Soil physical properties affected by biochar addition at different plant phaenological phases. Part I

Soil amendment usage can substantially modify soil structural and hydraulic properties, with the aim of improving its water, air and nutrition management along with crop growth. The purpose of the present study was to investigate the physical changes in soil through different plant growing stages caused by biochar addition to silt loam soil. This research focused on changes in structural stability, and macro- and microaggregate stability. The soils were amended with different amounts of biochar (control with 0, BC0.5 with 0.5%, BC2.5 with 2.5%, and BC5.0 with 5.0% biochar, by weight). Capsicum annuum L. were planted at a two-four leaf stage. Soil samples were taken at 6, 10 and 12 weeks after planting. The results showed increasing macroaggregate stability values with increasing biochar addition; however, higher values were also detectable in control treatments over time. Increased microaggregate stability values were observed during the plant maturing phase and the decrease, which occurred during fruit development was more pronounced. The largest microaggregate stability value was observed in the case of BC2.5 among all treatments, which corresponded better to plant growth rather than to the amount of added biochar. It was also found that the laser diffraction method is a suitable alternative technique to the sieve-pipette method for analysing biochar and biochar-amended soil particle size distribution and structure.