Search

Due to global climate change, Korea is facing severe droughts that affect the planting and early vegetative periods of upland crops. Soybean and adzuki bean are important legume crops in Korea, so it is critical to understand their adaptations to water stress. This study investigated the changes in root morphological properties in soybean and adzuki bean and quantified the findings using fractal analysis. The experiment was performed at the National Institute of Crop Science in Miryang, Korea. Soybeans and adzuki beans were planted in test boxes and grown for 30 days. The boxes were filled with bed soil with various soil moisture treatments. Root images were obtained and scanned every two days, and the root properties were characterized by root length, depth and surface area, number of roots, and fractal parameters (fractal dimension and lacunarity). Root depth, length and surface area and the number of roots increased in both crops as the soil moisture content increased. The fractal dimension and lacunarity values increased as the soil moisture content increased. These results indicated that the greater the soil moisture, the more heterogeneous the root structure. Correlation analysis of the morphological properties and fractal parameters indicated that soybean and adzuki bean had different root structure developments. Both soybean and adzuki bean were sensitive to the amount of soil moisture in the early vegetative stage. Soybean required a soil moisture content greater than 70% of the field capacity to develop a full root structure, while adzuki bean required 100% of the field capacity. These results would be useful in understanding the responses of soybean and adzuki bean to water stress and managing irrigation during cultivation.

Soil and plant samples were collected from 84 fields where medicinal plants were cultivated to determine the effect of soil phosphate (P) on the concentration of plant-available arsenic (As) and cadmium (Cd) and on the uptake of these toxic elements by medicinal plants. Concentrations of total P and available P in soils affected the phytoavailability of As and Cd differentially. Plant-available As in the soil and its uptake in the plant increased with increasing concentration of plant-available P in the soil due to competition between arsenate and P for the adsorption site at the soil surface and an increase in soil pH caused by specific adsorption of P. In contrast, phytoavailability of Cd decreased with increasing concentration of available P in soil. This was mainly attributed to an increase in Cd adsorption caused by P-induced negative charge of soil.

Direct seeding of sorghum (Sorghum bicolor L. Moench) has a problem of low yield including poor establishment. This poor establishment results from poor quality seed, poor seedbed preparation, seedling pests, poor sowing technique and high soil temperature. This study sought to establish the age at which sorghum seedlings can be transplanted with minimal effects on grain yield. Transplants were raised in 128 nursery tray pot. Five seedling ages were established by transplanting at 10 (T10), 15 (T15), 20 (T20), 25 (T25) and 30 (T30) days after planting (DAP). The treatment combinations were arranged in a randomized complete block design and replicated three times with an individual plot size of . Each plot had five ridges with a planting space of at one plants per stand. Results showed that seedling age on transplanting significantly affected growths and yields to sorghum after transplanting. Plant heights and diameters of transplants at T15 were longer than the other transplants. Conclusively, The advantages of this practice were better control of crop density and greater yields; either to fill gaps after emerging and thinning of crops or to compensate for a growth period that was too short for a complete crop cycle.

This study was conducted to serve as a basis for establishing a stable production of proso millet on the rotational paddy-upland field by looking out the physicochemical and moisture characteristics of soil and the growth characteristics of proso millet by ridge width. Plant height showed Manhongchal was the smallest 71.3 cm in 240 cm wide of ridge in the first year, Ibeakchal was the highest 69.7 cm in 60 cm wide in the second year, Hwanggeumchal was the highest 72.8 cm in 60 cm wide in the first year. The retention time of the excess water in the soil during cultivation was extended wider the width of ridge. The variation width of the water content was higher by the wider the width of ridge. Yield components showed the longest ear length were 35.1 cm of Manhongchal, 34.8 cm of Ibeakchal in 60 cm wide of ridge in the first year. As the width of ridge extended, ear weight of all variety increased. 1,000 seed weight of the 60 cm wide of ridge was Manhongchal 6.8%, Ibeakchal 46.2% heavier than the 240 cm wide of ridge. Yield showed Manhongchal 221, Ibeakchal 223, Hwanggeumchal in 60 cm wide of ridge in the first year. The similar pattern of amount showed Manhongchal 278, Ibeakchal 221, Hwanggeumchal in 60 cm wide of ridge in the second year. This showed Manhongchal 103%, Ibeakchal 119%, Hwanggeumchal 85.2% was more than the 240 cm wide of ridge.

This study was conducted to evaluate basic seed characteristics such as morphological characteristics and various seed vigor using 4 sorghum varieties, Nampungchal, Donganme, Hwanggeumchal and Whinchal. No difference was shown in morphological characteristics of the varieties except that the width. Whinchal has bulb-shaped seed, while the other varieties have oval-shaped seeds. The seed coat color of Whinchal is obviously different from those of the other varieties; especially, Nampungchal and Hwanggeumchal are not glossy. Germination rate were Hwanggeumchal > Nampungchal > Donganme > Whinchal in the order of higher rate in standard germination tests and cold germination test. In the ageing test, Donganme showed the lowest 15% decrease in comparison with the standard cultivar. Electric conductivity (EC) has negative correlation with standard germination tests, cold germination test and accelerated ageing test. In the percentage of emergence (PE), Hwanggeumchal was the highest 85.7% which was more than 40% to the lowest Whinchal. Mean emergence time (MET) showed significant difference between the varieties; Whinchal showed the slowest 6.0 days.

The effects of cover crops on weed suppression were evaluated in this study. Weed suppressing effects of hairy vetch cover crops were evaluated in summer grain fields. Cover crops were sown at the sowing rate of 60 ㎏ ㏊ -1 on Oct. 2012 and Feb. 2013 without basal fertilization. Three weeks old sorghum seedlings were transplanted after minimum tillage on June 2013. Hairy vetch cover crop treatment significantly reduced weed biomass in the transplanted sorghum. By smothering, the cover crops reduced weed biomass to economic level in sorghum. Besides the weed suppression, hairy vetch cover crop resulted in green manure effect on crop growth. Hairy vetch treatment showed beneficial effects on sorghum growth. Reduction of weeds caused by use of strip-tillage machine and polyethylene film mulching was 71% and 88%, respectively. At harvest, yield of sorghum was greater in order of polyethylene film mulching ＞ hairy vetch cover crop ＞ control in transplanted fields.

This study was conducted to evaluate effect of plants number per hill (PNH) on growth and yield of sorghum in drained paddy field for 2 years. Crop growth and development and yield in the field was examined to know the efficiency of proposed cropping system. At seeding after 40 days, leaf number and stem diameter were highest at 1 PNH plot, on the other hands, plant height was at 5 PNH plot the 1 st and 2 nd , respectively. The harvest stage, 5 PNH plot was highest culm length of 183, 188 ㎝ the 1 st and 2 nd , however, culm diameter was lowest. Culm length of sorghum was highest by 183, 188 ㎝ at 5 PNH plot also, culm diameter was thickest by 19.18, 20.13 ㎜ at 1 PNH, respectively. Yield components of ear length, seed number per ear and 1000-seed weight were highest at 1 PNH the 1 st and 2 nd , respectively. As yield of sorghum was highest at 2 PNH plot 344 ㎏․10a -1 , 382 ㎏․10a -1 yearly, respectively that it were in order of 1 PNH plot > 3 PNH plot > 4 PNH plot > 5 PNH plot.

The effects of long-term fertilization on soil biological properties and microbial community structure in the plough layer in a rice paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK + Compost) for last 40 years. No fertilization plot (Control) was installed for comparison. Though fertilization significantly improved rice productivity over control, the long-term fertilization of NPK and compost combination was more effective on increasing rice productivity and soil nutrient status than single application of compost or chemical fertilizer. All fertilization treatments had shown significant improvement in soil microbial properties, however, continuous compost fertilization markedly increased soil enzyme and microbial activities as compared to sole chemical fertilization. Results of microbial community structure, evaluated by EL-FAME (ester-linked fatty acid methyl esters) method, revealed big difference among Control, NPK, and Compost. However, both Compost and Compost+NPK treatments belonged to the same cluster after statistical analysis. The combined application of chemical fertilizer and organic amendments could be more rational strategy to improve soil nutrient status and promote soil microbial communities than the single chemical fertilizer or compost application.

Fertilizer management has the potential to promote the storage of carbon and nitrogen in agricultural soils and thus may contribute to crop sustainability and mitigation of global warming. In this study, the effects of fertilizer practices [no fertilizer (Control), chemical fertilizer (NPK), Compost, and chemical fertilizer plus compost] on soil total carbon (TC) and total nitrogen (TN) contents in inner soil profiles of paddy soil at 0-60 cm depth were examined by using long-term field experimental site at 42 nd years after installation. TC and TN concentrations of the treatments which included N input (NPK, Compost, NPK+Compost) in plow layer (0-15cm) ranged from 19.0 to 26.4 g kg -1 and 2.15 to 2.53 g kg -1 , respectively. Compared with control treatment, SOC (soil organic C) and TN concentrations were increased by 24.1 and 31.0%, 57.6 and 49.7%, and 72.2 and 54.5% for NPK, Compost, and NPK+Compost, respectively. However, long term fertilization significantly influenced TC concentration and pools to 30 cm depth. TC and TN pools for NPK, Compost, NPK+Compost in 0-30 cm depth ranged from 44.8 to 56.8 Mg ha -1 and 5.78 to 6.49 Mg ha -1 , respectively. TC and TN pools were greater by 10.5 and 21.4%, 30.3 and 29.6%, and 39.9 and 36.3% in N input treatments (NPK, Compost, NPK+Compost) than in control treatment. These resulted from the formation and stability of aggregate in paddy soil with continuous mono rice cultivation. Therefore, fertilization practice could contribute to the storage of C and N in paddy soil, especially, organic amendments with chemical fertilizers may be alternative practices to sequester carbon and nitrogen in agricultural soil.

Sustainability index was calculated to determine the best management for rice productivity under long-term inorganic fertilizer management’s practices. It is based on nutrient index, microbiological index and crop index related to sustainability as soil function. Indicators for calculating sustainability index were selected by the comparison of soil properties and rice response in paddy soil with fertilization. Total twenty two indicators were determined to assess nutrient index, microbiological index and crop index in order to compare the effect of different fertilization. The indices were applied to assess the sustainability with different inorganic fertilizer treatments such as control, N, NK, NP, NPK, NPK+Si, and NPK+Compost. The long-term application of compost with NPK was the highest sustainability index value because it increased nutrient index, microbial index and crop index. The use of chemical fertilizers resulted in poor soil microbial index and crop index, but the treatments like NP, NPK, and NPK+Si were maintained sustainability in paddy soil. These results indicate that application of organic and chemical fertilizer could be a good management to improve rice sustainability in paddy soil.

Green manure cultivation affects soil productivity and nutrient conservation in paddy soil at winter season. This study was to evaluate nitrogen behavior released from chinese milk vetch (CMV) as green manure by using stable trace during rice cultivation. The CMV used in the experiment was 29.9 of C/N ratio and 14.1 g N ( 0.388 atom % excess) and was applied at rates of 10 and in pot of 1/2000a size. Rice growth and N uptake increased with higher levels of CMV application at harvesting stage. Among total N uptake, 14.6 and 26.8 % of nitrogen was released respectively from the two different rates of CMV application. Stable recovery by rice biomass was 60%, 54% to the input, respectively, of CMV application, which decreased in order of grain, root, and straw of rice biomass. Total N content in the soil after rice harvest was 1.9 and 2.1 g N , respectively, with increasing N input by the different rates of CMV application and the rate of recovery derived from CMV in the soil was 3.8 and 4.8 %, respectively. N input by CMV application induced rice growth and productivity during rice cultivation. However, it might need proper managements to reduce N loss because about 36-41 % of nitrogen was lost from N input by CMV application.

This study was conducted to evaluate the weed suppressing effects of different cropping system including hairy vetch (Vicia villosa) and rye (Secale cereale) cover crops, polyethylene plastic film, and transplanting film mulching in direct sowing and transplanted sorghum field in 2011. Crop growth and development and weed occurrences in the fields were examined to know the efficiency of proposed cropping system. In polyethylene film mulching treatment, heading date of sorghum was earlier by 3 days than control, on the other hands, rye cover crop mulching delayed heading date by 11 days. Besides the effect of cover crop on the heading of sorghum, the residues changed growth characteristics. Plant height of sorghum was increased by 27.3% at hairy vetch treatment although it was reduced by 47.5% in the rye cover crop treatment. Hairy vetch treatment showed beneficial effects on sorghum growth reduced the occurrences of grasses and broadleaf weeds to 84% and 96%, respectively, as compared to control in sorghum fields. While rye cover crop treatment showed poor sorghum growth reduced less strongly grasses and broadleaf weeds by 35% and 71%, respectively. At harvest, yield of sorghum was greater in order of hairy vetch cover crop > polyethylene film mulching > rye cover crop control in both transplanted and direct sown fields.

Weed control is of fundamental importance when planting cereal crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Field experiment was conducted to evaluate the effect of ethanol treatment on the weed control efficacy in cereal crops in protected vinylhouse. Five treatments like water, 25 L, 50 L, 75 L, and 100 L per m -2 at 2% ethanol were applied and covered with vinyl on 10 days before foxtail millet seeding. After that, foxtail millet seeds were sown on June 20 at 60×10cm planting distance and weed control efficacy was recorded at 30, and 50 days after seeding based on the dry weight. Soil oxidation-reduction potential was recorded -200～-400 ㎷ after treatment 2 days. Weed control efficacy of at 75 L, and 100 L per m -2 was observed 92%, 84% in 2% ETOH, respectively. Yields of foxtail millet at 75 L, and 100 L per m -2 were 1,570 kg ha -1 , 1,230 kg ha

This survey of weed population by different soil moisture with paddy-upland rotation was conducted to investigate information on weed flora and its ecology between two years. Weed species were assessed in April : 2009, 2010. Soil samples were taken from each study plot to assess the impact soil moisture on the occurrence and abundance of dominance weed species. Soil water of poorly drained field ranged from 10.2~18.2% more than 11.8~14.3% of somewhat poorly drained field. Weeds of fields composed of 19 species belonging to 12 families. Among 12 families, 6 weed species belonged to Compositae (31.6%) were the biggest family, Cruciferae were 2 species (10.5%), and Rubiaceae were 2 species (10.5%), respectively. Youngia japonica had the highest summed dominance ratio(SDR) (97.0%) and followed by Conyza canadensis (92.1%), Galium spurium (35.3%) and Hemistepta lyrata (28.4%) of somewhat poorly drainage in 2009. Artemisia princeps the highest SDR (100%) and followed by Stellaria alsine(55.2%), Y. japonica (38.3%) and Nasturtium officinale (28.5%) of poorly drainage in 2009. And, Stellaria alsine had the highest SDR (86.8%) and followed by Alopecurus aequalis (77.7%), Astragalus sinicus (68.7%) and Y. japonica (46.3%) of somewhat poorly drainage in 2010. S. alsine the highest SDR (93.7%) and followed by A. aequalis (78.6%), Nasturtium officinale (31.3%) and Y. japonica (30.4%) of poorly drainage in 2010. Simpson`s index was calculated to 0.12~0.23, which showed that weed occurrence with different soil moisture in paddy-upland rotation and between years was various. Similarity coefficient between years was 43.0% (2009) and 74.2% (2010), which indicate a low diversity because of the moisture in the agro-ecosystem.

An optical sensing approach based on diffuse reflectance has shown potential for rapid and reliable on-site estimation of soil properties. Important sensing ranges and the resulting regression models useful for soil property estimation have been reported. In this study, a similar approach was applied to investigate the potential of reflectance sensing in estimating soil properties for Korean paddy fields. Soil cores up to a 65-cm depth were collected from 42 paddy fields representing 14 distinct soil series that account for 74% of the total Korean paddy field area. These were analyzed in the laboratory for several important physical and chemical properties. Using air-dried, sieved soil samples, reflectance data were obtained from 350 to 2500 nm on a 3 nm sampling interval with a laboratory spectrometer. Calibrations were developed using partial least squares (PLS) regression, and wavelength bands important for estimating the measured soil properties were identified. PLS regression provided good estimations of Mg (

Soil texture has an important influence on agriculture, affecting crop selection, movement of nutrients and water, soil electrical conductivity, and crop growth. Soil texture has traditionally been determined in the laboratory using pipette and hydrometer methods that require a considerable amount of time, labor, and expense. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture where more data is needed than in conventional agriculture. This paper is a part of overall research to develop a soil texture classification system using image processing. Application of image processing was motivated by simple traditional approaches such as visual inspection and the “hand-feel” method. In this paper, the potential of soil texture classification using RGB histograms was investigated. Seven sites representing major Korean paddy soil series were selected, 4-6 core samples up to a 50-cm depth were obtained from each site, and each sample was segmented by 5-cm intervals. For each segmented soil sample, four surface images were taken using a miniaturized CCD camera, and texture fractions were determined by the pipette method. Scatter plots showed linear patterns between silt content and histogram variables such as brightness, skewness, and mode - brightness. When 5% averaged silt content was linearly regressed with mode - brightness, R 2 , RMSEC, and RMSEP were 0.96, 2.2%, and 6.3%, respectively. When soils were classified using USDA criteria, the laboratory method and the in-situ image processing method produced the same results for 48% of the samples.

This paper reports development of a thresher for small grain cereal crops. Target small grain cereal crops were sorghum, proso millet, and foxtail millet. A commercially available 2.2-kW soybean thresher was used as a main body, and major design parameters such as rotational speed of the threshing drum (i.e., speed of threshing teeth), opening size of the screen to remove stem part, and air velocity to separate dust and grain. First, design parameters were determined to minimize grain loss to stem and dust discharging exits through factor experiments. For sorghum, selected air velocity, speed of threshing teeth, and opening size of the screen were 4.5 m/s, 13.5 ~ 14.6 m/s, and 10 ~ 12 mm, respectively. For proso millet and foxtail millet, air velocity values were 2.62 and 2.40 m/s, respectively. Teeth velocity was 15.7 m/s and screen opening was 8 ~ 10 mm. Second, a prototype thresher was constructed using the determined design parameters and the performance was evaluated. For sorghum, grain loss weight through stem and dust discharging exits was 5.6% of the total grain weight, and 96.9% of the materials discharged from the grain exit was grain. For proso and foxtail millets, grain loss ratios were 6.47 and 2.18%, respectively. Production cost of the small grain cereal crops would be reduced considerably with utilization of the developed thresher.