Effects of Cover Crop Mixtures on Soil Health and Spring Oat Productivity

Growing cover crop mixtures is a sustainable agriculture tool that helps to reduce fertilizer use and, at the same time, ensures lower environmental pollution. The aim of this research is to assess the biomass of the aboveground part of cover crop mixtures and the nutrients accumulated in it and to determine their influence on the soil properties and productivity of spring oats (Avena sativa L.). The biomass of the aboveground part of cover crop mixtures of different botanical compositions varied from 2.33 to 2.67 Mg ha−1. As the diversity of plant species in cover crop mixtures increased, the accumulation of nutrients in the aboveground part biomass increased, and the risk of nutrient leaching was reduced. The post-harvest cover crop mixture TGS GYVA 365, consisting of eight short-lived and two perennial plant species, significantly reduced the mineral nitrogen content in the soil in spring and had the strongest positive effect on organic carbon content. Post-harvest cover crop mixtures TGS GYVA 365 and TGS D STRUKT 1 did not affect the content of available potassium in the soil but significantly reduced the content of available phosphorus. All tested cover crop mixtures, including the undersown TGS BIOM 1 and the post-harvest mixtures TGS D STRUKT 1 and TGS GYVA 365, reduced soil shear strength and improved soil structure, although the reduction was not statistically significant for TGS D STRUKT 1. Cover crop mixtures left on the soil surface as mulch had a positive effect on the chlorophyll concentration in oat leaves, number of grains per panicle, and oat grain yield. A significant positive correlation was found between oat grain yield and several yield components, including crop density, plant height, number of grains per panicle, and grain mass per panicle. These findings highlight the potential of diverse cover crop mixtures to reduce fertilizer dependency and improve oat productivity under temperate climate conditions.