Fate of phosphorus added with urban compost to a calcareous soil

Abstract

The effect of successive applications of urban compost (up to 150 and 400 t ha^‐1 during eight years) on the status of phosphorus in a calcareous soil (20%) was tested in a greenhouse experiment. An 8–15–15 complex fertiliser was also applied for comparison. Five years of ryegrass and three of horticultural plants (tomato and eggplant) were successively cropped during the experiment. Increases of total‐ and available‐P were observed with both organic and inorganic fertilisation. Total‐P increased more in soils treated with the highest compost dose. Generally, available‐P was similar for soils treated with the highest compost dose and inorganic fertiliser. Also a slight but significant increase of organic‐P was found in soils treated with compost. Phosphorus added to soil tends to increase soluble‐ plus exchangeable‐P (more in inorganic fertiliser treatment), P in calcium phosphates (more in highest compost treatment) and residual‐P, the latter being greater in soils treated with compost.