The Effect of Black Medic (Medicago lupilina , cv George) and Kura Clover (Trifolium ambiguum) Cover Crops on Arbuscular Mycorrhizal Fungi Colonization and Nutrient Uptake in Flax (Linum usitatissium).
Marie-Soleil Turmel, University of Manitoba, Dept. Plant Science, 222 Agriculture Bldg., Winnipeg, MB R3T 2N2, Canada, Martin Entz, University of Manitoba, University of Manitoba, Dept. of Plant Sciences Fort Garry, Winnipeg, MB R3T 2N2, CANADA, Mario Tenuta, Univ of Manitoba, 362 Ellis Bldg.-Dept of Soil Sci, 362 Ellis Bldg.-Dept of Soil Sci, Winnipeg, MB R3T 2N2, CANADA, William May, Indianhead Agri Research, PO Box 156, PO Box 156, Indian Head, SK S0G 2K0, CANADA, and Guy Lafond, Agriculture and Agri-Food Canada, Indian Head Research Farm, RR#1 Gov. Rd, Box 760, Indian Head, SK S0G 2K0, CANADA.
Cover crops improve agricultural ecosystems in many ways such as reducing nitrogen leaching, erosion and nitrogen volatilization, adding organic matter to the soil, nitrogen fixation and enhancing beneficial soil biota. Arbuscular mycorrhizal fungi (AMF) are beneficial soil microorganisms that form symbiotic relationships with many important agricultural plants. AMF symbiosis increases the phosphorus and micronutrient uptake and growth of the plant by increasing the volume of soil explored with fungal hyphae. Both Black Medic (Medicago lupilina, cv George) and Kura Clover (Trifolium ambiguum) are self-regenerating, nitrogen-fixing and mycorrhizal. The purpose of our research was to determine if Black Medic and Kura Clover cover crops enhance mycorrhizal activity and subsequent uptake of phosphorus and micronutrients. Long term Black Medic trials were established in 2001 at the University of Manitoba Research Station (UMRS) in Winnipeg, Manitoba, and the Indian Head Research Farm, Saskatchewan and the Kura Clover trial was established in 2002 at the UMRS. Flax (Linum usitatissium) was used as the main crop due to its high dependency on AMF mediated phosphorus uptake at low and intermediate soil phosphorus concentrations. In 2005 the medic cover crop increased early phosphorus and micronutrient uptake at the lowest nitrogen level in Indian Head. There was no significant difference in flax grain yield with and without black medic. At Indian Head there were significantly more arbuscules (AMF P exchange structures) in the medic treatment at the intermediate N level whereas the Winnipeg trial had fewer arbuscules in the medic treatment. There were no significant differences in the phosphorus and micronutrient uptake at the Winnipeg trial. Information from the 2006 fields trials and the Kura Clover trial will be discussed.