Weed management alternatives for organic coffee agroforestry systems of Puerto Rico

Weed management alternatives for organic coffee agroforestry systems of Puerto Rico

Summary

A comparison of different organic weed management practices in organic coffee agroforestry systems (CAFS) is providing insight into the effectiveness of organic weed management practices at both suppressing weeds and conserving the natural resource base of coffee farms. The weed management practices being evaluated are mechanical control, use of cover crops and natural herbicide. Weed suppression, coffee production, labor time and provision of ecosystem services (i.e. soil conservation, natural pest control and nematode diversity conservation) are being examined. Farmers’ perceptions of different organic weed management practices are being assessed through visits to experimental sites, surveys, interviews and workshops.

Objectives/Performance Targets

1) Evaluate the effectiveness of different organic weed management practices in established organic coffee agroforestry systems (CAFS) and coffee farms transitioning to organic CAFS.
2) Determine the effect of different organic weed management practices on labor time and coffee production.
3) Determine the effect of different organic weed management practices on the ecosystem service of soil conservation.
4) Determine the effect of different organic weed management practices on the ecosystem service of natural pest control.
5) Determine the effect of different organic weed management practices on the ecosystem service of soil nematode diversity conservation.
6) Evaluate farmers’ perceptions of different organic weed management practices.
7) Develop guidelines for weed management in organic coffee farms.

Accomplishments/Milestones

Project accomplishments for each project objective are presented below.

A. Activities completed by December 2011
1) Establishment and maintenance of experimental plots in Utuado and Orocovis.

2) Monthly weed management treatment application/maintenance in Utuado site, and bimonthly weed management treatment application/maintenance in Orocovis.
At the Orocovis site, the Heterotis rotundifolia cover crop was not evaluated, as the farm owner had concerns over the plant becoming a weed.

3) Monthly weed biomass data collection in Utuado site.
Preliminary observations suggest that the two cover crop treatments (Arachis pintoi and Heterotis rotundifolia) reduced noxious weed biomass more than the trimmer, herbicide and control treatments.

4) Bimonthly weed biomass data collection in Orocovis site.
Preliminary observations suggest that noxious weed biomass does not differ between weed management treatments. The Orocovis study site is an established organic coffee agroforestry system (i.e. with shade trees), and has less noxious weed biomass than the Utuado site.

B. Activities to be completed after December 2011
1) Continue weed biomass data collection.
2) Conduct statistical analyses.
3) Taxonomic identification of weed species present in experimental plots.
4) Repetition of experiment during the dry season of 2012.
5) Characterization of Utuado and Orocovis agroforestry systems.
6) Presentation of results at local and national congresses.
7) Manuscript preparation of experiment results.

A. Activities completed by December 2011
1) Monthly labor time data collection in Utuado site.
Preliminary observations suggest that labor time is higher for the two cover crop treatments (Arachis pintoi and Heterotis rotundifolia) during the first four months (during cover crop establishment) of the experiment, but after this period, it does not differ from trimmer or herbicide treatments.

2) Bimonthly labor time data collection in Orocovis site.
Preliminary observations suggest that labor time is higher for the cover crop treatment, during the first month of the experiment, but after this period, it does not differ from machete or herbicide treatments.

3) Brix data collection in Utuado and Orocovis sites.

B. Activities to be completed after December 2011
1) Continue labor and brix data collection.
2) Conduct statistical analyses.
3) Coffee production data collection (if there is coffee production in experimental plots).

A. Activities completed by December 2011
1) Pre-treatment soil sampling to create baseline data of soil nutrients and basic soil characterization.
Bulk density, soil water content, pH, organic matter and general nutrient status were evaluated for each experimental plot. Bulk density at the 0-5cm depth averaged 1.24 g/cm3 for Utuado site and 0.76g/cm3 for Orocovis site. Bulk density at the 5-15cm depth averaged 1.45 g/cm3 for Utuado and 1.14g/cm3f or Orocovis site. Overall soil volumetric water content (cm3/cm3) averaged 0.42 for Utuado site and 0.48 for Orocovis site.Soil pH at the 0-5 cm depth averaged 5.3 for Utuado site and 4.9 for Orocovis site. At the 5-15 cm depth, soil pH averaged 4.7 for Utuado and 4.9 for Orocovis site.Soil organic matter at the 0-5 cm depth averaged 2.6% for Utuado site and 4.5% for Orocovis site. At the 5-15 cm depth, soil organic matter averaged 1.4% for UPRU and 2.8% for Orocovis site.

2) Establish a trap channel and sediment collector at the bottom of each experimental plot to measure runoff and eroded soil.

3) Rainfall, soil eroded and runoff data collection.

B. Activities to be completed after December 2011
1) Continue rainfall, soil eroded and runoff data collection.
2) Conduct statistical analyses.

A. Activities completed by December 2011
1) Bimonthly predatory arthropods sampling.

2) Bimonthly coffee berry borer and coffee leaf miner sampling.
Preliminary observations suggest that coffee berry borer and coffee leaf miner abundances do not differ between weed management treatments at the Utuado site. Coffee leaf miner damage was not observed at the Orocovis site. Also, few coffee berry borers have been collected at the Orocovis study site.

B. Activities to be completed after December 2011
1) Taxonomic identification of all predatory arthropods collected.
2) Conduct statistical analyses.

A. Activities completed by December 2011
1) Pre-treatment soil nematode sampling.

2) Taxonomic identification of nematode genera collected.
A total of 18 soil nematode genera have been identified from Utuado samples, and a total of 14 genera from Orocovis samples.

B. Activities to be completed after December 2011
1) Continue taxonomic identification of nematode genera collected.
2) Post-treatment soil nematode data collection.
3) Pre and post-treatment soil nematode data collection for second experiment.
4) Conduct statistical analyses.

A. Activities completed by December 2011
1) Development of pre-workshop surveys for farmers and agriculture students.
Pre-workshop surveys ask farmers and students to rate: their level of knowledge regarding soil, weed and pest management strategies; their level of agreement on several statements associated with soil, weed and pest management; and the soil, weed and pest management strategies they currently use. Three survey techniques (self rated knowledge, agreement with statements, and usage questions) were used to reduce the effect of any tendencies participants may have had to answer questions in ways that they thought were socially acceptable or that represented what the project team members were looking for.

2) Facilitate farmer and agriculture student workshops on organic coffee farming and organic coffee weed and pest management (including guided visits to experimental areas).

3) Provide pre-workshop surveys to workshop participants.
Twenty-one students and twenty-eight farmers filled out the pre-test during the fall of 2011. Students were 62.5% (10) male and 37.5%(6) female. Gender data was missing on five students. Their ages ranged from 17 to 45, with the mean age being 22 and the median 20. Farmers were 64% (16) male and 36% (9) female. Gender data was missing on one farmer. Farmer ages ranged from 17 to 63, with mean age being 40 and the median 41.

4) Pre-workshop survey preliminary data analyses.
The current sample of participants is small in nature, which prevented an analysis of statistical significance. The sample size will increase in time, which will allow these analyses to take place. Otherwise, the project evaluator may then employ the use of certain nonparametric statistical tests.

5) Interview organic coffee farmers in Puerto Rico about their current weed management practices.

B. Activities to be completed after December 2011
1) Continue to facilitate farmer and student workshops on organic coffee farming and organic coffee weed and pest management (including guided visits to experimental areas).
2) Continue to provide pre-workshop surveys to workshop participants.
3) Provide post-workshop surveys to workshop participants (after a year).
4) Continue to interview organic coffee farmers in Puerto Rico about their current weed management practices.
5) Facilitate project results workshops (including group SWOT Analysis).
6) Conduct Statistical Analyses.

A. Activities to be completed after December 2011
1) Development of organic weed management manual.
2) Distribution of manual to workshop participants and interest groups.
3) Visit to farms of farmers who received the manual, and evaluation of weed management practices used by these farmers.
4) Final project evaluation.

Impacts and Contributions/Outcomes

The project has benefited producers/consumers in the Southern Region through changes in knowledge, actions and conditions.

A. Changes in knowledge
1) Increased knowledge of ecosystem services and practices that conserve them in farms.
2) Increased knowledge of organic weed (and pest) management practices.
3) Increased knowledge of organic coffee farming.
4) Increased knowledge of organic agriculture in general.

B. Changes in actions
1) Farmers consider several factors (e.g. ecological and financial) when deciding which weed (and pest) management practices to use.
2) Coffee farmers consider organic production as a viable alternative.
3) Organic and transitioning coffee farmers have more weed management alternatives to choose from.

C. Changes in conditions
1) Organic coffee farms provide more ecosystem services.
2) A higher number of farmers start producing organic coffee.

Collaborators: