• Korean Journal of Soil Science and Fertilizer
• /
• v.35 no.5
• /
• pp.314-325
• /
• 2002

The effects of arbuscular mycorrhizal (AM) fungus (Glomus intraradices) on plant growth and N metabolic responses were examined in perennial ryegrass plants exposed to drought-stressed or well-watered condition. Mycorrhizal inoculation improved significantly leaf water potential, dry mass and P content. Drought stress increased significantly nitrate concentration in roots where the increase was much less in AM than non-AM. Drought stress decreased the concentration of soluble proteins in non-AM shoots, whereas non-significant decline occurred in AM shoots even under drought condition. The concentrations of ammonia and proline in drought stressed non-AM plants significantly increased, while mycorrhizal inoculation lowered significantly ammonia and proline accumulation. The decrease in leaf dry weight in drought stressed-plants was significantly correlated to the increase in ammonia (p<0.01) and proline concentration (p<0.01). These results suggested that the increased P content and N assimilation by mycorrhizal inoculation may be associated with drought stress tolerance, showing the moderating effects on shoot growth inhibition and ammonia accumulation in drought stressed-plants.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.3
• /
• pp.173-183
• /
• 2006

Purpose of this study was to estimate of soil erosion, which is related with crop productivity and water quality in watershed, in Seonakdong river watershed using USLE. The data set for USLE estimation were derived from detailed digital map(K factor), satellite imagery(C and P factors) and DEM(LS factor). The R factor was calculated by AWS data from Kimhae agricultural technology center. The soil loss from arable land was equivalent of 31.5% of total soil loss in Seonakdong river watershed. The soil loss amount of paddy field and upland were 2.8% and 97.2% of arable land, respectively, even in the area where paddy field was occupied much largely as 76.3%. The reason of large amount of soil loss from upland was that 30.4% of upland was distributed at "severe" and "very severe" soil erosion grade in watershed. The distribution of soil erosion grade during cropping season(May-Sept.) was similar to the annual soil loss. Soil erosion of non-cropping season(Oct.-Apr.) was small due to a low R factor. But, soil erosion grade of near mountain footslope areas showed severe and very severe even in non-cropping season.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.3
• /
• pp.192-200
• /
• 2009

Soil testing is one of the best management practices for sustainable agriculture. Recently, as increasing soil testing needs, simplification of soil analytical procedure has been required. To determine recommendable multi-element extractant, the soil testing results of available phosphate and exchangeable cations between the conventional methods (Lancaster and 1M $NH_4OAc) and multi-element extraction methods such as Mehlich III, Modified Morgan and Kelowna methods were compared. There were highly significant correlation between the conventional methods and multi-element extraction methods (Mehlich III, Modified Morgan and Kelowna) for available phosphate and exchangeable K, Ca, Mg and Na. The coefficients of determination ($R^2) between available phosphate extracted by Lancaster method and multielement extraction methods were in the order of Mehlich III ($0.979^{***}$) > Kelowna ($0.977^{***}$) > Modified(Mod.). Morgan ($0.553^{***}$). For exchangeable cations, there were highly significant correlations between 1M $NH_4OAc method and Mehlich III, Mod. Morgan and Kelowna. However, exchangeable K, Ca and Mg by Mehlich III method were more highly correlated with conventional method than other methods. Therefore, Mehlich III extraction method could be recommended as a single extractant for simultaneous measurement using ICP in the analysis of avaliable phosphate and exchangeable cations.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.4
• /
• pp.317-322
• /
• 2009

Healthy seedling generation is the major concern in overcoming adverse effects of biotic and abiotic stresses during tender stage of development in vegetables and horticultural crops. Because of this, priority is given to research leading to the generation of healthy seedlings in crops subjected to transplanting and bedding. In this study, growth pouch experiments were conducted to determine the effect of inoculation of six different strains of Methylobacterium sp. namely, M. oryzae CBMB20, M. phyllosphaerae CBMB27, M. suomiense CBMB120, and Methylobacterium strains CBMB12, CBMB15 and CBMB17 on the seedling development of the vegetable crops cabbage, Chinese cabbage and cucumber; and horticultural crops tomato and red pepper. Crops treated with the test strains generally showed higher seedling dry matter accumulation compared to the control. Significantly higher accumulation was exhibited by CBMB12, CBMB17, and CBMB20 in cabbage, as well as for CBMB27 and CBMB120 on tomato and Chinese cabbage, respectively. Furthermore, all the strains promoted root elongation in cucumber and tomato seedlings while in Chinese cabbage and red pepper, root elongation was observed with CBMB120 and CBMB12 inoculation, respectively. Large scale nursery study is needed to develop a thorough protocol for healthy seedling development with the use of these strains.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.4
• /
• pp.255-261
• /
• 2007

Soil aggregates, resulting from physico-chemical and biological interactions, are important to understand carbon dynamics and material transport in soils. The objective of this study is to investigate stable macro-aggregate (> 0.25mm diameter) in wet sieving (SM) and their relation to soil properties in 15 sites. The clay contents of soils were ranged from 1% to 33%, and their land uses included bare and cultivated lands of annual upland crops, orchard, and grass. Undisturbed 3 inch cores with five replicates were sampled at topsoil (i.e., 0- to 10-cm depth), for analyzing SM and physico-chemical properties, after in situ measurement of air permeability. SM of sandy soils, with clay content less than 2%, was observed as 0%. Except the sandy soils, SM of soils mainly depended on land uses, showing 27%~35% in soils with annual plants such as vegetable and corn, 51% in orchard, and 75% in grass. This sequence of SM is probably due to the different strength of soil disturbance like tillage with different land uses. SM had significant correlation with cation exchange capacity, organic matter content, sand, clay, silt, bulk density, and exchangeable potassium (K) and magnesium (Mg), whereas fluctuating properties with fertilization such as pH, EC, and water soluble phosphorus weren't significantly correlated to the SM. Particularly, exchangeable calcium (Ca) had significant relation with SM, only except soils with oversaturating Ca. This study, therefore, suggested that SM could perceive different land uses and the change of soil properties in soils, necessarily considering soil textures and Ca over-saturation.

• Korean Journal of Soil Science and Fertilizer
• /
• v.14 no.1
• /
• pp.44-50
• /
• 1981

A pot experiment was conducted to find the nitrogen fixing activities associated with ice rhizoplane in nine varieties at various growth stage by acetylene reduction technique. Results obtained ware Summarized as follows. 1. Nitrog en fixing activites associated with rice rhizoplane differ by the rice variety and the growth stage. The activities increased with progressing of growing time, and maximum activities were obtained from the ear forming stage to the heading stage. 2. The application of rice straw did not greatly enhanced the nitrogen fixing activities associated with rice rhizoplane. However, somewhat increasing tendency was obtained in the Kataktara, TKM-6, Centrypartna. Daegujo, and Jodongji varieties. 3. The nitrogen fixed during the one rice cropping period was estimated as 0.55kg of N per 10a by Milyang-23 variety to 2.6kg of N per 10a by Jodongji variety. 4. The amount of rice root showed no significant relationship with the amount of nitrogen fixed during the growing period of rice plant.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.5
• /
• pp.362-368
• /
• 2008

In order to isolate novel oligotrophic bacteria exhibiting antifungal activities, soils were collected from pepper-cultivated fields of Yeongyang, Jecheon, Nonsan, Eumsong and Goesan area in Korea. From soils in pepper cultivated area, a total of 9,354 strains were isolated as oligotrophic bacteria by the R2A dilution method. Among 9,354 oligotrohic bacteria candidates, 1A strain was selected by screening against Phytophthora capsici causing phytophthora blight of hot pepper in the greenhouse and field. The strain was identified as Bacillus vallismortis based on its 16S rDNA sequence and key characteristics as compared with those of authentic cultures of B. vallismortis(KACC 12149) and B. mojavensis(KACC 12096). The strain showed broad spectrum of antibiotic activity in vitro test, as revealed in its strong inhibitory activity to the genera Phytophthora, Collectotrichum, Botrytis and Fusarium, but not to Rhizoctonia and Magnaporthe. In pot experiments, infection rate of hot pepper in the non-treated pots was about 89%, while it was only 29% in the pots treated with 1A strain. The result indicated B. vallismortis 1A is a potential biocontrol agent for phytophthora blight of hot pepper

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.6
• /
• pp.453-462
• /
• 2000

This study was carried out to know the effect of urea addition for composting of paper mill sludge(PMS). For the purpose. PMSs containing 0%, 1.5%, 3%, and 6% urea were composted at aerated static pile(ASP) for about 80day periods. During the composting, the basic physical, chemical, and biological parameters such as temperature, color. C/N ratio, cation exchange capacity, and phytotoxic test were investigated. From the measurement of the parameters, 0~3% urea-containing PMS except for 6% urea-containing PMS showed to be normally stabilized. Thus among these treatments, 0% and 3% urea-containing PMS were applied at agitated bed system(ABS), a pilot plant of a large scale, to evaluate the possibility of practical use. Considering to the changes of the parameters investigated during composting in ASP and ABS, PMS showed to be successfully stabilized in the two facilities. However, when composted with PMS and urea, even the final PMS compost stabilized for a period enough brought out the bright grayish color. So it may be necessary to add a subsidiary amendments such as animal manure to form brown-colored products.

• Proceedings of the Korean Society of Environment and Ecology Conference
• /
• 2003.10a
• /
• pp.105-126
• /
• 2003

In Korea most of annual rainfall is concentrated in several episodic heavy rains during the season of summer monsoon and typhoon. Because of uneven rainfall distribution many dams have been constructed in order to secure water supply in dry seasons. The Han River system has the most dams among Korean rivers, and the river is a series of dams now. Reservoirs need different strategy of water quality control from river water. Autochthonous organic matter and phosphorus should be the major target to be controlled in lakes. In this Paper some problems are discussed that makes efforts of water quality improvement ineffective in lakes of Korea, even after the substantial investment to wastewater treatment facilities.1) Phosphorus is the key factor controlling eutrophication of lakes and the reduction ofphosphors should be the major target of water treatment. However, water quality management strategy in Korea is still stream-oriented, and focused on BOD removal from sewage. Phosphorus removal efficiency remains as low as 10-30%, because biological treatment is adopted for both secondary treatment and advanced treatment. The standard for TP concentration of the sewage treatment plant effluent is 6 mgP/l in most of regions, and 2 mg/l in enforced region near metropolitan water intake point. TP in the effluents of sewage treatment plants are usually 1-2 mg/1, and most of plants meet the effluent regulation without a further phosphorus removal process. The generous TP standard for effluents discourages further efforts to improve phosphorus removal efficiency of sewage treatment. Considering that TP standard for the effluent is below 0.1 mg/l in some countries, it should be amended to below 0.1 mg/l in Korea, especially in the watershed of large lakes.2) Urban runoff and combined sewer overflow are not treated, even though their total loading into lakes can be comparable to municipal sewage discharges on dry days. Chemical coagulation and rapid settling might be the solution to urban runoff in regard of intermittent operation on only rainy days.3) Aggregated precipitation in Korea that is concentrated on several episodic heavyrains per year causes a large amount of nonpoint source pollution loading into lakes. It makes the treatment of nonpoint source discharge by methods of other countries of even rain pattern, such as retention pond or artificial wetland, impractical in Korea.4) The application rate of fertilizers in Korea is ten times as high as the average ofOECD countries. The total manure discharge from animal farming is thought to be over the capacity of soil treatment in Korea. Even though large portion of manure is composted for organic fertilizer, a lot of nutrients and organic matter emanates from organic compost. The reduction of application rate and discharge rate of phosphorus from agricultural fields should be encouraged by incentives and regulations.5) There is a lot of vegetable fields with high slopes in the upstream region of the HanRiver. Soil erosion is severe due to high slopes, and fertilizer is discharged in the form of adsorbed phosphorus on clay surface. The reduction of soil erosion in the upland area should be the major preventive policy for eutrophication. Uplands of high slope must be recovered to forest, and eroded gullies should be reformed into grass-buffered natural streams which are wider and resistant to bank erosion.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.1
• /
• pp.29-37
• /
• 2006

In remediation of the contaminated soil, it requires to select at least more than two remediation technologies depending on the fate and transport phenomena through complicated reactions in soil matrix. Therefore, methodologies related to develop the integrated remediation technology were reviewed for agricultural soils contaminated with heavy metals. Pneumatic fracturing is necessary to implement deficiency because soil washing is not effective to remove heavy metals in the subsurface soil. But it needs to evaluate the characteristics such as essential data and factors of designated technology in order to effectively apply them in the site. In the remediation site, the important soil physical and chemical factors to be considered are hydrology, porosity, soil texture and structure, types and concentrations of the contaminants, and fate and its transport properties. However, the integrated technology can be restrictive by advective flux in the area which remediation is highly effective although both soil washing and pneumatic fracturing were applied simultaneously in the site. Therefore, we need to understand flow pathways of the target contaminants in the subsurface soils, that includes kinetic desorption and flux, predictive simulation modeling, and complicated reaction in heterogenous soil.