• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.203-209
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• 2009

Yield monitoring is one of a precision agriculture technology that is used most widely. It is spatial variability analysis of yield information that should be attained with yield monitoring system development. This experiment was conducted to evaluate spatial variability of yield and grain moisture content in rice paddy field, and their relationships to rice productivity. It is necessary to minimize sampling interval for accurate yield map making or to control cutting width of rice combine. Considering small rice plots such as $0.2{\sim}0.4$ ha, optimum size of sampling plot was below 15 m more than 5 m in with and length. In variable rate treatment field, average yield was similar, but yield variation was reduced than conventional field. Gap of yield by another plot in same field was bigger than half of average yield than yield variation was significantly big. Therefore yield measuring flow sensor must be able to measure at least 300 kg/10a more than 1000 kg/10a. Variation of moisture content in same field was not big and spatial dependance did not appear greatly. But, variation between different field is appeared difference according to weather circumstance before harvesting. Change of spatial dependence of yield was not big, because of field variation of moisture content is not big.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.4
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• pp.369-376
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• 2002

The dielectric properties of cereal grains such as short-grain rough rice, brown rice and barley with various moisture contents were determined by measuring the attenuation and phase shift of the microwave signal trough the grain samples at 9.5GHz. The microwave free-space transmission measurement system consisted of sample holder, horn antenna and network analyzer. Dielectric constant and loss factor of grain samples increased with moisture content and bulk density and agreed well with previous research results. Moisture density, which is defined as the product of moisture content and bulk density, was proposed as a bulk density and variety compensation factor. The technique for measurement of dielectric properties based on free-space transmission may be useful for other particulate materials.

• The Korean Journal of Ecology
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• v.23 no.3
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• pp.255-266
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• 2000

생물권보전지역으로 지정된 점봉산의 온대낙엽수림(참나무 성숙림)에서 임상초본식물의 공간분포를 정량화하고, 이들의 공간분포에 미치는 미소환경요인의 영향을 파악하였다. 대부분의 임상초본식물들은 영구 방형구내 미소지소간에 큰 변이를 나타내었다. 초봄에 출현하는 임상초본식물중 공간의존도가 높은 식물은 현호색, 애기나리 및 노랑제비꽃이었고, 가을에 출현하는 임상초본식물중 공간의존도가 높은 식물은 벌깨덩굴, 쌀새 및 도라지모시대이었다. 초봄에 출현하는 홀아비바람꽃과 얼레지 그리고 가을에 출현하는 도라지모시대와 쌀새의 공간의존거리가 상대적으로 짧은 편이었다. 초봄에 출현하는 노랑제비꽃, 애기나리 및 얼레지는 관목이 적고, 낙엽층이 얇으며,토심이 깊고, 토양수분함량, 유기물함량 및 염기성양이온함량이 상대적으로 적은 생육지를 선호하였고, 애기앉은부채 와 현호색은 관목이 밀집하고, 낙엽층이 두꺼우며, 토심이 얇고, 유기물함량, 토양수분함량 및 영양염류함량이 높은 생육지를 선호하였다. 오리방풀은 빛조건이 좋고, 낙엽층이 두꺼우며, 토양수분함량과 영양염류가 풍부한 생육지를 선호하였고, 단풍취, 대사초, 개별꽃, 참취, 쌀새 및 도라지모시대는 토심이 깊고, 낙엽층이 얇으며, 토양수분함량과 영양염류함량이 상대적으로 적은 생육지를 선호하였다. 본 참나무 성숙림에서 토양수분함량, 유기물함량 및 영양염류함량은 바람, 미소지형 및 관목의 밀집정도에 의해 공간적으로 재배치되는 낙엽층 두께에 의해 영향을 받고 있기 때문에 초봄과 가을에 관찰되는 임상초본식물의 공간분포는 낙엽층의 불균등한 분포에 의해 가장 큰 영향을 받고 있는 것으로 추정되었다.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.3
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• pp.123-135
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• 2006

Spatial variability and distribution map of soil properties and the relationships between soil properties and crop yields are not well characterized in agroecosystems that have been land leveled to facilitate more cultivation of the new reclaimed sloping highland. Potato, onion, carrot, Chinese cabbage and radish were grown on the coarse sandy loam soil in 2004. Soil moisture content, soil penetration resistance and crop yield were sampled in the $10m{\times}50m$ field consisted of five plots. Sampling sites of each cultivation plot were 33 for the soil moisture, 11 for the soil penetration and 33 for the crop yield. The results of semivariance analysis, most of models were shown spherical equation. The significant ranges of each spatial variability model for the soil moisture, soil penetration and crop yield were broad as 33-35 meters in the potato cultivation plot, and that in the Chinese cabbage cultivation plot was narrow as 5-6 meters. The coefficient of variances (C.V.) of moisture, penetration and yield were various from 14 to 59 percents in five cultivation plots. The highest C.V. of potato yield was 59 percents, and that of the radish cultivation plot was as low as 14 percents. The required sample numbers for the determination of soil moisture content, soil penetration resistance and crop yield with error 10% at 0.05 significant level were ranged 8-40 for soil moisture, 7-25 for soil penetration and 424-4,678 for crop yield. The variogram and distribution map by kriging described field characteristics well so that the spatial variability would be useful for soil management for better efficiency and precision agriculture in the reclaimed highland.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.73-78
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• 2002

전기전도도 센서와 GPS장치를 연계하여 논 포장에서 실시간으로 전기전도도를 측정하는 기초시험을 실시하였다. 그 결과 아래와 같은 결과를 얻을 수 있었다. 가. 농기포장에서의 전기전도도의 평균값은 4.llmS/m인 반면, 같은 논 포장임에도 불구하고 호시포장에서는 평균값이 17.35mS/m를 나타내었다. 농기포장에서는 전기전도도의 변이계수가 34.66%, 호시포장에서는 13.15%로서 아주 큰 변이를 보였다. 나. 전기전도도 센서와 DGPS장치로부터 취득한 정보를 기반으로 지도를 작성할 수 있었다. Kriging 방법을 이용하여 지도를 작성함으로서 포장내·포장별 전기전도도 값의 공간변이가 존재함을 알 수 있었다. 다. 전기전도도 센서는 포장내·포장별 토양의 전기전도도를 측정하는데 문제점을 발견할 수 없었다. 그러나, 전기전도도 측정에 영향을 미치는 토양의 입자크기, 수분 함량 등의 영향을 고려한 좀 더 많은 연구가 진행되어야 할 것으로 판단되었다.

• Korean Journal of Plant Taxonomy
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• v.45 no.4
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• pp.353-361
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• 2015

Spatio-temporal variation in fruit set in orchids would affect long-term population viability and will influence genetic diversity over many generations. The aim of this study was to examine the breeding system of the nectariferous terrestrial orchid Epipactis thunbergii, to specifically determine levels of fruit set in terms of time and space under natural conditions. We examined pollination under natural conditions and conducted hand pollination experiments during a 2-year survey in four populations located along 1.5 km of coastal line in Jinguiri (rual village) [Jeollanam-do (province), southern Korea]. We found that, over a 2-year period, levels of percentage of fruit set were similar within patches of the four populations. By contrast, we detected significant differences in the percentage of fruit set among patches. We also found that plants with larger inflorescence size produced significantly more fruits than plants with fewer flowers. Over a 2-year period, the percentage of fruit set for E. thunbergii was similar but low (14.1%) compared to that averaged for eighty-four rewarding species (37.1%). However, an increase in fruit set was achieved by hand-pollinations: artificial self-pollination (90.5-95.2%), artificial geitonogamy (94.7-95.0%), and cross-pollination (artificial xenogamy, 91.3-91.4%). No emasculated flowers produced fruits and no automatic pollination was found in E. thunbergii. Our findings suggest that E. thunbergii is a self-compatible terrestrial orchid that depends on pollinators (insects) to achieve fruit set in natural habitats, and that local environmental conditions were similar over a period of 2 years in the study area. Our results also highlight the cryptic variation of fruit production in time, but more pronounced variability in space.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.309-315
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• 2009

Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30cm depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (< 10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30cm was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops ($r^2$${\geq}$0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2003.10a
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• pp.156-157
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• 2003

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.08a
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• pp.122-123
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• 2005

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.29-35
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• 1999

Soil structure and organic matter have been known to strongly affect water flow and solute transport, yet little information is available concerning soil hydraulic properties related to soil physical and chemical properties in the forest site. The purpose of this study was to quantify the spatial variability and spatial correlation of the measured parameter values from the plots established with the rainfall simulator on Japanese larch(Larix leptolepis) dominated site in Kwangju. Kyunggi-Do. Measurement of soil water flux and retention were made with the inherent soil texture, soil structure, and organic matter. The method was based on the observation that when water was applied at a constant rate to the soil surface on each plot. The method was simple to apply and consists of following steps: (i) Wet the soil from a rainfall simulator with several known discharge rates on a relatively leveled soil surface with and without organic matter. (ii) Once the borders of the ponded zone were steady, saturated hydraulic conductivity( $K_{s}$) and the matric flux function(F) was evaluated from a regression of flux vs. the reciprocal of the ponded area. A conductivity of the form $K_{i+}$$_1$ $_{c}$= $K_{i}$( $_{c}$) [1-d /dz] where flux continuity implies. For this, continuity of matric potential at the interface at all times are as follows: $_1$( $Z_{c}$) = $_2$( $Z_{c}$) = $_{c}$ for steady state intake from water ponded on the soil surface. Results of this investigation showed the importance of understanding spatial variability in wide differences of water retention and saturated hydraulic conductivity with respect to pore geometry and organic matter contents which influenced the water flux throughout the soil profile.l profile.ile.