Abstract
Erosion survey of apple orchards were practised during the years 1951 and 1952 on the Nagasaka Hill, Rokugo Village, Minamitsugaru-County, Aomori Prefecture. This hill has 219 acres of land, about 188 acres of which are occupied by apple orchards. The first apple trees on this hill were planted during 1909 to 1913 after land clearing. From the soil type, the soils of this hill are classified into ando soils and brown podzolic soils. About 89 per cent of the slope is at an angle of 8 to 25 degrees and the longest slope is 500 meters in length. The principal results obtained in this survey are summarized as follows.
1. About 61 per cent of the total area of the Nagasaka Hill exclusive farm road were subject to severe sheet erosion: and 12 per cent, to very severe sheet erosion. The approximate acreage and percentage of each erosion condition in apple orchards are given in the left table.
2. Soil erosion decreased the contents of the nutrients (humus, nitrogen and exchangeable calcium), non-capillary porosity and aggregation coefficient of the sloping apple orchard soils and consequently productivity of apple orchards decreased remarkably.
