• Journal of Bio-Environment Control
• /
• v.31 no.4
• /
• pp.401-408
• /
• 2022

As research on a controlled environment system based on crop growth environment sensing for sustainable production of horticultural crops and its industrial use has been important, research on how to properly utilize soil moisture sensors for outdoor cultivation is being actively conducted. This experiment was conducted to suggest the proper method of utilizing the TEROS 12, an FDR (frequency domain reflectometry) sensor, which is frequently used in industry and research fields, for each orchard soil in three regions in Korea. We collected soils from each orchard where fruit trees were grown, investigated the soil characteristics and soil water retention curve, and compared TEROS 12 sensor calibration equations to correlate the sensor output to the corresponding soil volumetric water content through linear and cubic regressions for each soil sample. The estimated value from the calibration equation provided by the manufacturer was also compared. The soil collected from all three orchards showed different soil characteristics and volumetric water content values by each soil water retention level across the soil samples. In addition, the cubic calibration equation for TEROS 12 sensor showed the highest coefficient of determination higher than 0.95, and the lowest RMSE for all soil samples. When estimating volumetric water contents from TEROS 12 sensor output using the calibration equation provided by the manufacturer, their calculated volumetric water contents were lower than the actual volumetric water contents, with the difference up to 0.09-0.17 m³·m^-3 depending on the soil samples, indicating an appropriate calibration for each soil should be preceded before FDR sensor utilization. Also, there was a difference in the range of soil volumetric water content corresponding to the soil water retention levels across the soil samples, suggesting that the soil water retention information should be required to properly interpret the volumetric water content value of the soil. Moreover, soil with a high content of sand had a relatively narrow range of volumetric water contents for irrigation, thus reducing the accuracy of an FDR sensor measurement. In conclusion, analyzing soil water retention characteristics of the target soil and the soil-specific calibration would be necessary to properly quantify the soil water status and determine their adequate irrigation point using an FDR sensor.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.19 no.1
• /
• pp.73-83
• /
• 2016

Forest degradation reduces ecosystem services provided by forest and could lead to change in composition of species. In North Korea, there has been significant forest degradation due to conversion of forest into terrace fields for food production and cut-down of forest for fuel woods. This study analyzed the phenological changes in North Korea, in terms of vegetation and moisture in soil and vegetation, from March to Octorber 2013, using MODIS (MODerate resolution Imaging Spectroradiometer) images and indexes including NDVI (Normalized Difference Vegetation Index), NDSI (Normalized Difference Soil Index), and NDWI (Normalized Difference Water Index). In addition, marginal farmland was derived using elevation data. Lastly, degraded terrace fields of 16 degree was analyzed using NDVI, NDSI, and NDWI indexes, and marginal farmland characteristics with slope variable. The accuracy value of land cover classification, which shows the difference between the observation and analyzed value, was 84.9% and Kappa value was 0.82. The highest accuracy value was from agricultural (paddy, field) and forest area. Terrace fields were easily identified using slope data form agricultural field. Use of NDVI, NDSI, and NDWI is more effective in distinguishing deforested terrace field from agricultural area. NDVI only shows vegetation difference whereas NDSI classifies soil moisture values and NDWI classifies abandoned agricultural fields based on moisture values. The method used in this study allowed more effective identification of deforested terrace fields, which visually illustrates forest degradation problem in North Korea.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.47 no.5
• /
• pp.15-22
• /
• 2015

The crop production technologies keep in improving and the cultivation becomes more standardization owing to the significant developments of various agricultural materials. The artificial soil and base system for root could be one of the major technologies for the modern cultivation especially for controlled horticulture. Although the perlite, cocopeat, and peat moss are the major components of the artificial soil and are broadly used for various application, there is a great need for the new alternative materials for overcoming the low nutrition and the possible shortage of raw materials. In this study, the application of oil palm EFB fiber as an alternative materials for artificial soil especially for the seeding pad components was evaluated. The changes in the structural properties and the functional properties such as moisture holding properties were compared by laboratory produced seeding pads with different mixture of oil palm EFB fiber. The addition of fibrillated EFB fiber resulted in the significant increase in durability of the seeding pad, which showed the possible application of EFB fiber to the seeding pad instead of the wood fiber (UBKP). The moisture holding properties and the germination condition characteristics of the EFB fiber showed the slight less than those of the cocopeat, which require more sophisticated study for improving the functional properties of seeding pad made of the EFB fiber.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.22 no.3
• /
• pp.152-163
• /
• 2020

The present study introduces a procedure to prepare and manage a high-resolution rainfall and soil moisture (SM) database in the LAMP prediction system, especially for landslide researchers. The procedure also includes converting the data into spatial resolution suitable for their interest regions following proper map projection methods. The LAMP model precipitation and SM data are quantitatively and qualitatively evaluated to identify the model prediction characteristics using the ERA5 reanalysis precipitation and observed 10m depth SM data. A detailed process of converting LAMP Weather Research and Forecasting (WRF) output data for 10m horizontal resolution is described in a step-wise manner, providing technical convenience for users to easily convert NetCDF data from the WRF model into TIF data in ArcGIS. The converted data can be viewed and downloaded via the LAMP website (http://df.ncam.kr/lamp/index.do) of the National Center for AgroMeteorology. The constructed database will contribute to monitoring and prediction of landslide risk prior to landslide response steps and should be data quality controlled by more observation data.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.9 no.4
• /
• pp.234-246
• /
• 2007

The role of macropore in the hydrological processes is important at the hillslope scale. Developments and distribution of macropores have not been investigated in conjunction with the characteristics of the hillslope such as topography, soil property, and soil moisture. In this study, macropore properties, such as macropore flow and saturation hydraulic conductivity were measured at a hillslope located in Gwangneung Research Forest, Pochun-gun, Gyeonggi-do, South Korea. An intensive field survey provided a refined Digital Elevation Model (DEM) for surface and subsurface topography. Spatial distributions of upslope area and topographic index were obtained through the digital terrain analysis. The total number of monitoring points was 22, and the selected points were distributed along the transect of the digital contour map. Vertical fluxes through macropores were measured using a tension infiltrometer at the depth of 0.1 m from the surface. Spatial and temporal distributions of soil moisture were obtained using an on-line measurement system, TRASE, installed in the study area. Soil moisture for the aforementioned points was measured at 0.1 and 0.3m depths below the surface. The results from tension infiltrometer experiments present that the macropore flows ranged between 21 and 94%, and the measured macroporosities varied from 1.4 to 47%. Macropore flows and macroporosities tended to increase as the measurement location moved to downslope. The ability for water conduction through macropores becomes increasingly developed as the location approaches the outlet of the hillslope.

• Journal of Korea Water Resources Association
• /
• v.48 no.10
• /
• pp.831-843
• /
• 2015

This study estimates MODIS-derived evapotranspiration data quality by revised RS-PM algorithm in Seolmacheon test basin. We used latent flux with eddy covariance method to evaluate MODIS-derived spatial evapotranspiration and gap-filled these data by three methods (FAO-PM, MDV and Kalman Filter) and to quantify daily evapotranspiration. Gap-filled daily evapotranspiration data was used to evaluate evapotranspiration computed by revised RS-PM algorithm derived MODIS satellite images. For the water budget analysis, we used soil moisture content that is quantified to average individual soil moisture rate observed by TDR (Time Domain Reflectometry) sensor at soil depth. The soil moisture variation is calculated in consideration from initial to final soil moisture content. According to the result of this study, evapotranspiration computed by revised RS-PM algorithm is very larger than eddy covariance data gap-filled by three methods. Also, water budget characteristics is not closed. We could analysis that MODIS-derived spatial evapotranspiration does not represent actual evapotranspiration in Seolmacheon.

• Korean Journal of Environmental Agriculture
• /
• v.14 no.1
• /
• pp.28-44
• /
• 1995

Residue level of myclobutanil[2-p-chlorophenyl-2-(1H-1,2,4-trizol-l-yl-methyl) hexane nitril] and number of soil microorganism were investigated at different environmental conditions such as the sterile and the non-sterile soils, moisture content, pH, temperature, application rate, and soil types under laboratory and field to study the effect of those factors on degradation characteristics of this fungicide and change of microflora in soil. Decomposition rate of myclobutanil was 3.9 times faster in the non-sterile soil than in the sterile soil, 1.6 times in the field than in the laboratory, 1.4 times in the concentration of 10ppm than in that of 20ppm, and 1.2 times in the clay loam soil than in the silty loam soil. Degradation rate of myclobutanil was the fastest at pH 9.0 among the tested pHs and the latest at pH 5.5. Degradation rate of myclobutanil was in order of $27^{\circ}C$ > $37^{\circ}C$ > $17^{\circ}C$. Otherwise, the effect of soil water content on myclobutanil degradation was found not clear. Number of microorganism in the non-sterile soil was remarkedly more than that in the sterile soil. Numbers of microbes were not significantly different between treatment plot and non-treatment plot of myclobutanil at the different conditions of soil moisture content, pH, temperature and soil type. Numbers of fungi and total microbes were more in the treatment than in the non-treatment of myclobutanil at field test but the same trends were not found at laboratory test. Within non-treatment of myclobutanil, numbers of microbes were not significantly different under the various condition of pH, application rate, and soil type in laboratory and upland field. The number of bacteria were more in 60% moisture content of water holding capacity than in 40% and the number of fungi were more in $17^{\circ}C$ of soil temperature than in $37^{\circ}C$. Within the application plot of myclobutanil, numbers of microbes were not significantly different at various pH in laboratory and upland field. The number of bacteria and total microbes were more in 80% moisture content of water holding capacity than in 40% and 60% and actinomycetes were more at $27^{\circ}C$ in the clay loam soil than at $17^{\circ}C$ in the silty loam soil.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.8 no.2
• /
• pp.1193-1199
• /
• 1966

More stable and higher yields in rice paddy depend mainly upon an adequately balanced supply of water for higher yield. Rice paddy is supplied naturally by rainfall but inevitably requires artificial supplenental irrigation for higher yields. Even though it may be true that the water requirement of rice plants is generally higher than those of other crops, the submerged condition is not necessarily required for rice. The moisture requirements of rice vary according to its growing stages and it is possible to increse the irrigation efficiency by means of lessening the loss due to percolation and evapolation in the field. This experiment was conducted on the effect of the various amount of water supply and different irrigation periods for yield and yield components, and was carried out to find out the most suitable irrigation method and to increase the irrigation efficiency for higher yields in rice paddy. Randomized block design with 3 replications was employed where the 3 levels of the amount of irrigation water; (120% moisture contents), unirrigated (90~100%) and more un irrigated candition (80~90% moisture content), and levels of the various irrigation periods; usual, initial, intermediate and final periods, being treated. The results obtained in this experiment are as follows: 1. As for the physical and chemical and soil properfies, and other characteristics, there are no differences among the treatments enough to be effective for the growth of rice plants. 2. Culm length was measured after harvest as shown in table 2. 3. Difference of the amount of irrigation water did not change the culm length and ear length, however it also indicated more apparent increase in final treatment plots thatn that of usual. 3. No difference in the number of ears and number of ears pers per hill was founded treatments both in the difference of water supply and in the various irrigation periods. 4. There is no difference in the maturing rate and 1000 grains weight. 5. The number of panicles and grains and more increased in 80~100% moisture contents soil than those of 120%. and it shows in un irrigated plots, more irrigated plots and control plots in turn. Other wise according to the period\ulcorner of irrigation the trend is appeared in turn initial, usual, final and intermediate treatments.6. Yield as shown in table 7. 8 was more increased in unirrigated plots(90~IOO% moisture content) than the control plots (120% moisture content) by up to 8.2% and also 3. 2% in more unirrigated plots than that of control by periods is shown: usual plots final, initial, inter mediate treatment plots in turn. 7. The above resutts lead to the conclusion that no remarkable, differences in yields and soil properties are made by the unirrigation. However, it is apparent that this treatment has .some advantages in the points that one could spare the amount of water supply for irrigation with more increase in yield. In addition, a higher temperature and a brisk oxygen supply would be possible throug h this treatments. Accordingly, these treatment would be a more reasonable and economical cultivation method of rice for the better harvest.

• Journal of Ecology and Environment
• /
• v.42 no.1
• /
• pp.20-29
• /
• 2018

Background: For various reasons such as agricultural and economical purposes, land-use changes are rapidly increasing not only in Korea but also in the world, leading to shifts in the characteristics of local carbon cycle. Therefore, in order to understand the large-scale ecosystem carbon cycle, it is necessary first to understand vegetation on this local scale. As a result, it is essential to comprehend change of the carbon balance attributed by the land-use changes. In this study, we attempt to understand accumulated soil carbon (ASC) and soil respiration (Rs) related to carbon cycle in two ecosystems, artificially turned forest into pastureland from forest and a native deciduous temperate forest, resulted from different land-use in the same area. Results: Rs were shown typical seasonal changes in the alpine pastureland (AP) and temperate deciduous forest (TDF). The annual average Rs was $160.5mg\;CO_2\;m^{-2}h^{-1}$ in the AP, but it was $405.1mg\;CO_2\;m^{-2}h^{-1}$ in the TDF, indicating that the Rs in the AP was lower about 54% than that in the TDF. Also, ASC in the AP was $124.49Mg\;C\;ha^{-1}$ from litter layer to 30-cm soil depth. The ASC was about $88.9Mg\;C\;ha^{-1}$, and it was 71.5% of that of the AP. The temperature factors in the AP was high about $4^{\circ}C$ on average compared to the TDF. In AP, it was observed high amount of sunlight entering near the soil surface which is related to high soil temperature is due to low canopy structure. This tendency is due to the smaller emission of organic carbon that is accumulated in the soil, which means a higher ASC in the AP compared to the TDF. Conclusions: The artificial transformation of natural ecosystems into different ecosystems is proceeding widely in the world as well as Korea. The change in land-use type is caused to make the different characteristics of carbon cycle and storage in same region. For evaluating and predicting the carbon cycle in the vegetation modified by the human activity, it is necessary to understand the carbon cycle and storage characteristics of natural ecosystems and converted ecosystems. In this study, we studied the characteristics of ecosystem carbon cycle using different forms in the same region. The land-use changes from a TDF to AP leads to changes in dominant vegetation. Removal of canopy increased light and temperature conditions and slightly decreased SMC during the growing season. Also, land-use change led to an increase of ASC and decrease of Rs in AP. In terms of ecosystem carbon sequestration, AP showed a greater amount of carbon stored in the soil due to sustained supply of above-ground liters and lower degradation rate (soil respiration) than TDF in the high mountains. This shows that TDF and AP do not have much difference in terms of storage and circulation of carbon because the amount of carbon in the forest biomass is stored in the soil in the AP.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.5
• /
• pp.189-197
• /
• 2003

The treatment and hauling of surplus soils which occur from construction activity are costly and have been demanding a reasonable recycling method. This study presents laboratory test results regarding the mechanistic properties of asphalt stabilized soils. The foamed asphalt equipment which generates the asphalt bubble was used to mix the soil. The marshall stability, indirect tensile test, resilient modulus, creep test and triaxial test(UU) were conducted to find out the performance of the asphalt stabilized soil. The test results were compared with the samples that fabricated in different conditions(the samples without asphalt and the reinforced samples using 2% cement). The inclusion of the asphalt in the soil has improved the marshall stability, resilient modulus and moisture susceptibility, and the addition of the 2% cement has even more increased these properties. The amount of the fines and the optimum moisture contents for mixing affects the mechanistic properties and important parameters for mix design.