Developing legume shade trees for Sustainable coffee production in Puerto Rico
Coffee production in Puerto Rico is located in the central mountain region, mostly on acid, highly erodible soils. Many small and medium scale farmers have limited resources and use questionable practices. Long-term, sustainable coffee production using environmentally sound practices should include shade trees and, if possible, fast-growing, nitrogen fixing trees (FGNFT). In an effort to increase coffee production, sun grown coffee was promoted by the Agriculture Department. Unfortunately, this system of production requires high inputs and is environmentally damaging. To help coffee farmers, we will determine the best agroecological zone, evaluate legume trees species with potential for shade use, and determine management alternatives for high-quality, sustainable coffee production.
Objective 1. Survey present coffee production systems used by farmers in Puerto Rico
In spite of the initial delayed, during the past year the field work for this objective has been completed by Mr. Miguel Arango (MS student). Using the amount of coffee produced by municipality, the 20 highest coffee producing municipalities were selected for field sampling. Combing the number of farms with shaded coffee with the map of coffee production area, coffee growers were located and interviewed. Each farm was sampled (1,000 sq meters plots) up to 5 acres or 2 plots for larger farms. In each plot, tree species were identified, measured for diameter at breast high (DBH) and tree high estimated. Plots were georeferenciated with GPS, and located in a GIS map, to correlate with soil map and altitude. Climatic data, potential plant growth estimates and soil characteristics were combined to produce a coffee agro zoning map. Results were presented at two scientific meetings.
Objective 2. Evaluate the potential value of fast growing nitrogen fixing trees for the production of shade coffee.
As indicated in previous year report, the original list (42) of potential trees for testing (Nitrogen fixation ability) has been reduced, since it was impossible to obtain seeds from some rare species (see Accomplishments). Available species were evaluated in greenhouse experiments in two representative soils. Plant height and dry weight, nodule number and weight and nitrogenase activity (ARA) were measured. Data have been statistically analyzed and results are being compiled for a MS thesis defense (Mr. Manuel Santana).
Using the coffee farmer’s database compiled previously, field trips to all larger coffee producing municipalities and neighborhoods were taken. Over 110 farmers with shaded coffee have been sampled. Results indicate that more than 63 species (IVI, Index of Value Importance) with DBH> 10 cm are present. The predominant species found were Inga vera, Citrus sp., and Andira inermis, with 33.7%, 11.3% and 9.1% of IVI, respectively. The values for basal area (BA) were 36.5%, 5.8% and 7.0% in that order. The correlation between basal area and crown area (CA) was highly significant (r=0.48, P<0.0001). Clearly, coffee farmers select legume trees for shade and include a fruit species for additional income.
Data for climate (Puerto Rico Climate Center) and soils of Puerto Rico (USDA-NRCS) were obtained, digitized and prepared as excel data tables. A map with agroecozones for coffee production was developed by adding optimum ecological layers, soils and appropriate information using ArcGIS (v.9.1). The new map will substitute the present imprecise map of the coffee producing area, and could be used to give more incentives to farmers located in the best zone for coffee production. Management options for farmers (amount of shade, fertilization, tree species, etc) can also be deduced from this map.
The two most extensive soils from the coffee region (Los Guineos and Humatas series; Oxisol and Ultisol respectively) were selected for the greenhouse experiments. They have been analyzed and both are acid and poor in available N.
The greenhouse (6 kg of soil/pot) experiment with selected legume tree species was carried out with a reduced number of species. This objective faces some problems due to the lack of seeds, since:
1) We had to wait for seed production for many local species in order to obtain seed. For some species we have not been able to locate trees producing, or their fructifying period is unknown. To facilitate future work and seed collection, we are preparing tables with species location (GPS) and the period of flowering/seed production. Seeds from a few other species were obtained from ECHO (Florida).
2) Some species (mostly of the genus Inga), even when harvested in the most appropriate time, are recalcitrant and don’t germinate after 2 weeks in the best storage condition. Therefore, some of these species were included in the first, smaller experiment. For comparative purposes, seeds of Pithecellobium carbonarum (carbonero) where included as control, and were included in every planting date. This species that shows good shade characteristics was recorded as very susceptible to nematodes, at least in one soil.
The gas chromatograph (for the ARA analysis) purchased with the project funds has been installed in the laboratory (February 2006), and problems with software, column and gases were solved in time to measure ARA at the 6 months harvest. Alternatively, the species that were harvested earlier (recalcitrant seeds, genus Inga) were analyzed by Kjeldahl to estimate the amount of N fixed. The results have been analyzed and are the write-up stage. Therefore, we can estimate that to complete the project, an extension without additional funds will be required. A letter requesting extension was send on November 16th, 2006.
Left to do: Perform N balance study.
Impacts and Contributions/Outcomes
1. A WEB page about the project (link to SARE) is available in the INTERNET at:
A complementary web page in Spanish, more accessible for farmers and with more practical information was also recently prepared, and can be found at:
This page will be updated more frequently and include recent news and future activities.
2. Two graduate students initiated in January 2006 their MS studies and will conduct their thesis within the SARE LS04-162 PROJECT (Glenny López, from the Dominican Republic and Ixia A. Avilés from Puerto Rico). More recently, Feliciano Andujar (Dominican Republic), started his studies or an MS degree and will participate in the project by expanding the number of species tested for ARA and evaluate which soil factors limit biological nitrogen fixation.
3. Data and results from the project have been presented at:
a) CFCS (Caribbean Food Crops Society) Annual Meeting (San Juan, PR, July, 2006), and
b) Sigma Xi Scientific Society Poster Day. Mayagüez, April 26, 2007.
An exhibit about Sustainable coffee production and legume trees was displayed at the Agricultural students Agricultural Fair (5 Days with our Land, March, 2007).
Final arrangements have been made to hold the Sustainable Coffee Forum in May 30th, 2007 (as proposed in the grant). Dr. Jeff Jordan (SARE, Southern Region) has been invited to attend. Scientists, graduate students, extension agents, NCSU personnel and some coffee farmers will participate in this Forum. A publication with extended abstracts of the presentations will be produced.
During this project, probably up to 5 graduate students will obtain their M.S. degrees and trained in the production of sustainable coffee. The major project outcome will be:
1) Identification of the best area for growing coffee in Puerto Rico (ecozoning) and
2) Farmers and extension agents will be able to select the best tree species for each soil and altitude.
However, due to the slow initial start and some of the administrative and scientific problems, and to complete N balance studies and prepare publications, an additional extension of one year for the grant (with no additional funds) is necessary.
Agricultural Experiment Station
HC-01 Box 4508
Adjuntas, PR 00601-9717
Office Phone: 7878290012
Sustainable Agriculture Coordinator
University of Puerto Rico
Agricultural Extension Service
Department of Agricultural Economics
Mayagüez, PR 00681-9030
Office Phone: 7878324040
Agricultural Extension Service
University of Puerto Rico
PO Box 9030
Mayagüez, PR 00681
Office Phone: 7872654130