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What have we learned about building science assessments for state-level nutrient reduction strategies?. Jane Frankenberger Purdue University. Goal: Provide a science base that informs but does not provide the policy.
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What have we learned about building science assessments for state-level nutrient reduction strategies? Jane Frankenberger Purdue University
Goal: Provide a science base that informs but does not provide the policy • Opportunity for agreement -- Even people with widely divergent views can agree on numbers drawn from the literature.
Broad idea of what an assessment might include • Estimate baseline condition • Identify practices that have high benefits • Assess load reductions possible • Create plausible scenarios and assess benefits
Who might be involved • University and ARS researchers • State Department of Agriculture scientists • State regulatory agency scientists • NRCS, Agricultural organizations, Environmental groups • Even if some have an agenda, assessment based on published research only.
Enough research has been conducted on conservation practice effects to develop a reasonable assessment • Sometimes we focus on the gaps more than what is known. • (We will always need to polish the hubcaps, but can we focus on the engine in the driveway?)
A list exists of the limited number of practices for which there is solid evidence of N or P reduction. • If others should be added to the list, evidence needs to be provided. • If the effect should be assumed to be somehow different within a system of practices, evidence should be provided.
(If there was any doubt….) Practices to reduce nitrogen and phosphorus are very different, due to different transport pathways • Let’s move away from lumping them as “nutrients”. It confuses. • To address nitrogen, we need to focus on the flow through tile drains. • The practices are not as effective as we wish they were at reducing nitrate (Table 1, page 5) except for changing land use.
daunting, but not impossible The task is daunting.Example scenarios: • All fertilizer applied at MRTN Rate • 60% of corn/soybean has cover crops • 27% treated with wetland • 60% of drained land has bioreactor 42% N reduction; 30% P reduction • All fertilizer applied at MRTN Rate • 95% of corn/soybean has cover crops • 34% in two MLRAs treated with wetland • 5% land retirement 42% N reduction; 50% P reduction
How to aggregate loadings and effects? • Major Land Resource Areas • Ecoregion (Level 3 or 4) • HUC 6 or 8 • Soil parent material, or drainage class?
What data/evidence to use in estimating reductions? • Only monitoring data? • Only our state and surrounding states? • Peer-reviewed literature only?
Could baseline come from existing assessments? • Use the Iowa or Minnesota assessment, just changing numbers? • Use SPARROW? • Other?
Have the excellent presentations and studies shown put to rest the myths raised by Mark David in opening presentation? • a few (bad) actors are the problem • just targeting a few fields will solve most of the problem • A single type of practice or system of practices (edge of field denitrification, no-till, soil health) can solve the problem • the response will take a long time (decades?)
“We know what to do” - Dr. Mark David, opening presentation • A state-level nutrient reduction strategy can: • Clarify what it is that we know. • Expand the “we” in “we know”. • Provide a broadly-agreed-on foundation for a nutrient reduction strategy that will be developed in our states.