Short-term effects of cover crops and compaction on soil properties and soybean production in Illinois

Cover crops (CC) are being actively promoted in Illinois as a tool to improve soil properties and enhance crop performance and yield. Our goals were to assess the short-term ability of radish (Raphanus sativus L. var. longipinnatus) and companion CC to improve (i) soil properties and (ii) soybean (Glycine max L. Merr.) growth and yield following compaction and CC treatments under conventional systems. We used a 6 × 3 factorial arrangement of the CC and compaction treatments in a completely randomized design with two replications in two independent year-locations hereby referred as environments. Cover crop treatments included radish alone "R", and with rye (Secale cereale L.) "RR", triticale (× Triticosecale 'Presto') "RTR", buckwheat (Fagopyrum esculentum L. Moench) "RB", or hairy vetch (Vicia villosa Roth) "RHV", and a control with no cover crop "NCOV". Compaction treatments were no compaction (Nc), and two levels of compaction achieved with a large tractor (LT) or a hauling truck (TK). Compaction was temporarily achieved and disappeared after the CC growing season. Cover crop treatments significantly lowered soil NO₃-N compared to NCOV yet no further effect was evident on soils. Soybean yield for CC treatments were not different from control plots. Results from this study showed that one growing season was not enough time to evidence changes in soil properties related to cover cropping yet they were useful tools for retaining NO₃-N in the system. In addition, following adequate management practices, CC should not affect soybean growth and yield.