WATER, AIR AND SOIL POLLUTION : AN INTERNATIONAL JOURNAL OF ENVIRONMENTAL POLLUTION, cilt.234, sa.1, ss.1-22, 2023 (SCI-Expanded)
Although adding organic matter by applying sewage sludge and recycled wastewater in agricultural lands is benefcial for most functions expected
of soils, mainly by improving soil structure and fertility, it is a potential source of carbon dioxide (CO2)
emissions. This study aimed to analyze the changes in
CO2 emissions by season and per unit of organic matter from bare soil with the organic matter added under
recycled wastewater irrigation conditions. Therefore, an experiment in containers was conducted in
a greenhouse with two water types (freshwater and
recycled wastewater) at fve diferent organic matter
levels (control: 1.91%, and then 2.45%, 2.99%, 3.53%,
and 4.07%) by mixing in stabilized sewage sludge.
The experiment was repeated three times in total.
Containers were irrigated a total of ten times at 6-day
intervals. CO2 emissions were directly measured at
the beginning and end, and at 3 days after each irrigation cycle, with an EGM-5 infrared gas analyzer
device. Water (H2O) emissions from the soil, the soil
moisture, and temperatures were also recorded during
the CO2 emission measurements. The results showed
that higher rates of organic matter in soil resulted
in higher CO2 emissions from the soil that linearly
increased with organic matter content for both water
types, while there were lower CO2 emissions per
unit of organic matter. The mean CO2 emissions
with increasing doses were found to be higher by
17.9%, 30.6%, 43.0%, and 56.4%, respectively, compared to the control. Recycled wastewater resulted in
9.5% higher emissions compared to freshwater. The
decreasing amounts of CO2 emissions per unit of
organic matter with increasing doses were determined
to be 8.1%, 17.1%, 24.6%, and 27.2%, respectively,
compared to the control. Increasing organic matter
and irrigation with recycled wastewater increased
soil moisture and temperature values while decreasing H2O emissions from the soil. Strong linear correlations of CO2 emissions with H2O emissions, soil
moisture, and temperatures were determined. Therefore, soil carbon sequestration in irrigated conditions
can be improved by managing soil moisture; thus, the
contribution of the increased organic matter in the
soil to improve soil properties and productivity can be
increased.