M.S. Level Student
University of Illinois at Urbana-Champaign
ceg7@illinois.edu
Advised by Dr. Zhongjie Yu and Mr. Lowell Gentry

Fine Tuning Cereal Rye Management Ahead of Soybean Production

Cover crops are being evaluated as nitrogen (N) catch crops in tile drained regions of the Upper Midwest. In Central Illinois, producers can be very successful using cereal rye as an overwintering cover crop, especially ahead of soybean production; however, it is unknown what is the relationship of cereal rye biomass production and tile nitrate reduction. This study evaluates the relationship among cereal rye biomass, biomass N, and tile nitrate reduction. Drawing from two 6-yr studies, a range of cereal rye biomass was produced (<0.5 ton/A to 2.75 tons/A) ahead of soybean production. No observable reduction in tile nitrate occurred during a cold spring in 2018 when cereal rye biomass was <0.5 tons/A, whereas cereal rye biomass of 2.75 tons/A (containing 50 lbs of N/A) in 2020 decreased the annual flow weighted mean nitrate concentration of the tile to 1.5 ppm (nearly an 80% reduction in tile nitrate). However, this large amount of cover crop biomass was difficult to no-till plant and led to a soybean yield loss (-13%). Cover crop biomass amounts between 1 and 2 tons/A may represent the best compromise between nitrate reduction potential and risk to soybean production.