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 resources of coffee farms. Although it required more labor time, the use of cover crops was more effective in suppressing weeds than mechanical and natural herbicide treatments. The provision of ecosystem services (i.e. soil conservation, natural pest control and nematode diversity conservation) did not differ between organic weed management treatments. Most farmers surveyed had positive opinions of the cover crops evaluated.

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 during the reporting period are presented below.

I. Objectives 1 and 2

A. Activities completed from January 2013-December 2013

1) Results were presented at a workshop for farmers held on April 19, 2013 at UPR-Utuado. Also, results were presented at the International Congress of Agroecology on September 10, 2013 held in Lima, Perú.

2) Results and resulting recommendations were included in the manual of organic weed management in coffee agroecosystems.

B. Activities to be completed from January 2014-August 2014

1) Presentation of results at local and national congresses.

2) Manuscript preparation of experiment results.

3) Submit manuscript to peer-reviewed journal.

II. Objective 3. Determine the effect of different organic weed management practices on the ecosystem service of soil conservation.

A. Activities completed from January 2013-December 2013

1) Erosion measurements UPR-Utuado site

       In this report, we present summarized results for the data collected from February 2012 to February 2013.  This period represent the entire data collection period for the erosion measurements. Overall soil erosion for the treatments was: 0.026 g/m2/day for the control, 0.013 g/m2/day for the organic herbicide, 0.044 g/m2/day for the mechanical (trimmer), 0.017g/m2/day for the cover crop A. pintoi and 0.061 g/m2/day for the cover crop Heterotis rotundifolia.  Repeated measures ANOVA on soil eroded data showed no treatment effect (p = 0.06) and no time effect (p = 0.20) at the UPR-Utuado site.  No consistent pattern was found in soil eroded with time. However, our data showed a trend that A. pintoi and herbicide treatments had lower soil eroded values throughout the year measured, however control, mechanical and H. rotundifolia treatments showed more variability with time.

2) Water runoff measurements UPR-Utuado site

We present summarized results the data collected from February 2012 to February 2013.  This period represent the entire data collection period for the runoff measurements. Overall water runoff for the treatments was: 156 ml/m2/day for the control, 165 ml/m2/day for the organic herbicide, 160 ml/m2/day for the mechanical (trimmer), 135ml/m2/day for the cover crop A.pintoi and 195 ml/m2/day for the cover crop Heterotis rotundifolia.  Preliminary statistical analysis using repeated measures ANOVA on water runoff data showed treatment effect (p = 0.04) and significant time effect (p < 0.001).The A. pintoi treatment showed lower measurements of water runoff than the rest of the treatments.  In addition, water runoff followed changes in precipitation corresponding with high or low precipitation seasons.

3) Soil erosion results were presented at the workshop for farmers celebrated on April 19, 2013.

4) Recommendations of management practices to reduce soil erosion were included in the manual of organic weed management in coffee agroecosystems.

B. Activities to be completed from January 2014-August 2014

1) Finish statistical data analysis for runoff and soil nutrients for the UPR-Utuado site.

III. Objective 3. Determine the effect of different organic weed management practices on the ecosystem service of natural pest control.

A. Activities completed from January 2013-December 2013

1) The taxonomic identification of predatory arthropods collected is still in progress.

B. Activities to be completed from January 2014-August 2014

1) Continue the taxonomic identification of all predatory arthropods collected.

2) Conduct statistical analyses considering the abundance of all predatory arthropod species collected.

IV. Objective 5. Determine the effect of different organic weed management practices on the ecosystem service of soil nematode diversity conservation.

A. Activities completed from January 2013-December 2013

1) Finish nematode sampling and identification

A total of 28 soil nematode genera were present at the UPR-Utuado site, and a total of 34 genera at the Orocovis site.The community of nematodes at both experimental sites was dominated by plant feeders. No significant differences were observed in total abundance, nor in species richness of nematodes among weed management treatments in Utuado (p= 0.3940; 0.5759) or Orocovis (p=0.8682; 0.9900). However, the abundance of omnivore nematodes was higher in the cover crop Heterotis rotundifolia treatment at the UPR-Utuado site. In addition, Principal Components Analyses showed an association of omnivore nematode genera to the H. rotundifolia treatment.

2) The Young Scholar Enhancement Grant recipient, Nydia Mejías, actively participated in the completion of this project objective.

3) Nematode results were presented at the Organization of Nematologists of Tropical America (ONTA) Congress on October 22, 2013 held on La Serena, Chile.

4) Nematode results were presented at the workshop for farmers celebrated on April 19, 2013.

5) Nematode results were included in the video of organic weed management in coffee agroecosystems.

B. Activities to be completed from January 2014-August 2014

1) Finish statistical analyses.

V. Objective 6. Evaluate farmers’ perceptions of different organic weed management practices.

A. Activities completed from January 2013-December 2013

1)  Facilitate project results workshops that included survey distribution, and strength and weaknesses analyses.

More than one hundred participants attended the project results workshop held on April 19, 2013 at UPR-Utuado. The workshop included the distribution of a pre-survey, a formal presentation of results, a visit to UPR-Utuado experimental site, a strength and weaknesses analysis of the weed management practices evaluated, and a post-survey. Pre and post surveys  asked participants 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. In addition post-surveys ask participants about what they learned, and their perceptions about the different organic weed management practices evaluated.

Fifty-six participants completed the pre-survey and thirty-six the post-survey.  Pre and post survey results do not indicate statistically significant changes in respondent’s self-reported levels of knowledge regarding soil, weed and insect management, nor in their endorsement of sustainable agriculture values. However, 100% of post-survey respondents expressed that they had learned from the workshop. All post-survey respondents had positive opinions (eg. soil conservation properties, esthetic beauty, habitat for beneficial insects) about the use of Arachis pintoi as a cover crop. Most respondents also had positive opinions about H. rotundifolia, except one respondent that expressed that it could become a weed. Thirty-seven percent of respondents had negative opinions of the use of the trimmer, indicating that it could be dangerous, polluting and expensive. However, 63% of respondents indicated that it is the most effective practice to control weeds.

B. Activities to be completed from January 2014-August 2014

1) Facilitate a project results workshop at Orocovis site.

2) Provide surveys to workshop participants..

5) Conduct statistical analyses of workshop survey data.

VI. Objective 7. Develop guidelines for weed management in organic coffee farms.

A. Activities completed from January 2013-December 2013

1) The content of the organic weed management manual was developed.

2) A short educational video about organic weed management alternatives in coffee farms was also developed.

B. Activities to be completed from January 2014-August 2014

1) Printing and online publication of manual.

2) Online publication of educational video.

3) Distribution of printed manual and video to interest groups.

4) Collect data about farmers perceptions of manual and video content.

5) Analyses of farmers perception data.

6) 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 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: