Research Paper
Effects of cover crop presence, cover crop species selection and fungicide seed treatment on corn seedling growth
- Lara A. Schenck, Matthew G. Bakker, Thomas B. Moorman, Thomas C. Kaspar
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- Published online by Cambridge University Press:
- 11 July 2017, pp. 93-102
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Cover crops can offer erosion protection as well as soil and environmental quality benefits. Cereal rye (Secale cereale L.) is the most commonly used winter cover crop in corn–soybean rotations in the upper Midwest of the USA because of its superior winter hardiness and growth at cool temperatures. Cereal rye cover crops, however, can occasionally have negative impacts on the yield of a following corn crop, which discourages broader adoption and introduces substantial risk for corn farmers employing cover crops. We hypothesized that because cereal rye shares some pathogens with corn, it may be causing increased disease in corn seedlings planted soon after cereal rye termination. To test this, we performed a series of experiments in a controlled environment chamber to assess the response of corn seedlings with and without a commercial fungicide seed treatment to the presence of cereal rye or other species of cover crops that were terminated with herbicide prior to corn planting. Our results indicate that under cool and wet conditions, cereal rye reduces corn seedling growth performance and increases incidence of corn seedling root disease. Fungicide seed treatment had limited efficacy in preventing these effects, perhaps because environmental conditions were set to be very conducive for disease development. However, hairy vetch (Vicia villosa Roth) and winter canola (Brassica napus L.) cover crops had fewer negative impacts on corn seedlings compared with cereal rye. Thus, to expand the practice of cover cropping before corn, it should become a research priority to develop alternative management practices to reduce the risk of corn seedling root infection following cereal rye cover crops. Over the longer term, testing, selection and breeding efforts should identify potential cover crop species or genotypes that are able to match the winter hardiness, growth at cool temperatures and the conservation and environmental quality benefits of cereal rye, while avoiding the potential for negative impacts on corn seedlings when environmental conditions are suitable for disease development.
Organic farmer perceptions of reduced tillage: A Michigan farmer survey
- Carolyn J. Lowry, Daniel C. Brainard
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- Published online by Cambridge University Press:
- 11 July 2017, pp. 103-115
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A common critique of organic farming is that it is very tillage intensive, and therefore deleterious to soil quality. However, little information is available on the tillage practices currently employed by organic farmers, as well as organic farmers’ attitudes toward reduced tillage (RT). To address these knowledge gaps, a detailed written survey of Michigan organic field crop and vegetable farmers was conducted to investigate their current tillage practices, as well as their perceptions of the barriers and benefits to adoption of RT. Respondents reported a wide range in tillage frequency and intensity, both across and within production of specific crops, with operations split evenly between field preparation and cultivation. Compared with field crop growers, vegetable growers were generally smaller scale and relied more heavily on a limited set of tillage (e.g., rototiller) and cultivation tools. Interest in adoption of RT practices among respondents was low to moderate with median Likert scale ratings (0–7 scale with 0 representing no interest and 7 extreme interest) of 4 or less for all forms of RT. Vegetable growers were most interested in permanent beds, rotational tillage and strip tillage, whereas field crop growers were most interested in rotational tillage and strip tillage. The greatest perceived benefits to adoption of RT were improved soil quality and fuel savings. Both groups ranked weeds, impacts on yields, residue management and crop establishment as high barriers to RT adoption. Vegetable growers also cited lack of scale appropriate equipment as a major barrier. Survey results suggest that future research efforts should focus on overcoming key barriers to adoption, such as weed management and access to low-cost adaptable RT equipment rather than reiterating relatively well-known soil quality benefits. Our results also suggest that promotion of incremental reductions in the frequency and intensity of tillage operations on organic farms may be more realistic and equally valuable compared with promotion of more extreme forms of RT such as no-till.
Drivers of farmers’ decisions to adopt agroforestry: Evidence from the Sudanian savanna zone, Burkina Faso
- L. Sanou, P. Savadogo, Eugene E. Ezebilo, A. Thiombiano
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- Published online by Cambridge University Press:
- 04 July 2017, pp. 116-133
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In most developing countries, there has been a long-standing conflict of interest between using land for agriculture and the conservation of biodiversity. This paper reports on a study of factors influencing farmers’ decisions to integrate trees into their agricultural practice. We also discuss the possibility of protecting and managing planted and naturally regenerating trees on farmland in order to restore degraded land and improve biodiversity. Data were collected from interviews with farmers in the Center-West region of Burkina Faso and analyzed using Principal Component Analysis, multiple linear regression and binary logistic regression. The results show that farmers’ decisions to incorporate trees into their farmland were mainly influenced by silvicultural knowledge and skills, participation in farmers’ groups or other social organizations with an interest in tree conservation, the social value of biodiversity in the rural landscape, and the perceived economic benefits of trees on farmland. The most important factors associated with variation in levels of motivation to conserve trees on farms included household wealth, gender, age, education level, marital status, residence status, farmland size, household size and technical support. We conclude that an agroforestry project will be more successful if the local biophysical conditions and diversity of smallholder socio-economic characteristics and their perceptions, needs and preferences are considered in its design. There is also an immediate need for coordinated development of information and training to raise local community awareness of the potential of agroforestry as well as to disseminate information about adding value to tree products in order to encourage farmers to protect on-farm trees.
Productivity and water use of organic wheat–chickpea intercropping system under limited moisture conditions in Northwest India
- Balwinder Singh, C.S. Aulakh, S.S. Walia
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- Published online by Cambridge University Press:
- 10 October 2017, pp. 134-143
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Intercropping of legumes in cereals and manuring are important measures to sustain soil fertility and enhance crop productivity in general and under organic and limited moisture conditions in particular. This study evaluated different wheat (Triticum aestivum L.) + chickpea (Cicer arietinum L.) row ratios as intercrops under organic and limited moisture conditions in Northwest India with an aim to find out the suitable row ratio to get higher system productivity under these conditions. Chickpea, being a legume, produces nitrogen compounds that help the plant to grow itself and also makes them available to the companion wheat plants and thus helps in wheat nutrition, which otherwise becomes limited due to less mineralization of nitrogen under organic and cold weather conditions. The primary aim of the study was to get better productivity of wheat crop as this is an assured crop of this region. The intercropping system was evaluated in a randomized complete block design with four replications at Ludhiana, Punjab in Northwest India during 2013–2014 and 2014–2015. Effective tillers m−1 row length, number of grains spike−1 and 1000-grain weight of wheat were higher in wheat + chickpea (2:1) intercropping system as compared with sole wheat. This intercropping system produced significantly higher wheat grain yield, wheat equivalent yield and land equivalent ratio than sole wheat. Wheat + chickpea (2:1) and wheat + chickpea (3:1) intercropping systems gave higher water-use efficiency than sole wheat. However, chickpea gave higher yield attributes and seed yield as sole crop than that in different intercropping systems. Wheat + chickpea (2:1) and wheat + chickpea (3:1) intercropping systems produced mean wheat grain yields of 5.11 and 4.79 Mg ha−1, respectively, along with additional mean chickpea seed yields of 0.28 and 0.24 Mg ha−1, respectively.
Cutting management and alfalfa stand age effects on organically grown corn grain yield and soil N availability
- Adria L. Fernandez, Karina P. Fabrizzi, Nicole E. Tautges, John A. Lamb, Craig C. Sheaffer
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- Published online by Cambridge University Press:
- 14 August 2017, pp. 144-154
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Alfalfa is recommended as a rotational crop in corn production, due to its ability to contribute to soil nitrogen (N) and carbon (C) stocks through atmospheric N2 fixation and above- and belowground biomass production. However, there is little information on how alfalfa management practices affect contributions to soil and subsequent corn crop yields, and research has not been targeted to organic systems. A study was conducted to determine the effects of alfalfa stand age, cutting frequency and biomass removal on soil C and N status and corn yields at three organically managed Minnesota locations. In one experiment, five cutting treatments were applied in nine environments: two, three and four cuts with biomass removal; three cuts with biomass remaining in place; and a no-cut control. In the other experiment, corn was planted following 1-, 2-, 3- or 4-year-old alfalfa stands and a no-alfalfa control. Yield was measured in the subsequent corn crop. In the cutting experiment, the two- and three-cut treatments with biomass removal reduced soil mineral N by 12.6 and 11.5%, respectively, compared with the control. Potentially mineralizable N (PMN) was not generally affected by cutting treatments. The three-cut no-removal increased potentially mineralizable C by 17% compared with the other treatments, but lowered soil total C in two environments, suggesting a priming effect in which addition of alfalfa biomass stimulated microbial mineralization of native soil C. Although both yields and soil mineral N tended to be higher in treatments where biomass remained in place, this advantage was small and inconsistent, indicating that farmers need not forgo hay harvest to obtain the rotational benefits of an alfalfa stand. The lack of overall correlation between corn grain yields and mineral and potentially mineralizable N suggests that alfalfa N contribution was not the driver of the yield increase in the no-removal treatments. Alfalfa stand age had inconsistent effects on fall-incorporated N and soil N and C parameters. Beyond the first year, increased alfalfa stand age did not increase soil mineral N or PMN. However, corn yield increased following older stands. Yields were 29, 77 and 90% higher following first-, second- and third-year alfalfa stands than the no-alfalfa control, respectively. This indicates that alfalfa may benefit succeeding corn through mechanisms other than N contribution, potentially including P solubilization and weed suppression. These effects have been less studied than N credits, but are of high value in organic cropping systems.
Economic and productivity incentives to produce organically in Brazil: Evidence from strawberry production in the Federal District
- M. A. Resende Filho, D. A. Andow, R. G. Carneiro, D. R. Lorena, E. R. Sujii, R. T. Alves
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- Published online by Cambridge University Press:
- 31 August 2017, pp. 155-168
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Brazil has the largest market for organic products in Latin America, but only 1.04% of its agricultural land is utilized for organic production (OP). We compared organic and conventional production (CP) in economic and productivity terms using data from a randomized survey of 86 organic and conventional strawberry growers (response rate 85.2%) in Brazlândia, Federal District, Brazil. Probit model selection estimates showed that the use of technical assistance from rural extension and producer gender had no effect, but growers with greater age, higher indebtedness, smaller strawberry production area, more education and less experience on growing strawberries were more likely to produce organically. For growers with more than 5.6 years of education and less than 13.54 years of experience, more education and experience make them less likely to produce strawberry organically. Thus, we expect growers’ probabilities of conversion for strawberry OP will remain about the same over time in the study area. The average treatment effect for the treated (ATT) was estimated using nearest neighbor/propensity score matching and endogenous switching regression (ESR). These showed that producing strawberry organically had no effect on productivity or total cost per box, but increased revenue and profit per box, probably as a result of the price premium for organic strawberries. As only 4.8% of farmers had converted to organic production, conversion costs and non-economic factors, such as psychological factors and social capital, may be barriers to conversion.
New Concepts and Case Studies
Curbing food waste: A review of recent policy and action in the USA
- Bhavneet Walia, Shane Sanders
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- Published online by Cambridge University Press:
- 06 September 2017, pp. 169-177
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The present study reviews previous published estimates as to the scale of food waste in the USA and its ecological toll (e.g., in terms of methane emissions and water usage to support the production of wasted food). The review further discusses recent public policy and private action designed to curb food waste or to apply wasted food toward hunger alleviation, biofuel production and soil nourishment. We further consider and expand upon previous estimates comparing the scale of food waste to the present scale of the US hunger problem. These estimates suggest that the recovery and redirection of an additional 15% of the present stock of edible food waste would meet 35% of the caloric needs of all Americans living in a food insecure household or very low food security household. Then, a modest to moderate proportional increase in edible food waste recovery could greatly reduce the US hunger problem in its present state. We estimate that the successful redirection of 15% of presently-wasted (edible) food in the USA would be sufficient to fully sustain 18.45 million individuals. Given available data, we cannot precisely assess the nutritional characteristics of this potential stock of food. The present study emphasizes the traditional and future importance of integrated public policy and private action at the municipal level, as food waste is typically disposed of or recovered at this level.