The long-term changes in the soil properties are closely related to the policy direction and the national program for the soil management. In this study, chemical properties of paddy soils in Jeonnam province were investigated at four-year interval since 1999 and the factors affecting change of chemical properties were analyzed in relation to the soil management policies. Chemical fertilizers supplied to Jeonnam province reduced by 57% in 2013 as compared with 1999, and the ratio of Jeonnam province to the national fertilizer supply gradually decreased to 14.1% in 2013 from 17.6% in 1999 due to national policies to reduce use of chemical fertilizers in the 2000s. In the chemical analysis of paddy soils in Jeonnam province, pH value tended to increase gradually within the optimal range. Available phosphate and exchangeable potassium content were always higher than the optimal range and showed no significant difference since 1999. Organic matter, exchangeable calcium and available silicate content were found to be lower than average content in the whole country as well optimal range for rice cultivation in 1999, but were higher than average content in the whole country and optimal range in 2011 because of faster rate of increase in Jeonnam province than the other region since the mid-2000s. The cause of increase in organic matter, exchangeable calcium and available silicate contents is considered to be the increased use of green manure crops and by-products fertilizer as an alternatives for conventional application of chemical fertilizers and soil amendment such as silicate fertilizer for agronomic control of the disease and insect pest in rice cultivation of environmentally-friendly agriculture.
Organic grape was generally produced in rainshield or plastic greenhouse culture while most of fruits were produced in open field. But little attention has been given to soil properties with different culture facilities in organic grape cultivation. This study was conducted to investigate soil physico-chemical properties of organic grapes farms with different culture facilities and soil management practices. Organic fertilizer was main resource to manage soil at organic grapes farms. Organic grapes farms were applied with total amount of organic fertilizer at one time, either at basal or additional fertilization, whereas conventional grapes farms applied with split fertilization. Bulk density and penetration resistance of soil were lower at both rainshield and green manure-applied plastic greenhouse cultures than those at clean plastic greenhouse culture. Especially, in plastic greenhouse, sod culture with natural weed after green manure application was more effective than general sod culture in improving physical properties of the rhizosphere. The contents of organic matter, available phosphate and exchangeable potassium tended to increase in the soils applied with green manure, and the difference of soil chemical properties were significant between rainshield and plastic greenhouse cultures. The optimum soil management was required in plastic greenhouse because pH, available phosphate and exchangeable cations reached over optimum range. Consequently, the ground cover management is the key factor to affect the chemical properties as well as soil physical properties extensively in plastic greenhouse. It is found that sod culture with natural weed after green manure application resulted in enhancement of utilization efficiency of nitrogen, phosphoric acid and potassium in soil in comparison with general sod culture.
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