• Korean Journal of Soil Science and Fertilizer
• /
• v.4 no.1
• /
• pp.33-40
• /
• 1971

Using radioactive $^{40}K$ in potassium, a study was conducted to evaluate the potassium supplying power of different soil types developed on different parent materials. A conversion factor based on two parameters namely $\frac{available\;K_{soil}}{total\;K_{soil}}$ and $\frac{K_{plant}}{K_{soil}}$ was developed and found to be closely related to plant response. According to this characterization soils derived from the various parent materials were ranked as basalt >Silla series>gneiss>porphyry>granite${\gg}$schist. From the point of view of potassium response as measured by yield as similar response pattern was observed. That is, soils derived from basalt to be most responsive as compared to the other soils. The variations among the soils may be accounted for to their potassium bearing mineralogical composition and their stability.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.35-35
• /
• 2017

How do plants take up water from soils especially when water is scarce in soils? Plants have a strategy to respond to water deficit to manage water necessary for their survival and growth. Plants regulate water transport inside them. Water flows inside the plant via (i) apoplastic pathway including xylem vessel and cell wall and (ii) cell-to-cell pathway including water channels sitting in cell membrane (aquaporins). Water transport across the root and leaf is explained by a composite transport model including those pathways. Modification of the components in those pathways to change their hydraulic conductivity can regulate water uptake and management. Apoplastic barrier is modified by producing Casparian band and suberin lamellae. These structures contain suberin known to be hydrophobic. Barley roots with more suberin content from the apoplast showed lower root hydraulic conductivity. Root hydraulic conductivity was measured by a root pressure probe. Plant root builds apoplastic barrier to prevent water loss into dry soil. Water transport in plant is also regulated in the cell-to-cell pathway via aquaporin, which has received a great attention after its discovery in early 1990s. Aquaporins in plants are known to open or close to regulate water transport in response to biotic and/or abiotic stresses including water deficit. Aquaporins in a corn leaf were opened by illumination in the beginning, however, closed in response to the following leaf water potential decrease. The evidence was provided by cell hydraulic conductivity measurement using a cell pressure probe. Changing the hydraulic conductivity of plant organ such as root and leaf has an impact not only on the speed of water transport across the plant but also on the water potential inside the plant, which means plant water uptake pattern from soil could be differentiated. This was demonstrated by a computer simulation with 3-D root structure having root hydraulic conductivity information and soil. The model study indicated that the root hydraulic conductivity plays an important role to determine the water uptake from soil with suboptimal water, although soil hydraulic conductivity also interplayed.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.5
• /
• pp.351-358
• /
• 2013

A suitable supply of mineral elements into shoot via a root system from growth media makes plants favorable growth and yield. The shortage or surplus of minerals directly affects overall physiological reactions to plants and, especially, strongly influences carbohydrate metabolism as a primary response. We have studied mineral uptake and synthesis and translocation of soluble carbohydrates in N, P or K-deficient tomato plants, and examined the interaction between soluble carbohydrates and mineral elements. Four-weeks-old tomato plants were grown in a hydroponic growth container adjusted with suboptimal N ($0.5mmol\;L^{-1}\;Ca(NO_3)2{\cdot}4H_2O$ and $0.5mmol\;L^{-1}\;KNO_3$), P ($0.05mmol\;L^{-1}\;KH_2PO_4$), and K ($0.5mmol\;L^{-1}\;KNO_3$) for 30 days. The deficiency of specific mineral element led to a significant decrease in its concentration and affected the concentration of other elements with increasing treatment period. The appearance of the reduction, however, differed slightly between elements. The ratios of N uptake of each treatment to that in NPK sufficient tomato shoots were 4 (N deficient), 50 (P deficient), and 50% (K deficient). The P uptake ratios were 21 (N deficient), 19 (P deficient), and 28% (K deficient) and K uptake ratios were 11 (N deficient), 46 (P deficient), and 7% (K deficient). The deficiency of mineral elements also influenced on carbohydrate metabolism; soluble sugar and starch was substantially enhanced, especially in N or K deficiency. In conclusion, mineral deficiency leads to an adverse carbohydrate metabolism such as immoderate accumulation and restricted translocation as well as reduced mineral uptake and thus results in the reduced plant growth.

• The Korean Journal of Applied Statistics
• /
• v.1 no.2
• /
• pp.34-44
• /
• 1987

In order to estimate the optimum fertilizer level for rice, a major food crop, the experimental results obtained from the fertilizer trials conducted at 642 experimental sites(farmers' fields) throughout the country for the period from 1976 to 1979 were examined. Since non-significant interactions among fertilizers have been ovserved from the past experiences, only thirteen treatments(combinations of fertilizer levels) for the experiments as given in the Table 1 were chosen such that simple response curves can be fitted with independent variables being N, $P_2O_5, and K_2O$. Weighted combining analysis of variance was also carried out for each type of paddy fields to test the significance of Treatments $\times$ Experimental sites interaction, and highly significant variability in response to treatments among experimental sites in the same type of paddy fields was observed in most types of fields. For the types of paddy fields where the treatments $\times$ experimental sites interaction was not significant, separate response curves for N, $P_2O_5, and K_2O$ were estimated on the basis of the mean yields of rice, and common values of the optimum levels of fertilizers were extimated thereform. When the interaction is significant, response curves were fitted for each experimental sites. The average fertilizer doses estimated for the types of paddy fields based on the individual sites are given in Tables 7-1 and 7-2.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.4
• /
• pp.492-496
• /
• 2012

Fertigation with drip irrigation provides effective and cost-efficient way to supply both nutrient and water to crop. However, inappropriate management of fertigation systems may cause inefficient nutrient and water use, thereby diminishing expected yield benefits as well as contributing to deterioration of soil properties. In this study, greenhouse experiments were conducted to investigate the optimal concentration of N, P and K fertigation solution for maximum production of oriental melon (Cucumis melo L.) using a response surface methodology, to evaluate an efficiency of nutrients uptake and an effect on soil chemical properties. Canonical analysis of response surface and contour plot interpretation revealed that $108.3mg\;L^{-1}$ of nitrogen (N), $54.8mg\;L^{-1}$ of phosphorous (P) and $158.3mg\;L^{-1}$ of potassium (K) resulted in maximim yield of oriental melon ($2,966kg\;10a^{-1}$). Compared to conventional practice, fertigation increased fruit yield up to 23.0% (p<0.001), uptake of N and K by plant also up to 33.3% (p<0.001) and 15.7% (p<0.01), respectively. These results suggest that fertigation has the advantage of the increase in yield and fertilizer use efficiency.

• Korean Journal of Soil Science and Fertilizer
• /
• v.20 no.3
• /
• pp.285-299
• /
• 1987

Timing and placement of fertilizer applications are two managerial means to improve the fertilizer use efficiency. The relative importance of these two means is determined by the application rate. With the realistic rate of N application recommended to the small farmers in the tropics, at present and in the near future, basal application in right manner, seems to be more important than split application at different times. In wetland rice soils, deep placement by whatever available means is desirable. But in the situations where perfect deep placement is very difficult to implement, the whole-layer application may be worth trying, until better methods become available. In rainfed uplands, N fertilizer application plans should be contingent upon the amount and distribution of rainfall: apply a less risky rate as subsurface banding near the crop rows to start with; then, depending upon the rainfall prospects in the season, apply or omit the additional dose. Because the patterns of crop response to N fertilizer can be significantly different between the research farms and farmers' fields, it seems imperative to have information on the patterns of crop response to N under farmers' management conditions, for the development of realistic fertilizer application recommendations. To enable the farmers to adopt improved fertilizer application technologies, it is essential to develop and make available to farmers convenient fertilizer applicators. Past experience with the improved fertilizer use technologies indicates that, in the long run, the development of fertilizers that are not only effective and convenient for farmers to use but also easy to produce without major modifications of existing fertilizer production systems is the ultimate solution to the problem of low N fertilizer use efficiency.

• Korean Journal of Soil Science and Fertilizer
• /
• v.27 no.2
• /
• pp.78-84
• /
• 1994

Yield response of tomato to nitrogen and potassium fertilizer and the balance of the two elements were determined in salt-accumulated greenhouse soil to improve the efficiency of fertilizer appiication. The response of tomato yield to nitrogen and potassium fertilizer application was not significant. The current parameters such as OM and $K/{\sqrt{Ca+Mg}}$ that were used to determine the level of nitrogen and potassium fertilizer in open field were not suitable in salt-accumulated greenhouse soil condition. The temporal and spatial distribution of $NO_3{^-}-N$showed the same pattern to those of $Cl^-$ ion that is non-reactive with soil, while the content of Ex. K was extraordinarily high in soil after harvesting of tomato, which had experienced relatively dry condition during harvesting time. The loss of $NO_3{^-}-N$ and Ex. K out of 28cm below the soil surface was 2~5 and 1.5~3.5 times greater than the amount of nitrogen and potassium uptake by the plant.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.23 no.2
• /
• pp.77-80
• /
• 2003

This study was conducted to determine the optimum organic fertilizer rate (0, 100, 200, 300, 400, 500, 600kg/10a) of worm casting on growth response and yield of Ieol´ radish in Jeiu island. The results obtained were summarized as follows; plant height was getting bigger as organic fertilizer increased from 0 to 500kg/10a and then became smaller at 600kg/10a. But was no significance from 200 to 600kg/10a. Number of leaves, leaf width and root diameter were the same trend with plant height response. Root length was not significantly affected by organic fertilizers. SPAD reading value of leaves increased as increasing of organic fertilizers. Fresh matter yield (top+root) increased significantly 2,949∼4,561kg/10a as fertilizer rate increased from 0 to 200kg/10a, increased 5.096∼5,707kg/10a from 300 to 500kg/10a of fertilizer rate and decreased to 4,873kg/10a at 600kg/10a. Top and root weight were the same trend with fresh matter yield.

• Korean Journal of Plant Resources
• /
• v.14 no.1
• /
• pp.43-47
• /
• 2001

For the purpose of sweet potato varietal improvement, yulmi, shinyulmi, gunmi, hongmi and seonmi, whose source and sink are different one another, were cultivated at different amount of fertilizers, and then defoliation at initial stage of tuberous root weight increase on the relation of source and sink was observed as follows. The response of stem, leaf and tuberous root weight by amount of fertilizer and defoliation rate of sweet potato varieties was different. Stem and leaf weight increased along with heavy dressing by the following order; shinyulmi> seonmi> hongmi> gunmi> yulmi. Tuberous root number was the most at $N-P_2O_5-K_2O=60-70-190kg/ha$ amount of fertilizer, showing seonmi the most number. The number of stem, leaf and tuberous root increased along with the lowered rate of defoliation. In case of $N-P_2O_5-K_2O=20-30-90kg/ha$ amount of fertilizer, tuberous root weight increased by increase of stem and leaf weight up to 50% defoliation and the difference of stem, leaf and tuberous root number was low as defoliation rate increases. The total dry weight matter was the most at heavy dressing amount of fertilizer.

• Korean Journal of Environmental Biology
• /
• v.32 no.4
• /
• pp.327-334
• /
• 2014

Emission reduction of $CH_4$ (methane gas) from rice paddy soil is a very important measure for climate change mitigation in agricultural sector. In this study, we investigated the changes in crop yield and $CH_4$ emissions in response to application of biochar and fertilizers. The experimental site is located in Hwasung, Kyunggido and experimental design is the split-plot method with three replicates. Treatments included rice straw (RS) and biochar (BC) amendments nested with the conventional NPK fertilizer (NPK) and slow release fertilizer (SRF). Control was also prepared with the soil with the conventional NPK fertilization with no amendment. Measurement of $CH_4$ emission was conducted during the growing season of 2014 using a dynamic chamber method. The results showed that application of rice straw increased daily $CH_4$ emission rate by 15%, while application of biochar reduced daily $CH_4$ emission rate by 38%. When we combined biochar application with slow release fertilizer, $CH_4$ emission was reduced by 45%. Further, the crop yield was also increased in all treatments compared with the control except for the treatment of rice straw application with slow release fertilizer. Overall results imply that biochar amendment to agricultural soil can be an effective strategy to decrease annual $CH_4$ emission with no reduction in crop yield.