• Korean Journal of Soil Science and Fertilizer
• /
• v.25 no.1
• /
• pp.16-25
• /
• 1992

A pot experiment was conducted to understand effect of soil temperaute on soybean shoot and root growth, and its relations to nutrient uptake including phosporus and potassium. Pregerminated soybean seedlings, Paldal cultivar, were planted for 43 days on the pots with Ihyeon silt loam and Samgag sandy loam in the temperature controled water baths at 17, 25 and $32^{\circ}C$. Shoot and root samples were taken at four times and analyzed. Shoot and root dry matter weights were heavier as higher soil temperaure. The root dry matter increased faster than shoot at earlier period. Shoot dry matter weights grown at 17 and $25^{\circ}C$ showed little difference between two soils, however, those grown in silt loam at $32^{\circ}C$ were heavier than sandy loam. The total lengths of roots were longer as higher soil temperature, and longer in silt loam than sandy loam. The roots grown in sandy loam at low temperature were thicker than the roots grown in silt loam at high temperature. The uptakes of phosphorus and potassium were higher as higher tempeature with same trend with dry matter. The uptake rate of unit root surface area was higher in sandy loam soil than silt loam. The uptake rates showed strong dependence on soil temperature as well as dependence of water uptake rate. Based on Dalton and Gardner model, at high temperature the dependence trend of phosphorus and potassium on soil temperature showed with active uptake model, while at low temperature the dependence showed without active uptake model.

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.6
• /
• pp.416-431
• /
• 2000

The objective of this study was to determine the effects of various kinds of composts on the change of soil chemical properties in upland soils. Field experiments were conducted in the loam and sandy loam soils. Various kinds of composts such as poultry manure compost(PMC), cow manure compost(CMC), human excrement sludge(HES), and food industrial sludge compost(FISC) were applied annually at rates of 0, 40, and $80Mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : The continuous application of human excrement sludge decreased soil pH up to 4.4~5.0, while other compost treatments increased soil pH compared with control plot. The EC increased initially and showed their maximum values at 20days after compost application, and then decreased up to 40 days, thereafter kept a certain level. The available phosphorous accumulated at 0~20cm depth in loam soil, and 0~50cm in sandy loam soil. Annual accumulation rates were 17% higher in sandy loam soil than loam soil. The more compost application rates and times, the higher base saturation percentage increased in upland soils. Four year's application at a rate of $80Mg\;ha^{-1}$ per year increased the base saturation percentage to 87~97% compared with 45% at control plot in the loam soil. While in sandy loam soil only three year's application of same rate increased the base saturation percentage to 81~92% compared with 30.4% at control plot. The average annual increasing rate of base saturation percentage at the same application rates of composts were higher in sandy loam soil by 2.0~3.7 times than in loam soil. The application of compost increased the exchangeable Ca, Mg, and K contents of soils by 2, 2~3, and 3~5 times, respectively, compared with the control. The contents of exchangeable cations were high in surface soil, and decreased with increase of soil depths. In the case of heavy metal content, there were no difference at the application of PMC and CMC but Ni, Fe, Zn, Cu was increased a little when the HES applied, and Ni and Cr was increased application with FISC.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1996.06a
• /
• pp.144-148
• /
• 1996

• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.5
• /
• pp.564-571
• /
• 2016

As the amount of rice straw collected increases, green manure crops are used to provide the needed organic matter. However, as green manure crops generate methane in the process of decomposition, we tested with different tillage depths in order to reduce the emission. The atmosphere temperature of the chamber was $25{\sim}40^{\circ}C$ during the examination of methane and soil temperature was $2{\sim}10^{\circ}C$ lower than air temperature. The redox potential (Eh) of the soil drastically fell right before irrigated transplanting and showed -300~-400 mV during the cultivating period of rice (7~106 days after transplant). When hairy vetch was incorporated to soil and the field was not irrigated, the generation of methane did not occur from 12 to 4 days before transplanting rice and started after irrigation. Regarding the pattern of methane generation during the cultivation of rice, methane was generated 7 days after transplanting, reached the pinnacle at by 63~74 days after transplanting, rapidly decreased after 86~94 days past transplanting and stopped after 106 days past transplanting. When tested by different soil types, methane emission gradually increased in loam and clay loam during early transplant, whereas it sharply increased in sandy loam. The total amount of methane emitted was highest in sandy loam, followed by loam and clay loam. In all three soil types, methane emission significantly reduced when tillage depth was 20 cm compared to 10 cm. The rice growths and yield were not affected by tillage depth. Therefore, reduction of methane emission could be achieved when application hairy vetch to the soil with tillage depth of 20 cm in paddy soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.5
• /
• pp.336-344
• /
• 2017

The soil water characteristics curve (SWCC) represents the relation between soil water potential and soil water content. The shape and range of SWCC according to the relation could vary depending on soil characteristics. The objective of the study was to estimate SWCC depending on soil types and layers and to analyze the trend among them. To accomplish this goal, the unsaturated three soils were considered: silty clay loam, loam, and sandy loam soils. Weighable lysimeters were used for exactly measuring soil water content and soil water potential. Two fitting models, van Genuchten and Campbell, were applied. Two models entirely fitted well the measured SWCC, indicating low RMSE and high $R^2$ values. However, the large difference between the measured and the estimated was found at the 30 cm layer of the silty clay loam soil, and the gap was wider as soil water potential increased. In addition, the non-linear decrease of soil water content according to the increase of soil water potential tended to be more distinct in the sandy loam soil and at the 10 cm layer than in the silty clay loam soil and at the lower layers. These might be seen due to the various factors such as not only pore size distribution, but also cracks by high clay content and plow pan layers by compaction. This study clearly showed difficulty in the estimation of SWCC by such kind of factors.

• Journal of Biosystems Engineering
• /
• v.25 no.5
• /
• pp.369-378
• /
• 2000

The purpose of this study is to developed high-efficient rotary tillage system for a power tiller by improving the rotary blade. A kind of the rotary blade with single-edged blade(DS) was developed that requires lower tillage energy than conventional double-edged blade(CD) on the design theory for Japanese rotary blade. In order to find out the tillage characteristics between the single-edged blade and the double-edged blade for power tiller, experiments were performed in soil-bins which were filled up clay loam, loam and sandy loam, and then analyzed the effects of the factors such as soil texture, travelling speed, rotational speed, and tillage depth to each of the blades. And field tests were carried out to compare tillage performances of the two blades using rotary cultivator driven by conventional power tiller. The results of this study were summarized as follows; 1) On the soil bin experiment, it was found that tillage torque of the single-edged blade was less than the ones of the double-edged blade. The decreasing ratios of maximum tillage torque of the single-edged blade to the ones of the double-edged blade were 1 to 8% at clay loam, 5 to 20% at loam and 9 to 31% at sandy loam, respectively. 2) By the field tests, that the tillage performances with the single-edged blade compared with the double-edged blade was improved about 19% in field capacity, about 34% in fuel consumption, and 12.5% in soil breaking ratio. Furthermore, the fluctuation of engine speed, the variation of exhaust gas temperature, and the amount of soil clogging on the blade and straw wound on the rotary shaft showed lower values with the developed blade than the conventional blade. So, it may be concluded that tillage performance by the developed single-edged blade was improved compared with the one by the conventional double-edged blade.

• Korean Journal of Soil Science and Fertilizer
• /
• v.34 no.4
• /
• pp.265-272
• /
• 2001

A manure compost has been identified as an alternative to fertilizer to increase soil fertility and crop production in farming fields. The aim of the present study was to evaluate the effects of pig manure compost on soil properties and rice productivity as well as to determine the optimum application rate. In 1997, a field experiment was carried out to evaluate the growth of rice on sandy loam, loam, and clay loam soils amended with 0, 5, 10, and $20Mg\;ha^{-1}$ of pig manure compost plus NPK, which decided by soil testing. Rice yields were higher in soils receiving manure compost amendment. The maxim um yields were evaluated with $7,520kg\;ha^{-1}$ in the levels of $4.2Mg\;ha^{-1}$ of pig manure compost application plus NPK in sandy loam, $7,320kg\;ha^{-1}$ in the levels of $10.7Mg\;ha^{-1}$ in loam, and $6,320kg\;ha^{-1}$ in $17.2Mg\;ha^{-1}$ in clay loam soil. The optimum application rate of pig manure compost, which decided for 95% of maximum yields, was $4.0Mg\;ha^{-1}$ in sandy loam and $7.0Mg\;ha^{-1}$ in loam and clay loam soils under the condition of chemical fertilization by soil diagnosis. An increase in rice yield indicated a better nutrient status in compost-amended soil which was supported by the higher nutrient contents of N, P and K in shoot of plants grown in soil with manure compost amendment. Addition of manure compost increased available phosphate, silicate and exchangeable K in the amended soils according to the rate of compost application rate. It can be concluded that the manure compost could be a suitable organic fertilizer for improving rice productivity and soil fertility, and an application rate of $4.0Mg\;ha^{-1}$ in sandy loam and $7.0Mg\;ha^{-1}$ in loam and clay loam soils would give the optimum rice yields in the standard fertilization by chemical fertilization.

• Korean Journal of Soil Science and Fertilizer
• /
• v.33 no.6
• /
• pp.432-445
• /
• 2000

The objective of this study was to determine the effects of various kinds of composts on the change of nutrition loss in upland soils. Field experiments were conducted in the loam and sandy loam soils, while the clay loam and sandy loam soils were used for laboratory experiments. Various kinds of composts such as poultry manure compost(PMC), cow manure compost(CMC), human excrement sludge(HES), and food industrial sludge compost(FISC) were applied annually at rates of 0, 40, and $80mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : The loss of nutrients in the form of cation and anion by run-off water increased with the increase of compost application rate. Compared with bare soils, maize cultivation decreased the nutrient loss by run-off from soils by 43% in anionic form and 32% in cationic form. Amount of cation loss were ordered $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ > $NH_4{^+} $ and that of anion loss were ordered $SO_4{^{2-}}$ > $NO_3{^-}$ > $Cl^-$ > $PO_4{^{3-}}$. Nutrient loss of sand loam soil in the cation and anion by percolation water increased 1.7 times compared with loam soil. $NO_3{^-}-N$ contents in percolated water were high at the initial stage after compost application, and the amounts were higher in sandy loam soil than loam soil. The maize cultivation also decreased the $NO_3{^-}-N$ contents in percolated water by 82% in loam soil, and 58% in sand loam soil. Soil pH of composts determined by laboratory incubation test increased pH 6.1~6.8 application with poultry and cow manure compost but application with human excrement sludge decreased pH 4.5~4.7. Soil EC were increased initially composts application and decreased up to 2 weeks, thereafter kept a certain level. Nitrogen mineralization rates of composts determined by laboratory incubation test at $25^{\circ}C$ were 39~76% in sandy loam soil, and 16~48% in clay loam soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.18 no.1
• /
• pp.14-19
• /
• 1985

This study was conducted to evaluate the effects of red earth addition in sandy loam paddies. Clay contents of the red earths were 19% (loam) and 35% (clay loam). The treatments were 3 levels of red earth and 2 levels of fertilizer. The results were summerized as follows: 1. Water decrease rate was lowered with the increase of clay by the red earth application in sandy loam paddies. 2. Red earth addition increased CEC and available $SiO_2$ in sandy loam, and integrated soil improvement showed higher pH and lower Eh than standard fertilizer application. 3. Rice yields in the red earth addition of loam were decreased by 2-3% at standard fertilizer application and increased by 2-4% at integrated soil improvement. Otherwise, rice yields in the red earth application of clay loam were increased by 1-4% at standard fertilizer application and 3-8% at integrated soil improvement.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.11 no.1
• /
• pp.1561-1579
• /
• 1969

In Korea, the duty of water in paddy fields was measured at the Agricultural Experimental Station in Suwon about 60 years ago. After that time some testing has been made in several places, but the key points in its experiment were the water depth of evapo-transpiration. Improved breeds, progress in cultivation and management techniques as well as development of measuring apparatus in recent years have necessitated the review of the duty of water in paddy fields. The necessity of reviewing the conventional methods has become even more important, as no source of information has been made available through survey of water utilization on a soil use basis which requires data on peculiar features of the water depth of evapo-transpiration. For example, the duty of water in paddy field is largely affected by the water depth of evapo-transpiration in connection with the wetted paddy field, whereas in connection with the normal paddy fields without this characteristic the vertical percolation become the predominant factor in measuring the decreasing depth of water. Therefore, it becomes important. that not only the water depth of evapotranspiration but also the vertical percolation process should also be observed in order to arrive at a realistic conclusion. As the vertical percolation has aclose relationship to the height of the underground water, the change of the latter can be measured. As the conclusion of this experiment, the following subjects are indicated. 1. In order to determine the economic duty of water in paddy fields on a basis of varying soil features, the varying soil features in the benifited area should be investigated thoroughly. The water depths of evapo-transpiration(ET) ratio to evaporation in the evaporator(V) on a basis of the varying soil features are as follows: clay loam ET/V = 1.11, loam ET/V = 1.64, sandy loam ET.V = 1.63 2. The decreasing depth of water consists of the water depth of evapotranspiration, the vertical per colation and the percolation of foot path. Among these three, the percolation of foot path can be utilized again. 3. As the result of this experiment, it shows the decreasing depth of water as follows. clay loam 9.3 mm/day, loam 13.5mm/daty, sandy loam 15.3mm/day 4. On a basis of the varying soil features and the height of the underground water, the vertical percolation varies. 5. The change of the vertical percolation on a basis of the varying soil features shows as follows: clay loam $1{\sim}2$ mm/day, loam $2{\sim}3$mm/day, sandy loam $3{\sim}4$mm/day 6. The level of the underground water changes sensibly by priority of clay loam, loam, sandy loam. When it rains, the level of the underground water rises fast and falls down slowly. 7. The level of the underground water changes within the scope of 25cm 8. The transpiration ratio is given in table 8 and their value are as follows: clay loam 168.8, loam 255.6, sandy loam 272.5