Soil chemical properties in paddy fields were found to be varied depending upon different cultivation methods such as environmentally-friendly, conventional, and two-crop farming systems and different topographical regions, namely plain, middle mountainous, and reclaimed land regions. Overall soil pH was found to be in optimal range (pH 5.5~6.5) for rice cultivation, except with conventional cultiva-tion fields of the reclaimed lands in Jeonnam province. Electrical conductivity (EC) was relatively higher in the two-crop cultivation fields than in others. How-ever, the concentrations of available phosphate as P2O5 were exceptionally higher in the two-crop farming fields, thus in submerged paddy condition the phosphate could be released into streams and rivers. Soil organic matter (SOM) contents were mostly in optimal range (25~30 g kg-1) for paddy field in Jeonbuk province, but in Jeonnam province they were slightly higher values of the range. The concentra-tions of available silicate (SiO2) were mostly depended on the cultivation methods and the region, but some of paddy fields contained extremely high SiO2 concentra-tion. Statistical relationships among the soil chemical properties showed as follows: Correlations between EC values and exchangeable cation concentrations, between SOM contents and CEC values, and between available SIO2 concentrations and pH, EC, exchangeable cations, and CEC values were positively significant, whereas total nitrogen concentrations were significantly negatively correlated with the concentrations of exchangeable K and Mg. These results might be very useful to establish benchmark paddy fields contained with certain levels of soil fertility.

농경지의 볏짚 수거량이 증가하면서 부족한 유기물을 공급하기 위하여 녹비작물을 이용하고 있다. 녹비작물은 유기물공급과 화학비료 대체가 가능한 우수한 유기물원이다. 그러나 농경지에서 분해되는 과정에 메탄을 발생시키기 때문에 메탄발생량을 줄이기 위한 노력이 요구된다. 따라서 논토양에서 녹비작물을 이용할 때 메탄발생량을 줄이기 위하여 경운깊이를 달리하여 시험하였다. 벼 생육기간 중 메탄 발생량은 이앙 후 63일, 74일에 가장 많았고 이앙 후 74일 이후부터 감소되었으며 이앙 후 106일에는 거의 발생되지 않았다. 녹비종류에 따른 메탄발생량은 보리환원구에서 가장 많았고, 그 다음은 헤어리베치, 화학비료 순이었다. 경운 깊이에 따른 메탄발생량은 10 cm경운보다 20 cm로 경운함으로써 화학비료는 22.5%, 헤어리베치 환원구는 12.4%, 보리환원구는 11.7% 감소되었다. 벼 재배기간 동안 대기온도는 30~40℃였고, 지온은 대기온도보다 약 2~10℃정도 낮았다. 산화환원전위(Eh)는 이앙 전 관개를 시작하면서 급격히 토양이 환원되어 (-)값을 나타냈다. 작물 재배기간 동안 산화환원전위차는 –300~-500 mV으로 낮았으며 관개가 중단된 이앙 후 106일 이후에는 다시 급격하게 증가되었다. 쌀 수량은 경운깊이에 따른 차이는 없었으나 녹비작물중에서는 헤어리베치 환원구에서 가장 많았다. 논토양에서 헤어리베치를 이용할 때 20 cm로 경운하여 메탄발생을 효과적으로 줄일 수 있었다.

Physiological disorders such as symptoms in leaf colored with brown spots are so many occurred in ginseng garden cultivated with paddy soil. This study was carried out to inhibit the symptoms of brown-colored leaf in 3-year-old ginseng by fertilizing calcium hydroxide [Ca(OH)2] of 100 ~ 400 ㎏ per 10a on paddy soil before transplant of seedling. Soil pH was rapidly increased, while Fe was decreased in soil by the increase of application level of calcium hydroxide. Soil pH was increased from 4.53 to 6.18 when calcium hydroxide was fertilized at level of 100kg per 10a. The content of Fe in ginseng leaf was decreased more than the control by fertilizing calcium hydroxide in soil. Ratio of brown-colored leaf and plant height and leaf area were decreased by the increase of calcium hydroxide. Ratio of survived root and yield of root showed the peak at the application level of 100 ㎏ per 10a, and both of them were gradually decreased by the increase of calcium hydroxide. The decrease of missing plant rate above the application level of 200 ㎏ per 10a had a negative effect on the decrease of yield of root.

Rice (Oryza sativa) is the most important staple food of over half the world’s population. This study was conducted to evaluate the possible impact of transgenic rice cultivation on the soil microbial community. Microorganisms were isolated from the rhizosphere of GM and non-GM rice cultivation soils. Microbial community was identified based on the culture-dependent and molecular biology methods. The total numbers of bacteria, fungi, and actinomycete in the rhizosphere soils cultivated with GM and non-GM rice were similar to each other, and there was no significant difference between GM and non-GM rice. Dominant bacterial phyla in the rhizosphere soils cultivated with GM and non-GM rice were Actinobacteria, Firmicutes, and Proteobacteria. The microbial communities in GM and non-GM rice cultivated soils were characterized using the denaturing gradient gel electrophoresis (DGGE). The DGGE profiles showed similar patterns, but didn’t show significant difference to each other. DNAs were isolated from soils cultivating GM and non-GM rice and analyzed for persistence of inserted gene in the soil by using PCR. The PCR analysis revealed that there were no amplified protox gene in soil DNA. These data suggest that transgenic rice does not have a significant impact on soil microbial communities, although continued research may be necessary.

So far, most studies associated with soil carbon sequestration have been focused on long term aspect. However, information regarding soil carbon sequestration in short term aspect is limited. This study was conducted to determine changes of soil organic carbon content and stability of carbon in response to compost application rate and tillage management during rice growing season(150 days) in short term aspect. Under pot experiment condition, compost was mixed with an arable soil at rates corresponding to 0, 6, 12, and 24 Mg/ha. To determine effect of tillage on soil carbon sequestration, till and no-till treatments were set up in soils amended with application rate of 12 Mg/ha. Compost application and tillage management did not significantly affect soil organic carbon(SOC) content in soil at harvest time. Bulk density of soil was not changed significantly with compost application and tillage management. These might result from short duration of experiment. While hot water extractable organic carbon(HWEOC) content decreased with compost application, humic substances(HS) increased. Below ground biomass of rice increased with application of compost and till operation. From the above results, continuos application of compost and reduce tillage might improve increase in soil organic carbon content and stability of carbon in long term aspect.

This study was carried out to investigate the cause of leaf discoloration occurring frequently in paddy cultivation. Chemical property of soil and inorganic nutrient component of leaf were analyzed on abnormal fields of 7 regions where leaf discoloration occurred severely and normal fields of 7 regions among ginseng garden. The pH of abnormal fields was strong acidic condition (pH 5.51) compare to normal fields of slightly acid condition (pH 6.42). Calcium and magnesium content in abnormal fields were lower distinctly than that of normal fields, while EC, organic matter, phosphate, and potassium content showed not distinct difference between abnormal and normal fields. Whereas calcium and magnesium content were distinctly high in normal fields, both of potassium and iron content of ginseng leaf were distinctly high in abnormal fields. In particular, iron content of abnormal fields was more 1.94 times in soil, and 3.03 times in leaf than that of normal fields. In soil chemical property, there were significant negative correlation between leaf discoloration ratio and soil pH, and there were also significant positive correlation between leaf discoloration ratio and iron content. In ginseng leaf, there were highly significant negative correlation between leaf discoloration ratio and calcium content, and there were also highly significant positive correlation between leaf discoloration ratio and iron content.

Rice (Oryza sativa) is the most important staple food of over half the world’s population. This study was conducted to evaluate the possible impact of transgenic rice cultivation on the soil microbial community. Microorganisms were isolated from the rhizosphere of GM and non-GM rice cultivation soils. Microbial community was identified based on the culture-dependent and molecular biology methods. The total numbers of bacteria, fungi, and actinomycete in the rhizosphere soils cultivated with GM and non-GM rice were similar to each other, and there was no significant difference between GM and non-GM rice. Dominant bacterial phyla in the rhizosphere soils cultivated with GM and non-GM rice were Actinobacteria, Firmicutes, and Proteobacteria. The microbial communities in GM and non-GM rice cultivated soils were characterized using the denaturing gradient gel electrophoresis (DGGE). The DGGE profiles showed similar patterns, but didn’t show significant difference to each other. DNAs were isolated from soils cultivating GM and non-GM rice and analyzed for persistence of inserted gene in the soil by using PCR. The PCR analysis revealed that there were no amplified protox gene in soil DNA. These data suggest that transgenic rice does not have a significant impact on soil microbial communities, although continued research may be necessary.

본 연구는 중금속으로 오염된 논토양에서 비소 흡수능이 우수한 봉의꼬리(Pteris multifuda)를 재배할 때 차광처리가 봉의꼬리의 생육과 토양 내 비소 흡수에 미치는 영향을 분석하기 위하여 수행하였다. 비소로 오염된 (구)장항제련소 인근의 논토양에서 수행하였으며, 각 실험구의 크기를 2×2m로 조성하였고, 동일한 생육단계의 봉의꼬리를 20×20cm 간격으로 식재하여 24주간 재배하였다. 차광조건에 따른 봉의꼬리의 생육을 조사하였고, 식물체 내 비소 축적량 및 토양의 비소 변화량은 ICP를 이용하여 분석하였다. 연구의 결과, 중금속으로 오염된 논토양에서 차광에 의한 봉의꼬리의 생육은 무차광에 비해 차광 처리구에서 왕성하였다. 봉의꼬리 지상부의 비소 축적량은 차광(140.9mg·kg-1)에 비해 무차광 처리구(169.8mg·kg-1)에서 다소 높았으며, 지하부의 비소 축적량은 비슷한 경향을 보였다. 그러나 생육은 70% 차광 처리구에서 월등히 우수하여, 토양에서 흡수한 비소의 함량은 차광처리구에서 오히려 더 많았다. 봉의꼬리의 비소 이동계수(TR)는 차광처리에 관계없이 0.87~0.89로 매우 높아 흡수한 비소를 지상부로 빠르게 이동시키므로 생육 후 지상부의 제거처리에 의해 토양 내의 비소를 효과적으로 제거할 수 있으리라 생각된다.

Supplying rate of nitrogen at HV was 172.8 kg ha-1, HV/B was 64.3 kg ha-1 and B was 38.6 kg ha-1. The Rice yield was 7.05 ton ha- I when the nitrogen supply was the largest with HV and 5.42 ton ha- I was produced on HV/B. The chemical characteristics of soil have lower pH and exchangeable cations(Ca and Mg) at B, HV and HV/B, rather than at CF because green manure was applied at the former step. However, the physical characteristics of the soil and the porosity showed different tendency which was that it was better at the green manure crops than CF. Nitrogen nutrient balance was showed the most balanced at CF and field of application of green manure crops were required the appropriate management if future crops would be cultivated because nitrogen nutrient could be exhausted or accumulated. Introduction

인삼 논재배 안전생산기술을 개발하기 위해 배수불량지와 배수약간불량지 논토양에서 청3+흑1중직 차광망, 청색차광지 및 은박차광판 해가림을 처리하여 3년생 천풍의 생육특성 및 진세노사이드 함량을 조사한 결과는 다음과 같다. 해가림 유형별 투광량과 기온은 차광지 > 은박차광판 > 차광망 순이었다. 배수불량지의 토양수분장력은 평균 64mbar (절대토양수분함량 25%)로 과습한 조건이었으며, 배수약간불량지에서는 평균 123 mbar (절대수분함량 17%)이었다. 배수불량지의 토양수분장력은 계절과 해가림 유형별 뚜렷한 차이를 보이지 않았지만 배수약간불량지에서는 60~200 mbar의 범위에서 계절적 변화를 보였으며, 해가림유형에 따라 약간의 차이를 보였다. 배수불량지의 수량성은 황증과 적변 발생율의 증가로 배수약간불량지보다 현저히 감소되었다. 해가림 유형별 수량성은 배수불량지에서 차광지가, 배수약간불량지에서 차광망이 가장 높았다. 적변 발생율은 배수등급과 해가림 유형에 따라 일정한 경향이 없었다. 배수불량지는 Panaxatriol 계열 (Rg1, Re 및 Rf)의 진세노사이드 함량이 감소되고 Panaxadiol 계열 (Rb1, Rc 및 Rd)의 함량이 증가되었다. 총 진세노사이드 함량은 배수불량지보다 배수약간불량지에서 높았으며, 해가림 유형별 총 진세노사이드 함량은 배수등급에 관계없이 차광지에서 가장 높았다.

This study was conducted to assess water movement in paddy-upland rotation soil scheduled for ginseng cultivation through the measurement of infiltration and permeability of soil water. Soil sample was divided with four soil layers. The first soil layer (to 30cm from top soil) was loamy sand, the second and the third soil layers (30~70 ㎝) were sand, and the fourth (〈 120 ㎝) was sandy loam. The soil below 130 ㎝ of fourth soil layer was submerged under water. The shear strength, which represents the resisting power of soil against external force, was 3.1 kPa in the first soil layer. This corresponded to 1/8 of those of another soil layer and this value could result in soil erosion by small amount of rainfall. The rates of infiltration and permeability depending on soil layers were 39.86 cm hr-1 in top soil, 2.34 cm hr-1 in 30~70 ㎝ soil layer, 5.23 cm hr-1 and 0.18 cm hr-1 in 70~120 ㎝ soil layer, with drain tile, and without drain tile, respectively. We consider that ground water pooled in paddy soil and artificial formation of soil layer could interrupt water canal within soil and affect negatively on water movement. Therefore, we suggest that to drain at 5 m intervals be preferable when it makes soil dressing or soil accumulation to cultivate ginseng in paddy-upland rotation soil to reduce failure risk of ginseng cultivation.

To selection of optimal shading material, two-year-old ginseng (Panax ginseng C. A. Meyer) of new cultivar, 'Cheonpoong' (CP), and native species 'Hwangsookjong' (HS) were cultured under three kinds of shading materials such as three-layered blue and a one-layered black PE (polyethylene) net (TBSB), blue PE sheet (BS), and aluminium coated PE sheet (AS) in imperfectly drained paddy soil. Growth characteristics, yield and ginsenoside contents were investigated under three shading materials. Yield and ginsenoside contents of ginseng were distinctly affected by intensity and quality of sunlight penetrated through shading materials. Light transmission ratio, air and soil temperature according to shading materials were higher in order of BS, AS, and TBSB. However, ratio of aerial phase and porosity of the soil were higher in order of AS, BS, and TBSB, respectively. There was no significantly difference in the ratio of rusty colored root by shading materials. CP showed higher stem length, leaf area, and root weight than that of HS, while the former showed distinctly lower discolored leaf ratio than that the other. Eight kinds of ginsenosides content of CP were higher than that of HS in Rg1, Re, Rf, Rb1 and Rc except Rg2, Rb2, and Rb3. Total ginsenoside contents of CP was distinctly higher than that of HS. Total ginsenoside contents as affected by shading materials was higher in order of BS, TBSB, and AS in CP, while TBSB, BS, and AS in HS.

This study was carried out to investigate the optimum application time of basal fertilization in direct-seeded rice on flooded paddy surface at medium saline soil in southwestern reclaimed saline area which is Munpo series and have 0.3 or more soil salinity. The nitrogen fertilizer level were 14, 17, 20kg per 10a, and the basal fertilization were applied before sowing, 10, 20, 30 days after sowing along with topdressing at tillering stage, respectively. The summarized experimental results are as follows. Seedling stand was proper when basal fertilization was applied before sowing, but lower than appropriate seedling stand when basal fertilization were applied 10, 20, 30 days after sowing along with topdressing at tillering stage. The rice yield were 509-541kg/10a when 14-20kg/10a basal fertilization was applied before sowing, and 368-481kg/10a when basal fertilization were applied 10, 20, 30 days after sowing along with topdressing at tillering stage. Considering the yield and salt injury at medium saline soil in southwestern reclaimed saline area, the application of basal fertilization before sowing was superior for improving seedling stand, and 14-20kg/10a fertilization rate was allowable.

본 연구는 논에서 콩을 연속으로 재배 하였을 때 연차별 토양 특성 및 생산력 변화를 구명하여 식용콩 자급률을 높이기 위한 기초 자료를 제공하고자 시험한 결과를 하면 다음과 같다. 1. 논-밭 윤환에 따른 토양 물리성은 표토의 기상률은 매년 윤환구에서 17.4%였으나 콩 4년 재배구에서는 21.8%로 증가하였고, 액상률은 29.0%에서 24.5%로 낮아졌으며, 심토도 비슷한 경향을 나타내었다. 2. 토양 화학성분의 변동은 콩 1년 재배지에 비하여 유기물은 콩 1년 재배지 21.5gkg1보다 2년 재배지가 21.8gkg1로 약간 높아졌다가 3년부터는 떨어지는 경향이었으며, 치환성가리는 약간 감소하는 경향이었으나 그밖에 무기성분은 증가하는 경향을 보였다. 3. 콩 생육은 콩 1~2 년 재배구에 비하여 콩 3~4 년 연작구가 경장도 5~9cm 짧고 분지수도 0.5~1.0 개 적었으며, 엽색도도 3.5~7 정도 낮았는데 이는 연작기간이 길어질수록 생육이 떨어지는 것을 알 수가 있었다. 4. 콩 수량은 논밭 윤환시 255 kg/10a에 비하여 2년 연작시 222 kg/10a로 12.9%, 3년 연작시 201 kg/10a로 21% 감수하였으며, 생육시기별 뿌리혹 건물중 및 뿌리혹 착생은 1년 재배지에 비하여 재배 년수가 증가할수록 감소하는 경향을 보였다.

보리 후작 평야지 논에서 콩 안전 재배기술을 확립코자 보릿짚 시용 후 무경운, 경운로타리 등 경운방법을 달리하여 시험한 결과는 다음과 같다. 1. 보릿짚 시용으로 경운 유무에 관계없이 토양 중 유기물함량, 총질소, 인산 및 치환성 양이온 등이 증가하였다. 2. 토양물리성 중 공극과 토양수분함량은 경운로타리 > 로타리 > 경운로타리 후 보릿짚피복 >보릿짚소각 후 경운로타리 > 무경운 순으로 높았다. 3. 보릿짚 분해율은 파종후 30일째까지 빨랐고 그 이후는 서서히 분해되었으며, 얕게 매몰된 무경운이 경운로타리보다 빨리 분해되었고, 잡초발생량은 무경운과 보릿짚 피복에서 관행대비 각각 36%, 40% 억제되었다. 4. 콩의 뿌리활력과 근류형성능 및 콩 개화기의 생육은 무경운에서 가장 높은 값을 보였고 보릿짚 시용 후 경운로타리에서 낮은 값을 보였다. 5. 수량은 볏짚시용 후 무경운 처리에서 3,070 kg/ha으로 보릿짚 소각한 관행에 비하여 19% 증수되었으나 경운로타리는 관행수준이 었다. 따라서 평야지 논에서 콩 재배시 강우가 잦을 경우 보릿짚 시용 후 경운로타리는 토양과습을 더욱 조장하므로 무경운 골 작조 후 재배함이 가장 적절하다고 판단된다.

서남부 간척지에서 벼 담수표면산파재배시 토양 염분농도별 적정 파종량을 구명하고자 2003~2004 년에 걸쳐 호남 농업 연구소 계화도출장소 시험포장인 문포통(세사양토)의 저영답(토양 염농도 0.1%)과 중염답(토양 염농도 0.3%)에서 서간벼를 공시하여 파종량별 입모수, 생육, 수량 및 백미 외관 품위 등을 검토한 결과를 요약하면 다음과 같다. 1. 입모수는 중염답보다 저염답에서 파종량이 증가할수록 많았다. 2. 간장과 수장은 중염답이 저염답보다 파종량이 증가할 수록 짧았으며, 도복은 토양염농도에 상관없이 파종량이 증가할수록 심했다. 3. 완전미 수량은 저염답에서는 파종량 5 kg/10a까지, 중염답에서는 파종량 7 kg/10a까지는 증가되었으나 그 이상의 파종량에 서는 수량이 증가하지 않았다. 4. 백미의 외관상 품위는 파종량이 증가할수록 저염답보다 중염답에서 완전미율이 낮았다. 5. 따라서 서남부 간척지에서 벼 담수표면산파재배시 입모, 벼 생육, 완전미 수량 및 백미의 외관상 품위 등을 고려할 때 적정 파종량은 저염답은 5~7kg/10a , 중염답은 7~9kg/10a 이 적당할 것으로 생각된다.

A long-term experiment was carried out to examine the effects of compost on the long-term trends and synergy effects with chemical fertilizer and saving the chemical fertilizers of paddy cropping. The experiment was conducted for the past 36 years with constant amounts of N, P, K and compost in a paddy field at Milyang, South Korea. Grain yield was significantly increased in the plots with compost application. Twenty five years after the compost treatment, grain yield was significantly increased and it reached almost 90% of NPK plots. The effect of rice straw compost on grain yield was not clear during the early cropping years about 60%, but it slightly increased there after about 95% during the late five years. In compost plots, soil organic matter content, K and SiO2 was greater in the compost applied plots than with application of recommended doses of NPK. However, soil pH was reduced in compost applied plots and Ca, and Mg were remained unchanged when compared to the application of recommended doses NPK. Soil nutrient contents were less in compost applied plots than with the application of recommended doses of NPK along with compost but was found to be increased than that of un-fertilized plots. The present study indicated that the application of rice straw compost with NPK is the best of all and followed by NPK and Compost. However, treatment of Compost is time consuming and hard working desired and eventually non economical practice in mechanized agricultural systems, even though Compost is very useful source of improving the soil fertility and its physical characteristics and also the application of inorganic N and P are essential for sustaining high yield.