Preliminary Report
To each their own: case studies of four successful, small-scale organic vegetable farmers with distinct weed management strategies
- Bryan Brown, Eric R. Gallandt
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- Published online by Cambridge University Press:
- 28 November 2017, pp. 373-379
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Organic vegetable farmers execute weed management using many overall philosophies, including focusing management during the early-season critical period, managing the weed seedbank with a ‘zero seed rain’ strategy, or physically suppressing weeds with plastic or natural mulches. While these strategies vary in their ecological and economic implications, farmers’ reasons for adopting specific weed management approaches, and the related practical implications of each approach remain unclear. To better understand farmer motivations and ecological impacts of broad weed management philosophies, we conducted case studies of four successful organic vegetable farmers with specialization in different management approaches. The farmers were interviewed about their experiences and soil samples were collected for weed community and soil organic matter (SOM) analysis. The farmer who controls weed seedlings primarily during the critical period has appreciated the associated weeding labor savings, but late-season weeds have contributed to a large weed seedbank (38,482 seeds m−2), which is necessitating a change in his management. Conversely, the zero seed rain strategy of another farmer required a large amount of labor in the initial years, but weeding labor requirements have lessened every year due to decreased weed emergence from his diminishing weed seedbank (3065 seeds m−2). Another farmer utilizes plastic mulch in many crops in order to reduce weeding labor during the busy spring planting season. Finally, the farmer that uses natural mulches has high labor costs, but they are offset by the benefits of weed suppression, soil moisture conservation and increases to SOM. The two farmers utilizing mulch had the greatest portion of monocotyledonous weeds, perhaps relating to their morphology allowing them to emerge through the mulch. In ranking management criteria based on their importance, the case study farmers generally valued the criteria that are benefited by their strategy, indicating a strong relationship between their priorities and their management. Overall, there was no ‘best’ weed management strategy, but farmers may benefit from the consideration of how their management priorities match the practical tradeoffs of each strategy.
Research Paper
Productivity and profitability of manual and mechanized conservation agriculture (CA) systems in Eastern Zambia
- W. Mupangwa, M. Mutenje, C. Thierfelder, M. Mwila, H. Malumo, A. Mujeyi, P. Setimela
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- Published online by Cambridge University Press:
- 29 November 2017, pp. 380-394
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Climate variability and declining soil fertility pose a major threat to sustainable agronomic and economic growth in Zambia. The objective of this study was to assess crop yield, land and labor productivity of conservation agriculture (CA) technologies in Eastern Zambia. On-farm trials were run from 2012–2015 and farmers were replicates of a randomized complete block design. The trials compared three CA systems against a conventional practice. Yield and net return ha−1 were determined for maize and legume yield (kg ha−1) produced by ridge and furrow tillage, CA dibble stick planting, CA animal traction ripping and direct seeding. The dibble stick, ripline and direct seeding CA systems had 6–18, 12–28 and 8–9% greater maize yield relative to the conventional tillage system, respectively. Rotation of maize with cowpea and soybean significantly increased maize yields in all CA systems. Intercropping maize with cowpea increased land productivity (e.g., the land equivalent ratio for four seasons was 2.01) compared with full rotations under CA. Maize/cowpea intercropping in dibble stick CA produced the greatest net returns (US$312-767 ha−1) compared with dibble stick maize-cowpea rotation (US$204-657), dibble stick maize monoculture (US$108-584) and the conventional practice (US$64-516). The net-return for the animal traction CA systems showed that maize-soybean rotations using the ripper were more profitable than the direct seeder or conventional ridge and furrow systems. Agronomic and economic benefits of CA-based cropping systems highlight the good potential for improved food security and agricultural productivity for smallholder farmers.
The role of local agriculture in the new natural resource economy (NNRE) for rural economic development
- Susan Lurie, Christy Anderson Brekken
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- Published online by Cambridge University Press:
- 05 December 2017, pp. 395-405
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Rural communities have faced significant socio-economic challenges for the past several decades due to structural shifts and changing social expectations regarding the management, production of, and markets for natural resources, including production agriculture. The New Natural Resource Economy (NNRE) is an economic development approach to the use of natural resources, including agriculture, in ways that can build healthy environments and healthy, resilient local economies (Hibbard and Lurie, 2013). A major attribute of the NNRE is its focus on very small businesses, the predominant business type in rural settings. Emerging trends, such as regional food networks (RFNs) that connect food producers to consumers within a state or local region, may provide opportunities for rural communities to diversify and expand local businesses around the use of natural resources, thereby helping to restore greater capacity for self-direction and adding to local community vitality. Thus, we address whether RFNs in rural Oregon counties display characteristics of an NNRE development strategy through the relationships between agricultural producers and consumers that support very small agricultural enterprises. Based on analysis of Oregon producer survey data from 2016 in the more rural resource-dependent Oregon counties, we find that the RFN producer survey respondents are indeed very small businesses engaged in small-scale, multifunctional agriculture. They are motivated by economic, social, and environmental concerns as they contribute to the economic activity in their communities. We also surveyed Oregon consumers, finding that although consumer survey respondents in the same region are not primarily driven to buy local based on environmental considerations, they are nonetheless interested in supporting agriculture and local businesses. The demand for local products can create a virtuous cycle contributing to the economic, social, and environmental sustainability of the community. Given appropriate policy and program support, there is fertile ground to create new opportunities to generate farm income and acquire food within the NNRE healthy environment-healthy economy paradigm for rural economic development.
Effects of cover crop termination and cotton planting methods on cotton production in conservation systems
- Leah M. Duzy, Ted S. Kornecki
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- Published online by Cambridge University Press:
- 14 December 2017, pp. 406-414
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In conservation agriculture, cover crops are utilized to improve soil properties and to enhance cash crop growth. One important part of cover crop management is termination. With smaller profit margins and constraints on time and labor, producers are searching for ways to reduce time and labor required to terminate cover crops while maintaining or increasing profitability. This study examined the effect of 11 different combinations of terminating cereal rye (Secale cereale L.) and planting cotton (Gossypium hirsutum L.) on population, seed cotton yield, total costs and net returns; and how combined operations affect labor, fuel consumption and carbon (CO2) emissions in a conservation system. Cereal rye followed by cotton was planted in central Alabama during the 2009–2011 crop years. Treatments included cotton planted directly into standing cereal rye, cover crops terminated at early milk growth stage using mechanical (roller or roller/crimper) with or without chemical termination (spraying) followed by cotton planting, and cover crop termination combined with cotton planting using spraying with or without rolling termination. While the 2011 crop year had the lowest plant populations, there was no year effect on seed cotton yields, total costs or net returns. Rolling with or without spraying yielded higher plant populations (26%), seed cotton yields (18.3%) and net returns (17.2%) than cotton planted into standing rye; however, rolling with or without spraying also had 23.8% higher costs due to increased fuel usage, machinery and labor hours, and yield varying costs. While rolling with spraying had slightly higher total costs compared with rolling alone (6.5%), plant populations, seed cotton yields and net returns were 11.42%, 6.4% and 6.5% higher, respectively. Converting from three separate operations for cover crop termination and cotton planting to rolling and spraying combined with planting, producers could potentially reduce CO2 emissions from fuel use and labor hours associated with cover crop termination and cotton planting by up to 51%.
Do direct market farms use fewer agricultural chemicals? Evidence from the US census of agriculture
- Ethan D. Schoolman
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- Published online by Cambridge University Press:
- 16 January 2018, pp. 415-429
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Are strong local food systems better for the environment than conventional food systems where relatively close proximity between points of production and consumption is not a defining characteristic? Despite growing support for efforts to strengthen local food systems, surprisingly little is known about the relationship of local food to environmental sustainability. In particular, the relationship of local food systems to the use of agricultural chemicals to manage pests, weeds and disease has not been a subject of systematic research. In this paper, I use longitudinal data from the US Census of Agriculture to explore whether growth in local food systems is associated with decreased on-farm use of agricultural chemicals. Drawing on county-level data from 1997 to 2012, I find that an increase in the strength of local food systems—whether measured as the number of farms that market products directly to consumers, or as the total value of direct market products—has been broadly associated with a decrease in spending on agricultural chemicals in the USA as a whole. But the magnitude of the relationship between direct marketing to consumers and changes in agricultural chemical use has dwindled over time, to the point where it is not clear whether contemporary local food systems are still incentivizing farmers to reduce their use of pesticides. Overall, this study lends new credence to the idea that robust local food systems can benefit the environment. But even where just one dimension of agriculture's impact on the environment is concerned, the characteristics of local food systems appear to have varied over time—a qualification that argues strongly for further research into the relationship of local food to agricultural practice.
Processing methods of organic liquid fertilizers affect nutrient availability and yield of greenhouse grown parsley
- Bhaniswor Pokhrel, Jorn Nygaard Sorensen, Henrik Bjarne Moller, Karen Koefoed Petersen
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- Published online by Cambridge University Press:
- 24 January 2018, pp. 430-438
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The demand for organic foods is increasing globally, but a key limiting factor to the production of organic greenhouse produce is the lack of certified liquid fertilizers. In this experiment, four organic fertilizers were produced using either acidic extraction, anaerobic digestion or both of ensiled biomass of organic red clover and white mustard. The resulting fertilizers were applied to greenhouse-grown parsley either alone, or in combination with nitrogen (N)-enriched water produced by flushing acidic water with ammonia, to determine their effect on plant growth and the nutrient concentrations of parsley. Six combinations of fertilizer treatments were included in the greenhouse experiment. Three treatments received either fertilizers derived from acidic extraction, anaerobic digestion or both and three treatments received fertilizers derived from acidic extraction combined with N-enriched water. Conventional inorganic liquid fertilizer, chicken manure extract and no liquid fertilizer (only water) were added as control treatments. A higher N-min (ammonium and nitrate) to potassium (K) ratio was found in fertilizers after anaerobic digestion compared to acidic extraction. All organic fertigation treatments resulted in high pH, high K and chloride concentrations and high NH4/NO3 ratios in the root zone. In addition, high electrical conductivity (EC), P, K and Mg concentrations were found when only acidic extracted fertilizers were applied. Application of plant-based organic fertilizers without amending with N-enriched water resulted in biomass yields that were 21–26% lower than the inorganic fertigation control. However, fertigation with chicken manure extract, or a combination of fertilizer derived from acidic extraction and N-enriched water, resulted in similar plant growth as inorganic fertilizer. The lower yield from fertilizer derived from acidic extraction was due to elevated EC levels in the growing medium. Our results suggest that yield of greenhouse-grown parsley using either organic fertilizers combined with N-enriched water or chicken manure extract is similar to conventional fertilizer.
Weeds, nitrogen and yield: measuring the effectiveness of an organic cover cropped vegetable no-till system
- David Robb, Geoff Zehnder, Robin Kloot, William Bridges, Dara Park
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- Published online by Cambridge University Press:
- 29 January 2018, pp. 439-446
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Organic vegetable growers rely heavily on mechanical methods such as tillage and other forms of labor-intensive soil cultivation for weed management despite the negative effects to soil health associated with intensive soil disturbance. The use of cover crops and no-till (NT) vegetable production represents an alternative approach to weed control that can enhance rather than degrade soil health; however, there are challenges inherent with this practice and previous results in vegetable production have been mixed. Field experiments were conducted over 2 yr at the Clemson Student Organic Farm to examine the effects of tillage [NT versus conventional tillage (CT)] on weed development and management in organic tomato and summer squash production under different nitrogen (N) fertility regimes, and to assess soil N dynamics in both systems. Squash yields were similar between tillage treatments in both years. NT tomato yields were 43% greater than CT yields in 2014, whereas CT tomato yields were 46% greater than NT yields in 2015. Squash and tomato yields per unit of management labor (time) were significantly greater in NT compared with CT treatments for both years. There were no statistical differences in squash and tomato yields between N fertilization treatments in either year. Pre- and post-season soil N results were mixed. Pre-season soil N levels were significantly higher in NT tomato plots in 2014 but similar between tillage treatments in tomato plots in 2015 and in squash plots both years. Post-season soil N levels in tomato plots were similar between tillage treatments both years. Post-season soil N levels were significantly higher in NT squash plots in 2014 and in CT squash plots in 2015. Roller-crimped NT mulches provided adequate early-season weed suppression in both years and saved considerable weed management and seedbed preparation labor. Overall, the results demonstrated that organic NT is a viable method for reduced tillage summer vegetable production in the southeastern Piedmont region.
Effectiveness of mechanical weed control on Italian flint varieties of maize
- Silvia Fogliatto, Marco Milan, Fernando De Palo, Aldo Ferrero, Francesco Vidotto
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- Published online by Cambridge University Press:
- 01 February 2018, pp. 447-459
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Weed control is one of the most important practices for a satisfying crop performance. In organic farming, weeds are mainly controlled by using mechanical methods, which may result in incomplete crop selectivity. Maize is one of the crops for which mechanical weed control is commonly applied. To assess weed control efficacy and the possible crop injuries caused by mechanical interventions (harrowing, hoeing and ridging), a field experiment was carried out in 2013–2014 on traditional flint Italian varieties of maize (Marano, Ottofile, Pignoletto, Nostrano and the hybrid Maranello) suited for organic food production. The study included the following treatments: weed control with a spring tine harrow + hoeing and ridging (STH), manual weed removal all season long (MWR), spring tine harrowing + manual weed removal (STH + MWR) and an untreated check (CHK). In the 2 years, the experiment was carried out in two similar fields in which 60 plots (6 × 10 m) were arranged in a RCBD with three replications. Weed control efficacy was assessed by determining weed density, weed species composition and weed cover after each mechanical intervention in the STH and CHK plots. Weed diversity indices were also calculated at the final assessment. The possible crop injuries caused by mechanical means were assessed by determining maize plant height, number of leaves, and plant density after each mechanical intervention. At maturity, maize yield and other yield-related traits (1000-seed weight, hectolitre weight, and grain moisture) were determined. The results showed that the mechanical treatments lowered the weed infestation, without changing weed species dominance and slightly lowering species richness; even though they were not able to completely control the weeds. In both years, the final weed density in STH plots was of about 50 plants m−2. Better weed control was obtained when weeds were at early growth stages and with a repeated number of harrowing. Mechanical weeding did not cause significant injury in terms of plant height nor density; however, for Marano and Maranello, a delay in the crop cycle was observed as shown by the lower number of leaves in STH compared with MWR. Yield ranged from 0.3 t ha−1 for Marano CHK to 10.4 t ha−1 for the hybrid Maranello in MWR + STH. Yield and yield-related traits were not affected by mechanical weeding.
In the weeds: distinguishing organic farmers who want information about ecological weed management from those who need it
- Doug Bessette, Sarah Zwickle, Robyn Wilson
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- Published online by Cambridge University Press:
- 31 January 2018, pp. 460-471
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The benefits of farming organically in the USA are increasingly known; however, organic farmers also encounter considerable risks, especially from weeds. Without herbicides, organic farmers can rely only on crop rotations, mechanical cultivation, manual weeding, beneficial insects and other cultural practices, termed ecological weed management (EWM), to control weeds. Despite promising results and the many ways in which EWM can be employed, it remains poorly adopted by the organic community. Organic farmers resist research and recommendations from University scientists and Extension, instead preferring to rely on local family and friends and their own experience to guide decisions. Here we investigate factors that may lead organic farmers to recognize that they need additional information about EWM and to seek that information out. Using a national survey of organic farmers (n = 554) and a risk-information seeking and processing model, we show that farmers’ risk and benefit perceptions, worry, social norms encouraging seeking out information, and farmers’ own perceived knowledge gaps, particularly with respect to their most problematic weed, influence information-seeking behavior. Identifying characteristics that may distinguish those organic farmers who need and want additional information, we provide recommendations to Extension and University scientists about how best to communicate, build trust and provide decision support to the organic community with respect to EWM.
Review Article
Securing fresh food from fertile soil, challenges to the organic and raw milk movements
- Joseph R. Heckman
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- Published online by Cambridge University Press:
- 29 November 2017, pp. 472-485
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In recent decades, a diverse community of dairy farmers, consumers and nutrition advocates has campaigned amidst considerable government opposition, to secure and expand the right of individuals to produce, sell and consume fresh unprocessed milk, commonly referred to as ‘raw milk’. This advocacy shares important parallels with battles fought in the organic food movement over the past century. Both the raw milk and organic food movements originated with farmers and consumers who sought to replace industrialized food production and processing practices with more traditional ones. Both movements equate the preservation of natural integrity in farming and food handling with more wholesome, nutritious food and environmental conservation. Both movements have had to work diligently to overcome a false perception that their practices are anachronistic, notably with regard to productive output of organic agriculture and the safety of fresh unprocessed milk. There is also the failure of opponents to acknowledge a growing body of scientific evidence for health benefits associated with drinking of fresh unprocessed milk. The raw milk movement has the potential to economically benefit family farmers, much as organic agriculture has done. Building soil fertility, a foundational principle of organic farming, would benefit from having numerous small pasture-based dairies spread across the land providing fresh unprocessed milk. Agricultural universities and the Cooperative Extension System could seize a real leadership opportunity by promoting and participating in this reinvention of dairy farming, and restoring the ecology of this traditional food and farming system.