Selection and application of agri-environmental indicators to assess potential technologies for nutrient recovery in agriculture

The adverse effects of agriculture and livestock production on the environment are well-known and require
mitigation in order to achieve sustainability in the food production chain. This study focused on adverse effects
related to biogeochemical flows of phosphorus and nitrogen cycles which natural balances have been greatly
disturbed by current practices. To assess the potential benefits and detrimental effects of proposed mitigation
measures, adequate impact indicators are required. The challenge lies in identifying and providing indicators
that cover the important aspects of environmental sustainability and allow a direct comparison of policy alternatives.
A review of potential indicators that are also consistent with those used to indicate the performance of
agricultural and general sustainability (i.e. the European Green Deal) led to the selection of fifteen agrienvironmental
indicators covering the main environmental issues in agriculture. The indicators identified
offered an effective representation of environmental behaviour and would be useful in communicating a
comprehensive ‘dashboard’ for professional end users of solutions to nutrient recovery and nutrient efficiency
improvement in arable and livestock systems. The selected dashboard indicators (DBI) covered the dimensions of
‘use of primary resources’, ‘emissions to the environment’ and ‘resilience to climate change’. Five case studies
were investigated to test the DBI using an Excel questionnaire applying the qualitative approach of the Delphi
method together with expert knowledge. As expected, the results indicated that there were potential benefits of
the technologies in terms of improved ‘nutrient recovery’ and decreased ‘nitrate leaching’. Potential disadvantages
included increased electricity and oil consumption and greater ammonia volatilisation due to the increased
use of organic fertilisers. The indicator ‘water’ received more neutral responses; thus, the specific technology was
not expected to consistently affect the indicator. In relation to ‘particulate matter’, the results were indicated to
be ‘unknown’ for some solutions due to the difficulty of predicting this indicator. Furthermore, methodologies for
estimating quantitative values for the dashboard indicators were proposed, and a quantitative assessment was
performed for the solution ‘catch crops to recover nutrients’, confirming the responses in the qualitative
assessment. The dashboard indicators selected covered the main aspects of the solutions, identified in more
comprehensive studies of environmental impacts, as being suitable for the rapid assessment of technologies for
nutrient recovery in agriculture. As such, they can be used as a pre-screening m