning standard policy for various crops at the highland agricultural fields, without causing problems agronomically and environmentally.

• Korean Journal of Environmental Agriculture
• /
• v.25 no.4
• /
• pp.339-345
• /
• 2006

Accumulation of nitrate in green vegetables is undesirable due to potential risks to human health. Lettuce was cultivated in pots under greenhouse conditions with compost applications of 2,000 and 4,000 kg/10a, and the growth and nitrate accumulation of lettuce were compared with those found in the lettuce cultivated with chemical fertilizers of recommended levels. Content of $NH_4-N$ in the soils of compost applications were much lower than those found in the soil of chemical fertilizer application. Two weeks after lettuce transplant $NH_4-N$ was not found in the soils of compost applications, and in the soils of chemical fertilizers application $NH_4-N$ was not found three weeks after lettuce transplant. One week after lettuce transplant content of $NO_3-N$ was much higher in the soils of compost applications, and the contents were rapidly decreased. While, the content of $NO_3-N$ in the soil of chemical fertilizers application was rapidly increased due to the nitrification of $NH_4$ released from the applied urea. At the time of harvest contents of $NO_3-N$ in the soils of compost applications were less than 1.4 mg/kg, but in the soil of chemical fertilizers application the content of $NO_3-N$ was 54.2 mg/kg. Contents of $NH_4$ in lettuce were about 20 mg/kg FW and were not much different among the treatments. However, contents of $NO_3$ in lettuce were significantly different between the treatments of chemical fertilizer and compost. There were significant differences in fresh and dry weights, and growth of lettuce in the compost treatment of 4,000 kg/10a was highest among the treatments. These results indicate that the cultivation with compost only as N source can produce higher yield of lettuce and significantly reduce nitrate accumulation as compared to the conventional cultivation with chemical fertilizers.

• Korean Journal of Soil Science and Fertilizer
• /
• v.36 no.6
• /
• pp.384-390
• /
• 2003

Removal of phosphate from soil by leaching, runoff, and plant uptake is strongly influenced by the content and absorption characteristics of P in soil. In this study the relationships between water soluble phosphate and phosphate retention capacity of the soil was investigated. Water soluble and available phosphate, and phosphate absorption characteristics of 35 paddy soils were measured during incubation at $25^{\circ}C$. Water soluble phosphate content was highly correlated with available phosphate content, phosphorus absorption capacity (PAC), and phosphate absorbed (PS) in air-dried and wet soils. The most significant relationship was found between water soluble phosphate and the ratio of available phosphate and phosphate sorbed, and the relationship $0.01M\;CaCl_2-P=0.0828$ (Av. $P_2O_5/PS$)+0.0374 could be suggested for the estimation of water soluble phosphate from soil phosphorus characteristics.

• Korean Journal of Environmental Agriculture
• /
• v.3 no.2
• /
• pp.55-61
• /
• 1984

농업(農業)은 동식물(動植物)을 대상으로 하는 응용생태학(應用生態學)의 한 분야(分野)로 그의 발전과정(發展過程)은 환경(環境)과 밀접(密接)한 관계가 있다. 환경조건(環境條件)의 다양성(多樣性)은 대상생물(對象生物)의 종류(種類)를 풍부하게 하고 순화(馴化)된 생물(生物)의 사양(飼養) 과정에서 다양(多樣)한 농업형태(農業形態)를 발전시켰다. 생웅계(生熊系)는 자연(自然)의 한 단위로 구성요소(構成要素)들은 기능적(機能的)으로 통일성(統一性)을 유지하고 있다. 농생태계(農生態系)는 생산(生産)을 목표(目標)로 하는 동식물(動植物)을 중심(中心)으로 하는 생태계(生態系)로 자연생태계(自然生態系)와 기본적(基本的) 성질(性質)은 동일하나 인위적(人爲的) 요소(要素)가 크게 작용하고 있는 특리(特異)한 생태계(生態系)이다. 작물(作物)이나 가축(家畜)은 수천년에 걸친 생산력(生産力)의 증대(增大)를 목표(目標)로 인위적(人爲的)인 선발을 거친 것으로 자연조작하(自然條作下)에서 심한 경쟁(競爭)을 거치면서 진화(進化)한 야생생물(野生生物)들에 비하면 선천적(先天的) 포약성(胞弱性)을 갖고 있어 인간(人間)의 보호(保護)(에너지보조(補助))를 필요로 하고 있다. 농생태계(農生態系)는 공간적(空間的) 격리(隔離)와 구성종(構成種)의 단순화(單純化)로 공간적(空間的) 연쇄성(連鎖性)과 종다양도(種多樣度)가 큰 자연생태계(自然生態系)에 비하면 외적(外的) 충격에 대한 내부적(內部的) 완충능력(緩衝能力)이 약하다. 더우기 농생태계(農生態系)는 시간적(時間的) 연속성(連續性)이 없어 극상천이(極相遷移)단계에 달할 수 있는 시간적(時間的) 여유가 없어 생물상호간(生物相互間)의 관계는 초기(初期) 천이(遷移)단계의 특성(特性)인 종다양도(種多樣度)가 낮고 직선적(直線的)이고 단순(單純)한 먹이연쇄성(連鎖性)을 갖고 있다. 생물군집(生物群集)의 천이진행(遷移進行)에 따르는 종다양도(種多樣度)의 증가(增加)는 생물군집내(生物群集內) 현재량(現在量) 증가와 더부러 먹이 연쇄상(連鎖相)을 직선상(直線狀)에서 망상(網狀)으로 변화시키고 주된 물질(物質)${\cdot}$유전회로(流轉回路)를 포식(捕食)먹이 연소회로(連銷回路)에서 부식(腐食)먹이연쇄회로(連鎖回路)로 전환시켜 생태계(生態系)의 물질(物質)은 생태군집내(生態群集內)에 보존(保存)하는 능력(能力)을 증대(增大)시키고 토양(土壤)의 물리(物理) 화학적성질(化學的性質)을 개선하여 계내(系內) 물질(物質)의 유실(流失)을 억제하기도 한다. 농생태계(農生態系)는 생산성(生産性)의 증대(增大), 관리(管理)의 편의(便宜) 기타의 이유(理由)로 구성종수(構成種數)를 인위적으로 제한(制限)하고 관리(管理)를 통하여 발아(發芽), 생장(生長), 개화(開花)등 여러가지 생물학적(生物學的) 현상을 극도로 균질화(均質化)시키고 있어 어떤 생육단계(生育段階)의 생물(生物)이 넓은 면적(面積)에 동시에 존재하게 되는데 이것은 외적조건(外的條件)의 변동(變動)에 대한 감수성(感受性)을 증대시킨다. 이와 같은 자연생태계(自然生態系)와 농생태계(農生態系)의 생태학적(生態學的) 특성(特性)에 관한 이해(理解)와 인식(認識)은 농생태계(農生態系)의 생산성(生産性) 증대(增大)와 영구적(永久的) 유지(維持)를 위한 합리적(合理的) 관리(管理)를 위한 기본(基本)이 될 것이다.

• Korean Journal of Agricultural Science
• /
• v.4 no.1
• /
• pp.61-65
• /
• 1977

To select some salt tolerant pasture species for grassland establishment on the west coastal saline land in Korea, this work was carried out from March to October in 1976 with 5 pasture seeds mainly were introduced from Australia. On the soil salt content was 0.4%, all seeds germination were failure, but all species were survived on the 0.2% salt content land. The yield of forage were much better from Kikuyu grass and Pearl millet but poor from other species. The Meadow grass could be used for protect soil erosion by lot of tillers. By the result from this experiment, only Kikuyu grass and Pearl millet were possible to use for forage crops. But to continue this work, it is suggested to introduced more effective species such like Saltwater couch, Saltshore ryegrass, Puccinella, Salt bush, Blue buch, Samphire and so on.

• Korean Journal of Soil Science and Fertilizer
• /
• v.38 no.4
• /
• pp.218-221
• /
• 2005

The present study was investigated in the Chittagong hill forest of Bangladesh to assess the feasibility of ginger cultivation under multipurpose forest and fruit tree species. There were three treatments such as i) ginger grown under open field condition, ie. full sunlight (T1), ii) ginger grown under Gamar tree (spacing of $90{\times}90cm$ (T2) and iii) ginger grown under guava tree (spacing $180{\times}180cm$) tree (T3). The experiment was laid out in randomized block design (RBD) and each treatment was replicated three times. From data it was observed that some morphological parameters of ginger such as plant height, number of leaves per plant, leaf length and leaf breadth were higher in the treatments T2 and T3 as compared to the treatment T1. A positive and linear relationship was observed between the weight of rhizome and yield of ginger which caused the highest yield of ginger ($23.63Mg\;ha^{-1}$) under guava tree species at partial shaded condition in the T3 treatment ($180{\times}180cm$), whereas the lowest yield ($15.64Mg\;ha^{-1}$) was recorded in the T2 treatment when ginger was cultivated under Gamar tree species at closer spacing ($90{\times}90cm$). Therefore, it was revealed that partial shaded condition favoured the optimum growth and yield of ginger, whereas the dense shade from intensively planted tree species badly affected the dry matter production and yield of ginger.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.323-323
• /
• 2016

최근 강우강도 등의 기후변화로 인한 표토침식량이 증가하고 있고, 이에 따른 사회적 환경적 문제가 부각되고 있다. 특히 표토는 인류에게 식량생산의 기반이 되고, 정주공간을 제공할 뿐만 아니라 에너지 생산, 수자원 함양, 기후변화 대응, 생물 다양성 유지, 생태계의 건전성, 자원함양 및 순환, 오염물질 정화 등 소중한 생명자원이다. 이에 환경부에서는 2012월 12월 표토의 침식현황에 관한 고시를 제정하고, 표토 유실 대책 방안을 수립하기 위한 노력을 기울이고 있다. 이에 자원으로서의 표토를 보전하기 위한 단기적 관점의 대책 수립을 위한 웹GIS 기반 단일 강우에 의한 표토침식량을 예측하는 시스템을 개발하였다. 본 연구는 크게 표토침식 예측 모듈 개발과 정확성 평가를 위한 시험포 단위 모니터링 그리고 모듈을 적용한 웹GIS 시스템 개발, 시범적용을 위한 강원도 홍천군 자운리 DB 구축으로 구분된다. 표토침식예측 모듈의 정확성을 검증하기 위하여 가로 4m ${\times}$ 세로 22m, 경사도 3%, 9% 시험포 2개를 조성, 2015년 5월 11일부터 2015년 11월 23일까지 강우량, 유출량, 표토침식량을 조사하였으며, 웹 GIS 시스템은 Open Source Software인 Geoserver, PostGIS, OpenLayers를 활용하여 개발하였다. 마지막으로 개발된 웹GIS 표토침식예측시스템의 시범적용을 위하여 강원도 홍천군 자운리의 농경지 경계, 경사도, 경사장, 작물특성 등에 대한 GIS DB를 구축하였다. 시험포 모니터링 결과 강우발생일수는 총 64일로 관측되었고, 이중 유출은 총 30회가 발생되었다. 이 결과를 활용하여 표토침식 예측 모듈을 검증한 결과 3 % 시험포의 유출량 NSE : 0.88, $R^2$ : 0.91, 표토침식량 NSE : 0.87, $R^2$ : 0.90, 9 % 시험포의 유출량 NSE : 0.76, $R^2$ : 0.82, 표토 침식량 NSE : 0.82, $R^2$ : 0.88로 나타났다. 웹GIS 표토침식 예측 시스템은 Layer 정보, 맵, GIS tool, 경작기 정보, 날씨 정보 등으로 구성되어 있으며, 기상청 Open API와 연동하여 당일의 강수량 예보 데이터와 표토침식량 산정 모듈을 이용하여 예측 표토 침식량 데이터를 제공한다. 하루가 지나면 기상청에서 실측한 강수량 데이터를 이용하여 표토 침식량 산정모듈이 자동적으로 수행된 뒤 실측 강우량에 대한 표토침식량 정보가 제공된다 본 연구에서 개발된 웹GIS기반 표토침식 예측 시스템은 시범 대상 유역인 강원도 홍천군 자운리 유역을 대상으로 구축되었으며, 지속적으로 대상유역을 확대할 계획이다.

• Korean Journal of Soil Science and Fertilizer
• /
• v.18 no.4
• /
• pp.366-372
• /
• 1985

Soil temperatures and soil physical properties were investigated in order to better understand the effects of mulchings in the red pepper field. The red pepper was planted in the lysimeter installed at the Yesan sandy loam with 20% slope and 10cm slope length. The results were summarized as follows: 1. Average soil temperatures at 10cm and 20cm depth in vinyl mulching plots were $1.6^{\circ}C$ and $1.1^{\circ}C$ higher than those of control, respectively. However, the average soil temperatures in rice straw mulching plots were relatively lower than those of control during the growing season. 2. The greatest diurnal fluctuation of soil temperature was found at the vinyl mulching plots and it was decreased with increasing soil depth. 3. The calculated thermal diffusivities were 0.011, 0.009 and $0.007cm^2/sec$ for the vinyl mulching, control and straw mulching, respectively. 4. Soil losses were 103kg/10a for the vinyl mulching and 36kg/10a for the straw mulching which were nearly negligible as compared to the control. 5. Soil physical properties such as bulk density, hardness and water content were significantly improved by the vinyl and straw mulchings.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.1
• /
• pp.55-63
• /
• 2001

N fertilizer recommendations to optimize with consideration to maximum crop yields, maximum profits, and minimum N losses to ground or runoff water, an advisory system. Nitrogen Expert System (NES), was developed. The system was to estimate the optimal rate of N fertilizer application cornfields in Illinois. NES was constructed using Smart Elements, a knowledge-based system that manages the expertise of human experts. NES was reinforced by addition of the effect of a productivity index (PI), soil organic matter content (SOM), and pre-sidedressing of nitrate concentration (PSNT) to the optimal N fertilizer recommendation. NES contains 49 rules, 1 class, 14 objects, and 2 properties. NES was successfully operated, showing N recommendations with inputs of three soil properties including PI, SOM, and PSNT. NES can reduce N loss to the environment, but adherence to the recommendations may also reduce farmers income. Therefore, NES will be more effective by evaluating both environmental damage assessment and other economic agricultural management parameters and other soil physico-chemical parameters.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.40 no.2
• /
• pp.157-166
• /
• 1995

The fate and use efficiency of applied nitrogen were evaluated in a pot experiment with different fertilizers and water management practices during 30days after fertilizer application. N-P-K compound fertilizers, 13-10-1l(F-l) for upland Crop use and 15-10-10(F-3) for rice Crop use, and mixed fertilizer, 21-17-17(F-2) for basal dressing in rice were used. Fertilizers corresponding to 1.8g N were mixed thoroughly with the whole volume of sandy loam soil in a pot. The pots were flooded upto 3cm above soil surface for O(0dF), 10(10dF), 20(20dF), and 30(30dF) days after fertilizer application and all the treatments were flooded continuously from 30 days after fertilizer application. During the flooding period water percolation rate was adjusted to 2.5mm/day. Rice seedlings were transplanted 40 days after fertilizer application. The pH of infiltrated water increased with increasing duration of flooding. The pH of F-2 was higher than those of F-1 and F-3 between which there were no differences. The applied nitrogen remained 23% in F-1, 29% in F-2, and 29.1 % in F-3, and 45.0% in 0dF, 26.6% in 10dF, 24.8% in 20dF, and 20.3% in 30dF as inorganic nitrogen at 63 days after fertilizer application. Nitrogen losses by leaching amounted to 51.3%, 32.1% and 48.1% of applied nitrogen in F-1, F-2 and F-3, respectively. Nitrogen leaching losses increased with increasing duration of flood- ing, amounting to 25.7%, 29.8%, 32.7%, and 35.8% in 0dF, 10dF, 20dF and 30dF, respectively. Gaseous loss of applied nitrogen was greatest in F-2, followed by F-1 and F-3. Total loss of nitrogen due to gaseous volatilization and leaching was greatest in F -1, followed by F -2 and F-3, and were greater in the treatments with longer flooding after fertilizer application. Nitrogen recovery by rice shoot until 72 days after transplanting were 23.2%, 24.7% and 27.4% of applied nitrogen in F-1, F-2 and F-3, respectively and 34.1%, 25.5%, 21.1%, and 21.2% in 0dF, 10dF, 20dF and 30dF, respectively.