CO2-emission from arable chernozems of western Nransbaikalia

CO₂-Emissions from agrochernozems of dispersed carbonate Tugnui basin and agrochernozems of quasi-clay Yeravninsky basin of western Transbaikalia were studied. To compare CO₂-emissions from soils, the virgin land variants of the same name are taken. The aim of the study is to quantify and comparatively evaluate the production of carbon dioxide from arable chernozems with contrasting temperature and moisture conditions. The measurement of CO₂ fluxes from the soil was carried out by a closed chamber method with a portable infrared CO₂ gas analyzer AZ 7752 (AZ Instrument Corp., Taiwan). CO₂-emissions were largely dependent on hydrothermal conditions. Its minimum at the beginning of the growing season was associated with the effect of low soil temperatures, the maximum was more often noted after precipitation. The peaks of CO₂-emissions coincided with an increase in temperature and humidity from June to early August, in conditions of a lack of readily available moisture, and were also associated with a humidification regime. The limiting factor of the CO₂ flux for quasi-clay chernozems was the soil temperature, for dispersed carbonate chernozems – humidity. It has been established that the total CO₂-emission in arable soils is significantly less than in virgin soils, this is explained by the peculiarities of the agrogenic environment. Arable soils are warmer in summer, and they cool down more and deeper in winter. The transformation of the water regime occurs in the direction of reducing moisture and increasing its contrast during the warm period. The total carbon loss index varies in a series: dispersed-carbonate chernozem → quasi-clay chernozem, virgin soil → arable land.