• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.159-164
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• 1991

A field microplot(D 20cm, L 85cm) experiment filled with Bonryang sandy loam soil (Typic Udifluvents) was conducted to obtain quantitative information on the movement of applied nutrients under diffetent soil moisture regimes and ladino clover cultivation. Chloride moved rapidly with soil water. When soil moisture tension was maintained at loer than 0.2 bar most of the Cl appeared to move outside the microplot 4 month after the microplot installation. Regardless of soil moisture condition, Cl was not detected in the soil due to the fast movement of the Cl beyond the microplot after 5.5 months Although large amount of P and water were applied to the soil of high available P during the field experiment, movement of P was negligible and most of P remained in thc place where applied due to the low solubility of the fused and superphosphate. Phosphate in the soil extracted by Bray No.1 solution and taken up by plant increased with soil moisture. Under the condition of irrigation at 0.2 bar, plant took up 23% of the applied P, and 24% of the P was extracted by Bray NO.1 solution, while plant took up 14% and 13% of the P was turned out to be Bray No.1 P. at thc nonirrigated condition after final harvest.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.14-20
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• 1986

Responses of three different crops to soil water status were investigated in a Bonryang Sandy loam for 5 years. The changes in soil water potential, water and nutrient uptakes, growth pattern, water use efficiency and yield were analyzed under different irrigation conditions. Chinses cabbage showed more water stress than radish and red pepper in the non-irrigatedcultivation. The higher soil water potential, the more nutrient and water uptake, and evapotranspiration were observed. Water use efficiency was increased with the increase of evapotranspiration up to the optimum amount, whereas the efficiency was decreased when evapotranspiration was exceeded the optimum lebel. Little growth of chinese cabbage was observed when the soil water potential was lower than -1.7 bar at 20-30 cm depth in spring cultivation. The optimum soil water potential for irrigation was -0.2 bar, -0.5 bar and -0.2 - -0.5 bar for chinese cabbage, radish and red pepper, respectively. Optimum irrigation markedly improved the crop quality and yield in comparison to non irrigation condition.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.96-110
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• 1994

The purpose of this study is to develop soil salt prediction model for the estimation of irrigation water requirements for dry field crops in reclaimed tidelands. The simulation model based on water balance equation, salt balance equation, and salt storage equation was developed for daily prediction of sa]t concentration in root zone. The data obtained from field measurement during the growing period of tomato were used to evaluate the applicability of this model. The results of this study are summarized as follows: 1.The optimum irrigation point which maximizes the crop yield in reclaimed tidelands of silt loam soil while maintaining the salt concentration within the tolerance level, ws found to be pF 1.6, and total irrigation requirement after transplanting was 602mm(6.7 mm/day)for tomato. 2.When the irrigation point was pF 1.6, the deviation between predicted and measured salt concentration was less than 4 % at the significance level of 1 7% 3.Since the deviations between predicted and measured values data decrease as the amount of irrigation water increases, the proposed model appear to be more suitable for use in reclaimed tidelands. 4.The amount of irrigation water estimated by the simulation model was 7.2mm/day in the average for cultivating tomato at the optimum irrigation point of pF 1.6.The simulation model proposed in this study can be generalized by applying it to other crops. This, model, also, could be further improved and extended to estimate desalinization effects in reclaimed tidelands by including meteorological effect, capillary phenomenon, and infiltration.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.232-237
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• 1994

Field microplot(D 20cm, 1 85cm) experiment filled with Bonryang sandy loam soil(Typic Udifluvents) was conducted to obtain quantitative information on the movement of applied nitrogen under different soil moisture regimes and ladino clover cultivation. Urea applied to the soil was quickly transformed into $NH_4$-N which was slowly to $NO_3$-N which governed the downward movement of inorganic N applied in the soil. Downward movement of inorganic nitrogen was relatively slow in the early growing stages of ladino clover when $NH_4$-N form was the major inorganic nitrogen in the soil. In the later growing stages when $NO_3$-N was the major form, inorganic nitrogen moved rapidly with soil water. Favorable soil moisture condition increased downward movement and plant uptake of inorganic nitrogen. In the non irrigated bare soil 92% of applied nitrogen was leached downwards out of the microplots at the final harvest. Under the non-irrigated condition 57% of applied nitrogen was taken up by plants and 37% of nitrogen remained in the soil 5.5 months after sowing. Nitrogen uptake by plants in the microplots irrigated at 0.2 bar was 4.03g/microplot at the final harvest, which was more than the amount of nitrogen applied.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.1
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• pp.55-71
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• 1990

The purpose of this study is to find out the basic data for irrigation plans of red pepper and radish during the growing period, such as total amount of evapotranspiration, coefficent of evapotranspiration at each growth stage, the peak stage of evapotranspiration, the maximum ten day evapotranspiration , optimum irrigation point, total readily available moisture and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation point with pH1.7-2.0, pF2.1-2.4 and pF2.5-2.8, at soil texture of sandy soil, sandy loam and silty clay for both red pepper and radish, with two replications. The results obtained are summarized as follows. 1.1/10 exceedance probability values of maximum total pan evaporation during growing period for red peppr and radish were shown as 663.6 mm and 251.8 mm. respectively, and those of maximum ten day pan evaporation for red pepper and radish, 67.1 mm and 46.9 mm, respectively. 2.The time that annual maximum of ten day pan evaporation can he occurred, exists at any stage between the middle of May and the late of August for red pepper, and at any stage between the late of August and the late September for radish. 3.The magnitude of evapotranspiration and its coefficient for red pepper was occurred large in order of pF1.7-2.0 pF2.1-2.4 and pF2.5~2.8 in aspect of irrigation point and the difference in the magnitude of evapotranspiration and of its coefficient between levels of irrigation point was difficult to be found out due to the relative increase in water consumption resulted from large flourishing growth at the irrigation point in lower water content for radish. In aspect of soil texture they were appeared large in order of sandy loam, silty clay and sandy soil for both red pepper and radish. 4.The magnitude of leaf area index was shown large in order of pF2.1-2.4, pF2.5-2.8, and pFl.7-2.0, for red pepper and of pF2.5-2.8, pF2.1-2.4, pFl.7-2.0 for radish in aspect of irrigation point, and large in order of sandy loam, silty clay, sandy soil for both red pepper and radish in aspect of soil texture 5.1/10 exceedance probability value of evapotranspiration and its coefficient during the growing period for red pepper were shown as 683.5 mm and 1.03, respectively, while those of radish, 250.3 mm and 0, 99. respectively. 6.The time that the maximum evapotranspiration of red pepper can be occurred is in the middle of August around the date of ninetieth to hundredth after transplanting, and the time for radish is presumed to be in the late of September, around the date of thirtieth to fourtieth after sowing. At that time, 1/10 exceedance probability value of ten day evapotranspiration and its coefficient for red pepper is assumed to be 81.8 mm and 1.22, respectively, while those of radish, 49, 7 mm and 1, 06, respectively. 7.Optimum irrigation point for red pepper on the basis of the yield of raw matter is assumed to be pFl.7-2.0 for sandy soil, pF2.5-2.8 for sandy loam, and pF2.1-2.4 for silty clay. while that for radish is appeared to be pF2.5-2.8 in any soil texture used. 8.The soil moisture extraction patterns of red pepper and radish have shown that maximum extraction rates exist at 7 cm deep layer at the beginning stage of growth in any soil texture and that extraction rates of 21 cm to 35 cm deep layer are increased as getting closer to the late stage of growth. And especially the extraction rates have shown tendency to be greatest at 21cm deep layer from the most flourishing stage of growth for red pepper and at the last stage of growth for radish. 9.The total readily available moisture on the basic of the optimum irrigation point become 3.77-8.66 mm for sandy soil, 28.39-34.67 mm for sandy loam and 18.40-25.70 mm for silty clay for red pepper of each soil texture used but that of radish that has shown the optimum irrigation point of pF2.5-2.8 in any soil texture used. 12.49-15.27 mm for sandy soil, 23.03-28.13 mm for sandy loam, and 22.56~27.57 mm for silty clay. 10.On the basis of each optimum irrigation point. the intervals of irrigation date at the growth stage of maximum consumptive use of red pepper become l.4 days for sandy soil, 3.8 days for sandy loam and 2.6 days for silty clay, while those of radish, about 7.2 days.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.4
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• pp.255-262
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• 1994

Field microplot(D 20cm, L 85cm) experiment filled with Bonryang sandy loam soil(Typic Udifluvents) was conducted to obtain quantitative information on the movement of applied nutrients under different soil moisture regimes and ladino clover cultivation. The slaked lime was detected as an exchangeable Ca in the layer applied. The released Ca into the soil water proceeded rapid downward movement. Ca content in the soil was lowest at 20~30cm and tended to increase with soil depth. Downward movement of Mg in the slaked lime was similar to the movement of Ca to a greater extent. Plant uptake of Mg and leaching loss out of the microplot increased with lowering soil moisture tension. Downward movement of K was rapid in comparision with Ca and Mg. Lowering soil moisture tension enhanced both plant uptake and leaching loss of applied K. Irrigation at 0.2bar soil miosture condition increased plant uptake of Ca, Mg and K by 55, 71 and 76 % to compare to the plant uptake of Ca:0.49g, Mg:0.21g and K:1.90g/microplot at the nonirrigated condition respectively. Distribution of each of these elements seemed to be greatly affected by the downward movement of Ca with soil moisture, plant uptake of Mg(69%), and plant uptake and downward movement of K.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.4
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• pp.269-274
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• 1994

An experiment was carried out to investigate the effects of irrigation period on the yield and quality of melon (Cucumis melo L.) cultivated in green house 1992~1993. Four different irrigation period was applied ; from transplanting to harvest(Irrigation I), from initial flowering to 35 days after flowering(Irrigation II), from initial flowering to 20 days after flowering(Irrigation III), from initial flowering to 5 days after flowering(Irrigation IV). The water was applied by drip irrigation when the soil water potential of 15cm depth reach at -0.5bar. The results obtained were as follows ; 1. The amount of water applied during the periods were 170.5mm, 145.0mm,126.9mm and 78.8mm for irrigation period I, II, III and IV, respectively. 2. Average evapotranspiration during the cultivation of melon was 3.31mm/day. Evapotranspiration was the highest at the period from 5days after flowering to 15days after flowering. 3. The total yield was increased with the higer amount of water applied, and the yield was in the order of Irrigation I, II, III and IV. However, the yield with economically high quality was the highest in Irrigation III. 4. The sugar content and quality of Net form were decreased with higher irrigation amount.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.5
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• pp.350-357
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• 2001

This study was performed to evaluate an effect of soil water retention and chinese cabbage growth on application of super water absorbent(CPAM-AS-hyd). In seedling experiments, the CPAM-AS-hyd application rates were 0, 5 and 10kg/10a in bed soil of experimental field. The emergence percentage of chinese cabbage was increased by 9% with application of CPAM-AS-hyd otherwise emergence rates was delayed by 1 day. Water content in soil with CPAM-AS-hyd(10kg/10a) was 27.6%(v/v) at 10days after irrigation and that of control was 20.7%. The CPAM-AS-hyd application caused to alleviate wilting point by 5 days. The content of NO3-N in bed soil was increased with CPAM-AS-hyd application. In the field experiments, as the CPAM-AS-hyd application rates were 5kg/10a and 10kg $10a^{-1}$, the irrigation amounts applied during the growth periods were 1.87 ton, 1.65 ton and 1.53 ton at-0.2bar irrigation frequence and 1.38 ton, 1.25 ton and 1.15 ton at -0.5bar for growth period control, in the CPAM-AS-hyd of 5kg $10a^{-1}$ and CPAM-AS-hyd of 10kg $10a^{-1}$ plot, respectively. The CPAM-AS-hyd application caused to increase yield of chinese cabbage by 9~34% as compared to the control. The contents of $NH_4-N$ and $NO_3-N$ in soil were decreased with the CPAM-AS-hyd application in 10 days after transplanting of chinese cabbage, but the contents of those in soil were increased with the CPAM-AS-hyd application as compared to the control in 20 days after transplanting. The T-N, CaO, MgO and $K_2O$ contents in chinese cabbage increased due to the CPAM-AS-hyd application however $P_2O_5$ content was similar to the control.