Impact of different fractions and dosages of bio-char on some agrophysical properties of soddy-podzolic soils

The influence of different dosages and fractions of bio-char on agrophysical properties and aggregate structure of soddy-podzolic soils was studied in 100-day model experiment. Two kinds of soddy-podzolic soils - sand and clay loam - contrasting in texture were investigated. In the experiment greenwood bio-char prepared by industrial methods was used. Bio-char fractions of 3-5 mm and ≤ 2 mm at the dosages of 2 % and 5 % by weight of the soil were used. In several variants of the experiment the bulk density, total water capacity, thermal capacity of dry soil and aggregate size distribution (dry- and wet-sieving) were measured. Soil without the addition of bio-char served as a control. For statistical data processing one-way ANOVA with post-hoc analysis by Tukey's HSD test was applied. As a result, changes in all investigated agrophysical properties of soils were revealed. It was shown that bulk density of both soils was reduced in the variants at 5 % dosage of bio-char regardless of fraction. Significant changes of total water capacity are observed in sandy soil irrespective of the dosage of bio-char. Significant change of total water capacity of clay loam soil was recorded only for the variants with a 5 % dosage of bio-char. The greatest effect on the indicators of thermal capacity in both soils was provided at 5 % dosage of coarse bio-char. The application of bio-char improves the aggregate state and the structure index of clay loam soil as well as increases the coherence of sandy soil, fundamentally not changing the indicators of water resistance of both soils. A significant effect gain in using bio-char at a higher dosage was noted almost for all indicators.