Farm gate level nitrogen balance and use efficiency changes post implementation of the EU Nitrates Directive

• Published in: Nutrient cycling in agroecosystems Vol. 104; no. 1; pp. 1 - 13
• Main Authors: Buckley, Cathal, Wall, David P, Moran, Brian, O’Neill, Stephen, Murphy, Paul N. C
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.01.2016; Springer Nature B.V
• Subjects: Agricultural production; Agriculture; Aquatic environment; Biomedical and Life Sciences; Climate change; climatic factors; Contact potentials; cost effectiveness; dairy farming; Dairy farms; Efficiency; European Union; extension education; Farms; Fertilizers; Land use; Life Sciences; Livestock; Longitudinal studies; milk; Nitrates; Nitrogen; Nitrogen balance; nitrogen fertilizers; nutrient use efficiency; Nutrients; Organic chemistry; Original Article; prices; Regulations; risk; Risk reduction; Stocking; stocking rate; Stocking rates; Nitrogen use efficiency; Farm gate balance; Nitrogen; Random effects panel data model
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1007/s10705-015-9753-y

Farm gate nitrogen (N) balance and use efficiency was estimated across 150 specialist Irish dairy farms over a 7 year period between 2006 and 2012 using nationally representative data. The study period coincided with the introduction of EU Nitrates Directive regulations aimed at minimising losses of N to the aquatic environment and results indicated that N balance declined by 25.1 kg ha⁻¹ from 180.4 to 155.3 kg ha⁻¹ over the study period. This decline can almost entirely be attributed to reduced chemical N fertiliser inputs of 23.1 kg ha⁻¹ over the period, equivalent to 1247 kg N, or a cost saving of €1347 per annum across the average dairy farm. Nitrogen use efficiency also increased by 2.1 % points over the period from 20.8 to 22.9 %. This was achieved while increasing milk solids output from 405.3 to 449.6 kg ha⁻¹ in the context of a declining stocking rate (1.86–1.84 livestock units ha⁻¹). These results suggest some positive impact of the regulations on N management on Irish dairy farms at the nutrient source end of the nutrient transfer continuum. This increased N management efficiency has a potential double dividend effect of increased returns to agricultural production while reducing the risk of N transfer to the aquatic environment. In addition to the introduction of the regulations, results of a random effects panel data model indicated that N balance and use efficiency are significantly influenced by factors such as fertiliser prices, stocking rates, land use potential, contact with extension services and climatic variables.