Laboratory determination of soil water retention curve of biochar treated soils

Bc. Kamila Folaufová

Master's thesis

Abstract:

Recently, potential of biochar amendment into soil has gained a considerable interest globally. Biochar is a carbon rich material produced mainly by slow pyrolysis. Biochar treatment is supposed to reduce bulk density, improve soil structure, and soil hydrophysical properties. Improvement of plant water availability is one of the main reasons why biochar is applied into the soils while biochar amended soils could also reduce the amount of irrigation water required by crops, or help to the crops to overcome drought periods in rainfed agriculture. Therefore, adding biochar into soil can positively affect crop yield. Main objective of the thesis was to determine and evaluate soil water retention curve for selected soils from the Czech Republic mixed with different amount of biochar in laboratory, and the biochar itself. The study was conducted on repacked soil core samples with specific attention to maintaining the dry bulk density of the soils in order to reduce the natural soil heterogeneity and thus allow a comparison of the effects of various biochar admixtures on the selected soils. Three soils were chosen: first, graded fine silica sand; second, silty loam chernozem soil which was collected in Prague-Suchdol; and third, clay loam luvisol from Prague-Uhříněves. Three concentrations of biochar were used: control treatment without any biochar addition and two treatments with biochar admixture, 0.001 g.g-1 and 0.01 g.g-1, which correspond roughly with field application rates 2.6 or 26 t.ha-1, respectively. Each treatment was done at least three-times. Evaporation method using Hyprop device (UMS GmbH.) was employed to measure the soil water retention curve. All data were processed and statistically evaluated. Results showed small increase of water retention in case of the higher biochar concentration, in average 3.5% by volume on luvisol, while effect on sand was not statistically significant (P=0.05), yet noticeable, and effect on chernozem was not noticeable. Objectives of the thesis were fulfilled and results provided important information for practical use and future studies.

Keywords

soil water retention curve, biochar, carbonisation

Language used: English

Date on which the thesis was submitted / produced: 18. 4. 2017

Thesis defence

• Supervisor: Ing. Markéta Miháliková, Ph.D.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Master programme / field:
Natural Resources and Environment / Natural Resources and Environment