| Abstract: | Relationships between the duration (in years) of practice and soil (0–30‐cm layer) chemical properties of 189 upland fields under organic farming in Japan were investigated. Electrical conductivity and available phosphorus (P), nitrate nitrogen (NO 3‐N), Cl− and sulphate sulphur (SO 4‐S) decreased and became constant with increasing duration of practice. This was probably because of the absence of mineral fertilizers and the reduced use of animal‐based fertilizers as the duration of organic farming increased. |
