• Korean Journal of Soil Science and Fertilizer
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• v.25 no.1
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• pp.99-107
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• 1992

Effects of the indigenous Vesicular-arbuscular mycurrhizal fungi(VAMF) on early growth response of greenhouse grown crops were experimented. This study was done to evaluate the benefit of indigenous VAMF inoculation on the early growth and the subsequent growth after transplanting of some crops such as cucumber, tomato, hot pepper, eggplant, and melon. Leaf area, shoot dry weight, and plant length of mycorrhizal greenhouse crops showed the tendency of significant or no significant increase over control plants receiving no inoculation. The levels of VA mycorrhizal colonization were increased with plant growth, and infection rates of horticultural crop except hot pepper around one week after transplanting were decreased, while that of 8 weeks after emergence of mycorrhizal seedlings were increased again and infected by around 50% at harvesting time. In spore densities in the rhizosphere soil of craps experimented, the number of spore ranged from $72.7{\pm}26.3$ to $100{\pm}10.3g^1$ on dried soil basis and high density showed in both cucumber and tomato. Total nitrogen contents in shoots were lower in the mycorrhizal plants than non-mycorrhizal one, whereas P uptake in mycorrhizal hot pepper and tomato were highly ramarkable. The K contents in the shoots of mycorrhizal cucumber and eggplent were highly enhanced. Inoculation of the indigenous VAMF enhanced shoot Ca and Mg in both tomoto and melon. The contents of Fe, Zn, Mn and Cu in shoots of mycorrhizal crops were higher than non-mycorrhizal plants and vice versa in case of eggplent. Inoculation of the indigenous VAMF to horticultural crops were effective for alleviation of transplanting shock, and pretransplanting infection improved subsequent growth by reducing the time required for establishment of a functional mycorrhizal symbiosis following transplanting.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.303-309
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• 2008

The physico-chemical properties of the rainfall interception culture (85 sites) and the open field culture soils (85 sites) in the area of Gochang-gun, Jeollabuk-do were surveyed. Soil textural distribution of the rainfall interception culture and the open field culture soils was 74% and 64% for silt loam, 16% and 35% for loam, and 10% and 1% for clay, respectively. The percentage of aggregate rates was higher in the open field culture soils (60.06%) than rainfall interception culture soils (55.84%). Electrical conductivity, exchangeable cations, and anions in the rainfall interception culture soils were higher than those in open field soils. Specially, accumulated amount of anion in rainfall interception culture soils was remarkably higher 2~3 times than open field culture soils. The results from the analyses of rainfall interception culture soils suggested that the most critical problem is the salts accumulation caused by over-fertilization of chemical fertilizer and compost. Therefore, application rates of chemical fertilizer and compost should be controlled in order to conservation of soil and water for sustainable agriculture.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.102-107
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• 2012

This study was carried out to investigate the optimum soil environmental conditions of ten contents on production of high quality fruit in 'Hongro' apple. The soil and fruit characteristics were analyzed at total 60 orchards in major apple producing areas such as Chungju, Moonkyeung, Yeongju, Andong, Yeosan and Yeongcheon (10 orchards an area). The soil environmental factors affected fruit weight were the highest relative contribution in saturated hydraulic conductivity of 33.3%. The cation was 24.6%, the bulk density, soil texture and solid phase were also high as relative contribution. The fruit weight was influenced by soil physical properties more than soil chemical properties. The soil environmental factors affected sugar content were highest soil texture of 21.9%, and the CEC and bulk density were low as relative contribution. The fruit coloring was the highest relative contribution in phosphate of 55.9%. While saturated hydraulic conductivity and organic matter content were low. The coloring was influenced by soil chemical properties more than soil physical properties. Fruit coloring was high influenced over 70% by soil physical properties. Finally, relative contribution on fruit quality related with sugar content, fruit weight, and coloring were high influenced by cultivation layer depth of 25.8%, soil texture 22.2%, and soil pH of 21.0% but bulk density and solid phase were low relative contribution. The fruit growth and soil chemical properties in 'Hongro' apple were very closely related. Therefore, orchard soil management to produce high quality fruit was very importance drainage management and organic matter application. We concluded that scientific soil management is possible by quanlifiable of soil management factors.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.31-38
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• 1994

This study was carried out to investigate the possibility of potential injury to crops which were exposed to precipitation. The rainwater were collected from May to September in 1992 and analyzed its chemical composition. The amounts of chlorophyll and cations in plant were measured, and the morphological structure of epidermis was also investigated by SEM. The results are summarized as follows: 1. The pH of precipitation in Suwon was relatively high even with high level of $SO_4^{2-}$ and monthly pH at May, June, July, August, and September were 4.65, 5.47, 5.32, 5.44 and 4.80, respectively. 2. The amount of ions in rainwater was in the order of $NH_4^+$, $Ca^{2+}$, $Mg^{2+}$ and $H^+$ for cations, and $SO_4^{2-}$, $NO_3^-$ and $Cl^-$ for anions. 3. pH of rain in less than 5mm of precipitation was higher than that in greater than 5mm of precipitation. 4. The amount of chlorophyll was higher in the plant exposed to rain than that in plant intercepted rain during the early portion of growing season, but at the later period, the trend was shown to be reversed. 5. When the sesame plants were exposed to rain at harvesting stage, they contained less amount of CaO, MgO and $Na_2O$ than those with the interception of rain. 6. Scanning electron microphotographs revealed the shringkage in glandular trichomes in the epidermis of sesame leaves when they were exposed to rain.

• Research in Plant Disease
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• v.15 no.3
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• pp.242-247
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• 2009

To select rotation crops for control of clubroot of Chinese cabbage, potato, corn, soybean, onion and groundsel were planted in the field infected with clubroot pathogen (Plasmodiophora brassicae) in highland area in 2000. In comparison of economical efficiency among rotation crops, potato and onion gained about 16.9 and 14.9 times higher, respectively, than successive cultivation of Chinese cabbage. Resting spore densities of Plasmodiophora brassicae after harvesting rotation crops were in the range of $0.3{\sim}1.2{\times}10^3/g$ soil in all cultivated soils with rotation crops while that of successive Chinese cabbage cultivation soil was very high as much as $89.3{\times}10^3/g$ soil. And disease severity of Chinese cabbage clubroot was 4.9, 20.2, 24.4, 25.1 and 27.8% in onion, soybean, potato, corn, and groundsel cultivation plot, respectively, while that of successive Chinese cabbage cultivation plot was very high as 77.8%. Effect of rotation period of onion, potato, soybean on disease control was investigated from 2002 to 2005. Resting spore densities of Plasmodiophora brassicae after cultivating rotation crops were decreased until $2^{nd}$ year and maintained low density at $3^{rd}$ year in all plots, while that of successive Chinese cabbage cultivation plot was increased 2.6 to 23.6 times for three years. When Chinese cabbage was rotation-cultivated with potato, soybean and onion for three years, disease severities of Chinese cabbage clubroot decreased 92 to 4.4%, 72 to 10.4% and 72 to 12.2%, respectively, while that of successive Chinese cabbage cultivation plot maintained 100%. As the rotation period increased, the yields of Chinese cabbage increased, while that of successive Chinese cabbage cultivation plot decreased. At $3^{rd}$ year, Chinese cabbage with high quality could be much more produced 2,205, 2,493 and 2,476 g in potato, soybean and onion cultivation plot, respectively, than 95 g in successive Chinese cabbage cultivation plot.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.86-108
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• 2017

The nationwide weed survey was conducted in arable land, paddy field, upland, orchard and pasture, over whole country of Korea during 3 years from 2013 to 2015. Also, these survey were conducted in order to determine a change of weed community and to identify a major dominant weed species, and problem weeds. Weeds of arable land were composed of 619 species belonging to 81 families. Weeds occurred in paddy field were 90 species belonging to 28 families, upland weeds were 375 species of 50 families, orchard weeds were 492 species of 63 families and pasture weeds 275 species of 52 families. Among total 81 families, the Asteraceae (15.5%) was the biggest family, followed by Poaceae (13.1%), Fabaceae (5.5%), Cyperaceae (5.2%), Polygonaceae (6.3%), respectively. And these weed species were composed of annual weeds of 209 species (33.8%), winter annual of 102 species (16.4%) and perennial weeds of 308 species (49.8%). Exotic weeds naturalized in Korea were investigated as 166 species. Weed flora in Korean cultivation area have been increased as much as 13 families and 186 species for 10 years compared to 2000~2004 weed survey result of 68 families and 433 species. The increment could be resulted from the change of weed population such as increase of the herbicide-resistant and the difference of investigation method.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.36-43
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• 2020

BACKGROUND: Wicheon watershed has the largest irrigation area among the mid-watershed of Nakdong river. However, no investigation of irrigation water quality has been conducted on the Wicheon watershed, which evaluates the effects on the soil quality and crop cultivation. Therefore, this study aims to provide various assessments of water quality of Wicheon watershed as the scientific basic data for efficient agricultural activities. METHODS AND RESULTS: Water sampling was performed in five locations of the first tributaries of Wicheon. Wicheon watershed showed clean water quality with very low organic matters and safe water quality from metals at all points of investigation. It was estimated that the natural chemical components of Wicheon watershed were originated from water-rock interaction in Gibbs diagram. All samples were concentrated in the type of Ca-HCO₃-Cl in the Piper diagram. The quality of irrigation water was evaluated with sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), and percent sodium (%Na). The values of these water quality indices were in the range of 0.37-0.67, -2.11--0.24, 41.13-84.52% and 11.28-21.84%, respectively, and were classified as good grades at all sites. CONCLUSION: The water quality of Wicheon watershed was very low in salt, indicating good irrigation water suitable for growing agricultural products. We hope that the results of this study will be used as the basic data for the cultivation of agricultural products and promotion of their excellence.

• Journal of the Korean association of regional geographers
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• v.2 no.1
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• pp.51-67
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• 1996

There are three main rice-growing regions in the United States: the prairie region along the Mississippi River Valley in eastern Arkansas; the Gulf Coast prairie region in southwestern Louisiana and southeastern Texas; and the Central Valley of California. The Central Valley of California is producing about 23% of the US rice(Fig. 1). In California. most of the crop has been produced in the Colusa, Sutter, Butte, Glenn Counties of the Sacramento Valley since 1912, when rice was commercially grown for the first time in the state(Fig. 2). Roughly speaking, the average annual area sown to rice in California is about 300,000 acres to 400,000 acres during the last forty years(Fig. 3). California rice is grown under a Mediterranean climate characterized by warm, dry, clear days, and a long growing season favorable to high photosynthetic rates and high rice yields. The average rice yield per acre is probably higher in California than in any other rice-growing regions of the world(Fig. 4). A dependable supply of irrigation water must be available for a successful rice culture. Most of the irrigation water for California rice comes from the winter rain and snow-fed reservoir of the Sierra Nevada mountain ranges. Less than 10 percent of rice irrigation water is pumped from wells in areas where surface water is not sufficient. It is also essential to have good surface drainage if maximum yields are to be produced. Rice production in California is highly mechanized, requiring only about four hours of labor per acre. Mechanization of rice culture in California includes laser-leveler technology, large tractors, self-propelled combines for harvesting, and aircraft for seeding, pest control, and some fertilization. The principal varieties grown in California are medium-grain japonica types with origins from the cooler rice climates of the northern latitudes (Table 1). Long-grain varieties grown in the American South are not well adapted to California's cooler environment. Nearly all the rice grown recently in California are improved into semidwarf varieties. Choice of variety depends on environment, planting date, quality desired, marketing, and harvesting scheduling. The Rice Experiment Station at Biggs is owned, financed, and administered by the rice industry. The station was established in 1912, as a direct result of the foresight and effort of Charles Edward Chambliss of the United States Department of Agriculture. Now, The station's major effort is the development of improved rice varieties for California.

• Journal of Bio-Environment Control
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• v.14 no.4
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• pp.284-288
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• 2005

This study was conducted to clarify the effects of supplying methods of selenium on the growth and Se uptake of hydroponically grown tomato plants. Tomato seeds (Lycopersicum esculentum Mill. cv. Momotaro T-93, Daki Seed Co.) were sown in plug tray with fifty holes, and raised for sixty days. Tomato seedlings transplanted to coco fiber slabs were supplied with the nutrient solutions adjusted to EC $2.3dS{\cdot}m^{-1}$ and pH $5.8\~6.2$ recommended by the Japanese Horticultural Experiment Station. Selenium forms used were inorganic $SeO_2$ (here in after referred to Se) and organic selenium chlenium with sugar fatty acid ester (here in after referred to chelated-Se). 10 ppm selenium solutions were treated to tomato plants with foliar applications, drenching, and foliar application plus drenching. Growth characteristics in terms of plant height, number of leaves, leaf area and chlorophyll content were significantly increased in the plot of foliar application ot Se, and in the plot of foliar application plus drenching of chelated-Se than other plots, respectively. Transported contents of selenium into the tomato fruits were highest as 0.302 ppm in the plot of foliar application plus drenching of chelated-Se. Also, it had tended to be higher in the plot of foliar application plus drenching than in the plots of foliar application or drenching in both of Se and chelated-Se. Foliar application and drenching of organic chelated-Se were effective to produce the functional tomato fruits.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.153-159
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• 2011

BACKGROUND: This experiment was conducted to investigate the distribution and burden characteristics of heavy metal in the rainwater sampled at Taean area, in the middle part of Korea, from April 2002 to October 2003. METHODS AND RESULTS: The relationship between concentration of heavy metal and other chemical properties in the rainwaters was also evaluated. Chemical properties in the rainwater were various differences with raining periods and years. It appeared that a weighted average pH values of rainwater was ranged from 5.0 to 5.1. Heavy metal concentrations in the rainwater were ranked as Pb > Zn > Cu > Ni > As > Cr > Cd. As compared with heavy metal concentrations of rainwater in 2002, Cu, Pb, and Zn were higher than other elements in 2003. There were positive correlation between major ionic components, such as ${NH_4}^+$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Na^+$, ${SO_4}^{2-}$ and ${NO_3}^-$, and As, Cd, Zn, Cr, and Ni concentrations in rainwater. For heavy metal distribution of rainwater, the order of average enrichment factor was Cd > Pb > As > Cu > Zn > Ni > Cr, and these were relatively higher than the natural components such as Fe, Mg and Ca. The monthly enrichment factor were relatively high, from August to October at Taean. The monthly amount of heavy metal precipitation was high in the rainy season from July to August because of great influence of rainfall. CONCLUSION(s): The results of this study suggest that the heavy metals(Cd, Pb, As, Cu, and Zn) of rainwater is strongly influenced by anthropogenic sources rather than natural sources.