Cover crops for late summer in organic cereal rotations

E. Ann Clark*, Les Eccles, and Karen Maitland

Abstract:
Cover crops perform system service functions, such as weed control or retention of soil N. Cover crop species differ in their suitability for specific applications. A study at the Guelph Organic Test Site of the Ignatius Jesuit Center compared 7 common and novel crops - 5 in each of 2003 and 2004 - for reliability in weed control, biomass addition, and N immobilization, with carryover effects monitored from a winter cereal harvest in 2005.

The best and most consistent service provider was sorghum-sudan, although buckwheat and oilseed radish also excelled in weed control and biomass. None of the legumes - soy, red clover, sweetclover, and hairy vetch - were uniform or effective in weed control. Legume N was equal or superior to that from buckwheat and oilseed radish, although inferior to that from sorghum-sudan. However, yield of fall rye in 2005 was lower following sorghum-sudan than other species, perhaps due to the large volume of wide C:N residues incorporated prior to rye planting in the fall. The lower straw and total yields, high HI, and high grain N content of rye following sorghum-sudan suggest a sparser stand. Following with a spring rather than a winter cereal may capture the system services of sorghum-sudan without reducing subsequent grain yield.


Source
Organic Agriculture Research Symposium held at the 25th Guelph Organic Conference, University of Guelph, January 2006


Author Locations & Affiliations
Plant Agriculture, University of Guelph and the Ecological Farmers Association of Ontario
* Corresponding Author: Ann Clark eaclark@uoguelph.ca


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