Effects of biochar and cover crops on physical properties of two soils in Ohio

Applying biochar (BC) and integrating cover crops (CCs) into crop rotations may enhance soil health. However, studies on the combined effects of these practices on soil physical health are scant. Therefore, this study evaluated the effects of BC, CC, and their combined (BC + CC) application on the physical properties of the medium and fine-textured soils in Ohio. In the fall of 2020, 10 Mg ha⁻¹ of pine (Pinus L.) wood chips derived BC was applied. Rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) were planted as CC in 2021 and 2022, respectively. Soil physical properties: bulk density, penetration resistance (PR), water retention, and wet aggregate stability were assessed in fall 2023. Note that 2 years of winter CCs alone did not generate evident effects on any soil's physical properties. However, adding BC and BC + CC improved some specific soil properties, with effects varying by soil texture. In the medium-textured soil, BC reduced soil PR from 1.18 MPa in the unamended control to 0.89 MPa at 7.5-cm depth, while BC + CC increased wet aggregate mean weight diameter by 0.6 mm, reaching 4.1 mm compared to the control for 0- to 10-cm depth. In the fine-textured soil, BC increased soil moisture retention at field capacity from 0.36 to 0.39 cm³ cm⁻³ and plant available water from 0.13 to 0.16 cm³ cm⁻³ in 0- to 5-cm depth. The BC + CC reduced PR by 32% to 0.93 MPa compared to control at 7.5-cm soil depth. Overall, this study highlights the potential of combining BC and CC to improve soil physical health, paving the way for improved soil management practices.