Compost has a slow release component. If the time of application and the resultant release rate result in more N being in the soil when leaching is likely to occur, then this can result in increased leaching.
This typically occurs if:
- The compost is added from mid-summer to early autumn
- The conditions at the beginning of the year encourage mineralisation
- N uptake is constrained.
This results in modelled soil N levels being higher in late autumn/early winter, and increased susceptibility to leaching.
Graphs of soil N levels and change in soil N pools are included in Block Details