Benchmarking Farm-Gate Nitrogen and Phosphorus Balances and Use Efficiencies of Nationally Representative Beef and Dairy Farms in Ireland to Encourage Improvements.

Agriculture faces considerable challenges of achieving sustainable intensification whilst also minimising nitrogen (N) and phosphorus (P) losses and meeting international obligations for water quality and greenhouse gas emissions. Reducing nutrient balance (NB) surpluses, and increasing nutrient use efficiencies (NUE), are critical in reducing diffuse pollution and improving farm profitability (a win-win). To set targets and motivate improvements in Ireland, nationally representative benchmarks were established. Annual farm-gate NBs (kg ha^-1) and NUEs (%) for N and P were calculated for 1215 nationally representative beef and dairy farms from 2008-2015 using import (fertiliser, forage, concentrates, livestock) and export (milk, wool, crops, livestock) data collected by the Teagasc National Farm Survey (part of the EU Farm Accountancy Data Network). Benchmarks for each farm category (sector, production intensity and soil type) were established by first identifying the farms with the lowest NB surplus per production intensity (total N or P exports ha^-1), using quantile regression analysis (75^th and 90^th percentile regression lines). By colour coding data points according to NUE (%) and gross margin (€ ha^-1) percentile rankings, optimal benchmark zones were identified which also identify those benchmark farms with the highest NUE and highest gross margins. Differences in farm characteristics and balance components between benchmark and poor performing farms were then investigated to explain nutrient management performance. Agricultural intensification (higher total exports) is likely to increase nutrient surpluses, use efficiencies and gross margins, but benchmark farms can minimise surpluses to relatively low levels. Results provide the foundation for a national benchmarking tool that allows comparisons of a farm’s performance and sets farm-specific benchmark targets. They also allow maximum and minimum permitted surplus standards (specific to sector and production intensity) to be set by policymakers using regression lines to encourage sustainable nutrient management.