Targeted Monitoring: Can We Monitor More Strategically to Enable Conservation Know-How,

Help Improve Models, and Inform Policy?

Mark Tomer

Why monitor at the field edge? (as opposed to watershed outlet)

Identify effectiveness of an individual conservation practice on runoff, nutrient and sediment losses.

Management system can be well documented.

Lag effects diminished. Spatial variability easier to characterize.

Why monitor at the field edge?

Identify effectiveness of an individual conservation practice on runoff, nutrient and sediment losses. (But compared to what?)

Management system can be well documented. (But many management actions are tactical adjustments to weather conditions.)

Lag effects diminished. (But not eliminated) Spatial variability easier to characterize.

(But temporal variability increases)

Why monitor at the field edge?

Edge of field monitoring is waiting (and waiting…) to measure and sample rapidly changing flows.

Long periods of monitoring are needed to help place into context impacts of large runoff events.

Yet, practices are proven through research on conservation effectiveness: Conservation Reserve plantings (P, sed, herbicides) Controlled drainage (NO3) Cover crops (NO3) Floodwater detention structures ($ flood damage) Livestock (whole farm) nutrient management (P) No tillage and strip tillage (P, sed, runoff) Nutrient removal wetlands (NO3) Perennial crops in rotation (runoff, sed, NO3) Riparian buffers (P, sed, herbicides) Split fertilizer applications (NO3) Two-stage drainage ditches (NO3) Wood chip bioreactors (NO3) Saturated buffers (NO3, P)

Effectiveness of Practices for Nitrogen Reduction-Results of Iowa Nutrient Reduction Strategy

Literature Review

Practice% Nitrate‐N Reduction [Average (Std. Dev.)]

Crop Rotation / Land Use

Cover Crops 31 (29)Perennial – Land retirement 85 (9)

Living Mulches 41 (16)Extended Rotations 42 (12)

Drainage Management

Controlled Drainage 33 (32)*Shallow Drainage 32 (15)*

Bioreactors 43 (21)

DownstreamWetlands 52 (flow dependent)Buffers 91 (20)**

*Load reduction not concentration reduction**Concentration reduction of that water interacts with active zone below the buffer

Where to from here?

Can we afford paired watershed experiments?

Are we still looking for the silver bullet? Can we shift focus to experimentally

evaluate performance of stacked practices?

The problems with experimental (paired watershed) design to assess conservation effects

1. Pretreatment calibration (2+ years)

2. Treatment evaluation (3+ years)

• Five years duration (minimum) • Requires two monitoring points to answer one question• How many fields are represented by this experiment?

Flow

Monitor inflow Monitor outflow

Evaluation of field edge practices (denitrifying bioreactor example)

• Three years duration (likely minimum) • Requires two monitoring points to answer one question• How many locations are appropriate for this practice?• How does in-field management impact EoF practice

performance?

An alternative experimental design(twice-paired watershed experiment)

1. Implement field edge practice and calibrate two fields (replicated

experiment, 2+ years)

2. Implement field practice evaluate two practices

(3+ years)

• Five years duration (but useful data within 2-3 years) • Requires four monitoring points but answers three questions• Can pair practices that represent regional opportunities

Distribution of Different Types of Watersheds Across the UMORB

Schilling et al, Environmental Management, 2015

Ho: Effectiveness of nutrient removal wetlands is influenced by cover crops

Ho: Effectiveness of denitrifying bioreactors is influenced by drainage water management

Ho: Effectiveness of saturated buffer is influenced by contour buffer strip placed to intercept runoff

An alternative experimental design(twice-paired watershed experiment)

1. Implement field edge practice and calibrate two fields (replicated

experiment, 2+ years)

2. Implement field practice evaluate two practices

(3+ years)

• Five years duration (but useful data within three years) • Requires four monitoring points but answers three questions• Can pair practices that represent regional opportunities

How to best use monitoring to assess practice performance, test models, and inform policy?

• Field-edge monitoring has improved understanding of conservation practice effectiveness, but has often given wide-ranging results (large error bars)

• Monitoring is both expensive, and difficult to do well. We should be asking how to best target monitoring efforts to better inform policy.

• Suites of practices may be suited to different types of landforms regions /watersheds –we can utilize this information to better target research on conservation effectiveness.

• Few studies have addressed the effectiveness of stacked practices. We may not reach WQ goals until we can leverage (and model) combinations of practices.

• A twice-paired watershed experimental design is proposed to address this knowledge gap. May inform reasons for variable performance of practices, and provide data to test models.

Thanks to:Sarah PorterDavid JamesDan Jaynes