Jinu Eo

Chemical and Biological Properties of Soils Converted from Paddies and Uplands to Organic Ginseng Farming System in Sangju Region

In recent years, organic ginseng cultivation has increased because customers prefer organic ginseng products due to the morphological quality as well as the safety such as the residuals of chemically-synthesized pesticides. Therefore, some of paddy and upland fields were converted into organic ginseng fields. Soil chemical properties, soil microflora, and soil-inhabiting animals were investigated in paddy-converted and upland organic ginseng fields in Sangju city, Korea. There was few difference in the soil chemical properties, and the soil nutrient concentrations, such as nitrate-N, Av. P₂O 5 between the two field types, and exchangeable cations such as K and Ca were within the ranges which are recommended by the standard ginseng-farming manual. Changes in microflora were also assessed by analyzing phospholipid fatty acid composition. Overall, indicators of microbial groups were greater in the upland field than in the paddy-converted soil, but they were not significantly different. In addition, there was no significant change in the abundance of nematodes, collembolans, and mites between the two field types probably because of the high variation within the field types. In this study, it was suggested that soil chemical and biological properties for organic ginseng cultivation were greatly influenced by the variation of topography and soil management practices rather than field types. Further study may be needed to investigate the influence of these factors on soil chemical and biological properties in organic ginseng soils.

Growth Characteristics and Ginsenosides Content of 4-Year-Old Ginseng by Spraying Lime-Bordeaux Mixture in Panax ginseng C. A. Meyer

Ginseng Research Division, Department of Herbal Crop Research, NIHHS, RDA, Eumseong 369-873, Korea.ABSTRACT : An important factor in the production of organic ginseng is the control of Alternaria blight and anthracnose,which mostly affect the leaves in the summer. We compared the effects of a lime-bordeaux mixture (LBM) and agriculturalchemicals on the growth characteristics and ginsenoside content in 4-year-old ginseng plants when they were sprayed at 15-day intervals from mid-June to the end of September. The increases in leaf length, and survive-leaf ratio in plants sprayedwith LBM were greater than the increases of the control plants, but less than those of agricultural chemicals treatment. Theroot weight per plant in the plants sprayed with LBM increased more distinctly than that in the control plants, while it wassignificantly lower than that in plants sprayed with agricultural chemicals. The root yield in plants sprayed with LBMincreased by 21% compared to the root yield in the control plants, but decreased by 7% compared to that in plants sprayedwith agricultural chemicals because of the decreases in leaf area and survive-leaf ratio. Spraying of LBM had a significanteffect on the ginsenoside contents. The total ginsenoside content was highest in the control plants and lowest in the plantssprayed with agricultural chemicals and total ginsenoside contents was great relative to survive-leaf ratio and root weight.Key Words : Panax ginseng, Lime-Bordeaux, Growth Characteristics, Root Yield, Ginsenoside Contents

Effects of Cover Plants on Soil Biota: A Study in an Apple Orchard

We aimed to investigate the responses of soil organisms to cover plants and to provide information for the selection of proper plant species. We studied the effects of 7 cover plants, including rye, oat, rattail fescue, Chinese milk vetch, red clover, crimson clover, and hairy vetch, on soil organisms in an apple orchard. An increase in the microbial phospholipid fatty acids (PLFA) and in the number of nematodes and microarthropods in the soil under the cover plants reflects elevated activities of soil organisms. A decrease in the level of some marker PLFA, which is an indicator of environmental stress, suggests that cover plants provide favorable environments for soil organisms. The population of fungi and animals that feed on fungi increased in the soil surface under red clover. The population density of nematodes and mites increased in the soil surface under rattail fescue, and that of mites and omnivorous nematodes increased in the soil surface under Chinese milk vetch. The level of microbial PLFA in the soil surfaces under the tested cover plants was higher than that under clean culture system. These results suggest that proper selection of the cover plants can facilitate the creation of favorable environments for soil organisms.

Short-term effects of organic waste amendments on soil biota: responses of soil food web under eggplant cultivation

The aim of this study was to investigate the effects of reusable organic wastes on soil organisms, with a focus on changes in the soil food web. Bone meal, de-oiled cake, and oyster shell were applied at 5 t ha–1, and the abundance and biomass of soil organisms were measured at 4, 8, and 13 weeks after treatment in soil under eggplant cultivation. The abundance of microflora and fauna was higher in the soils treated with bone meal or de-oiled cake than in untreated soils, suggesting that soil organisms are affected by the quality of applied organic wastes. Increases in the abundance of bacterivorous nematodes were observed under treatment with bone meal or de-oiled cake, but there was little change in the abundance of predatory nematodes. A positive response of microarthropods in the Collembola and Oribatida was apparent, and these organisms are involved as secondary consumers in the soil food web, but the predaceous Gamasida were relatively unaffected. The abundance of protozoa, microbivorous nematodes, Collembola, and Oribatida was correlated with the abundance of bacteria and fungi, indicating that both bacteria- and fungi-based food webs formed. The abundance of the secondary consumers was not significantly correlated with that of the predators. The study suggested that, in the short-term, organic waste alters the primary and secondary consumers but its effect may not extend to predators.

Changes in Soil Biota Affected by the Application of Organic Materials in Reclaimed Upland and Paddy-converted Soils Cultivated with Korea Ginseng

Cultivation of Korea ginseng in newly reclaimed and paddy-converted fields has been increasing, and evaluation of organic amendment effectiveness is needed in the two soil types. Soil organisms influence organic matter decomposition, and their responses to applications of organic matter were studied. De-oiled cake and compost were applied at and in both soil types. Changes in microflora were assessed by analyzing phospholipid fatty acid (PLFA). The abundance of nematodes and microarthropods was measured. Microbial PLFA indicators for microorganisms and microarthropod abundance were greater in reclaimed upland than in paddy-converted soil. There were few differences in the microflora and fauna of reclaimed uplands, regardless of treatment. In paddy-converted soil, the abundance of Oribatida was increased by the application of compost at and was correlated with PLFA indicators of fungi. The results suggested a minimal influence of organic amendments in reclaimed upland, because the organic matter content and abundance of soil organisms are low in mineral soils. In paddy-converted soil, the effects of organic amendment differ among different soil organisms, and soil properties are important mediators of the effect.

Effects of Cover Crops on Soil Chemical Properties and Biota in a Pear Orchard

The use of cover crops has a beneficial effect on sustainable soil management in pear orchards. We aimed to compare changes in soil chemical properties and biota with the use of different cover crops. We tested the effects of five cover plants, including hairy vetch, orchard grass, rattail fescue, rye, and perennial ryegrass. Use of different cover crops had a minimal impact on soil chemical properties through three year experiments. The aboveground biomass was greatest with the use of rye. The potential amounts of returnable N and P were highest when leguminous hairy vetch was used as a cover plant. Changes in the composition of the microbial community were investigated by phospholipid fatty acid (PLFA) analysis. Microbial PLFAs were highest with the use of rattail fescue and lowest with the use of hairy vetch. Minimal changes in the abundances of nematodes and microarthropods suggested that there was no bottom-up control in the soil ecosystem. The results also show that increases in aboveground biomass and nutrient content with the use of cover crops may not promote the abundance of soil organisms.

Effects of rice husk and rice husk biochar on root rot disease of ginseng (Panax ginseng) and on soil organisms

Abstract This study investigated the effects of rice husk and rice husk biochar on root rot (caused by Cylindrocarpon destructans and Fusarium solani) of ginseng (Panax ginseng) and on soil organisms. The effects were compared between paddy-converted and upland soils characterised by high and low nutrient content, respectively. The prevalence of root rot disease in the upland soil decreased in plots treated with rice husk at 5.2 Mg ha−1 compared to the untreated control. Small differences in soil chemical properties between different treatments suggested the role of biotic factors in the suppression of the disease. In both soils, the lowest hyphal growth of Fusarium solani was observed in soil collected from plots treated with rice husk at 5.2 Mg ha−1. The results suggested that the low incidence of root rot disease was due to the suppressive effect of soil on pathogenic fungi in the treated upland soil. Principal component analysis of phospholipid fatty acid results suggested that changes in microbial community structure contributed to soil suppressiveness in the paddy-converted soil. The highest density of fungivorous nematodes was observed with rice husk at 5.2 Mg ha−1 in the paddy-converted soil, and Aphelenchus sp. collected from the plots were successfully cultured on F. solani and C. destructans. This observation showed that the fungivorous nematodes have potential to suppress pathogenic fungi by feeding on them. It was shown that rice husk can be used in control of root rot disease while promoting the growth of beneficial organisms suppressing pathogenic fungi and that the effect may differ by soil type.

Abiotic effects on the distributions of major insect species in agricultural fields

We compared how abiotic factors affect the regional distributions of four insect groups (Dermaptera, Formicidae, Orthoptera and Diptera). Insects were collected using a pitfall trap from 36 agricultural field sites, and 31 933 individuals encompassing 139 species were observed. The distribution pattern of dominant species was not obviously different among the four groups. Species richness (H′) of Orthoptera showed a negative and positive correlation with precipitation and sunlight duration, respectively. Longitudinal zonation was the main distribution pattern of many dominant species. Overall, canonical correspondence analysis showed that temperature and precipitation were closely associated with the distribution of Orthoptera, but not that of Formicidae, implying that Formicidae may be affected less by abiotic factors compared to other taxonomic groups. Some orthopteran species such as Dianemobius nigrofasciatus and Polionemobius mikado showed a negative correlation with temperature. We suggest that these species can be categorized as susceptible to climate change. Our results also implied that the association between climate variables and distribution of insects should be evaluated at a species level.

Effects of Vermicompost Application on the Growth and Ginsenoside Content of Panax ginseng in a Reclaimed Field

The objective of this study was to evaluate the effects of the application of vermicomposts on the growth parameters and ginsenoside content of ginseng roots. Food waste vermicompost (FW), cow manure vermicompost (CM), and paper sludge vermicompost (PS) were applied at 10 and 40 t ㏊ -1 , respectively. One-year-old seedlings were transplanted and 4-year-old roots were harvested. Soil nitrate and phosphate concentrations were increased in the plots applied with FW and CM at 40 t ㏊ -1 . Soil pH and exchangeable Caconcentrations were higher at FW 40 t ㏊ -1 than at CM 40 t ㏊ -1 . Root yield increased when treated with FW 40t ㏊ -1 in comparison to the yield for the control. The incidences of root rot disease and ginsenoside content were not significantly affected by the treatments. The results suggested that application of vermicompost might not show a relationship between root biomass and ginsenoside content. It further showed that proper use of vermicompost can promote root yield without a reduction in root quality or an increase in the incidence of root rot disease in reclaimed fields.

Effect of Continuous use of Inorganic Fertilizer on the Soil Organisms and Food Chain

BACKGROUND: This study aimed to evaluate the combined effects of three components (NPK) of chemical fertilizers with basal application of compost on soil organisms.METHODS AND RESULTS: The soil was treated with five treatments continuously for 15 years: control, PK, NK, NP and NPK. The application of N increased plant growth or biomass, and enhanced organic matter content in the soils. Levels of microbial phospholipid fatty acids (PLFAs) in the soils did not show marked differences among the soils treated with different treatments. However, the principal component analysis showed the changes in the structure of the microbial community in the soil, depending on treatments added. Nitrogen application caused a decrease of pH and an increase of EC in the soils, and these environmental stresses appeared to offset the promoting effect of increased organic matter content on microbial abundance. The abundance of bacterivorous nematodes was the highest in the soils after treating NPK; however, the abundance of fungivorous nematodes was unaffected. There was no significant correlation between the abundances of microbial groups and their feeders. Organic matter content was significantly correlated with the abundance of nematodes in the soils.CONCLUSION: Our results showed that chemical fertilizers affect the soil food chains through both biotic and abiotic factors, and a trophic cascade in the soils may not occur in response to long-term fertilization.