초록 ▼

Ⅳ. 연구개발결과
1. 녹비작물 재배에 따른 논토양 양분관리 기술 개발
○ 시험포장의 연간 누적 강우량은 2013년 1,198㎜, 2014년에는 659㎜, 2015년에는 122㎜로 연차별로 큰 차이를 나타내었다. 강우에 따른 논의 유거수량은 2013년 926㎜, 2014년 174 ㎜, 2015년 122㎜로 강우량이 많은 년도에 더 많은 유거수량을 나타내었음
○ 논물의 TN 농도는 5 ㎎ L^-1 이하의 수치를 나타내었으나 화학비료 시용구에서는 질소비료 시용 후 2∼4일간은 매우 높은 농도를 나타내었

Ⅳ. 연구개발결과
1. 녹비작물 재배에 따른 논토양 양분관리 기술 개발
○ 시험포장의 연간 누적 강우량은 2013년 1,198㎜, 2014년에는 659㎜, 2015년에는 122㎜로 연차별로 큰 차이를 나타내었다. 강우에 따른 논의 유거수량은 2013년 926㎜, 2014년 174 ㎜, 2015년 122㎜로 강우량이 많은 년도에 더 많은 유거수량을 나타내었음
○ 논물의 TN 농도는 5 ㎎ L^-1 이하의 수치를 나타내었으나 화학비료 시용구에서는 질소비료 시용 후 2∼4일간은 매우 높은 농도를 나타내었다가 이 후 급격히 감소하는 경향을 보였음
○ 논물의 TP 농도는 0.8 ㎎ L^-1 이하의 값을 나타내었고 녹비투입구가 화학비료 시비구 높다 약간 높은 경향을 나타내었음
○ 유거수의 TN 농도는 표준시비구의 질소비료 시용 후 발생한 유거수를 제외하고는 대체로 5㎎ L^-1 이하의 값을 나타내었고 TP 농도는 0.2 ㎎ L^-1 이하의 값을 나타내었음
○ 유거수의 TN 유출량은 화학비료와 녹비 시용 간 차이가 없었으나 화학비료 시용 후 유거수가 발생한 2015년에는 표준시비구에서 더 많은 TN 유출이 일어났고 TP 유출은 녹비처리구 화학비료 시용구 보다 약간 더 많은 것으로 나타났으나 차이는 크지 않았음

2. 하천농경지 환경영향평가와 토양침식과 양분손실방지 토양·물관리 기술 개발
○ 2013∼2015 세종시 부강면 현장 연중 강우량 변화 (일 40 mm 이상 발생 일 수) : 19일∼22일
- 국지성 강우 발생 (2013, 2014년 시간당 최대 150mm 이상 3회 등)
- 국지성 강우 증가에 따른 침식 및 유거 증가 → 저감 방안 필요
○ 농경지에서 강우 시 침투량은 초기 5분 이내에 급격히 감소
- 양토의 경우 분당 0.33mm 이상 강우가 15분 이상 지속 시 유거 발생 가능
- 대부분의 하천변 농경지가 이에 해당
○ 녹비작물 토양환원 시 침투력 다소 향상
- 호밀 > 호밀+ 헤어리베치 > 헤어리베치 > 관행 → 시간 경과함에 따라 지속적 감소
- 시간별 (호밀) : 0.67 cm hr^-1 (녹비작물 환원 후) → 0.04 cm hr^-1 (74일째)
- 따라서 녹비작물 환원도 농경지에서 침식과 유거 저감에 다소 효과
○ 이랑크기와 주작물(옥수수) 재배와 유거수 발생 특성
- 단일 이랑의 길이가 길어지면 유거량도 증가
- 유거수 내 질소함량 : 질소시비량과 정의 상관 (단 녹비환원 형태, 작물생육 상태 등에 차이)
○ 침식 및 유거 방지 방안
- 작물재배 시기 조절 : 식생에 따른 캐노피 형성을 기준한 적정 작목
- 작물재배형태에 따른 이랑 및 두둑 토양구조 적용 (예 : Briggs Tied Ridger)
- 강우경향을 고려한 시비법 (수확량 중심 기비 대 추비 분배 시비방안 등)

3. 하천변 농경지 최적 관리를 위한 녹비작물과 주작물 작부체계 수립
○ 녹비 이용 옥수수 재배 시 광합성량은 호밀+헤어리베치 혼파처리가 호밀 또는 헤어리베치 단파 처리에 비해 높은 광합성을 나타냄
○ 녹비 이용 재배 시 옥수수의 견물중은 출웅기에는 관행재배구 보다 높은 경향을 보였으나 출사기에는 관행재배와 비슷하거나 약간 낮은 경향을 나타냄
○ 녹비 이용 옥수수 재배 시 옥수수의 수량은 헤어리베치 > 관행 > 혼파(헤어리베치+호밀) > 호밀 순으로 헤어리베치 투입이 가장 좋은 것으로 나타남

4. 녹비작물 토양환원과 양분수지 최적화를 위한 밭토양 양분관리 기술 개발
○ 토양환원 녹비작물 종류별 질소시비 수준에 따른 질소부하는 질소 시비량이 증가할수록 직선적으로 증가하였음
- 질소부하가 “0”이 되는 조건에서 HV 환원구의 질소 요구량은 -46.3 kg ha^-1로 추가적인 무기질비료 시비가 필요하지 않았던 반면 Rye와 Mixed 환원구의 질소 요구량은 각각 91과 23.4 kg ha^-1이었음
○ DNDC 모델을 통한 2014년과 2015년의 질소수지 결과를 종합해보면, 관행구에서 질소 시비는 질소 용탈과 대기 배출량이 증가를 초래하여 질소수지가 음의 값을 나타냈으며, 녹비작물 환원구에서는 질소 시비량과 관계없이 녹비작물의 환원량이 증가할수록 질소 양분수지를 증가시킨 것으로 예측되었음

5. 가축분퇴비 등 유기자원 이용에 따른 녹비작물의 최적이용 기술 개발
○ 녹비작물 및 유/무기 자재의 혼용처리에 따라 CO2 발생량 및 분해도가 매우 큰 차이를 보였으나, 혼용처리에 의해 분해도 증가
○ 화학비료는 토양 중 질산태 질소 농도가 높고 용탈량도 많지만, 녹비 단독 및 녹비 유기 자재 혼용처리의 경우 용탈 질소량이 적음
○ 작물재배에 대한 녹비 및 유기자재 혼용 처리 모델의 결과 역시, 단독처리에 비해 재배 작물에 대한 질소 공급력이 크게 향상되어, 옥수수 혹은 고추에 대해서도 혼용처리가 가능할 것으로 기대.
○ 녹비 혼용처리시 질소 용탈을 야기하는 질산태 질소의 생성과 관련된 질산화균의 군집이 증가하나, 미생물 체내로의 고정화도도 함께 증가되어 질소 용탈량은 감소하였음.

Abstract ▼

1. Development of nutrient management technology of paddy soil according to
green manure utilization
To develop green manure utilization technology for reducing non-point pollutant derived from paddy field adjacient to riverside, field experiments were conducted from Feb. 2013 to Dec. 2015. Th

1. Development of nutrient management technology of paddy soil according to
green manure utilization
To develop green manure utilization technology for reducing non-point pollutant derived from paddy field adjacient to riverside, field experiments were conducted from Feb. 2013 to Dec. 2015. This experiments were conducted at 3 experimental fields nearby river or stream located in Yongin city(2013), Suwon(2014), and Buan(2015). The soil series of experimental fields were Sachon(Yongin city), Sinheung(Suwon city) and Munpo(Buan county). Experimental treatments were incorporation of hairy vetch(HV), barley, HV+barley, chemical fertilizer and control. Soil incorporation of green manure was conducted between 13 May and 21 May and rice transplantation was conducted between 31 May and 9 June. Green manures were applicated based on N 9㎏/10a and chemicla fertilizer applicated by 9-3-3(N-P₂O₅-K₂O) in 2013, 2014 and 9-4.5-5.7 in 2015. The leeve height of experimental field was 50㎜. Annual cumulative rainfalls of experimental fields were 1,198㎜ in 2013, 659 ㎜, in 2014, and 122㎜ in 2015. Annual runoff amounts of experimental fields were 926㎜ in 2013, 174㎜ in 2014 and 122㎜ in 2015. The more amount of railfall was, the more runoff occurred. Generally, TN concentration of paddy water was below 5 ㎎ L^-1. But for 2∼4 days after chemical N fertilization TN concentration was very high in chemical fertilizer plot. TP concentration of paddy water was below 0.8 ㎎ L^-1. TP was slightly higher in plots treated with green manures than chemical fertilizer. TN concentration of runoff water was below 5 ㎎ L^-1 except for runoff water occurred immediately after chemical N fertilization. and, TP concentration of runoff water was below 0.2 ㎎ L^-1. The runoff amount of TN shows no significant difference between green manure and chemial fertilizer, but in 2015 more TN runoff was occurred in chemical fertilization because in 2015 runoff was occurred immediately after N fertilization. The runoff amount of TP was slightly higher by green manure incorporation than chemical fertilization.

2. Environtal impact assessment and development of soil and water management technoloty of farml and adjacent to riverside to protect soil erosion and nutrient loss
Regional torrential rains occur frequently with climate change continue to cause damage in farmland adjacent to riverside every year. Especially, heavy rains are causing serious environmental problems caused by soil erosion and nutrient runoff in riverside area used by farmland. Utilization of green manure is getting popular to reduce amount of chemical fertilizer application in farm land. Also green manure is improving soil quality and reducing soil erosion. The purpose of this study was environment impact assessment and development of soil and water management technology for reduction of soil erosion and nutrient at farmland adjacent to riverside. Experimental site (3600 m²) is located on the Geum river in sejong-si, Korea, and we had cultivated corn during three years from 2013 to 2015. Three treatment composed of hairy vetch (HV), rye (Rye), and hairy vetch with rye (Mixed) and four sub plots of N level, 0, 79, 158, and 236 kg N ha^-1. The result of researching rainfall amount every year, rainfall amount is decreased 50% in comparison with 3 years ago according to climate change. Soil hydraulic conductivity and leachate water sampling were measured by using acrylic column packed with soil samples amended liquid manure and green manure by using the constant-head method. From experimental result of soil samples in each percentage manure, the soil pH, EC, CEC, organic matter, total nitrogen, total phosphorous of soil samples increased. Hv treatment plot is shown the lowest value of runoff with rainfall, and runoff is related to green manure treatment.
From experimental result of field soil samples with green manure and N level , the soil pH, EC, OM, soil hydraulic conductivity was decreased as the percentage increasing of treatment. The result of physicochemical properties runoff water, EC value is shown that rye treatment plot has the highest more than other treatment plots. As the length of fullow increase, amount of runoff is decreased because of amount of water infiltration increase as the increasing of furrow length. The result of infiltration rate after utilization green manure, it is shown in order of rye>mixed>Hv>control, and after 3 hours infiltration, every plot is show similar value. The results compared with rainfall amount of furrow and ridge under crop, amount of rainfall at ridge grow down 50% in comparison with rainfall. The result will contribute to improving the farming land composition system according to improvement of soil structure and irrigation management, to apply green manure into the soil.

3. Establishment of croopping system utilizing green manure crop for optimum management of farmland adjacent to riverside
This experiment was carried out to figure out the growth and yield of waxy corn after cultivating the hairy vetch and rye which were mostly used as a green manure crops. The waxy corn showed the growth and yield efficiency relative to conventional culture after the hairy vetch was returned to as the green manure and the amount of nitrogen fertilizer increased, and the LAI was similar to the conventional culture when less than 18 kg. NDF and ADF content levels of maize were investigated with different nitrogen rates regardless of treatments. In the case of NDF, it showed a tendency to decrease after 8 days of tasseling date. ADF had also decreased after 15 days of tasseling date. Length of ear slightly decreased compared to 188 mm of conventional culture when the hairy vetch was used as the green manure and the amount of nitrogen fertilizer was less than 9 kg, but the length of ear increased relative to the conventional culture when the amount of applied nitrogen fertilizer was more than 18 kg. Nitrogen uptake of maize leaves with different nitrogen rates showed the highest level, 4.9 g kg^-1 with 36 kg treatment on the tasseling date. This was increased by 32.4% compared to untreated control. The highest 100-kernel weight was 35.4 g with the hairy vetch and 27 kg of nitrogen fertilizer treatment. The lowest 100-kernel weight was 27.4 g with the hairy vetch and 0 kg of nitrogen fertilizer treatment. Quantity with the hairy vetch and 9 kg of the nitrogen fertilizer treatment was similar the conventional culture. Suger content with the hairy vetch and more than 18 kg of the nitrogen fertilizer treatment was higher than the conventional culture. Thickness of pericarp showed no difference among treatments. Changes of photosynthetic rate in maize leaves depending on nitrogen treatments increased as much as nitrogen rates were increased up to the highest level, 36 kg. The component analysis on maize kernel with different nitrogen rates, starch showed no significant differences among treatments. Total sugar in 18 kg treatment represented the highest content level, 6.37%. In addition, Amylopectin in 18 kg treatment showed the highest content level of 90.38%. However, amylose in 18 kg treatment showed the lowest level, 9.62% which drew a conclusion that waxy of 18 kg treatment is considered to be the strongest one.

4. Development of nutrient management technology for optimum nutrient balance of upland utilizing green manure
Excess nitrogen (N) fertilizer application still has an adverse effect on various crop diseases and environmental loadings although N fertilization has been recommended based on soil physico-chemical properties in Korean agricultural land. Thus, this study was carried out in order to investigate the effect of green manure crops on replacing mineral N fertilizer for managing N fertilization to meet N balance. And soil organic matter model was applied to simulate N balance based on the observed data in upland soil. Experimental field was layed out with split plot design where three main plots composed of the kinds of green manure crop, hairy vetch (HV), rye (Rye), and hairy vetch with rye (Mixed) and four sub plots of N level, 0, 79, 158, and 236 kg N ha^-1 were allocated for corn cultivation during three years (2013 to 2015). For the comparison of N balance between no green manure crop (None) and green manure crops, None had only one level of mineral N application (158 kg N ha^-1). The results showed that total amounts of N in green manure crops were 176, 59, and 146 kg N ha^-1 of HV, Rye, and Mixed, respectively. When green manure crops were incorporated to the soil, they contributed to increase the contents of soil total N (T-N) to the levels of 0.15, 0.15, and 0.11% at HV, Rye, and Mixed as compared to None (0.09%). However, no significant difference of T-N contents was observed at eight days after incorporation of green manure crops. The response of mineral N fertilizer to corn growth was evaluated and the results showed that there was no N response to corn growth because of green manure incorporation which have already enough N amounts for corn growth. After corn harvest, soil inorganic N contents were increased due to green manure crop incorporation to soil and the increase of N fertilizer level. Based on the result of input (application of green manure and mineral fertilizer, kg N ha^-1) and output (amount of total N uptake by corn plants, kg ha^-1), N loading calculated by input minus output was evaluated and linear increase was obtained with the increase of mineral fertilizer N. According to the curves, minimum N loading could be determined at -46.3, 91, and 23.4 kg N ha^-1 for HV, Rye, and Mixed treatment, respectively. We applied denitrification-decomposition (DNDC) model to simulate N balance based on the results of field experiment. The model results could not fit to the observed results because the model required more specific crop parameters such as maximum biomass, crop fraction, their C/N ratios, and etc., however, we could not help using only default values. Moreover, due to short experimental period the results were hardly fitted to the model. In conclusion, hairy vetch and mixed green manure crops contributed sufficient amount of N to following crop and could be useful for replacing mineral N fertilizer. Quantification of N balance in upland field through field experiment and model simulation was difficult. Thus, it is necessary to study further model simulation of soil carbon and nitrogen dynamics as green manure crop applied to the upland soil in relation to environmental concern and crop productivity.

5. Delopment of optimum utilization technology of green manure acording to soil incorporation of organic resources
Fertilizers and pesticides used on crop cultivations act as a major non-point pollution source. Whereas green manure is amended in soil to reduce amount of chemical fertilizers applied, its technical development is insufficient. In addition, excess applyment of livestock manure and compost can cause water pollution so it is difficult to dispose. The aim of this study was development of optimal amendment of green manure with organic materials for riverside agricultural land use. We examined decomposition rates and nutrient supplement of green manure (rye, hairy vetch) and organic materials (compost, oil cake, SCB biofiltrate) as sigle and combined treatment among different ratio. Most decomposition rates of combined treatments were equal or higher than single treatment of green manures. N supplyment in soils amended green manure and SCB biofiltrate was most closest to N requirement of main crops. Analysis of leachate resulted that leaching N contents of combined treatments was reduced to half of single treatments. And incubation time goes by, N was more released by decomposing of microbial body. In most of combined treatments, N content fixed in microbial body showed increasing but nitrifier's DNA amount was also increased. When crop productivity and effects on envirionmental pollution were considered, other organic materials with green manure were recommended rather than SCB biofiltrate because of it liquid characteristic. According to regional characteristic (leaching strength, soil fertility etc.,), green manure with organic materials and chemical fertilizer can be used in adequate mixing ratio.