• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.176-180
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• 2011

Rice production depended on the weed control. The purpose of this study was conducted to evaluate the influence of tillage with chemical amendments + 5 cm flooded, no-tillage without Chinese milk vetch + 5 cm flooded (NTNT 5 cm), no-tillage amended with Chinese milk vetch + 5 cm flooded (NTCM 5 cm), and no-tillage amended with Chinese milk vetch + 10 cm flooded (NTCM 10 cm) on weed occurrence and yield of rice in paddy. Triplicate experimental plots were laid out in a randomized complete block design and compared by employing least significant difference. The dry weights of weeds in NTCM 5 cm and NTCM 10 cm were 11% and 4% level of NTNT 5 cm (p<0.05) and were 3.2 times and 1.2 times more than in conventional tillage system. In addition, the Aneilema keisak and Ludwigia prostrata were significantly increased in NTNT 5 cm (p<0.05). The yield of rice grain in NTCM 10 cm was 2.6 times more than in NTNT 5 cm and was 89% level of conventional tillage system. Our findings suggest that NTCM 10 cm should be enhance of weed control as well as improving of yield of rice in paddy.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.140-147
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• 2012

Purpose: This study was conducted to understand the work performance of crank-type rotavators and compare them with those of rotary-type rotavators in Korean farmland conditions. Methods: Tillage operations were carried out using both rotavators with the same nominal rotavating width and rated power. During the operations, PTO speed and torque, actual work speed, and rotavating width and depth were measured. To evaluate work performance, pulverizing ratio, inversion ratio, and specific volumetric tilled soil were calculated and compared for each rotavator. Results: It is found that the crank-type rotavator has better specific volumetric tilled soil performance and deep tillage, while the pulverizing ratio is worse. Conclusions: Crank-type and rotary type rotavator have diffenent properties each other in several work performances. It's important, therefore, to choose a suitable type of rotavator that satisfy the farmer's requirements in accordance with the condition of field and the purpose of tillage operation.

• Journal of Biosystems Engineering
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• v.33 no.5
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• pp.355-361
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• 2008

As agricultural machinery has become larger and tillage practices have changed in recent decades, compaction as a result of wheel traffic and tillage has caused increasing concern. If strategies to manage compaction, such as deep tillage, could be applied only where needed, economic and environmental benefits would result. For such site-specific compaction management to occur, compacted areas within fields must be efficiently sensed and mapped. We previously developed an on-the-go soil strength profile sensor (SSPS) for this purpose. The SSPS measures within-field variability in soil strength at five soil depths up to 50 cm. Determining the variability structure of SSPS data is needed for site-specific field management since the variability structure determines the required intensity of data collection and is related to the delineation of compaction management zones. In this paper, soil bin data were analyzed by a spectral analysis technique to determine the variability structure of the SSPS data, and to investigate causes and implications of this variability. In the soil bin, we observed a repeating pattern due to soil fracture with an approximate 12- to 19-cm period, especially at the 10-cm depth, possibly due to cyclic development of soil fracture on this interval. These findings will facilitate interpretation of soil strength data and enhance application of the SSPS.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.521-528
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• 2002

Rotary and plow implements are mainly utilized for the tillage operation in Korea, and a implement control system for agricultural tractors was designed and fabricated to improve the working accuracy and efficiency. The control system was composed of three units: 1) sensors fur detection of angle of liftarm, draft force, engine rpm, tillage depth and so on, 2) a controller, and 3) hydraulic circuits, which included solenoid valves and so on, for operation of three point linkage and implements. The control system can control the speed(high and low speed) of implements by adjusting input flow rates of the hydraulic cylinder which was controled by two speed valve, which was composed of a solenoid valve and a orifice. Indoor experiments were conducted to evaluate response characteristics of the designed implement control system under experimental conditions of various engine nm, two kinds of input flow rates of the cylinder and some input frequency. The results of experiments showed the response characteristics sufficient to use as the implement control system fur agricultural tractors.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.420-428
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• 1996

This study was conducted to investigate the response of growth and yield of rice under five different cultural methods, machine transplanting(MTNT), puddled drill seeding (PDSNT), drill seeding on soil surface (DSNT) , broadcasting on soil surface (BSNT) under no-tillage paddy condition and conventional machine transplanting(MTT) in Jeonbuk series(siltyloam soil) from 1993 to 1995. Soil hardness was higher in no-tillage soil and increased with highly difference between tillaged and no-tillage soil with deeper soil depth. Bulk density was heavier in no-tillage soil and porosity was higher in tilled soil than that of the control. The rate of effective tiller was higher in MTT, following MTNT, PDSNT, DSNT and BSNT. Weed occurrence was more serious in no-tillage soil, than that of tillaged soil. The rate of lower internode length was lower in DSNT and BSNT and was similar with MTT in PDSNT and MTNT. Height of center gravity in terms of lodging tolerance was lower in direct seeding than in machine transplanting. Depth of buried culm was shorter in no-tillage soil, especially in DSNT and BSNT. Total amount of root was higher in MTT, following MTNT, PDSNT, BSNT and BSNT and the distribution rate of root in shallower soil layer was higher in no-tillage soil, especially in BSNT and DSNT. Field lodging occured highly in BSNT, following DSNA, PDSNT and MTNT with high lodging scale in DSNT and BSNT. Panicle number per unit land square meter was the highest in MTT and the least in BSNT. Ripened grain ratio was low in BSNT and DSNT due to heavy lodging. Yield of milled rice was 93% in PDSNT, 87% in DSNT, 81% in BSNT and 96% in MTNT, compared with 534kg /10a in MTT.

• Agricultural and Biosystems Engineering
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• v.5 no.1
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• pp.10-20
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• 2004

Precision agriculture aims to minimize costs and environmental damage caused by agriculture and to maximize crop yield and profitability, based on information collected at within-field locations. In this process, quantification of soil physical properties, including soil strength, would be useful. To quantify and manage variability in soil strength, there is need for a strength sensor that can take measurements continuously while traveling across the field. In this paper, preliminary analyses were conducted using two datasets available with current technology, (1) cone penetrometer readings collected at different compaction levels and for different soil textures and (2) tillage draft (TD) collected from an entire field. The objective was to provide information useful for design of an on-the-go soil strength profile sensor and for interpretation of sensor test results. Analysis of cone index (CI) profiles led to the selection of a 0.5-m design sensing depth, 10-MPa maximum expected soil strength, and 0.1-MPa sensing resolution. Compaction level, depth, texture, and water content of the soil all affected CI. The effects of these interacting factors on data obtained with the soil strength sensor should be investigated through experiments. Spatial analyses of CI and TD indicated that the on-the-go soil strength sensor should acquire high spatial-resolution, high-frequency ($\ge$ 4 Hz) measurements to capture within-field spatial variability.

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.129-135
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• 2007

Polycyclic aromatic hydrocarbons(PAHs) have been analyzed to assess vertical distribution of them with different land uses. The soils were collected from three layers; surface $(0{\sim}5cm)$, intermediate $(6{\sim}10cm)$, and deep $(11{\sim}15cm)$ layer, respectively considering land use; paddy, upland, and mountain in each site. Total 89 samples of soil from 10 sites were analyzed. Overall mean of ${\sum}PAHs$ were 137 (range $8.87{\sim}625{\mu}g\;kg^{-1}$), 203 (range $16.5{\sim}645{\mu}g\;kg^{-1}$), and $83.4{\mu}g\;kg^{-1}$ (range $6.65{\sim}667{\mu}g\;kg^{-1}$) for paddy, upland, and mountain soil, respectively. The dominant PAHs were fluoroanthene/benzo(b)fluoroanthene>pyrene>indeno(1, 2, 3-cd) pyrene in paddy, fluoroanthene/pyrene>benzo(b)fluoroanthene>chrysene in upland, and benzo(b)fluoroanthene>pyrene>chrysene in mountain soil, whereas the profile was quite similar for each other except that indeno(1, 2, 3-cd)pyrene and benzo(ghi)perylene are relatively higher in the paddy soils. Although the concentration gradient by depth was not observed in the paddy and upland soils because perturbation of soil layer by tillage, significant decrease was in the deep layer relative to the surface and intermediate layer. However, the concentration gradient of PAHs by soil depth was clearly shown in mountain soil without experiencing disturbance of tillage.

• Korean Journal of Medicinal Crop Science
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• v.16 no.2
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• pp.69-73
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• 2008

Fields experiments were conducted to investigate the effect of various tillage depth (TD) on productivity and quality of C. auriculatum Royle ex Wight from 2005 to 2006. The length of vine was elongated in lower TD treatments as 50 cm longer in 10 cm TD than 30 cm TD, and stem diameter and dry weight had increased in the lower TD. Length, width, and weight of leaves showed the quantitive growth in the lower TD treatments, but the chlorophyll content had increased in the deeper TD treatments. Root number and length had increased in the deeper TD treatments, but the root diameter and decomposed root was increased in the deeper TD. The total yield of root showed the increasing tendency in the deeper TD treatments as 6.2 ton/ha in 10 cm TD and increased as $7{\sim}9%$ in the 20 cm TD treatments.

• Korean Journal of Agricultural Science
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• v.42 no.3
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• pp.183-189
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• 2015

Plant root penetration through soil profile is restricted by compacted layer such as plow pan under conventional tillage. For detecting the compact layer, we made a graduated T-shape probe and measured compared between the depths with rapid change in feeling hardness of hand penetration using T-shape probe and with a rapid increase of penetrometer cone index. On upland crops, including red pepper, corn, soybean and cucumber, plow pan depth ranged from 10 cm to 25 cm depth. The effective rooting depth (ER) had significant correlation with the plow pan depth (PP) except soils with the shallow ground water and/or poorly drained soil. The regression equation was ER = 0.9*PP ($R^2=0.54^{**}$, N = 14) with the applicative PP range of 10-25 cm.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.2
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• pp.137-142
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• 1998

Assessment of N release pattern from hairy vetch (Vicia villosa Roth) residue is an important step for the efficient use of the residue as a green manure and the specific management strategy development. Objective of this research was to determine the changes of chemical composition, especially in light of the N release, when the residues of hairy vetch were applied in the soil. hairy vetch was harvested at different growth stages (April 23, May 9, and May 28) and the residues were encapsulated in the nylon mesh (1 mm) bag. The bags were placed on the surface of no-tillage plots and buried at 15cm in depth in conventional tillage plots of the corn field in early June. The bags were removed for measurements of dry matter and N content at 1, 2, 3. 5, 8 and 12 weeks after placement. Dry matter and N content of hairy vetch were higher when harvested closer to maturity, as also found in C/N ratio, cellulose and hemicellulose contents. The rate of N releases from hairy vetch residue under conventional tillage condition was greater than that under no-tillage condition. Percentages of N remaining in residue over the initial N contents under conventional tillage condition were in average 40, 23, and 15% for 1, 2, and 3 weeks after placement of mesh bag, respectively, compared with respective values of 71, 31, and 21% under no-tillage condition. The rate of N release was slower as the harvest time was closer to maturity of hairy vetch under both tillage conditions. Most of N in residue was released within 3 and 5 weeks, under conventional and no-tillage conditions, respectively. Results indicated that amounts of N released from hairy vetch residue were more closely related to the variability of N contents in residue due to the harvest time than changes of chemical composition of plant or soil management.