CHANGES IN PHYSICAL AND CHEMICAL PROPERTIES OF COMPOSTS BASED ON CATTLE SLURRY AND MILLED PEAT DURING INCUBATION

Fresh or old stocks of cattle slurry were added to milled peat to provide the same content of N or K as is used to prepare the Kinsealy Range Mix.
The composts based on slurry were assessed for changes in physical and nutritional (N, P and K) characteristics during 56 or 73 days of incubation, and for suitability as substrates for the growing -on of nursery stock compared with the Kinsealy Range Mix.

Although thermophilic temperatures were not achieved, there was marked improvement in the physical condition of the slurry based media.
All composts apparently ‘lost’ N between the start and end of incubation.
Composts in which relatively large amounts of slurry were used to supply the same N content as in the Range Mix were appreciably higher in extractable P and K than was the Range Mix.
They were similar to the Range Mix, however, in the content of mineral N (NH₄ + NO₃) and in the fact that NO₃ was the predominant form of N at the end of incubation.
In contrast, where smaller amounts of slurry were employed to provide the same K content as in the Range Mix, nitrification was inhibited and 37–56% of the mineral N at the end of incubation was present as NH₄. Composts containing the old slurry appeared to mineralize all of the slurry-P in contrast to those containing fresh manure.

Symposium on Substrates in Horticulture other than Soils in situ

B. O’Dwyer, M.A. Morgan, P.O. Toole

https://doi.org/10.17660/ActaHortic.1989.238.21