Impact of Biochar on the Physical Properties of Soil Under Corn-Soybean Rotation.

The incorporation of pyrogenic carbon rich biochar materials has been recently found to ameliorate physical and hydrological properties of soils. These biochars have unique surface morphology (high porosity with large inner surface area) that is hypothesized to influence soil physical properties. In a two-year on-farm study at Brookings, South Dakota, USA, biochar was incorporated into surface soils and measured the impacts on soil bulk density, pH, EC, and carbon fractions. Treatments included biochars produced from carbon optimized gasification of corn stover (Zea mays L.), Ponderosa pine (Pinus ponderosa Lawson and C. Lawson) wood residue, and switchgrass (Panicum virgatum L.); manure; a mixture of manure and pine wood biochar; and no amendment. Amendments were applied once at 10 Mg/ha rate to a Maddock soil (Sandy, Mixed, Frigid Entic Hapludolls) located in an eroded upper landscape position and a Brookings soil (Fine-Silty, Mixed, Superactive, Frigid Pachic Hapludolls) located in a depositional landscape position. The cropping system was a corn and soybean (Glycine max L.) rotation. Auger samples from both landscape positions were taken in 0-7.5, and 7.5-15 cm depths to measure the various soil parameters. Intact core samples were taken from two depths 0-7.5 and 7.5-15 cm depths for measuring bulk density. Preliminary data showed that in both soils, application of biochar and manure+biochar significantly increased soil pH during second year for 0-7.5 cm depth at both landscapes . Similar, there were significant differences in EC of the soil between the treatments before the planting of Corn in first year and after the harvest of Soybean in second year. Pine wood biochar and manure+biochar significantly decreased soil bulk density after harvest of soybean for both depths but only at depositional landscape. Carbon fractions data is under process that also will be presented in the talk. The preliminary data showed that biochar impacted soil surface properties but more study is needed to determine the long-term impacts of biochar application on soil surface physical properties