The Effect of Conventional, Reduced Tillage, and No-Till System on Cover Crop Aboveground Biomass

Tillage after harvesting main crops can affect the growth of subsequent stubble cover crops (CCs). In order to better understand the factors influencing CC performance, the field study took place at two locations—the cooler, wetter Lukavec site and the warm, drier Ruzyně site—from 2021 to 2023. Here, we examined the effects of moldboard plow (PLO), reduced shallow tillage (RET), and no-till (NOT) treatments on five mixtures of two species: buckwheat and mustard or phacelia; oats and vetch; cannabis and setaria; clover and camelina; and two single-species variants, mustard and phacelia. The ADM was significantly higher in all CC variants under PLO (170 and 81.8 g m−2 at Ruzyně and Lukavec, respectively) compared to RET (84.4 and 52.4 g m−2) and NOT (86.3 g m−2). Under the same tillage treatment, the differences in ADM among CC variants were over 100%, with the highest yields being from mustard (averaging 214.1 and 100.6 g m−2 at Ruzyně and Lukavec), oats and vetch (168.6 and 138.2 g m−2), and mustard and buckwheat (138.8 g m−2 at Ruzyně). Cannabis and setaria achieved the lowest yields (28.9 and 14.9 g m−2). No consistent differences were observed between single-species stands and two-species mixtures. The ADM of mustard under RET and NOT reached 66% and 60% of that under PLO, while phacelia and phacelia–buckwheat achieved between 17 and 44% of the same variable at Ruzyně. Better shoot growth significantly suppressed the growth of volunteer plants from previous cereal crops across all tillage types and at both sites. The study demonstrated that, despite differences in soil and climatic conditions, the aboveground yield of stubble cover crops was lower under reduced-tillage or no-till systems than under conventional tillage. Mustard, alone or mixed with buckwheat, and a mixture of oats and vetch responded to reduced tillage with less yield loss than the other species and mixtures. This results will aid in choosing suitable cover crop species for specific site conditions and tillage systems.