Investigating biological nitrification inhibition (BNI) mechanisms in perennial ryegrass *

Biological nitrification inhibition (BNI) has been observed in different perennial ryegrass (Lolium perenne) accessions including elite cultivars. Preliminary data indicate there are variations in the capacity of perennial ryegrass populations to inhibit nitrification and nitrous oxide emissions, with variations existing both between and within populations. The current research aimed to quantify the mechanisms influencing soil nitrate concentrations under different perennial ryegrass populations with high vs low BNI status. The primary objective was to distinguish between direct nitrification inhibition and indirect effects on other nitrogen transformation processes. After three months of growing contrasting perennial ryegrass plants (high vs low BNI status) in the glasshouse, 15N labelled fertilisers were applied and periodic soil and plant sampling occurred. Using 15N pool dilution technique, gross nitrogen fluxes were calculated and together with supporting soil parameters, the direct and indirect BNI effects were identified/quantified. The results of this experiment will be presented during this conference.

* Title in Abstracts book: Direct and indirect biological nitrification inhibition by perennial ryegrass