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United States Department of Agriculture

Agricultural Research Service

Research Project: Management Strategies to Sustainably Intensify Northern Great Plains Agroecosystems

Location: Northern Great Plains Research Laboratory

Title: Perennial crop phase effects on soil fertility

Authors
item Liebig, Mark
item Hendrickson, John
item Tanaka, Donald -

Submitted to: Proceedings Great Plains Soil Fertility Conference
Publication Type: Proceedings
Publication Acceptance Date: February 1, 2014
Publication Date: March 4, 2014
Citation: Liebig, M.A., Hendrickson, J.R., Tanaka, D.L. 2014. Perennial crop phase effects on soil fertility. p. 72-77. In: Shaver, T. (Ed.) Proc. Great Plains Soil Fertility Conf. Vol. 15. Denver, CO. 4-5 March 2014. Inter. Plant Nutr. Inst., Brookings, SD.

Interpretive Summary: Use of perennial forages in crop rotations can increase subsequent yields of annual crops, reduce synthetic inputs, and improve soil quality. Despite these known benefits, there is limited information in the northern Plains regarding agronomic and environmental outcomes associated with the use of perennial forages in cropping systems. Given this context, a study was initiated at the USDA-ARS Northern Great Plains Research Laboratory near Mandan, ND to evaluate effects of five perennial forages (alfalfa, intermediate wheatgrass, switchgrass, intermediate wheatgrass-alfalfa mixture, switchgrass-alfalfa mixture) on soil properties. Perennial forage effects on soil properties were modest, with treatments only affecting soil nitrate in the 0-12 inch depth. Unfertilized alfalfa and alfalfa-grass mixtures tended to possess greater soil nitrate compared to fertilized grasses, particularly as stand age increased. Correspondingly, spring wheat grain yield following alfalfa and alfalfa-grass mixtures tended to increase with longer perennial phases. Preliminary findings from this study suggest incorporation of alfalfa and alfalfa-grass mixtures in northern Plains cropping systems can serve to improve soil fertility and increase grain yield of annual crops.

Technical Abstract: There is a need to develop agricultural management systems that enhance soil fertility and reduce reliance on external inputs. Perennial phases in crop rotations are effective at restoring soil fertility, though little information exists in the northern Great Plains regarding soil-based outcomes resulting from different perennial crop types and phase lengths. In 2006, a study was initiated at the USDA-ARS Northern Great Plains Research Laboratory near Mandan, ND to evaluate effects of five perennial forages (alfalfa, intermediate wheatgrass, switchgrass, intermediate wheatgrass-alfalfa mixture, switchgrass-alfalfa mixture) on soil properties. Perennial forages were found to have a negligible effect on soil properties at 0-30 cm, with treatments only affecting soil nitrate. Unfertilized alfalfa and alfalfa-grass mixtures tended to possess greater soil nitrate compared to fertilized grasses, particularly as stand age increased. Correspondingly, spring wheat grain yield following alfalfa and alfalfa-grass mixtures tended to increase with longer perennial phases. Spring wheat grain yield was positively associated with soil nitrate over the course of the study (r=0.63; P=0.0029). Incorporation of alfalfa and alfalfa-grass mixtures in northern Plains cropping systems can serve to improve soil fertility and increase grain yield of annual crops.

Last Modified: 7/23/2014
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