A further problem with the reliance on incentive payments under voluntary conservation measures to help reduce agricultural water pollution is they can become uncompetitive as crop prices rise. More specifically, the Chesapeake Bay Programme has up to now placed much less emphasis on outlining the costs associated with farmer adoption of different abatement practices at the scale required to have an impact (Roberts et al., Some 30% (2008-10) of US agricultural producer support is based on commodity output and non-constrained variable input use, although this is a marked reduction from a 50% share in 1986-88 (Figure 1.3).