Extreme hydrological events, for instance extended drought and wet-dry cycles, happen more and more frequently all over the world due to climate change and can impact soil microbial activities in agriculture soils. Biochar is charcoal produced by pyrolysis of biomass and has been proposed as a soil amendment for agricultural soils to enhance soil carbon sequestration. At the same time, biochar addition to soil can have some agricultural benefits, such as increase water and nutrient retention. Due to its highly aromatic structure, biochar has a long average residence time in soils. Therefore, it is important to consider the impacts of biochar amendment under different combinations of environmental factors. Extreme hydrological events caused by climate change could strongly influence the effects that biochar amendment has on soil microbial community. Our research aims to discuss the interrelationship between agriculture soil moisture history, biochar and/or biosolid amendment and soil microbial communities.

A soil incubation experiment was conducted over 12 weeks under controlled temperature with three soil moisture treatments: simulated wet, drought, and wet-dry cycles with two biosolid amendments of 0, 10 t/ha biosolid and three biochar amendment treatments of 0, 10, 20 t/ha biochar under each of the soil moisture treatments. Walnut shell biochar, a high surface area biochar, was used in this incubation experiment. Our preliminary results show that 1) total phospholipid fatty acids (PLFA) is decreased by biochar amendment and increased by biosolid amendment, 2) total PLFA decreased by soil moisture decrease and increase of soil pH, 3) %fungi PLFA increased and %bacteria PLFA decreased by biochar amendment. These results indicate that biochar has the potential to negatively impact on some soil microbes in agriculture soil in the context of extreme hydrological processes. The combined effect of biochar, soil properties and climate conditions needs to be carefully considered before promoting widespread application of biochar to agriculture soils.

See more from this Division: SSSA Division: Soil Biology & Biochemistry
See more from this Session: Climatic Stress Effects on Microbial Communities and Agroecosysem Functioning