In the context of agricultural soil management, we define resource use efficiency as the ratio between benefits generated by agricultural production processes and the amount of stressed resources used. Stressed resources are resources for which competing demands or resource use conflicts exist. This can be due to the fact that a resource is scarce (such as land, water or money) or because its use conflicts with other societal targets (such as pesticide application with biodiversity conservation).

Only the amount of stressed resources is considered in efficiency assessments (di Maio et al., 2017). As benefit, any quantifiable, positive characteristic of a product can be chosen. This choice exerts a strong influence on calculated efficiencies and often determines efficiency rankings between production alternatives. For example, if weight of harvested biomass is considered, growing strawberries is less efficient than growing ryegrass whereas the situation is reversed if the evaluation is based on gross profits. As resource, any of the resources used in the production process can be chosen. Here, the system boundaries must be clearly defined because substantial resource consumption can occur in pre- or post-processes related to the process under investigation. For example, if energy efficiency is assessed, it is relevant whether or not energy used in the production of inputs or machinery is considered. Finally, leakage effects, indirect land use changes and especially rebound effects should be accounted for (Lambin & Meyfroidt, 2011).

The resource use efficiency of agricultural soil management can be assessed by means of efficiency indicators, calculated as the ratio between the amount of benefit generated and the amount of resources used. What type of efficiency indicator is assessed, i.e. the selection of which benefits and which resource use are to be compared, should be based on the intended result of the agricultural management, its main inputs, and the characteristics of management alternatives. More than one efficiency indicator may be required for a comprehensive assessment or to show trade-offs between different types of efficiency.

Combining multiple benefits or resources
Agriculture is characterised by the production of multiple benefits such as food, feed, fibre or fuel while using multiple resources like land, water, energy and nutrients. It also generates profits, provides employment and creates habitats for plant and animal species while requiring capital and labour. For a comprehensive efficiency assessment, the appraisal of several benefits and resource uses is therefore essential. For this, assessments can either use multiple efficiency indicators, or apply a single indicator in which multiple benefits or resources are combined. 

The most common method to create combined indicators is to express all benefits or resources in monetary terms, based on their explicit or implicit market value. While practical, this approach is often criticised due to the difficulties of reflecting environmental and social consequences in monetary terms, and because values attributed to non-marketed goods vary strongly between assessments (Baveye, 2016). Alternative methods are often based on benchmarking.

While combined efficiency indicators allow for a quick overview and may facilitate monitoring and communication with stakeholders and policy makers, the selection and weighing of the included efficiency categories and the interpretation of the resulting indicators is challenging. In detailed impact assessment, the use of multiple efficiency indicators may be preferable because they make trade-offs between different efficiency categories directly visible whereas such relationships may be obscured in the values of combined indicators.

Please note: Efficiency assessments are well suited to assess performance of agricultural production within a limited number of categories. However, they are unable to provide a holistic view of ecosystem interactions. In this regard, assessment of ecosystem services provides a well suited complementary perspective.

• Baveye P C, Baveye J, Gowdy J (2016) Soil“ecosystem”services and natural capital: critical appraisal of research on uncertain ground. Frontiers in Environmental Science, 4, article 41. doi:10.3389/fenvs.2016.00041

•  Di Maio F, Rema PC, Baldé K, Polder M (2017) Measuring resource efficiency and circular economy: A market value approach. Resources, Conservation and Recycling, 122. 163–171. doi:10.1016/j.resconrec.2017.02.009

• Lambin EF, Meyfroidt P (2011) Global land use change, economic globalization, and the looming land scarcity. PNAS, 108 (9), 3465–3472. doi:10.1073/pnas.1100480108