• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.5
• /
• pp.760-763
• /
• 2012

This study was conducted to investigate foliar treatment effects of organic agricultural materials for the environmentally-friendly cultivation of grape. The organic materials applied were chitosan, wood vinegar (pyroligneous acid), amino acid solution, and ginkgo leaf extract. All the organic materials were relatively strong acidic ranging lower than pH 4.6. when comparing with other organic materials, amino acid solution contained relatively high contents of selected plant nutrients, such as N, P, K, Ca, Mg, Cu, Fe, Mn, and Zn. As comparison of selected soil properties in the grape cultivating field, soil pH values were lower at the harvest stage than at the first stage of grape growing (before treating the organic materials), and electrical conductivity (EC) and soil organic matter content were higher at the harvest stage in the all plots. The concentrations of available phosphorus increased in most of the plot soils except in control plot (conventional treatment). The concentrations of exchangeable K decreased in the plot treated with ginkgo leaf extract and the control plot. The exchangeable Mg concentrations decreased in soils of all the plots. On the other hand, the concentrations of N and K in the grape leaves were higher with the treatments of chitosan and amino acid solution, P concentrations were higher with the applications of chitosan, wood vinegar and amino acid solution, and Ca and Mg concentrations were higher with chitosan and amino acid solution treatments, respectively, than with others. The yields of grape were higher, $1,581{\sim}1,583kg\;10a^{-1}$, in the control and wood vinegar treatment plots than others. Sugar contents of grape were not different among all the plots.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.5
• /
• pp.829-835
• /
• 2012

The cultivation of genetically modified (GM) crops has increased due to their economic and agronomic advantages. Before commercialization of GM crops, however, we must assess the potential risks of GM crops on human health and environment. The aim of this study was to investigate the possible impact of Bt rice on the soil microbial community. Microbial communities were isolated from the rhizosphere soil cultivated with Bt rice and Nakdong, parental cultivar and were subjected to be analyzed using both culture-dependent and molecular methods. The total counts of bacteria, fungi, and actinomycetes in the rhizosphere of transgenic and conventional rice were not significantly different. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes revealed that the bacterial community structures during cultural periods were very similar each other. Analysis of dominant isolates in the rhizosphere cultivated with Bt and Nakdong rice showed that the dominant isolates from the soil of Bt rice and Nakdong belonged to the Proteobacteria, Cloroflexi, Actinobacteria, Firmicutes, and Acidobacteria. These results indicate that the Bt rice has no significant impact on the soil microbial communities during cultivation period. Further study remains to be investigated whether the residue of Bt rice effect on the soil environment.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.1
• /
• pp.118-126
• /
• 2011

Ester-linked fatty acid methyl ester (EL-FAME) profiles were used to describe differences in soil microbial communities influenced by conventional farming system (CFS), and organic farming system (OFS) in controlled horticultural land. Soil physicochemical properties and soil microbial communities were determined in the experimental fields. Higher organic matter content in OFS reduced soil bulk density which in turn increased the soil porosity. Generally, soil chemical properties in OFS were higher than those of CFS, but EC value in OFS was significantly lower than that of CFS. With the exception of Fe content, other macronutrient contents and pH in both farming system decreased with the soil depth. Soil microbial biomass of OFS was approximately 1.3 times in topsoil and 1.8 times in subsoil higher than those of CFS. Lower ratios of cy17:0 to $16:1{\omega}7c$ and cy19:0 to $18:1{\omega}7c$ were found in the CFS soils than the OFS soils, indicating that microbial stress decreased. The ratio of MUFA to SFA was higher in OFS due to organic input to the soil. In principal components analysis (PCA), the first variable accounted for 54.3%, while the second for 27.3%, respectively. The PC1 of the PCA separated the samples from CFS and OFS, while the PC2 of the PCA separated the samples from topsoil and subsoil. EL-FAMEs with the positive eigenvector coefficients for PC1 were cy17: 0 to $16:1{\omega}7c$ ratio, cy19:0 to $18:1{\omega}7c$ ratio, soil pH, soil organic matter, and soil $NO_3$-N content. Our findings suggest that the shifting cy19:0 to $18:1{\omega}7c$ ratio should be considered as potential factors responsible for the clear microbial community differentiation observed between different cultivation systems and soil depth in controlled horticultural land.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.spc
• /
• pp.20-28
• /
• 2009

The sustainability of conventional agriculture which is characterized by input dependent and ecologically simplified food production system is vague. Chemicals and present practices used in agriculture are not only costly but also have widespread implications on human and animal health, food quality and safety and environmental quality. Thus there is a need for alternative farming practices to sustain food production for the escalating population and conserve environment for future generations. The present research scenario in the area of plant microbe interactions for maintaining sustainable agriculture suggests that the level of internal regulation in agro-ecosystems is largely dependent on the level of plant and microbial diversity present in the soil. In agro-ecosystems, biodiversity performs a variety of ecological services beyond the production of food, including recycling of nutrients, regulation of microclimate and local hydrological processes, suppression of undesirable organisms and detoxification of noxious chemicals. Controlling the soil microflora to enhance the predominance of beneficial and effective microorganisms can help improve and maintain soil chemical and physical properties. The role of beneficial soil microorganisms in sustainable productivity has been well construed. Some plant bacteria referred to as plant growth-promoting rhizobacteria (PGPR) can contribute to improve plant growth, nutrient uptake and microbial diversity when inoculated to plants. Term PGPR was initially used to describe strains of naturally occurring non-symbiotic soil bacteria have the ability to colonize plant roots and stimulate plant growth PGPR activity has been reported in strains belonging to several other genera, such as Azotobacter, Azospirillum, Arthrobacter Bacillus, Burkhokderia, Methylobacterium, and Pseudomonas etc. PGPR stimulate plant growth directly either by synthesizing hormones such as indole acetic acid or by promoting nutrition, for example, by phosphate solubilization or more generally by accelerating mineralization processes. They can also stimulate growth indirectly, acting as biocontrol agents by protecting the plant against soil borne fungal pathogens or deleterious bacteria. Present review focuses on some recent developments to evolve strategies for better biotechnological exploitation of PGPR's.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.2
• /
• pp.109-115
• /
• 2006

Understanding characteristics of claypan soils has long been an issue for researchers and farmers because the high-clay subsoil has a pronounced effect on grain crop productivity. The claypan restricts water infiltration and storage within the crop root zone, but these effects are not uniform within fields. Conventional techniques of identifying claypan soil characteristics require manual probing and analysis which can be quite expensive; an expense most farmers are unwilling to pay. On the other hand, farmers would be very interested if this information could be obtained with easy-to-use field sensors. Two examples of sensors that show promise for helping in claypan soil characterization are soil profile strength sensing and bulk soil apparent electrical conductivity (ECa). Little has been reported on claypan soils relating the combined information from these two sensors with grain crop yield. The objective of this research was to identify the relationships of sensed profile soil strength and soil EC with nine years of crop yield (maize and soybean) from a claypan soil field in central Missouri. A multiple-probe (five probes on 19-cm spacing) cone penetrometer was used to measure soil strength and an electromagnetic induction sensor was used to measure soil EC at 55 grid site locations within a 4-ha research field. Crop yields were obtained using a combine equipped with a yield monitoring system. Soil strength at the 15 to 45 cm soil depth were significantly correlated to crop yield and ECa. Estimated crop yields from apparent electrical conductivity and soil strength were validated with an independent data set. Using measurements from these two sensors, standard error rates for estimating yield ranged from 9 to 16%. In conclusion, these results showed that the sensed profile soil strength and soil EC could be used as a measure of the soil productivity for grain crop production.

• Korean Journal of Soil Science and Fertilizer
• /
• v.36 no.6
• /
• pp.367-375
• /
• 2003

The aim of this study was to investigate the soil physical properties and the traction characteristics of paddy field before tillage by a computer simulation. Soil physical properties, such as soil moisture content, bulk density, soil hardness, and soil texture were measured in the twelve rice production area. Mathematical model based on dimensional analysis which include soil physical properties and vehicle factors was used for the computer simulation. Most of the soil texture of the investigated area was silty loam, loam and silty clay loam. Soil moisture content ranged between 20 and 40% mostly. Soil bulk density was in the range of 1,500 to $1,700kg\;m^{-3}$. Soil hardness ranged between 2 to $12kg\;cm^{-2}$ mostly. Soil hardness incorporates the effects of many soil physical properties such as moisture content, texture and bulk density, and so the range of soil hardness was greater than that of any other physical properties. The predicted net traction was in the range of 70 to 1,500 kgf depending on the area, but it was above 1,000 kgf for most of the investigated area. Thus it was concluded that 50 HP tractor can pull the four row moldboard plow considering the conventional tillage depth and width. But for the soft soil area such as Andong and Namyang, tractor itself may have mobility problem and show high slip during plowing operation.

• Korean Journal of Environmental Agriculture
• /
• v.23 no.1
• /
• pp.7-14
• /
• 2004

This study was conducted to investigate the effect on agricultural environment and crop productivity by different amount of applied fertilizer in consideration of irrigation water quality. N, P and K contents of irrigation water used in this experiment were 6.16, 0.26 and 9.37 mg/L, respectively. N, P and K Concentrations of runoff water were lower than those of inflow water during rice cultivation. N, P and K Concentrations of ponded and percolated water were changed according to the amount and time of applied fertilization. During rice cultivation in paddy soil, nitrogen balance was closed to 0 in SFT 50% (50% level of soil testing fertilization), 0.14 kg/ha, but it was 95.3 kg/ha in CF (conventional fertilization) treatment In SW 50% and STF (soil testing fertilization) treatment yield of perfect rice was not greatly different as compared with CF treatment due to the superiority of ripening rate, 1,000 grains weight and milling characteristics. Mechanical paratability of rice was excellent in NF (non fertilization) treatment, STF 50% treatment showed higher in nutrient availability and fertilizers use efficiency than other treatments.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2005.08a
• /
• pp.57-74
• /
• 2005

Rice yield and protein content have been shown to be highly variable across paddy fields. In order to characterize this spatial variability of rice within a field, the two-year experiments were conducted in 2002 and 2003 in a large-scale rice field of $6,600m^2$ In year 2004, an experiment was conducted to know if prescribed N for site-specific fertilizer management at panicle initiation stage (VRT) could reduce spatial variation in yield and protein content of rice while increasing yield compared to conventional uniform N topdressing (UN, ,33 kg N/ha at PIS) method. The trial field was subdivided into two parts and each part was subjected to UN and VRT treatment. Each part was schematically divided in $10\times10m$ grids for growth and yield measurement or VRT treatment. VRT nitrogen prescription for each grid was calculated based on the nitrogen (N) uptake (from panicle initiation to harvest) required for target rice protein content of $6.8\%$, natural soil N supply, and recovery of top-dressed N fertilizer. The required N uptake for target rice protein content was calculated from the equations to predict rice yield and protein content from plant growth parameters at panicle initiation stage (PIS) and N uptake from PIS to harvest. This model equations were developed from the data obtained from the previous two-year experiments. The plant growth parameters for this calculation were predicted non-destructively by canopy reflectance measurement. Soil N supply for each grid was obtained from the experiment of year 2003, and N recovery was assumed to be $60\%$ according to the previous reports. The prescribed VRT N ranged from 0 to 110kg N/ha with average of 57kg/ha that was higher than 33kg/ha of UN. The results showed that VRT application successfully worked not only to reduce spatial variability of rice yield and protein content but also to increase rough rice yield by 960kg/ha. The coefficient of variation (CV) for rice yield and protein content was reduced significantly to $8.1\%\;and\;7.1\%$ in VRT from $14.6\%\;and\;13.0\%$ in UN, respectively. And also the average protein content of milled rice in VRT showed very similar value of target protein content of $6.8\%$. Although N use efficiency of VRT compared to UN was not quantified due to lack of no N control treatment, the procedure used in this paper for VRT estimation was believed to be reliable and promising method for managing within-field spatial variability of yield and protein content. The method should be received further study before it could be practically used for site-specific crop management in large-scale rice field.

• Korean Journal of Environmental Agriculture
• /
• v.31 no.4
• /
• pp.308-312
• /
• 2012

BACKGROUND: The nutrient balance in Korea during 1985-2006 had continually increased and maintained the highest levels among OECD countries. The use of green manure crops such as barley and hairy vetch is common practice for reducing chemical fertilizer application and maintaining soil fertility. However, green manure crops can also be used as a livestock feeding material which may reduce nutrient balance in the national scale. We calculated nitrogen and phosphate balance under green manure-rice cultivating system where all green manure was removed and used for feeding livestock. METHODS AND RESULTS: The barley and hairy vetch grown in pure stands or in mixtures with different sowing rates were tested for rice cultivation without chemical fertilization. The conventional fertilization (NPK) for rice cultivation was selected to compare nutrient balance with green manure-rice cultivation. Nitrogen and phosphate balance were calculated according to the surface balance method of the PARCOM guidelines. Total aboveground biomass of mixture (barley and hairy vetch) was higher compared to that of pure barley or hairy vetch. Among the mixture with barley and hairy vetch, the highest aboveground biomass was observed in B75H25 (barley 75%+hairy vetch 25%). The nitrogen and phosphate balance in the B75H25 mixture was-104 kg N/ha and-50.3 kg P/ha, respectively. CONCLUSION(S): The barley and hairy vetch mixture proved to be a very effective strategy for biomass production of green manure. The amount of nitrogen and phosphate fertilizer to be applied is estimated to be 104 kg N/ha and 50.3 kg P/ha in order to maintain soil fertility if all green manure and rice straw were removed from rice field for livestock feeding.

• Korean Journal of Soil Science and Fertilizer
• /
• v.50 no.5
• /
• pp.422-433
• /
• 2017

Unmanned Aerial Vehicle (UAV) has several advantages over conventional remote sensing techniques. They can acquire high-resolution images quickly and repeatedly. And with a comparatively lower flight altitude, they can obtain good quality images even in cloudy weather. In this paper, we developed for estimating garlic growth at field scale model in major cultivation regions. We used the $NDVI_{UAV}$ that reflects the crop conditions, and seven meteorological elements for 3 major cultivation regions from 2015 to 2017. For this study, UAV imagery was taken at Taean, Changnyeong, and Hapcheon regions nine times from early February to late June during the garlic growing season. Four plant growth parameters, plant height (P.H.), leaf number (L.N.), plant diameter (P.D.), and fresh weight (F.W.) were measured for twenty plants per plot for each field campaign. The multiple linear regression models were suggested by using backward elimination and stepwise selection in the extraction of independent variables. As a result, model of cold type explain 82.1%, 65.9%, 64.5%, and 61.7% of the P.H., F.W., L.N., P.D. with a root mean square error (RMSE) of 7.98 cm, 5.91 g, 1.05, and 3.43 cm. Especially, model of warm type explain 92.9%, 88.6%, 62.8%, 54.6% of the P.H., P.D., L.N., F.W. with a root mean square error (RMSE) of 16.41 cm, 9.08 cm, 1.12, 19.51 g. The spatial distribution map of garlic growth was in strong agreement with the field measurements in terms of field variation and relative numerical values when $NDVI_{UAV}$ was applied to multiple linear regression models. These results will also be useful for determining the UAV multi-spectral imagery necessary to estimate growth parameters of garlic.