Phosphorus pools and plant uptake in manure-amended soil

Abstract

To determine the effect of different types of manure without or with inorganic P fertiliser on soil P pools and P uptake by plants, two experiments were conducted. In experiment 1, sheep or cow manure (P concentration sheep > cow manure) were added at 1.0, 2.0 and 3.5 g kg⁻¹, additional treatments were unamended control and soil with inorganic N and P equivalent to 3.5 g kg⁻¹ cow manure. After 4 weeks compared to the unamended control, P pools were similar with cow manure P pools. But with sheep manure, citric acid P, HCl P and resin P with sheep manure were higher and increased with addition rates. Shoot P uptake with 3.5 g kg⁻¹ manure was higher than the unamended control but lower than with inorganic fertiliser. In experiment 2, the amount of P and N added was as in 3.5 g kg⁻¹cow manure applied either as manure (C) and inorganic P (F) alone and combinations (75C25F, 50C50F, 25C75F). After 4 weeks of wheat growth, citric acid P and resin P increased with the proportion of inorganic P. Shoot P uptake in manure/fertiliser treatments was higher than in manure alone and unamended control but lower than with inorganic fertilisers alone.