Progress 08/01/08 to 07/31/10
Outputs
OUTPUTS: Over the course of this funded project along with our long term commitment, our goal has been to develop integrated crop/livestock production systems that are economical and environmentally sustainable, provides benefits to both grazing livestock and crop farming systems, and offers opportunities for rural development through new enterprises focused on targeted grazing. We evaluated several interconnected issues including soil health and nutrient cycling, production of greenhouse gases, residue management, pest management, crop yields and profitability. Our research has shown that targeted sheep grazing provides several ecosystem services (Goosey et al., 2004, 2005, 2011-in review, Hatfield et al., 2007a, b, c; Sainju, et al., 2010, 2011). First, it can help reduce tillage intensity and soil erosion, promote nutrient cycling, and enhance soil tilth. Second, sheep grazing stubble results in the greatest levels of wheat stem sawfly (one of the most damaging insect pests to wheat production in the U.S.) mortality when compared to burned, tilled, and no no-till systems. Third, sheep grazing of alfalfa aftermath and early spring growth reduces alfalfa weevil numbers without reducing subsequent hay production. Finally, in a four-year comparison of winter and spring wheat rotations with summer fallow, targeted sheep grazing did not reduce yields when compared to tilled- or chemical-fallow (Hatfield et al., in review).
Carbon Sequestration, Nitrogen Cycling, and Greenhouse Gas Emission. We showed that soil organic C and total N levels were not significantly different among tillage, herbicide application, and sheep grazing methods of weed control (Sainju et al., 2011). Although soil NO3-N level was lower in the continuous wheat than in spring wheat-fallow and winter-wheat fallow systems, cropping sequence had no effect on soil NH4-N, organic and inorganic C and total N levels. The results indicate that reduced tillage with less intensive sheep grazing could be used to maintain soil C and N levels and sustain wheat yields. Although sheep grazing reduced soil P and K levels compared with tillage and herbicide application because of no application of these nutrients through fertilizers, other soil nutrients and chemical properties were largely not influenced.
Weed reduction ¿ comparing herbicides to grazing Cheatgrass (Bromus tectorum) and wild oat (Avena fatua) are problematic weeds in Montana agricultural systems spanning from rangeland to cropland. The primary focus of this project was to investigate how the incorporation of sheep grazing into agricultural systems impacts grassy weeds. Specifically, we evaluated the impact of incorporating sheep grazing into cropping systems on cheatgrass and wild oat populations at a large-scale replicated field experiment located at the Fort Ellis Research Farm near Bozeman, Montana. Demographic parameters including seedbank decay, seedling recruitment, seedling survival, and plant fecundity were obtained in three agricultural systems commonly used in Montana: continuous spring wheat, continuous alfalfa, and a 3-year (wheat, pea-hay barley, summer fallow) rotation. Two sets of paired quadrats were located within each plot and 5,150 seeds/m2 cheatgrass and 2,120 seeds/m2 wild oat were planted in each quadrat in fall 2009. Rotation plots were subjected to grazing or chemical treatment. Stocking rates on grazed plots ranged from 134 sheep days/ha to 537 sheep days/ha and were based on weed densities. Dicamba and/or glyphosate was applied at label rates in chemical treatment plots prior to planting. Subsequent herbicide treatments were done as needed. Weed seedling emergence, survivorship and seed production was monitored throughout the 2010 season. Preliminary data indicated grazed fallow plots resulted in a reduction in weed biomass by up to 95% compared to chemical fallow plots. Information gained from this study will be used to build a population growth model allowing producers to incorporate grazing into their agricultural management practices. PARTICIPANTS: Patrick G. Hatfield, PhD. Animal Scientist Hayes Goosey, PhD. Research Scientist Andrew Lenssen, PhD. Agro-ecologist Sue Blodgett, PhD. Entomologist Fabian Menalled, PhD. Weed ecologist TARGET AUDIENCES: Our primary target audience is sheep and grain producers in the northern great plains. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The potential impact is high. With 15.5 million acres of farmland rotated into summer fallow annually with up to 4 applications of herbicides annually for weed control bio-based alternative have both an economic and ecological attraction. As reduced tillage practices become more common, herbicide use will continue to increase. Currently, mechanical tillage is the only practical alternative to chemical fallow. However, tillage decreases residue cover and may increase soil erosion. Herbicide use in Montana¿s grain production systems represents the single largest use of pesticides in the state. Montana wheat producers alone use approximately 4.5 million pounds of active ingredient of herbicides annually for weed control on summer fallow ground. Our goal is to reduce pesticide use in grain farming operations while maintaining or improving grain production profitability. We have begun begun data analysis. Four years of field research indicate no difference in grain yield among summer fallow treatments.
Publications
- Hanson, M., P. G. Hatfield, H. Goosey, and F. Menalled. 2010. Impact of strategic sheep grazing on weed communities. Abst. Joint annual meeting, Soc. Range Manage. And Weed Sci. Soc. Of Am. Denver CO., Febuary, 2010
- Goosey, H. B. J. P. Hatfield, M. G. Rolston, K. M. O�Neill, G. D. Johnson, and P. G. Hatfield. Submitted. Hymenopteran parasitoid response to sheep grazing, tillage, and herbicides in wheat-fallow rotations. Journal of the Kansas Entomological Society. In review.
- Hatfield, P. G., H. B. Goosey, A. W. Lenssen, and S. Blodgett. Accepted. Sheep grazing to manage crop residues and control insects and weeds in northern plains Grain and alfalfa production. SARE learning center
- Sainju, U. M., A. W. Lenssen, H. B. Goosey, E. Snyder, and P. G. Hatfield. 2011 Sheep grazing in the wheat-fallow system affects dryland soil properties and grain yield. 2011. Soil Sci. Soc. Of Amer. J. (accepted on June 2, 2011)
- Sainju, U. M., A. W. Lenssen, H. B. Goosey, E. Snyder, and P. G. Hatfield. 2010. Dryland soil carbon and nitrogen influenced by sheep grazing in the wheat-fallow system. Agronomy J. 102: 1153-1561.
- Sainju, U. M., A. W. Lenssen, H.B. Goosey, E. Snyder, and P. G. Hatfield. Sheep grazing effect on dryland soil carbon and nitrogen in the wheat-fallow system. 2011. Western Nutr. Management Conf. 9: 146-151
- Sainju, U. M., A. W. Lenssen, H. B. Goosey, E. Snyder and P. G. Hatfield. 2011. Sheep grazing effect on dryland soil carbon and nitrogen in the wheat-fallow system. Proc. Western Nutrient Management Conference
- Graves,M., J. Mangold, H. Goosey, P. Hatfield, and F. Menalled. 2011. Impact of sheep grazing on demographic parameters of cheatgrass (Bromus tectorum) and wild oat (Avena fatua) in three common Montana agricultural systems. SRM
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