Agronomic assessment of cover cropping and tillage practices across environments

Abstract

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. 1 INTRODUCTION Soil degradation has been recognized as a major environmental threat to global food security and human health (FAO, 2015). Among the various causes of soil degradation

Microbial Shifts Following Five Years of Cover Cropping and Tillage Practices in Fertile Agroecosystems

“…Moreover, the high CEC of the present study's soil indicated a greater buffering capacity against pH changes ( Table 1). This innately high CEC would be resilient against changes from CC and tillage [13]. Indeed, a past meta-analysis on CC effects on soil properties reported smaller percentage changes in CEC than those of our results, but the differences in CEC were still not statistically significant [63].…”

“…Unlike the shifts in the soil microbiome we detected, chemical soil properties were only marginally influenced by cover crop rotations and tillage practices, partially because of the innate buffering capacity of the rich Mollisols across the region [13,14,58]. Soil NO 3…”

“…Overall, our results show that cover cropping and tillage benefit copiotrophic decomposers, which was more pronounced with legume-grass CC rotation than grass-only CC. Because legume CC can fix a considerable amount of N until suppression, copiotrophic decomposers compete less with the microbes for soil inorganic N than grass CC [12,13,97]. Under this N surplus, copiotrophs dominate the decomposition and promote a positive priming effect that decomposes SOM and crop residues [98,99].…”

“…The experimental site was established in the fall of 2012 at the Crop Sciences Research and Education Center at Urbana, IL, USA (40 • 03 25.2" N 88 • 13 37.2" W), as part of a larger CC and tillage study [13,14]. The site was level to gently sloping (from 0 to 2%) and spanned a Drummer (70%)-Catlin (10%)-Flanagan (20%) soil association that was dominated by fine-silty, superactive Mollisols [37].…”

“…Cover cropping (CC) benefits agroecosystem by improving soil organic matter (SOM) and water retention [5,6], suppressing weeds [7,8], reducing soil erosion [7], and preventing soil nutrient loss by scavenging excess nutrients [9][10][11][12]. The realization of benefits from CC depends heavily on weather conditions and management practices, such as tillage [13,14]. Tillage usually increases the aeration and temperature, as well as the susceptibility to erosion of the topsoil [15].…”