Adverse Selection

refers to the concept of information asymmetry between principal (e.g. state) and agent (e.g. farmer) which can lower environmental effectiveness of schemes (see also moral hazard).
This could be the case when land managers find themselves unable to deliver the environmental goods they have contracted to deliver. A lack of knowledge can be resolved by advice and training programmes or peer-to-peer information exchange (Franks, 2011).

References

Franks, J.R., 2011. The collective provision of environmental goods: a discussion of contractual issues, Journal of Environmental Planning and Management, 54:5, 637-660. DOI: 10.1080/09640568.2010.526380

Agglomeration bonus

is an additional payment to the providers of ecosystem services (ES) if an environmental outcome has been achieved at a larger spatial scale (e.g., beyond the field/ farm scale, within a predefined region/landscape or watershed). It is useful if the outcome requires the coordination of actors (e.g., rewetting of landscapes). 

Agri-environment-climate measures (AECM)

are a funding mechanism aiming to provide financial support to farmers to contribute to the protection or enhancement of biodiversity, soil, water, landscape, or air quality, or climate change mitigation or adaptation. A bundle of measures or options usually makes up a scheme. In the European Union this is an important part of the second pillar of the Common Agricultural Policy and implemented via the Rural Development Programmes of individual member states or regions.