Soil respiration, pH and EC as influenced by biochar

• Main Authors: Tasneem Shah, Sara, Zahir Shah
• Format: Article
• Language: English
• Published: Soil Science Society of Pakistan (SSSP) 2017-05-01
• Series: Soil & Environment
• Subjects: Biochar; pH; EC; microbial activity; gases emission
• Online Access: http://se.org.pk/File-Download.aspx?archivedpaperid=800

Biochar application to agricultural land is gaining significance as a strategy for C sequestration and improving soil health and nutrient cycling. Variable results have been reported for the effect of biochar on CO2 evolution. This study was planned to assess the influence of biochar application on soil respiration (CO2 evolution), soil pH and electrical conductivity (EC) in a silty clay loam soil during lab incubation experiments for a period up to 50 days. Surface soil sample (0-15 cm) was collected from a garden which had been used for growing vegetables for the last many years. The experiment was comprised of four treatments viz., 0, 5, 10 and 20 t biochar ha -1. The samples were incubated at 28 oC and taken out for CO2 measurements after 2, 5 and 10 days and for EC and pH after 0, 5, 10 and 50 days of incubation periods. The rate of CO2 evolution increased significantly with biochar application. During the first 2 days of incubation, the rate of CO2 evolution increased by 13.1% with 5 t, 22.4% with 10 t and 34.6% with 20 t ha-1 biochar over control treatment. The corresponding increases in CO2 evolution were 12.8% with 5 t, 23.3 % with 10 t and 22.1% with 20 t ha-1 of biochar during 5 days, and were 14.3% with 5 t, 30.4% with 10 t and 19.6% with 20 t ha-1 of biochar over control during 10 days of incubation period. Almost similar trend was observed for cumulative CO2 production. The soil EC and pH were also significantly greater in biochar than in the control treatment during all incubation periods. Although biochar application increased CO2 evolution, the %C evolved from added biochar C decreased with increasing levels of biochar as it was 1.74 % with 5 t, 1.66% with 10 t and 0.82% with 20 t ha-1 of the added biochar C during 10 days of incubation period. These results suggested that biochar application increased soil respiration, EC and pH, however, the ratio of the CO2 evolved to total biochar C generally declined with increasing levels of biochar.