Cover crops affect soybean yield components, but not grain quality

Abstract

AbstractCover cropping is mainly used to prevent soil erosion, but the effects of individual cover crops on the subsequent soybean [Glycine max (L.) Merr.] are hardly known. Therefore, two annual field trials with 15 cover crop species and bare fallow as control were conducted in semi‐arid East Austria in 2016 and 2017. Cover crops were sown in July in 3‐ × 10‐m plots in a randomized block design with three replicates and were incorporated in mid‐April before soybean were seeded. Cover crop biomass differed between plant species and year (2016, 626 ± 390; 2017, 84 ± 86.1 g m−2). Aboveground cover crop biomass did not affect soybean establishment, but single cover crop species such as ryegrass (Lolium multiflorum Lam. var. westerwoldicum Wittm.), kidney vetch (Anthyllis vulneraria L.), and corn cockle (Agrostemma githago L.) impeded soybean seeding due to high root densities and prevented germination or fostered outbreak of two‐spotted spider mites (Tetranychus urticae Koch). These three cover crops reduced soybean grain yield by 12–84%. Grain yield was a function of grain density m−2 in a three‐way interaction with year and cover crop treatment, but not by plant or pod density. Protein, oil, and sucrose content of soybean were unaffected by cover crop treatments. Overall, with the exception of ryegrass, kidney vetch, and corn cockle, cover crops can be grown ahead of soybean without any yield loss and can be used for their versatile ecosystem services.