0000000000668320
AUTHOR
Blanca González-méndez
Short-term emissions of CO 2 and N 2 O in response to periodic flood irrigation with waste water in the Mezquital Valley of Mexico
Irrigation with waste water adds labile carbon and nitrogen compounds to the soil, and when applied by flooding it rapidly changes the soil's atmosphere and redox potential. In the Mezquital Valley more than 90 000 ha is irrigated with waste water from Mexico City, and enhanced emissions of CO2 and N2O follow each flooding. We measured the emissions of these two gases from a field irrigated periodically with waste water and under three crops, namely alfalfa, rye-grass and maize, using static chambers for 21 months. We also measured emissions from a field growing rain-fed maize before and shortly after two rain events. The data from repeated measurements from the same chambers are correlated…
Changes in soil redox potential in response to flood irrigation with waste water in central Mexico
Irrigation with untreated sewage water adds fresh organic matter to the soil. When it is applied by flooding, as in the Mezquital Valley of Mexico, many of the pores in the soil become temporarily waterlogged and depleted of oxygen, and reduction generates nitrous oxide (N2O) and methane (CH4). We monitored the redox potential, Eh, in the soil at two sites in the Mezquital Valley to discover whether the short-term gaseous emissions matched the changes in Eh. One site is irrigated periodically by flooding with waste water and has alfalfa, rye grass and maize grown in succession; the other site grows maize with water from summer rain only. Each electrode buried in the soil for the purpose pro…