| dc.description.abstract | There are plans to vegetate soil of the former lake Texcoco and use wastewater sludge to provide nutrients.
However, the Texcoco soil is N depleted, so the amount of N available to the vegetation might be
limited and the dynamics of C and N affected. We investigated how emissions of CO2, N2O and N2, and
dynamics of mineral N were affected when different types of N fertilizer, i.e. NH4
+, NO3
−, or unsterilized
or sterilized wastewater sludge, were added to the Texcoco soil. An agricultural soil served as control.
Sewage sludge added to an alkaline saline soil (Texcoco soil) induced a decrease in concentrations of
NH4
+ and NO3
−. Addition of sewage sludge increased the CO2 emission rate > two times compared to
soil amended with sterilized sludge. The NH4
+ concentration was lower when sludge was added to an
agricultural soil for the first 28 days and in the Texcoco soil for 56 days compared to soil amended with
sterilized sludge. Production of N2O in the agricultural soil was mainly due to nitrification, even when
sludge was added, but denitrification was the main source of N2O in the Texcoco soil. Microorganisms
in the sludge reduced N2O to N2, but not the soil microorganisms. It was found that microorganisms
added with the sludge accelerated organic material decomposition, increased NH4
+ immobilization, and
induced immobilization ofNO3
− (in Texcoco soil). These results suggest that wastewater sludge improves
soil fertility at Otumba (an agricultural soil) and would favour the vegetation of the Texcoco soil (alkaline
saline).
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