| Abstrak/Abstract |
The objective of this study was to determine the changes in the basic soil chemical properties including pH,
electrical conductivity (EC), available phosphorus (P), dissolved organic carbon (DOC) and inorganic
nitrogen (NH4-N and NO3-N) after approximately 15-40 years’ land use change from rice paddy field to
orchard, wetland and upland in northeast Japan. Five land use change fields were investigated, including,
forest, rice paddy, orchard, wetland, and upland near Kumagai shrine, Shonai-machi, Yamagata, Japan. Soil
samples were collected from surface layer (0-15 cm) and sub-surface layer (15-30 cm) in October 2015. Soil
chemical properties of pH, EC, available-P, DOC and inorganic-N (NH4-N and NO3-N) were analyzed on
air-dried samples. The pH increased significantly in the upland after 15 years conversion from rice paddy in
both layers, with other land use changes only increasing pH in sub-surface layer. EC significantly decreased
in the surface layer of orchard and upland fields and in sub-surface layers of all the converted fields.
Available-P significantly decreased in the converted fields, except in the upland sub-surface layer. DOC
amounts were not significantly different after land use changes from paddy fields. The NH4-N decreased
significantly only in the surface layer of upland, while NO3-N increased significantly only in the surface
layer of wetland. Significant changes in soil properties were observed after 15 years conversion to upland
and 40 years conversion to orchard and wetland from former rice paddy field in this study. |
