• Korean Journal of Environment and Ecology
• /
• v.15 no.3
• /
• pp.213-223
• /
• 2001

This study was carried out to clarify the distribution pattern of Salicaceae species which are considered as obligatory riparian vegetation, and also the correspondence between their distribution and the environment factors. Eighty-three study sites by stratified sampling were selected from the upstream to the downstream of An-sung stream. Vegetation factors such as coverage by species, disturbance, etc., and environmental factors including microtopography, soil properties, etc., measured and analyzed. Salicaceae species were identified as total 2 genera, 11 species through all study area, and the average occurring species were 2.8 species.5. koreensis among other species showed highest occurring frequency at An-sung streams, and also it was distributed widely through study area. S. gracizistyla was mainly fecund at upstream sites, where sandy soil texture and high longitudinal slope were developed. S. purpurea vats. japonica was mostly observed in the sandy soil, the same as S. gracilistytu and however, was not dominant but rather mixed with S. gracitistyta and S. koreensis. On the other hand, distribution of S. glandulosa were closely related with littoral zone of the lake and the lower sea level with sandy loam and loamy sand Boils of high organic matter content. Under CCA, canonical correspondence analysis, distribution of Saticaceae species was positively correlated with environmental gradients such as soil properties along to topography.

• Journal of Korea Water Resources Association
• /
• v.55 no.4
• /
• pp.291-300
• /
• 2022

Artificial disturbance in mountainous areas increases the sensitivity to erosion by exposure of the subsoil with a low loam ratio to the surface. In this study, rainfall simulations were conducted to evaluate the erodibility of sand and loamy sand in the interrill erosion by the rainfall-induced sheet flow. The mean diameters of sand and loamy sand used in the experiment were 0.936 mm and 0.611 mm, respectively, and the organic matter content was 2.0% and 4.2%, respectively. In the experimental plot, the runoff coefficient of overland flow increased 1.16 times in loamy sand rather than sand. Mean sediment yields of loamy sand and sand by sheet erosion were 3.71kg/m²/hr and 1.13kg/m²/hr respectively. The erodibility, the rate of soil erosion for rainfall erosivity factor, was 3.65 times greater in loamy sand than in sand. As the gradient of the steep slope increased from 24° to 28°, the sediment concentration and the erodibility for two soils increased by about 20%. The erodibility factor K of sandy soils for small plots was overestimated compared to the measured erodibility. This means that RUSLE can overestimate the sediment yields by sheet erosion on sandy soils.

• Korean Journal of Soil Science and Fertilizer
• /
• v.26 no.4
• /
• pp.241-248
• /
• 1993

An experiment was conducted in 1990~1991 to study the effects of various soil amelioration on the soil productivity and machine workability at tidal land paddy field of Kyewhado Substation, Homam Crop Experiment Station. The soil, Munpo Series(fine sandy loam, Typic Fluvaquents) was treated with gipsum, rice straw, rice straw compost and foreign soil(at 20cm depth) after deep ploughing. The results are surmerized as follows. 1. Sand and clay were slightly increased, while silt was slightly decreased in the rice straw and compost plots. The soil texture was changed from loam to sand loam by the addition of foreign soil 2. Soil bulk density and porosity was decreased in the rice straw, compost and foreign soil addition plots. 3. Cone penetration resistance was $12.5kg/cm^2$ at 10cm of soil depth before experiment and $12.5kg/cm^2$ at 20cm of soil depth after experiment except control, and the root zone was expended down to 20cm. 4. Soil salt content before experiment was 0.46 and 0.48% for surface soil(10cm) and subsoil(20cm), respectively ; The salt content of ameliorated plot was 0.26~0.32% and 0.16~0.31%, respectively, indicating good leaching of soil salt by the soil improvements. 5. The yields of rice in different treatments were in the order of the foreign soil addition > compost > gypsum > rice straw > control.

• Korean Journal of Food Science and Technology
• /
• v.45 no.6
• /
• pp.682-692
• /
• 2013

We investigated out the effect of cultivation region on the physicochemical characteristics of starch in six sweetpotato cultivars. The following sweetpotato cultivars were analyzed: Daeyumi, Shingeonmi, Jinhongmi, Shinyulmi, Yulmi, and Yeonhwangmi. Samples were cultivated in Muan, Iksan, Nonsan, Boryeong and Hamyang. The soil texture was found to be sandy loam in Muan, Iksan, and Boryeong, sandy clay loam in Nonsan, and loam in Hamyang. The starch content of the sweetpotato was higher in Muan than in Hamyang. The amylose content was 22.3-30.9%, and the highest amylose content was found in samples from Iksan. Rapid viscosity analysis showed that the samples from Hamyang had the lowest values of pasting temperature, while samples of the Daeyumi cultivar had the highest values. Thermal analysis with a differential scanning calorimeter showed that the Muan samples had the highest values of onset temperature, maximum peak temperature, and completion temperature, and the samples from Hamyang had the lowest values. There was no difference between the cultivation regions or the cultivar in the X-ray pattern of the starch or its appearance in scanning electron micrographs. Therefore, the results of this study confirm that cultivation region and cultivar play an important role in determining the quality of sweetpotato and the physicochemical characteristics of sweetpotato starch.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.5
• /
• pp.688-695
• /
• 2011

This study was carried out for some survey about soil compaction in the multi-cropping system of paddy field. Investigated sites were 90 farmer's fields in south-eastern part of Korea. The tillage practices season was different according to cropping system of paddy; in spring for mono rice cultivation and in autumn for the multi-cropping field. The average tillage depth in investigated sites was about 25 cm, however, it is different between the farmer's tillage practices and soil characteristics. It is high correlation to tillage deep and minimum resistance of penetration. The reaching soil deep to maximum resistance of penetration was about 27 cm, and average penetration resistance of the deep is 1.8~2.0 MPa for moderately fine-textured soils and more than 3.0 MPa for moderately coarse-textured soils. The difference of penetration resistance between cultivating and compacted layer was in order to sandy loam > clayey loam > clayey, and the difference was lesser in poorly drained soils than somewhat poorly ones. In the rice mono cropping field, the maximum resistance in no-tillage for 15 years was 1.18~1.25 Mpa at 20~25 cm in soil deep, however, the resistance of field with every year tillage practices was 2.03~2.21 Mpa. In the extremely compacted sandy loam textured soils, the penetration resistance at 30 cm in soil depth was drastically reduced by the subsoil from 5.2 Mpa to 3.2 Mpa, and the watermelon root in plastic film house was deep elongated.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.2
• /
• pp.185-192
• /
• 1987

A green house experiment was conducted to find out the acetylene reducing and $N_2$-fixing activity from photosynthetic and aerobic heterotrophic nitrogen fixing microorganisms in submerged paddy soil under different agricultural locality, soil series, soil texture, soil type, and drainage condition in which samples taken from without nitrogen treatment plot of NPK trials on 16 sites of the farmer's field. The results obtained were summarized as follows: 1. The highest acetylene reducing activity was observed at 7 days after incubation in the light condition (photo synthetic microbes+heterotrophic bacteria) while it was observed at 35 days incubation in the dark condition (heterotrophic bacteria). 2. Among the soil series, photosynthetic nitrogen fixing activity was pronounced more in Jangae, Ogcheon and Hwadong series while lower was obtained in Buyong and Daejeong series. Aerobic heterotrophic nitrogen fixing activity was high in Buyong and Daejong series. 3. Estimated amount of $N_2$-fixation from acetylene reducing activity was equivalented to 3.0 mg in light condition and 4.9 mg/100g/105 days in dark condition. 4. Among the agricultural locality, photosynthetic nitrogen fixing activity was high in rather warm southern part while heterotrophic nitrogen fixing activity was predominated more in mountainous area and Chungcheong continental. 5. Photosynthetic nitrogen fixing activity was predominated in high productive soil while aerobic heterotrophic nitrogen fixing activity was pronounced more in crose coarse sandy soil. 6. The soils properties of high photosynthetic nitrogen fixing activity were constituted of poorly or imperfectly drained clay or clay loam soil while heterotrophic nitrogen fixing activity was pronounced more in well to moderately well drained sandy or sandy loam soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.6
• /
• pp.387-393
• /
• 2001

To use as a fundamental data for the sustainable agriculture, which is nowadays a major trend to keep the productivity and conserve the environment, 487 paddy soil samples were collected from 21 regions of the Gyeongnam Province and analyzed the chemical characteristics and microbial population of the soil. The microbial population densities were bacteria $298{\times}10^5$($4{\sim}3000{\times}10^5$ range), fungi $63{\times}10^3$($2{\sim}441{\times}10^3$ range), actinomycetes $19{\times}10^5$($0.2{\sim}1250{\times}10^5$ range), Bacillus sp. $53{\times}10^4$($4{\sim}890{\times}10^4$ range) and Pseudomonas sp. $198{\times}10^4CFU\;g^{-1}$($4{\sim}1724{\times}10^4CFU\;g^{-1}$ range), respectively. The microbial populations of the soil were in general higher in southern area than in the northern area of the Gyeongnam Province. The average ratio of bacteria/fungi population was 473. As soil clay content increased, the populations of aerobic bacteria, actinomycetes and Pseudomonas sp. were remarkably decreased. The ratio of aerobic bacteria and fungi was 1554 in sandy loam and clay loam 1144, while Bacillus sp./fungi ratio was 11 in clay loam and 10 in loam. On the topographical differences, aerobic bacteria and Bacillus sp./fungi ratio were the higher in coastal plains than any other areas. The microbial population densities from different soil types were generally lower in ill-drained paddy field than those of other paddy field. The content of $P_2O_5$, K, Ca, $NO_3-N$ and EC in soil were positively correlated to the population densities of aerobic bacteria, actinomycetes, fungi, Bacillus sp. and Pseudomonas sp.. The soil organic matter and Mg content were also positively correlated to the population densities of aerobic bacteria, actinomycetes, fungi and Bacillus sp.

• Korean Journal of Soil Science and Fertilizer
• /
• v.32 no.2
• /
• pp.123-131
• /
• 1999

To get the basic information for the improvement of the optimum levels of upland soil fertility and fertilizer application, the soil samples in two hundred fifteen site were collected from the major condiment vegetable cultivation areas such as red pepper, garlic and onion fields. Physico-chemical properties of the soil samples were investigated. Soil texture distribution of soil samples in red pepper, garlic and onion cultivation areas was in order of loam (L), sandy loam (SL), silt loam (SiL) and clay loam (CL) (35.4, 31.6, 14.9 and 7.0%, respectively). The average pH of soil in garlic and onion cultivation areas were over pH 6.0, whereas in red pepper was under pH 5.5. The frequency distribution of soil pH in total sampling sites were 58.7% in under pH 6.0 and 21.4% in below pH 5.0, in contrast to 10.3% in over pH 7.0. The organic matter contents were in the range of $20{\sim}30g\;kg^{-1}$, and the onion field soils was a little higher than those in red pepper or garlic. The available phosphate contents were in the range of $719{\sim}746mg\;kg^{-1}$ and were not different among in red pepper, garlic and onion. The frequency distribution of available phosphate in total sampling sites were found 62.8% of above $600mg\;kg^{-1}$, which was over the standard level for upland soil improvement, and then 22.3% was exceeded $1,000mg\;kg^{-1}$, especially. In the exchangeable cations, the K and Ca contents in garlic (1.27 and $9.11cmol\;kg^{-1}$) and onion (1.20 and $8.39cmol\;kg^{-1}$) were higher than in red pepper (0.96 and $5.87cmol\;kg^{-1}$), respectively. The Mg contents in garlic field soils ($2.17cmol\;kg^{-1}$) were higher than those in red pepper and onion (1.51 and $1.80cmol\;kg^{-1}$). This exchangeable K, Ca and Mg contents were higher than the standard level for upland soil improvement. The contents of microelement were ranged in $54.3{\sim}60.1mg\;kg^{-1}$ for Fe, $31.3{\sim}42.3mg\;kg^{-1}$ for Mn, $1.7{\sim}2.3mg\;kg^{-1}$ for Cu and $4.8{\sim}5.5mg\;kg^{-1}$ for Zn, respectively.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.664-670
• /
• 2012

Experiments were conducted to find out the landscape effects and green manure production at the same time in farmland. Cornflower was grown in different soil texture with sand, sandy loam, loam, clay loam, and was sowing with autumn and spring respectively. The overwintering rate of cornflower was at 58.7% in average, and the treatment at sand soil showed 62.1% that was highest among other soils, which cornflower is possible to winter landscape crop. After flowering of cornflower, the contents of total nitrogen (T-N) and total carbon (T-C) in plant were 15.0 and $409.2g\;kg^{-1}$, respectively, and the carbon-nitrogen ratio (C/N) was 28.6. The yield of cornflower biomass, which will be returned to soil as green manure, recorded $1,210{\sim}3,920kg\;ha^{-1}$ at the spring seeding higher than the autumn seeding as $1,540{\sim}3,170kg\;ha^{-1}$, and the biomass treated by soil texture were showed that the treatments at the clay loam had been the largest yields both spring and autumn seeding among at other treatment of soil. The heights of cornflower regardless of soil treatments were 52.8 to 73.6 cm at the autumn seeding and 35.5 to 79.2 cm at the spring seeding although it was more significant variation at the soil textures than the seeding periods. The flowering periods of cornflower ranged from $17^{th}$ to $20^{th}$ in May at the autumn seeding and from $19^{th}$ to $20^{th}$ in June at the spring seeding, which was faster 30 days approximately at the autumn seeding than the spring seeding. In a view of the cornflower application as green manure after flowering, the autumn seeding, when considered to combine with following crops, was more suitable and various than the spring seeding, even though the yield at spring seeding was higher than one at autumn seeding.

• Korean Journal of Soil Science and Fertilizer
• /
• v.9 no.1
• /
• pp.9-16
• /
• 1976

In order to investigate inherent erodibility of the soil, which is a major factor is soil erosion prediction, a survey on runoff and soil loss of reclaimed upland soil was carried out by using a portable rainulator. The relations of soil loss and some physical properties of the soil were discussed. The soil erodibility factor for Universal soil loss equation was calculated and compared with that of Wischmeier's nomograph. The result were as follows: 1. Total runoff increased for finer textured soil in order of Jeonnam silty clay loam, Songjeong clay loam, Yesan loam, Samgag and Sangju sandy loam. Total soil loss and soil content in runoff were not correspondently related with textural characteristic in order of Jeonnam, Samgag, Sangju, Yesan, and Songjeong. Total runoff, soil loss, and soil content in runoff were increased for steeper slope. 2. Soil loss and soil content in runoff negatively correlated with organic matter content of surface soil, while positively correlated with dispersion ratio, clay ratio, silt content, and significantly correlated with Middleton erosion ratio for coarser textured soil but not correctly related for finer textured soil. 3. The soil erodibilty factor K values for Universal soil loss equation were 0.32 for Jeonnam, 0.22 for Samgag, 0.17 for Sangju, 0.15 for Yesan, and 0.13 for Songjeong respectively. These values were close to those from Wischmeier's nomograph. So, it seems that the nomograph is useful for estimation of soil loss in Korea.