Nitrogen fertilizer replacement value of concentrated liquid fraction on grassland and effects on farm level

Bijeenkomst: EGF2015
Auteur: Van Middelkoop J.C. and Holshof G.
ISBN: 978-9090-289-61-8
Jaar van uitgifte: 2015
Producttype: Paper
In the Netherlands, initiatives are taken to process animal manure. In a pilot of manure processing a liquid fraction of pig slurry with mainly mineral nitrogen (N) and potassium (K) is produced. The liquid fraction is concentrated into mineral concentrate (MC). To determine the nitrogen fertilizer replacement value (NFRV) on grassland, field experiments took place on sand and clay. The N yields with MC, calcium ammonium nitrate (CAN) and liquid ammonium nitrate (LAN) were compared. The responses to MC and LAN were lower than expected, compared to CAN. This resulted in NFRVs for MC that varied between 44 and 82%, with CAN as a reference fertilizer. To consider the consequences at farm level, a farm is simulated. By replacing 80 kg N ha‑1 of CAN with 10 m3 ha‑1 of MC, the farm saves €4,864 for fertilizers but yield reduction is 12 Mg DM of grass silage, which equals €2,040. This indicates that the MC should cost €7.40 m-3 maximum to reach an equal income on the alternative farm compared with the reference farm. If the NFRV were to reach 100%, the MC should cost €12.80 m-3 maximum, the costs of the replaced mineral fertilizers N and K2O.