Restoration of Eroded Lands with Biochar as Soil Amendment in South Dakota

Biochar is produced from incomplete pyrolysis of plant biomass. Due to the unique properties of biochar such as a higher number of micropores, surface area and carbon content, and recalcitrant nature of carbon, biochar is hypothesized to improve physical and hydrological properties of soil. This study assesses the impact of biochar on soil organic carbon, physical and hydrological properties of two landscape positions under a corn (Zea mays L.)-soybean (Glycine max L.) rotation. Three types of biochar including corn stover, ponderosa pine (Pinus ponderosa Lawson and C. Lawson) wood residue, and switchgrass (Panicum virgatum L.) were applied in the field and compared with control and manure treatments. Data showed that biochar significantly affected the pH and labile carbon fraction at the eroded landscape position for 0-7.5 cm surface depth. Biochar can increase the pH of sandy loam acidic soil due to liming effect of biochar. The labile part of biochar may be degraded by microorganisms as suggested by significant differences in labile carbon of soil with biochar addition at the eroded landscape position. However, biochar, manure, and mixture of manure and biochar significantly impacted the hydrological properties of biochar. This suggested that specific properties of biochar including large number of inner pores and high surface area could be helpful to improve soil water retention (SWR) and water infiltration. Impacts of biochar varied for different years and soil types due to differences in feedstock used, and surface changes occurred in soil. Further field studies are required to determine changes in soil physical properties using higher rates than 10 Mg ha-1 (1% w/w) and different types of biochar. Also, longterm studies are needed in the future to better understand the effect of biochar on soil properties and carbon fractions, and results from our study need to be evaluated under different climatic conditions