Effects of Continuous Carnation ‘Nora’ Cropping for Twenty-five Years on the Physical and Chemical Properties of Soil, Yield and Quality of Cut Flowers

Abstract

The carnation ‘Nora’ was continuously cropped under the same soil management and fertilization over 25 years in an isolated bed in order to investigate the effects on the physical and chemical properties of the soil as well as the yield and quality of carnations. There were positive correlations between the years of continuous cropping and the phosphate buffer extractable nitrogen and Troug-phosphate in soil nutrients. There was a negative correlation between years of continuous cropping and the exchangeable magnesium in the soil nutrients. There was a positive correlation between the years of continuous cropping and pore space (the water and air ratio). There was a negative correlation between the years of continuous cropping and the solid ratio. There was no correlation between the years of continuous cropping and the plant nutrients. During 25 years of continuous cropping, the cut-flower total yield of the first year was less than the yields after 11 and 17 years of continuous cropping. However, there was no significant difference in cut-flower yields between 6 and 25 years of continuous cropping. Moreover, 6 to 25 years of continuous cropping did not affect the quality of cut flowers. Thus, it has been indicated that long-term continuous cropping in carnation cultivation is possible if the physical and chemical properties of the soil can be maintained at a suitable level in soil sterilized by steam in an isolated bed.