1. Enabling the Flow of Ecosystem
Services from Agriculture to
Improve Puerto Rico’s Water Quality
and Mitigate Global Climate Change
Authors:
Dr. Luis Perez-Alegria, University of Puerto Rico
Dr. Jonathan Winsten, Winrock International
Dr. Neville Millar, Michigan State University
Mr. Fabian Carmona, University of Puerto Rico
Presenter: Dr. Kristin Fisher, Winrock International

2. 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).

3. Approach and Methods
Goal: 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.

5. 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)

6. Manual Chambers for N2O Measurement

7. 1
32
GHG chamber placement
Irrigation/fertigation line
Plantain row
Alley (between rows)
Plantain
GHG 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

8. Chambers used to capture
nitrous oxide flux.
• 9 chambers/treatment
Also Measuring:
• Soil nutrient levels
• Plant height and biomass
• Plantain yield

9. N2O Flux Results
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0 20 40 60 80 100 120 140 160
Control (BAU)
Slow release N
UPRM-AES
No additional N
kgN2O-Nha-1
Days After Planting

10. Lysimeters used to capture
root zone leachate.
• 2 lysimeters/treatment
Gutters used to capture surface
runoff
• 1 gutter/treatment
Ground Level

11. 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.

12. Preliminary NO3 Results

13. Nitrate leaching estimation procedure:
Soil moisture at any day after
planting:
𝑆𝑀𝑖+1 = 𝐼𝑅𝑖+1 + 𝑅𝑖+1 − 𝐸𝑇𝑐𝑖+1 − 𝑅𝑂𝑖+1 + 𝑆𝑀𝑖
Where:
𝑃𝑖+1 = 𝑆𝑀𝑖+1 − 𝐹𝐶
𝐸𝑇𝑐 = 𝐾𝑐 𝐸𝑇𝑜
𝑅𝑂 =
(𝑅 − 0.2𝑆)2
(𝑅 + 0.8𝑆)
𝑆 =
25400
𝐶𝑁
− 254
𝑃𝑡𝑛 =
𝑃𝑖𝑡 𝐶
100
𝑃𝑖+1 = 𝑃𝑒𝑟𝑐𝑜𝑙𝑎𝑡𝑒𝑑 𝑤𝑎𝑡𝑒𝑟 𝑑𝑒𝑝𝑡ℎ 𝑚𝑚
𝐼𝑅𝑖+1 = 𝑇𝑜𝑡𝑎𝑙 𝑖𝑟𝑟𝑖𝑔𝑎𝑡𝑖𝑜𝑛 𝑤𝑎𝑡𝑒𝑟 𝑜𝑛 𝑑𝑎𝑦 𝑖 + 1 (𝑚𝑚)
𝑅𝑖+1 = 𝑅𝑎𝑖𝑛𝑓𝑎𝑙𝑙 𝑑𝑒𝑝𝑡ℎ 𝑜𝑛 𝑑𝑎𝑦 𝑖 + 1 𝑚𝑚
𝐸𝑇𝑐𝑖+1 = 𝐸𝑇 𝑎𝑐𝑐𝑢𝑚𝑢𝑙𝑎𝑡𝑒𝑑 𝑑𝑢𝑟𝑖𝑛𝑔 𝑑𝑎𝑦 𝑖 + 1 𝑚𝑚
𝑅𝑂𝑖+1 = 𝑊𝑎𝑡𝑒𝑟 𝑙𝑜𝑠𝑠𝑒𝑠 𝑑𝑢𝑒 𝑡𝑜 𝑟𝑢𝑛𝑜𝑓𝑓 𝑜𝑛 𝑖 + 1 𝑚𝑚
𝑆𝑀𝑖 = 𝑆𝑜𝑖𝑙 𝑤𝑎𝑡𝑒𝑟 𝑐𝑜𝑛𝑡𝑒𝑛𝑡 𝑜𝑛 𝑑𝑎𝑦 𝑖 𝑚𝑚
𝐾𝑐 = 𝐶𝑟𝑜𝑝 𝑐𝑜𝑒𝑓𝑖𝑐𝑖𝑒𝑛𝑡
𝐸𝑇0 = 𝑅𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝐸𝑇 𝑏𝑦 𝑃𝑒𝑛𝑚𝑎𝑛 − 𝑀𝑜𝑛𝑡𝑒𝑖𝑡ℎ 𝑚𝑚
𝑆 = 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝑝𝑜𝑡𝑒𝑛𝑡𝑖𝑎𝑙 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛
rainfall and runoff at the moment of rainfall
initiation (mm)
𝑃𝑖𝑡 = 𝑊𝑎𝑡𝑒𝑟 𝑑𝑒𝑝𝑡ℎ 𝑝𝑒𝑟𝑐𝑜𝑙𝑎𝑡𝑒𝑑 𝑚𝑚
𝑃𝑡𝑛 = 𝑇𝑜𝑡𝑎𝑙 𝑛𝑖𝑡𝑟𝑎𝑡𝑒 𝑚𝑎𝑠𝑠 𝑙𝑜𝑠𝑠
𝑘𝑔
ℎ𝑎
𝐶 = 𝑁𝑖𝑡𝑟𝑎𝑡𝑒 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑠𝑜𝑖𝑙 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛
𝑚𝑔
𝐿
𝐶𝑁 = 𝐶𝑢𝑟𝑣𝑒 𝑛𝑢𝑚𝑏𝑒𝑟, 𝑆𝐶𝑆 1972
Source: Paulino-Paulino et al. (2008). JAUPR. 92 (3-
4):135-152

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

15. 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

16. 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.

17. 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.