- Agronomic: rye, grass (misc. perennial), hay
- Fruits: cherries, general tree fruits
- Animal Production: feed/forage
- Crop Production: application rate management, cover crops, intercropping, no-till, nutrient cycling, organic fertilizers
- Education and Training: demonstration, extension, focus group, networking, on-farm/ranch research, participatory research
- Farm Business Management: agricultural finance, budgets/cost and returns
- Natural Resources/Environment: biodiversity, habitat enhancement, soil stabilization
- Pest Management: biological control, chemical control, cultural control, integrated pest management, mulches - killed, mulches - living, mulching - vegetative, physical control, weed ecology
- Production Systems: agroecosystems, holistic management
- Soil Management: green manures, organic matter, soil analysis, soil quality/health
- Sustainable Communities: analysis of personal/family life, social networks, sustainability measures
We investigated social and agroecological issues in tart cherry production in northern Michigan. Based upon grower interviews and industry reports, we documented the challenges Michigan tart cherry growers face and found that growers have used innovative agroecological strategies to remain economically viable. A comparison of alternative groundcover management systems (GMSs) to conventional herbicide/sod systems demonstrated no reductions in leaf nutrients or yields despite ½ rate fertilizer and herbicide elimination in the GMSs. Moreover, increased plant species richness and compositional cover in the GMSs resulted in higher richness and abundance of arthropod predators and parasitoids.
Michigan is the nation’s primary producer of tart cherries (Prunus cerasus L.), with roughly 75% of United States’ growers and production. The industry is an important component of Michigan’s economy, with an annual farm-gate value typically surpassing $75 million. Tart cherry growers must contend with two agricultural dilemmas: maintaining short and long-term tree productivity, and delivering acceptable fruit to processors. Several factors complicate these necessities. Inconsistent weather conditions create unpredictable harvests for growers, such that the production fluctuations are some of the most drastic of any agricultural commodity (Ricks et al. 1982). Moreover, the federal “zero-tolerance” policy forces tart cherry growers to use insecticides, because it prohibits cherries with any cherry fruit fly larvae from being accepted by processors; 99% of all U.S. tart cherry acreage receives insecticide sprays (USDA 2002). Unlike annual crops that typically provide economic returns in one season, tart cherries and other perennial tree crops require a long-term investment. As a result of these constraints Michigan tart cherry growers generally operate with prices below operating costs (Ricks et al. 1982). In addition to natural constraints, structural issues, and environmental concerns, cherry growers are faced with additional challenges. Michigan’s northwestern lower-peninsula contains some of the most development-threatened, high quality farmland in the nation (Sorensen et al. 1997). Land development has resulted in increasing residential proximity to orchards and heightened public concerns over the health and environmental effects of agrochemical use in northern Michigan.
As the structure of U.S. agricultural production and coordination has changed, farmers have been forced to bear the economic risks of production as they have become wedged between input monopolies and marketing/retail monopolies (FitzSimmons 1990). In addition to these macroeconomic pressures, farmers are continually constrained by the specific biological processes of the crops themselves; the entire production process is bound by the ecological functions and abiotic patterns surrounding the agroecosystem (FitzSimmons 1986). In this context, the situation of Michigan tart cherry farmers offers unique insight into the changing structure of specialty crop production in the U.S., farmer’s agroecological choices, increasing challenges, and innovative strategies that farmer’s employ to remain economically viable.
This project addresses two aspects of the complex circumstance of Michigan tart cherry farmers: 1. Farmer’s Agroecological Knowledge and Coping Strategies and 2. Groundcover Management Systems.
Farmer’s Agroecological Knowledge and Coping Strategies
Because of numerous constraints, farmers’ agroecological knowledge is an important component of their farming practices at an individual and community level. The theoretical basis for inclusion of different knowledge systems has existed for some time (Norgaard 1988, Anderson and Lockeretz 1991, Kloppenberg 1991, Selener 1997). Farming has been a dynamic process for many people, where knowledge and broad farm-level analysis have evolved over time in close relation to specific environments. Although proponents of farmer knowledge have been steadfast in their support for the inclusion of local knowledge system, local knowledge may not necessarily translate into more sustainable practices (Murdoch and Clark 1994). However, a combination of local and scientific knowledge systems is likely to result in innovations that are adopted. The Michigan tart cherry farming community has worked closely with extensionists and university researchers in seeking solutions to their agroecological challenges, but farmers at different scales report that they must make different choices to respond to the problems they face at scale.
Geographers have focused on issues surrounding the commodity production process at the farm scale. Lighthall (1995) analyzed the historical evolution of farm structure and process in Iowa and sought to determine the barriers to, and the process aiding adoption of, sustainable agricultural practices by investigating the natural, technological and social relations of production. Lighthall highlighted the importance of production risk and scale as two key factors in determining farmers’ decision making patterns. Production risk in this case was defined as the “relative probability of a breakdown in the production process due to natural forces, failure of production technology, human error, or…some combination of these”. Lighthall suggested that farm scale, farmer experience, ecological conditions, and requirements of the commodity system were all included in determining the production risk; and that the production risk could be seen as determining the sustainability of the production process. In Lighthall’s study, he compared the farming practices of a group of corn/soybean farmers making use of ridge-till strategies with reduced herbicide application with another group using heavy herbicide applications for weed control. He found that the scale of production (number of acres farmed) prevented larger farmers from adopting ridge-till techniques which used much less herbicide, because the temporal window for weed control without herbicides was too limited. Smaller farmers could practice ridge-till and reduce herbicide use because their smaller scale allowed them to manage weeds over their entire acreage during the temporal window within which physical control was feasible.
Guthman (2000) both echoes and expands upon these findings, using an agroecological framework for assessing use of ecological practices by organic growers in California. She assessed growers based upon six farm management criteria: fertility practices, pest and disease management, avoidance of restricted/controversial materials, weed control practices, bio-diversification, and evidence of planning and testing. Like Lighthall (1995) her findings suggest that scale influences grower practices, though farms of all sizes fell short of agroecological ideals in most cases because of agronomic challenges, competitive agricultural markets, and consumer expectations for cosmetically flawless products. Her research demonstrates that geographical conditions including climatic and biophysical conditions, social relations, institutional constraints, and regional norms all play a role, but that availability of technology to overcome crop-specific pressures was the key factor contributing to variation in grower practices irrespective of scale.
Groundcover Management Systems
Ground cover management to promote tree growth and crop yield is a key component of orchard crop production. In most cases, ground cover is managed to reduce nutrient and moisture competition with the trees, reduce damage from pests and disease, improve the ease of machinery movement, and to improve aesthetics. The standard groundcover management system (GMS) that best meets these goals in North American orchards is mowed grass alleys and herbicide maintained tree rows (Skroch and Shribbs 1986, Merwin 2003). This system has gained acceptance because it dramatically reduces erosion compared to clean cultivation, and herbicides reduce moisture competition between vegetation and trees in a relatively inexpensive manner. However, extended pre-emergent herbicide use diminishes soil organic matter, soil structure and lowers soil pH through leaching of exchangeable cations (Haynes 1981, Hipps and Samuelson 1991, Merwin 1998). Roundup, the most commonly used herbicide in Michigan cherry orchards (USDA NASS 2004a), is toxic to amphibians (Relyea 2005) and has indirect negative effects on spider diversity (Haughton et al. 1999, Sullivan and Sullivan 2003: review). Typical fertility management in conventional orchard systems includes significant amounts of inorganic N fertilizer (Weinbaum 1992), which has been shown to leach in the form of Nitrate-N (Merwin et al. 1996, Edson et al. 2003).
GMSs can reduce nitrate leaching (Merwin et al. 1996, Sanchez et al. 2003) improve soil quality (fertility, structure, organic matter content, porosity, bulk density) (Oliveira and Merwin 2001), tree nutrition (Marsh et al. 1996), crop yield (Sanchez et al. 2003) and increase natural enemy richness and abundance (Blommers 1994, Wyss 1995, Altieri and Nicholls 2004). Mulches in particular have been shown to improve soil conditions in agricultural systems (Merwin et al. 1994, Yao et al. 2005), reduce weed growth (Brown and Tworkoski 2004) and increase yields (Smith et al. 2000, Hipps et al. 2004).
However, GMSs do not always provide benefits and in some cases can have negative effects on orchard bio-physical conditions. For instance, groundcover can compete with tree crops for nutrients and water (Rogers et al. 1948, Anderson et al. 1992), decrease tree growth (Parker and Meyer 1996), decrease fruit yield (Pedersen 1997), host crop pests (Tedders 1983, Bugg 1992, Meagher and Meyer 1990), increase frost damage (Proebsting 1970), and become weedy (Ingels et al. 1994). Mulches have been found to increase Phytopthera root disease in apple orchards (Merwin et al. 1992), increase vole populations and rodent tree damage (Merwin et al 1999, Prokopy 2003), increase costs for growers (Merwin 1995), thereby making mulch systems less profitable than conventional orchard management (Edson et al. 2003).
Because of increasing awareness of potential environmental externalities, interest in organic produce, and increasing grower interest in alternatives, the need for alternative orchard production systems is growing (Merwin et al. 1996, Swezey and Broome 2000, Reganold et al. 2001, Kramer et al. 2006). While GMSs may be useful components of alternative orchard production systems, in order to be adopted by growers the benefits of GMSs must outweigh the potential negative effects.
Farmer’s Agroecological Knowledge and Coping Strategies
The manner in which biological constraints have been partially overcome by technological advancements determines the social relations of farming systems. Thus as Lighthall (1995) suggests, the production process itself serves as the nexus for social/nature relations and links the farm to the larger political economy. Insight from growers is crucial to determine how they overcome the many constraints associated with tart cherry production in northern Michigan in attempts to remain economically viable. Based largely upon interviews with forty farmers and review of agency and public documents, here I offer highlights of farmer’s agroecological knowledge. Investigating farmer’s circumstances illustrates agroecological constraints but also demonstrates farmer’s agroecological agency in the face of increasing economic vulnerability.
Groundcover Management Systems
The purpose of this research was to investigate the effects of three multi-species GMS treatments with varying levels of diversity (Five Species Mix: red clover, white clover, hairy vetch, cereal rye, and brown mustard; Clovers/Mustard: red clover, white clover, brown mustard; Rye/Vetch: cereal rye and hairy vetch) compared to the conventional production system on an operating tart cherry farm in northern Michigan. Here we evaluate tart cherry yield, leaf nutrients, arthropod richness and abundance, side-delivery mulch for weed control, 50% N fertilizer, and herbicide elimination.