a analysis found similar substitution among agricultural outputs in spain custa etal this economic behavior has implications for choices in which surface water versus groundwater infrastructure could each be improved or restored for example irrigators will invest today in a water conserving land improvement like drip irrigation if net farm income increases by more than over time in present value terms if not irrigators will avoid making the investment a range of resource allocation management decisions faced by farm managers can be addressed by applying one or more of these budgeting economic principles