Fertiliser N input

Fertiliser (N) input

Throughout the analyses and examples, we see fertiliser N input as a lead ‘driving’ variable. It features therefore as the x-axis in the illustrations of how the system responds to all other inputs and management variables.


It may seem a break from convention, that a section on ‘fertiliser N input’ deflects a reader elsewhere, but the implications of fertiliser N input, are so profound, it is important to see the effects of N inputs in the context of how these drive, and interact with all other variables.

N input and supplements

N input and irrigation

N input and animal class

N input and stocking rate

N input and system C and N balances

C sequestration

For each, we depict the effects of fertiliser (or other) N inputs on the rate of ‘production’ (we use units of kg protein-N for consistency across eg milk and meat); on C sequestration; on the total release of nitrogen to the environment; and on methane emissions. We also show the effects on ’emissions intensities’ (N releases per unit products; and methane emissions per unit product), and on ‘Nitrogen Use Efficiency’ (N in products per unit N inputs).

A breakdown of the effects of management variables on the whole C and N cycles (and a breakdown of the multiple release routes involved), are shown, both as the eventual sustainable steady states, but also during transitions between management combinations, under the headings above.

Hurley Pasture Model and Edinburgh Forestry Model A Massey Site