4R Phosphorus Management for Sustainable Crop...

4R Phosphorus Management

for Sustainable Crop Nutrition

Heidi Peterson

Phosphorus Program Director

Stillwater, Minnesota

hpeterson@ipni.net

MVTL 2018 Agronomy Update

New Ulm, MN

February 1, 2018

The International

Plant Nutrition

Institute is

supported by leading

fertilizer

manufacturers.

Its mission is to

develop and promote

science for

responsible

management of crop

nutrition.

Nutrient Stewardship Metrics for

Sustainable Crop Nutrition

Enablers(process metrics)

Actions(adoption metrics)

Outcomes(impact metrics)

• Extension & professionals

• Infrastructure

• Research & innovation

• Stakeholder engagement

Cropland • area under 4R [Requires regional definitions of 4R practices]

1. Farmland productivity

2. Soil health

3. Nutrient use efficiency

4. Water quality

5. Air quality

6. Greenhouse gases

7. Food & nutrition security

8. Biodiversity

9. Economic value

P is an Essential Fertilizer Ingredient

• Involved in photosynthesis, energy transfer, cell division and

enlargement

• Important in root formation and growth

• Improves the quality of fruit and vegetable crops

• Is vital to seed formation

• Improves water use

• Helps hasten maturity

P deficient corn

P Consumption

• P taken up by crops primarily as orthophosphate

(H2PO4- and HPO4

2-)

• U.S. annual consumption ~1.86 million tonnes P (IFA, 2015)

• Worldwide annual consumption ~20.3 million tonnes P (IFA, 2015)

DAP

Phosphate Rock Reserves

and Resources

• PR is a finite natural resource

• Reserves are generally defined as materials that can be

economically produced at the present time using

existing technology

• Resources include reserves and any other materials of

interest that are not reserves

• Some have predicted that we are nearing “peak

production” and that a scarcity of PR is looming

Phosphorus Fertilizer and the Soil

Common commercial P fertilizers are highly (• ≥90%) water

soluble

Once dissolved in soils, orthophosphate is available for •

plant uptake

P • chemistry in soils is complex ̶ P may become

sparingly available to plants in some soils due to

formation of less soluble products

Phosphorus Fertilizer Placement

• P fertilizer may be broadcast on the soil surface (liquid

or dry) or it can be placed in a concentrated band

• There may be advantages to banding, including

– Early crop growth enhancement

– Concentration of P to minimize soil contact and reaction

– Placement in the root zone

Why Focus on P?

Eutrophication • ̶ the natural

aging of lakes or streams by

nutrient enrichment

Nutrient additions can •

accelerate the process

P is often the limiting element•

Dissolved oxygen is depleted by •

excessive plant growth

Best management practices •

(BMPs) can help minimize P

runoff from fields

C+N Added

C+N+P Added

(blue-green algae)

University of Manitoba

Total P Load to Gulf of Mexico

Graph from the HTF 2017 Report to Congress

2035

2025

13% above

baseline

Ortho P Flux to Gulf of Mexico

Graph from the HTF 2017 Report to Congress

22% above

baseline

Ru

no

ff s

olu

ble

P, u

g/L

Soil box studies Field studies

Mehlich 3 or Bray-1 Soil P (mg kg-1)

Source: Vadas et al., 2005

(10-40% clay)

Soil P versus Runoff P

Soil Test P

Critical level is the soil test level where recommended nutrient rates

generally drop to zero in sufficiency approaches or to a crop removal level

in build maintenance approaches.

http://soiltest.ipni.net/charts/distribution

http://soiltest.ipni.net/charts/distribution

Soil Test P Distribution in Minnesota

47% below

Critical Level

14%

Phosphorus Use Efficiency (PUE)

Partial Nutrient Balance

Crop PUE = crop P removal

fertilizer P + manure P

applied

If PUE > 1: Soil P decreases = Crop mining P from soil

If PUE < 1: Soil P increases = P Storage

Photo Credit: Guentzel

IPNI’s NuGIS Database

http://nugis.ipni.net/map/

P Use Efficiency: Ratio of P Removal to Use

2012

4R Research Fund

Right Place: Tile Drains

and Fertilizer Placement

Compared preferential flow and P leachate concentrations

in:

• No-Tilled vs Tilled Fields

• Surface Broadcast vs Injected vs Incorporated P Fertilizer

Right Place: Tile Drains

and Fertilizer Placement Site Description:

NW Ohio • – Maumee River Watershed

Flat (<• 1% slope), Poorly Drained SL/SiCL Soils

Corn/Soybean or Corn/Soybean/Wheat Rotation•

Tile Description:

2.5 • - 3 ft depth

35• - 45 ft spacing

Right Place: Tile Drains

and Fertilizer Placement Fertilizer Application

Source: Monoammonium Phosphate (MAP; 11-52-0)

Rate: 67 lbs P/acre

Placement:

• Broadcasted (no-tillage)

• Incorporation via Tillage (8-10 cm)

• Incorporation via Injection (10 cm)

Timing: October 2016 after Harvest

Instrumentation

• Rainfall simulations conducted after fertilizer application

• Pan lysimeters installed to measure leachate

• Plot borders installed to collect surface runoff

Right Place: Tile Drains

and Fertilizer Placement

Leachate Concentration

• Mean Dissolved Reactive P (DRP)

concentration was significantly

greater for broadcast treatment.

• Mean Particulate P (PP) in

concentration was significantly

greater for broadcast treatment.

Right Place: Tile Drains

and Fertilizer Placement

Tillage did not significantly influence event water transport.•

Disruption of – macropore network not likely primary mechanism

responsible for decreased leachate P concentrations.

Differences in soil• -fertilizer-water contact, soil P sorption

capacity, and proximal P availability were the primary

factors resulting in P leaching reductions in injected and

tilled soils.

Subsurface injection of fertilizer in fine• -textured soils may

limit dissolved P leaching and minimize surface disturbance.

4R Research Fund

How will cover crops and fertilizer

management impact P loss, P use efficiency,

crop yield, and net return?

• How much does fertilizer

placement affect P loss?

(when at the right time)

• Will cover crops reduce P

loss in no-till?

• Will cover crops reduce P

loss from surface-broadcast

fertilizer?

Slide modified from Nathan Nelson, KSU.

Data from 2016 and 2017

• No-till corn-soybean rotation

• P treatments

– 0 lb P2O5/ac

– 55 lb P2O5 fall broadcast

– 55 lb P2O5 2x2 at planting

• Cover crop

– no cover crop

– winter wheat cover (2016)

– triticale & rapeseed (2017)

Slide modified from Nathan Nelson, KSU.

http://www.k-state.edu/kaw/News.html

Slide modified from Nathan Nelson, KSU.

Slide modified from Nathan Nelson, KSU.

Water Quality

Runoff•

Sediment•

Total P•

Dissolved P•

Farmland Productivity

• Yield

• Costs

• Net returns

Outcome Metrics

Slide modified from Nathan Nelson, KSU.

Cover Crop Effects on Sediment & P Loss

Decreased Erosion

~70%

Slide modified from Nathan Nelson, KSU.

Project is ongoing.

Cover Crop Effects on Form of P Loss

Decreased Particulate P

~40%

Slide modified from Nathan Nelson, KSU.

Increased Dissolved P

~65%

Project is ongoing.

Fertilizer Management Effects on P Loss

Project is ongoing.

Slide modified from Nathan Nelson, KSU.

Decreased Total P

~30%

Decreased Dissolved P

~45%

4R Efficacy for Reducing P Loss

Wide range of efficacies demands more site• -specific focus

Trade• -off between dissolved and particulate is important

Practice Dissolved P Particulate P

% Reduction

Source --- ---

Rate 60 to 88% negligible

Time 41 to 42% negligible

Place 20 to 98% -60% to NS

Soil inversion NS to 92% -59% to NS

Conservation tillage -308 to -40% -33 to 96%

Ranges found in field experiments across the USA and Canada

Dodd & Sharpley, 2015. Nutrient Cycling in Agroecosystems.

4R Phosphorus Management

Regions and Cropping Systems

2011 National Land Cover Database - http://www.mrlc.gov

2

6

5

4

3

1

Western 1.

Corn and

Soybean

Eastern 2.

Cereals and

Oilseeds

Wheat in the 3.

Great Plains

Irrigated 4.

Potatoes in

the

Northwest

Rice 5.

Irrigated 6.

vegetables

4R Phosphorus Practices for Western

Crops (including Minnesota & Iowa)• Basic

– Source: known or guaranteed analysis

– Rate: recommended soil sampling and soil test interpretation

– Timing: avoid frozen and snow-covered soils, forecast rainfall

– Placement: subsurface band encouraged; on surface only for no-

till when risk index is low

• Intermediate

– Source: manure nutrient analysis

– Rate: as in basic, plus: P index used

– Timing: as in basic, & use P Index and avoid seasonal rainfall

intensity

– Placement: as in basic, plus avoid furrows of furrow-irrigated

crops

4R Phosphorus Practices for Western

Crops (including Minnesota & Iowa)• Advanced

– Source: as in intermediate

– Rate: as in intermediate, plus: zone-specific based on soil

sampling every 2 years, and crop yield maps

– Timing: as in intermediate

– Placement: as in intermediate, plus: terrain analysis to manage P

loss

ADAPTIVE MANAGEMENT

– Decisions are site-specific and adaptive to changing conditions.

Not everything can be written down.

4R Certification

Iowa Consortium

Lake Erie Certification

Summary

• Losses of P, small relative to inputs and outputs, impact

water quality.

• Site-specific 4R phosphorus practices limit dissolved

losses and need to be synergized with conservation

practices controlling particulate losses.

• Quantification of practice impacts on P losses is

important to enabling sustainability investment decisions.

Heidi Peterson

Phosphorus Program Director

Stillwater, Minnesota

hpeterson@ipni.net

www.ipni.net

Thank you!

Photo Credit: Guentzel