Tatiana F. Rittl;Luiza P. Canisares;Edvaldo Sagrilo;Klaus Butterbach‐Bahl;Michael Dannenmann;Carlos Eduardo Pellegrino Cerr

Soil Science Department, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo 13418-900 (Brazil;Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen 82467 (Germany); Soil Science Department, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo 13418-900 (Brazil);Soil Science Department, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, São Paulo 13418-900 (Brazil);Brazilian Agricultural Research Corporation (Embrapa Meio-Norte), Teresina, Piauí 70770-901 (Brazil)

biochar-amended soil;biochar;the temperature;30;biochar application;sandy soil

Biochar application has the potential to improve soil fertility and increase soil carbon stock, especially in tropical regions. Information on the temperature sensitivity of carbon dioxide (CO2) evolution from biochar-amended soils at very high temperatures, as observed for tropical surface soils, is limited but urgently needed for the development of region-specific biochar management targeted to optimize biochar effects on soil functions. Here, we investigated the temperature sensitivity of soil respiration to the addition of different rates of Miscanthus biochar (0, 6.25, 12.5, and 25 Mg ha(-1)) in two types of soils with contrasting textures. Biochar-amended soil treatments and their controls were incubated at constant temperatures of 20, 30, and 40 degrees C. Overall, our results show that: i) considering data from all treatments and temperatures, the addition of biochar decreased soil CO2 emissions when compared to untreated soils; ii) CO2 emissions from biochar-amended soils had a higher temperature sensitivity than those from biochar-free soils; iii) the temperature sensitivity of soil respiration in sandy soils was higher than that in clay soils; and iv) for clay soils, relative increases in soil CO2 emissions from biochar-amended soils were higher when the temperature increased from 30 to 40 degrees C, while for sandy soils, the highest temperature responses of soil respiration were observed when increasing the temperature from 20 to 30 degrees C. Together, these findings suggest a significantly reduced potential to increase soil organic carbon stocks when Miscanthus biochar is applied to tropical soils at high surface temperatures, which could be counteracted by the soil- and weather-specific timing of biochar application.