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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS

Location: Agricultural Systems Research Unit

Title: Integrating sheep grazing into wheat-fallow systems: Crop yield and soil properties

Authors
item Lenssen, Andrew -
item Sainju, Upendra
item Hatfield, Patrick -

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 14, 2013
Publication Date: May 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/56105
Citation: Lenssen, A.W., Sainju, U.M., Hatfield, P. 2013. Integrating sheep grazing into wheat-fallow systems: Crop yield and soil properties. Field Crops Research. 146: 75-85.

Interpretive Summary: Conventional tillage and herbicide applications are the general practices used to control weeds during fallow periods in the wheat-fallow system. Both of these practices can increase cost of wheat production by increasing the cost of fuel or chemical used for weed control. While tillage can reduce soil quality by increasing organic matter mineralization and soil erosion, herbicide application can be a health hazard to both human and animal health. Targeted sheep grazing can be an alternative practice to control weeds, thereby reducing fuel and chemical use. We conducted a study near Bozeman, Montana, USA, comparing three fallow weed management systems in two crop rotations from 2005 to 2008. Fallow weed management systems were conventional tillage, chemical fallow (herbicide application), and sheep grazing. The two crop rotations were summer fallow-spring wheat and summer fallow-winter wheat. In late fall, chemical-fallow treatment had greater crop residue cover and gravimetric soil water content than did tilled- or grazed-fallow. At the 0 to 15-cm depth, soil had lower bulk density in chemical- and tilled-fallow than in grazed fallow. Similarly, soil NO3-N, Ca, SO4-S concentrations and EC were lower following grazed-fallow than tilled-fallow, but Na concentration was higher following grazed-fallow than tilled- or chemical-fallow. Following spring and winter wheat, soil properties were not influence by treatments. Grain yield was greater in winter wheat than in spring wheat but the trend reversed in protein concentration. Although soil properties varied among treatments, fallow management system had little influence on yield or quality of spring and winter wheats. Sheep grazing during fallow periods had limited impact on subsequent wheat yield and quality, and is a suitable practice for weed and residue management in wheat-fallow systems.

Technical Abstract: The two predominant systems for weed management in summer fallow are tillage with a field cultivator or multiple applications of broad spectrum herbicides with zero tillage. Both systems are based on substantial use of off farm resources. Strategic grazing of sheep may allow grain growers to more sustainably manage crop residues, volunteer crop, and other weeds during fallow periods. We conducted a study near Bozeman, Montana, USA, comparing three fallow weed management systems in two crop rotations from 2005 to 2008. Fallow weed management systems were conventional tillage, chemical fallow (herbicide application), and sheep grazing. The two crop rotations were summer fallow-spring wheat and summer fallow-winter wheat. In late fall, chemical-fallow treatment had greater crop residue cover and gravimetric soil water content than did tilled- or grazed-fallow. At the 0 to 15-cm depth, soil had lower bulk density in chemical- and tilled-fallow than in grazed fallow. Similarly, soil NO3-N, Ca, SO4-S concentrations and EC were lower following grazed-fallow than tilled-fallow, but Na concentration was higher following grazed-fallow than tilled- or chemical-fallow. Following spring and winter wheat, soil properties were not influence by treatments. Grain yield was greater in winter wheat than in spring wheat but the trend reversed in protein concentration. Although soil properties varied among treatments, fallow management system had little influence on yield or quality of spring and winter wheats. Sheep grazing during fallow periods had limited impact on subsequent wheat yield and quality, and is a suitable practice for weed and residue management in wheat-fallow systems.

Last Modified: 8/21/2014