Planting green of spring cover crops in the eastern US Great Plains: Biomass and soil benefits

Abstract

Information on soil benefits and biomass production of spring‐planted grass cover crops (CCs) that are terminated late (planting green) is limited. We quantified the impact of spring‐planted oat ( Avena sativa L.) and barley ( Hordeum vulgare L.) CCs, terminated about 3 weeks after soybean [ Glycine max (L.) Merr.] planting on CC aboveground and root biomass production, soil properties, and soybean yield in the eastern US Great Plains for 3 years. Oat (2.80 ± 1.01 Mg ha ⁻¹ ) produced more aboveground biomass than barley (1.54 ± 0.44 Mg ha ⁻¹ ), while total root biomass production was 1.40 ± 0.26 Mg ha ⁻¹ for oat, 1.16 ± 0.19 Mg ha ⁻¹ for barley, and 0.27 ± 0.15 Mg ha ⁻¹ for no CC in the 0‐ to 30‐cm soil depth. CCs did not affect soil bulk density, sorptivity, particulate organic matter, organic matter, C, N, available P, exchangeable K, and microbial properties in any year but increased the proportion of 0.25–0.5 mm aggregates by 7%–8% and reduced the proportion of <0.25 mm aggregates 8%–10% in Year 3. The latter suggests that at least two seasons may be needed for CCs to improve soil aggregation. Soybean yield remained unaffected. Short experimental duration (3 years), long‐term no‐till management, and fine‐textured and high‐organic‐matter soil at the site likely limited CC effects on soils. Overall, planting green of spring‐planted CCs for 3 years increases biomass input, but soil benefits may not be fully realized in early years.