Composition and Reactions of Liquid Manure (Gülle), with Particular Reference to Phosphate: I. Analytical Composition and Reaction with Poorly Crystalline Iron Oxide (Ferrihydrite)1
- A. W. Fordham and
- U. Schwertmann2
Samples of liquid cattle (Bos taurus) manure (gülle) of different maturity were collected from three sites in West Germany and analysed for several components, many of them relevant to the behaviour of phosphate in both liquid and solid phases. When gülle solutions were shaken with iron oxide, changes of inorganic phosphate concentration were generally very similar to those in comparable inorganic model systems. Thus, there was very little interference to sorption processes from organic components of gülle and, furthermore, no interferences developed during storage of samples at 4C, laboratory temperature, or during incubation at 35C for several months. Precipitation of inorganic phosphate, normally observed in these gülle samples during shaking, was minimized by rapid removal of phosphate from solution by adsorption on iron oxide. Organic phosphate in solution constituted only about 5% of total phosphate and very little, if any, was sorbed from solution by iron oxide.
Observations by other workers of deep penetration of phosphorus from gülle into a sandy soil were best explained by transport of finely divided solid particles of inorganic phosphate suspended in the large volumes of liquid applied to the soil. Rapid movement of phosphate in solid form would limit retention of soluble phosphate by soil components such as iron oxide.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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