• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.194-201
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• 2005

Silicate (Si) fertilizers are well-known for soil amendment and to improve rice productivity as well as nitrogen efficiency. In this study, we investigated the possible reduction level of nitrogen fertilization for rice cultivation by amending Si fertilizer application. Field experiments were carried out to evaluate the productivity of rice (Oryza sativa L.) on a silt loam soil, where three levels of nitrogen (0, 110 and $165kg\;ha^{-1}$) were selected and Si fertilizer as a slag type was applied at 0, 1 and 2 times of the recommendation level (available $SiO_2\;130mg\;kg^{-1}$). Application of Si fertilizer increased significantly the rice yield and nitrogen efficiency. With increasing N uptake of rice, 1 and 2 times of recommended levels of Si fertilization could decrease nitrogen application level to about 76 and $102kg\;N\;ha^{-1}$ to produce the target yield, the maximum yield in the non-Si amended treatment. Silicate fertilizer improved soil pH and significantly increased available phosphate and Si contents. Conclusively, the Si fertilizer could be a good alternative source for soil amendment, restoring the soil nutrient balance and to reduce the nitrogen application level in rice cultivation.

• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.829-846
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• 2015

This study was conducted to determine the effects of organic fertilization rates on the nutrient accumulation and recovery in radish (Raphanus sativus L.) as well as growth and yield of radish in Jeju island. An understanding the relationships between organic fertilization rate, crop nutrient recovery and crop yield can assist in making organic fertilizer recommendation which balances crop value and environmental risk in organic cultivation. Nitrogen (T-N), phosphate ($P_2O_5$) and potassium ($K_2O$) were applied at 0, 115-35-40, 230-70-80 (standard application rate), 460-140-160, 230-200-100 (recommended application rate) and 158-53-35 kg/ha (customary application rate), respectively as the broadcast application of mixed organic fertilizer (N 4.5% - $P_2O_5$ 1.5% - $K_2O$ 1%) in combination with langbeinite ($K_2O$ 22%), 100% at sowing period. The organic fertilizer was made of organic materials like oil cakes. Total yield of radish, as fresh weight of roots, increased with increasing organic fertilizer doses to a maximum at rate of standard or soil-testing application. Nitrogen, phosphate and potassium accumulations of radish increased curvilinearly with increasing organic fertilization rate to a maximum at rate of N 460 - $P_2O_5$ 140 - $K_2O$ 160 kg/ha. However, nitrogen, phosphate and potassium use efficiency of applied organic fertilizer decreased curvilinearly or linearly with increasing organic fertilization rate. Application of organic fertilizer in combination with langbeinite (as a potassium source) had significant effect on the yield of radish. Organic fertilization on a basis of standard or soil-testing application rate is recommended for maximun radish yield in organic cultivation.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.409-415
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• 2022

Plant growth and development are also affected by root-zone environment. Therefore, it is important to consider the variables of the root-zone environment when establishing an irrigation strategy. The purpose of this study is to analyze the relationship between the volumetric moisture content (VWC), Bulk EC (ECb), and Pore EC (ECp) used by plant roots using FDR sensors in two types of rockwool media with different water transmission characteristics, using the method above this was used to establish a method for collecting and correcting available root-zone environmental data. For the experiment, two types of rockwool medium (RW1, RW2) with different physical characteristics were used. The moisture content (MC) and ECb were measured using an FDR sensor, ECp was measured after extracting the residual nutrient solution from the medium using a disposable syringe in the center of the medium at a volumetric moisture content (VWC) of 10-100%. Then, ECb and ECp are measured by supplying nutrient solution having different concentration (distilled water, 0.5-5.0) to two types of media (RW1, RW2) in each volume water content range (0 to 100%). The relationship between ECb and ECp in RW1 and RW2 media is best suited for cubic polynomial. The relationship between ECb and ECp according to volume moisture content (VWC) range showed a large error rate in the low volume moisture content (VWC) range of 10-60%. The correlation between the sensor measured value (ECb) and the ECp used by plant roots according to the volumetric water content (VWC) range was the most suitable for the Paraboloid equation in both media (RW1, RW2). The coefficient of determination the calibration equation for RW1 and RW2 media were 0.936, 0.947, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.2
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• pp.138-145
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• 1989

Little information is available on the effects of low pH on nodulation and growth of subterranean clover cultivars. Plants of 11 cultivars were inoculated with an acid-tolerant strain of Rhizobium trifolii and grown for 28 days in continuously flowing nitrogen-free nutrient solutions maintained at six constant pH values from 4.0 to 6.5. At pH 4.0, 4 cultivars failed to nodulate and the remainder formed only a few nodules; nodulation was delayed by 2 to 3 days in this treatment. All cultivars nodulated at pH 4.5 but, with the exception of cv. Dwalganup, nodule numbers were significantly less than at $pH{\geq}5.0$. Only in cvv. Clare and Woogenellup were nodule numbers significantly greater at pH 6.5 than at 5.0. Whole plant dry matter yields were strongly depressed at pH 4.0(21 to 33% of maximum). At pH 4.5, relative yields of all cultivars except Dwalganup were significantly depressed without significant reductions in nodule dry weights, suggesting that nodule function was inhibited by acidity. These results are consistent with the view that nodulation and growth of plants dependent on symbiotic nitrogen fixation are much more sensitive to low pH per se than is host plant growth in the presence of adequate mineral nitrogen.

• Korean Journal of Plant Resources
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• v.32 no.1
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• pp.9-18
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• 2019

This study was carried out to investigate characteristics of growth and active compounds of Angelica gigas population distributed in Mt. Jeombong. Quadrates were established in native area to harvest root part of Angelica gigas and analyze soil properties in September and October 2017. It was found that Angelica gigas populations were collected above the altitude 758 m near the valley covered with Fraxinus mandshurica and Acer pictum, and so on. In case of soil nutrient, soil organic matter, available phosphorous, and total nitrogen ranged 5.8-25.2%, 23.0-67.9 mg/kg and 0.3-1.3% respectively. Also, the Fresh weight of root ranged 28.8-65.3 g in September and 22.3-75.6 g in October. The content of active compounds ranged 2.7-4.7% in decursin and 2.9-4.5% decursinol angelate in October that was increased by 1% and 2.4% respectively compared with that in September. In the final analysis, there was positive correlation between fresh weight of root and exchangeable cation (natrium, calcium, magnesium). Also, there was positive correlation between active compounds and the content of water in root part of Angelica gigas.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.2
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• pp.140-147
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• 1985

This experiment was conducted in the field to investigate the effects of mulched condition on nutrient's mineralization and its mobility as affected by environmental changes (soil moisture and soil temperature) in the plow layer. 1. Nitrogen mineralization was faster owing to the prevention of evaporation and the increase of soil temperature in the poly ethylene mulched plot. As a result, nitrate form of nitrogen was much earlier available for plant in mulched plot than in non mulched plot. 2. Available $P_2O_5$ content in the plow layer was kept highest in the fertilized zone (10-20 cm depth) regardless of difference between mulched and non mulched condition, and was nearly constant without showing difference between planting and non planting of tobacco due to the lower availability of phosphorus by tobacco. 3. Potassium applied in the plow layer was remained a large quantity until the latter growth stage resulting in the lower recovery of potassium by tobacco. 4. Mineralized nutrients such as $NH_4-N$, $NO_3-N$, and K in the plow layer of mulched plot were transported from the fertilized layer (10-20 cm depth) and accumulated to the surface layer (0-10 cm depth) as the growing time goes by, but those in non mulched plot were distributed to the deeper layer. 5. Mobility of available nutrients in the plow layer was If order as $NO_3-N$ $$\geq_-$$ $NH_4-N$ > K > available $P_2O_5$. 6. Leaching degree of mineralized nutrients in the mulched plot was much lower than in the non mulched plot.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.335-341
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• 2021

In this study, experiments were conducted to investigate the effects of high- temperature stress on paprika in a semi-closed greenhouse where cooling is available and a normal plastic greenhouse. Paprika grown in a semi-closed greenhouse in which geothermal cooling is provided showed a significantly higher speed of photosynthesis than paprika grown in a 3-layer plastic greenhouse in which there is no cooling system. It suggests that the photosynthesis speed of paprika in a plastic house decreases owing to high temperature stress. Plant height increased by 13cm more in the semi-closed greenhouse, and the size of leaf showed similar growth speed until the 2nd week after transplanting, however, after 3 weeks, the semi-closed greenhouse showed a big difference by 47% compared with the plastic greenhouse. In terms of the fruit count, the semi-closed greenhouse had 10.6 fruits/plant and the plastic greenhouse had 4.6 fruits/plant, indicating that the semi-closed greenhouse had a higher number of fruits by 130% than the plastic greenhouse. The fruit weight also presented a difference between the semi-closed greenhouse and the plastic greenhouse by 46%, which is 566.7g/plant and 387g/plant, respectively. According to the above mentioned results, it was validated that when paprika is cultivated in a semi-closed greenhouse where a cooling system is applied, photosynthesis and growth were better than in the normal plastic greenhouse. Thus, if the hot summer season is overcome by applying the elemental technologies for the cooling system to the normal plastic greenhouse, farm income may increase through improvement in the yield and quality.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.153-170
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• 1977

Considering the ways for the possible improvement of soil test for upland crops, various methods for the evaluation of K supplying power and testing of available soil K were reviewed in terms of theoretical principles and practical usefulness of the each method. The review was also made on the characteristics of upland crops in K requirement and on the chemical properties of major korean upland and lowland rice soils in terms of K availability. Following is the few remarks drawn from the review. 1. Quite large number of methods have been known for the evaluation of K supplying power and testing for available soil K. In nature, they can be divided into two categories; capacity-based methods and intensity-based methcds. The capacity-based methods usually measure the exchangeable and some portion of nonexchangeable K, while the intensity-based methods suggest to consider the ractivity ratios of major cations in soil solution and the energy requirement for the replacement of exchangeable soil K into soil solution. 2. As methodology for extraction of interested part of soil K, chemical extraction, electrodialysis and ion exchange methods have been known. Among these, chemical extract ion is favorable because of its simplicity. However, recently suggested Electro-Ultra-Filtration method seems to merit further study for wider use for not only K but also other nutrient availability of soils. 3. The intensity-based methods, although they are more theoretical, because of their complexity, in methods may not be adapted for practical soil tests. 4. The exchangeable K which is rather simple to measure and which well reflects the status of K reserve as nonexchangeable and is immediate pool of water soluble K may be good, if not best, criterion of soil K availability to plant in common soil testing. 5. Because there are evidences that the abundance of available K alone may not be good inclication for availability of K to plant, it is recommendable to interprete the exchangeable K data as percent saturation of exchangeable K to total C. E. C. of soil for the recommend ation of K fertilizer based on soil tests. 6. Some pot and field trial results showed the trends that percent potassium saturation to total C. E. C. better serve as the parameter for K fertilizer recommendation.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.2
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• pp.89-93
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• 1973

In order to study the effects of some chemical components of surface soils on the paddy yield in clayey Whadong series developed on old alluvium, NPK fertilizer experiments conducted from 1966 to 1969 were reviewed and discussed, and the results may be summarized as follows. 1. The paddy rice production of Whadong series without fertilizers varied from 156kg to 719kg per 10a. 2. The paddy yields in Whadong series were associated mainly with the contents of organic matter and available phosphorus in surface soils, but not with those of exchangeable K, Ca, and Mg and cation exchange capacity. 3. The contents of organic matter in these soils more effected in the paddy yield than those of phosphorus did. 4. In case less than 2.0% or more than 3.0% of organic matter in surface soils the effect of phosphate application was appreciable. The effect, however, was not recognized from 2.0 to 2.9% of organic matter. And the following suggestions were able to make. a. In case of less than 2.0% of organic matter, the effect was considered to be due to deficiency of available phosphorus in the soil. b. In case of more than 3.0% of organic matter, the greater effect was considered to be due to inhibition of P uptake even in higher P contents in soil. c. Consequently, correlation study of P testing in paddy soil should be limited to the soils which contains less than 2% of organic matter. d. If the contents of organic matter in paddy soils were above 3.0%, the effect of P application was considerable and considered to be due to inhibition of nutrient uptake. Accordingly, it is considered that only the increased application of P does not improve the production of paddy in such soils.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.235-242
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• 2015

The objective of this study was to determine the effects of soluble potassium silicate by soil drenching application on watermelon growth, yield, and nutrient uptake. The potassium silicate rates were control (No potassium silicate), 1.63mM, 3.25mM, 6.50mM. The potassium silicate were treated 6 times (twice before fruit forming and 4 times after fruit forming per 7 day. Soil chemical properties, such as soil pH, EC, available phosphorus and silicate, exchangeable K, nitrate-N levels were increased after potassium silicate treatment, while the concentrations of soil organic matter, exchangeable Ca and Mg were similar to control. The growth characteristics of watermelon, such as stem diameter, fresh and dry weight of watermelon at harvest were thicker and heavier for increased potassium silicate treatment than the control, while number of node, and plant length were same for all treatments. With increased potassium silicate treatment, nutrient concentrations, such as P and K in the watermelon leaf at harvest were increased, N concentration in the leaf was decreased, and Ca and Mg concentrations in the leaf were same. Chlorophyll content was increased with increased potassium silicate application. The occurrence of powdery mildew was lower for the potassium silicate treatments than the control. Fresh watermelon weight for the potassium silicate treatments was 0.1 to 0.5kg per watermelon heavier than the control, sugar content was 0.5 to $0.6^{\circ}Brix$ higher than control, and merchantable watermelon was 2 to 4% increased compared to the control. These results suggest that potassium silicate application by soil drenching method in the greenhouse can improve watermelon nutrient uptake, merchantable watermelon and suppress the occurrence of powdery mildew.