Phosphorus Movement in Calcareous Soils Irrigated with Waste Water from Potato Processing Plants

Total, organic, and acid-hydrolyzable phosphorus and orthophosphate concentrations were determined in waste waters from five potato (Solanum tuberosum L.) processing plants and the waste water volumes applied to cropped land were measured monthly for three processing seasons. These P forms were also measured in soil water samples extracted monthly at five depths to 1.5 m. Organic plus hydrolyzable fractions comprised 60 to 70% of the total P in the waste waters and 30 to 40% in the soil water extracts. When the numerical value of the relationship (kg P/ha applied per month) (mm of clay size material in 1.5 m)-¹ was <0.4, the total P concentration in the extracts at 1.5 m was