Agronomic assessment of cover cropping and tillage practices across environments

Cover crops (CCs) are considered one of the few agronomic strategies to help reduce environmental pollution, while improving soil properties. However, the use of tillage could negate those benefits entirely. Therefore, the goal of this study was to monitor soil properties and cash crop yields from five different CC rotations compared to fallow controls throughout Illinois. A split-block arrangement of tillage (chisel tillage vs. no-till) and CC rotations (six levels) in a randomized complete block design with four replications was set within each phase of the corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation at six locations, spanning 2-5 yr. Spring biomass was greatest in the CC rotations with cereal rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), and annual ryegrass (Lolium multiflorum Lam.) due to the four times greater survival percentage. Rotations with annual ryegrass reduced soil nitrate compared to bare fallows. Yet, the freshly added CC biomass only produced minimal increases in soil organic matter (SOM) compared to the other CC species. This rotation also reduces corn yields as is commonly observed when growing a grass CC species before a grass cash crop (corn). Chisel tillage was found to increase corn yields and reduce soil P levels compared to no-tilled plots regardless of CC rotation. In contrast, soybean yields were not affected by CCs or tillage options. With few choices of CCs that can overwinter in Illinois, our study provides necessary information to evaluate CC management practices and re-evaluate our current strategies.