Ground cover in coffee farmers observe weeds and propose management alternatives

In Central America coffee is often produced on sloped land, either under shade with low inputs or in open sun with pesticides and high levels of fertilizers (Rice & Ward, 1996). Yields vary from 200 to 2700 kg of green beans ha_1, depending on soils, climates, farm size, and farmer resources. The diversity of growing conditions and the layout of coffee fields create spatial and temporal variability in weeds, insect pests, and diseases. Improving yields and lowering production costs requires farmer management of heterogeneous conditions.

In the early 1990s, integrated pest management (IPM) specialists from the Center for Teaching and Research in Tropical Agriculture (CATIE) began a program in Nicaragua to improve pest management in coffee (Staver et al., 1995; Staver, 1998). In parallel with field studies of pest dynamics and replicated trials with new management practices, the team began work with groups of smallholder coffee growers. The team quickly found that growers had extensive practical experience, but had an incomplete understanding of pests and the reasons for their variability. Farmers were also uncertain about when to use specific practices and how to evaluate whether one practice was better than another. These difficulties limited their efforts to test and adapt alternative management options.

To improve grower capacity to evaluate practices and make decisions based on observation and ecological reasoning, the CATIE team has been using participatory training procedures. Farmer groups meet every six to eight weeks during the yearly crop cycle to discuss what they know about pests, how they decide to manage them, and to fill in gaps in their understanding with practical exercises. A nearby coffee field is used as a laboratory to observe pests and their variability and to learn scouting methods. Between sessions farmers analyze their own fields and bring results to the next meeting. Data variability among farmers, fields, and seasons is used to promote discussion on why pest populations fluctuate, the effectiveness of current practices, and the relationship between pest levels and control decisions. In this process farmers begin to develop their own ecological logic of how to manage pests better and become eager to test alternative practices in a group plot or in their own fields.

In the case of weeds, the participatory training takes into account farmer knowledge of weed types. In a quick walk through a nearby coffee field, farmers choose a weed they consider very damaging to coffee, one not so damaging, and one that does not affect coffee plants. With these weeds in hand, the group discusses the different species one by one, how they grow and reproduce, and what type of damage they do to coffee plants. Individual weeds are grouped into categories by growth habit. The group also analyzes other ground covers in the coffee field such as leaf litter, discusses the consequences of bare soil, and identifies the weeds and other ground covers that protect the soil without competing much with coffee. To measure the cover of each weed type in the field, the group uses a simple transect method, and analyzes how the current control practices favor certain weeds and reduce others. Finally, the group discusses the best combinations of ground cover and identifies practices to implement in their comparison plot. Progress is evaluated in follow-up sessions every two months. Have growers sampled weeds.? Are new practices being implemented? How effective are they? How much do they cost?

The framework for training based on weed types, sampling methods, and discussions of practices was developed by scientists, but has only advanced by incorporating coffee farmers' opinions and ideas. Scientists learn key words used by farmers, and farmers adopt scientists' vocabulary to refer to new ecological concepts. Standard weed scouting procedures have permitted comparisons between different fields and groups. Farmer groups have proposed that different weed species be used as ground cover depending on location. The approach has been successful in generating discussions about weed types and the importance of ground cover for soil conservation. Many farmers have tried selective weeding instead of total weeding. However, farmer groups have established few experimental plots to test alternative weed management practices. These farmers of low-yielding coffee may be stating that weed studies are not very important until they improve other problems, such as low coffee plant density and vigor, that have a greater impact on yields and profitability than do weeds.

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