Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 7/5/2000
Publication Date: N/A
Technical Abstract: Nitrate-nitrogen (NO3-N) loading from the Upper Midwest has been identified as a contributing factor to the hypoxic zone in the Gulf of Mexico. Nitrate losses through subsurface tile drainage under row crop systems often are in the range of 20 to 100 kg N/ha in the Upper Midwest. This experiment was initiated to determine whether NO3-N loss through subsurface tile lines could be reduced by introducing a fall-seeded cover crop following corn (Zea mays) in a corn-soybean (Glycine max) rotation. The experiment was conducted in southern Minnesota on a Webster clay loam (Typic Endoaquoll) soil. Winter rye (Secale cereale) was planted in the fall of 1998 and 1999. Weather conditions between fall 1998 and spring 1999 resulted in optimum growing conditions for the rye. During 1999, the rye cover crop reduced water loss from subsurface tile lines with cover crop treatments by 23% and lowered NO3-N loss by 50% compared with the corn-soybean rotation without the cover crop. Weather conditions during the fall of 1999 and spring of 2000 were dry, limiting rye growth. Water loss from subsurface tile lines occurred for a brief period in late spring 2000. Nitrate loss from subsurface tile lines from these 2 years of contrasting environmental conditions will be presented in the context of the historical weather record.