Combinations of pearl millet and brown mustard influence soil communities associated with potato yield

Abstract Aims Crop rotations are key to conditioning the soil biotic community that underpins agricultural productivity. For instance, mustards and pearl millet have the potential to alter soil biota and suppress soil diseases prior to a cash crop. Here we explore the effects of various combinations of brown mustard and pearl millet rotational treatments on potato yield, soil and root associated biota. Methods Brown mustard (var. Caliente-199) and pearl millet (var. CFPM-101) were grown in all possible pairwise rotational combinations and in mixtures two years prior to potato to assess their impact on root lesion nematodes (RLN) and Verticillium dahliae in the soil and the root microbiome of potato. Treatments included an intensive two-year potato-barley rotation and two-year perennial reduced tillage treatments of barley underseeded with a red clover–timothy mixture and a diverse crop mixture. Results Potato yield increased significantly with greater aboveground biomass of pearl millet produced in previous years. The potato root associated microbiome varied among cropping treatments which strongly corresponded with both potato yield and pearl millet biomass. V. dahliae was highest and the potato disease symptoms progressed faster in soils following potato. RLN only increased in both the two-year perennial treatments, likely due to the presence of host crops which resulted in the lowest potato yield. Conclusions Pearl millet grown within two years prior to potato can significantly support potato yields by limiting RLN population growth and conditioning the potato root associated microbiome.