Soil Organic Matter Management: The Roles of Residue Quality in C Sequestration and N Supply - Sustainable Management of Soil Organic Matter - page 187

OMDynamics in Soils M.L. Luna-Guidoet al.

3.12

Organic Matter Dynamics
in Soils of the Former Lake
Texcoco, Mexico

M.L. L UNA-GUIDO , I. B ELTRÁN-HERNÁNDEZ ,
F. M ERCADO-GARCIA , C. S IEBE , J.A. C ATT AND
L. D ENDOOVEN

Laboratory of Soil Ecology, Department ofBiotechnologyand
Bioengineering,CINVESTAV-IPN, Mexico City

Introduction

Lake Texcoco (east of Mexico City, Mexico) was drained from the 17th
century onwards to reduce the possibility of flooding of the city. An area
was created with little or no vegetation as the soils from volcanic origin are
saline or saline-sodic with a pH locally > 11. The natural drainage is poor,
with a water table at 0.25-1 m depth. Weathering is progressive, and high
evaporation (2000 mm) increases the salt concentration of the soil solution.
The bare soil is eroded readily by wind and causes severe dust pollution
over Mexico City. Pathogens carried in the dust aggravate the nuisance. A
programme was therefore started at the beginning of the 1970s to vegetate
the former lake, and a drainage system was installed to lower the water
table. Irrigation with sewage effluent was used to remove salts and improve
aeration in the root zone. A plan was also developed to apply sewage sludge
to fertilize the pioneer vegetation.
The application of 1000 mg of glucose C kg −1 soil did not result in
a significant increase in CO 2 production within 70 days of an aerobic
incubation at 22 C, nor did it do so in soils drained for 1 and 5 years

(Beltrán-Hernández et al ., 1999). However, application of glucose to a soil
drained for 8 years resulted in a significant increase in CO 2 production. To
detemine the reason for this phenomenon, we applied 14 C-labelled glucose
and investigated its fate in soil sampled from four locations characterized by
different periods of drainage and vegetation density.

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