Integrating sheep grazing into cereal-based crop rotations: spring wheat yields and weed communities

Authors: MILLER, ZACH - Montana State University; MENALLED, FABIAN - Montana State University; Sainju, Upendra; LENSSEN, ANDREW - Iowa State University; HATFIELD, PATRICK - Montana State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2014
Publication Date: 10/31/2014
Publication URL: http://handle.nal.usda.gov/10113/60674
Citation: Miller, Z.J., Menalled, F.D., Sainju, U.M., Lenssen, A.W., Hatfield, P.G. 2014. Integrating sheep grazing into cereal-based crop rotations: spring wheat yields and weed communities. Agronomy Journal. 107(1):104-112.

Interpretive Summary: Restoration of diversity in agricultural production systems through reintegrating livestock into diversified crop production systems has been postulated as an ecologically based approach to reduce off-farm inputs, alleviate negative side-effects of the agricultural enterprise, and increase the efficiency and profitability on the farm. To date, research has been conducted in diversified crop–livestock systems where the same field is used for crop and animal production at different times resulting in services being exchanged between livestock and crop components of the production system. However, these previous studies are mostly limited to relatively warm and wet environments where cattle graze on winter-grown cover crops planted into crop residues. Few studies have examined the integration of these practices in the semiarid areas of the northern Great Plains. A 3-year experiment was conducted near Bozeman, MT, to compare the effects of crop rotation diversity and weed management practices imposed during fallow periods (sheep grazing, reduced tillage, and conventional tillage) on spring wheat yields and weed pressure. Management treatments were applied to whole plots, within which the split-plots received crop rotation treatments [continuous spring wheat (CSW) and a 3-year rotation of annual forage, fallow, and spring wheat, where each phase was present in each year]. In the initial 2 years, the realized rotational treatments were wheat–fallow and CSW. In the final year, wheat was grown following all phases of the diversified rotation. Yields were similar among management treatments within the wheat–fallow and CSW rotations. Weed pressure was generally low but perennial weeds were more abundant in grazing-managed, wheat–fallow systems. The integration of livestock into the annual hay crop–fallow–spring wheat rotation was associated with a nearly 30-fold increase in weed pressure and a yield reduction of 51% compared to conventional management. The results suggest that although targeted sheep grazing is a viable alternative to conventional fallow management in CSW and wheat–fallow rotations, successful integration of livestock in diversified cropping systems requires more effective weed manage

Technical Abstract: Crop diversification and integration of livestock into cropping systems may improve the economic and environmental sustainability of agricultural systems. However, few studies have examined the integration of these practices in the semiarid areas of the Northern Great Plains (NGP). A 3-yr experiment was conducted near Bozeman, MT, to compare the effects of crop rotation diversity and weed management practices imposed during fallow periods [sheep (Ovis aries) grazing, reduced tillage, and conventional tillage] on spring wheat (Triticum aestivum L.) yields and weed pressure. Management treatments were applied to replicated whole plots, within which the split-plots received crop rotation treatments [continuous spring wheat (CSW) and a 3-yr rotation of annual forage, fallow, and spring wheat, where each phase was present in each year]. In the initial 2 yr, the realized rotational treatments were wheat–fallow and CSW. In the final year, wheat was grown following all phases of the diversified rotation. Yields were similar among management treatments within the wheat–fallow and CSW rotations. Weed pressure was generally low but perennial weeds were more abundant in grazing-managed, wheat–fallow systems. The integration of livestock into the annual hay crop–fallow–spring wheat rotation was associated with a nearly 30-fold increase in weed pressure and a yield reduction of 51.2% compared to conventional management. The results suggest that although targeted sheep grazing is a viable alternative to conventional fallow management in CSW and wheat–fallow rotations, successful integration of livestock in diversified cropping systems requires more effective weed management practices.