Enabling the Flow of Ecosystem Services from Agriculture toImprove Puerto Rico’s Water Quality and Mitigate Global Climate ChangeAuthors:

Dr. Luis Perez-Alegria, University of Puerto RicoDr. Jonathan Winsten, Winrock InternationalDr. Neville Millar, Michigan State UniversityMr. Fabian Carmona, University of Puerto RicoPresenter: Dr. Kristin Fisher, Winrock International

Background• Plantain/banana is #1 crop in Puerto Rico by acres (>25% of

cropland) and annual revenue ($80.5 million).• Plantain/banana is a very important crop throughout the tropics

and grown on an estimated 10.5 million hectares.• Very limited information available on environmental impact or

ways to lessen impact.• Agriculture is the leading source NPS pollution to ground and

surface waters in the U.S.• N2O is only 6% of U.S. GHG emissions, but 79% is from

agriculture.• Nitrous oxide (N2O) has 298 times the radiative forcing of carbon

dioxide (CO2).

Approach and MethodsGoal: Lay foundation for farmers to produce ecosystem services (water quality and/or GHG mitigation).• Working with large commercial farm on south central coast

(intensive ag area).• Taking field measurements of N2O, NO3, plant growth, and yields

from 3 treatments plus control.• Data used for cal/val of APEX model (via Nutrient Tracking Tool). • Calibrated NTT model will be available to estimate nutrient and

GHG losses in Puerto Rico.

Experimental Treatments• Control: Business as usual for farm (640 kgs N ha-1). • Treatment 1: Control release fertilizer (640 kgs N/ha-1)• Treatment 2: UPR Ag Experiment Station N rate

recommendation for plantain (241 kgs N/ha-1)• Treatment 3: No N applied (to understand lower bound)

Manual Chambers for N2O Measurement

1

32

GHG chamber placement

Irrigation/fertigation linePlantain rowAlley (between rows)PlantainGHG chamber

• 3 x chamber per ‘site’• 3 x ‘sites’ per treatment• 4 treatments (control + 3

treatments)• 1 background chamber per

treatment• 40 chambers used per sample

day• 4 samples pulled per chamber

‘Top’ view

Chambers used to capture nitrous oxide flux.• 9 chambers/treatment

Also Measuring:• Soil nutrient levels• Plant height and biomass• Plantain yield

N2O Flux Results

0 20 40 60 80 100 120 140 1600.0

1.0

2.0

3.0

4.0

5.0

6.0

Control (BAU)Slow release NUPRM-AESNo additional N

kg N

2O-N

ha-1

Days After Planting

Lysimeters used to capture root zone leachate.• 2 lysimeters/treatment

Gutters used to capture surface runoff• 1 gutter/treatment

Ground Level

Nitrogen Loss and Nitrogen Use Efficiency

• Measuring concentrations of N in lysimeters and surface traps to estimate total losses.

• Measuring residual N in soil and N content of plant biomass.

• Will calculate nitrogen use efficiency as contribution to literature.

Preliminary NO3 Results

Nitrate leaching estimation procedure: Soil moisture at any day after planting:

Where: rainfall and runoff at the moment of rainfall initiation (mm)

Source: Paulino-Paulino et al. (2008). JAUPR. 92 (3-4):135-152

Preliminary Yield Results• Wind damage affected harvest and yield measurement.

Next Steps• Field measurement results being used to cal/val NTT

model.• NTT model will be used to estimate potential

reductions across Puerto Rico. • Identify areas for greatest reductions

• Calculate full economic costs and estimate C offset supply curve

Preliminary Conclusions• Significantly reduced N2O flux from reduced N rates.• Impact on yield is still to be determined; observations

showed yields to be similar across treatments.

Further Research and Extension• Develop peer-reviewed GHG emission reduction factor

(scale) for plantain/banana based on N rate.• Work with American Carbon Registry to publish offset

methodology for “stacked” credits.• Education and outreach to plantain producers on

participation in environmental markets.