Field simulation of wet and dry years in the Chihuahuan desert: soil moisture, N mineralization and ion-exchange resin bags
Citation
Frederick M Fisher, and Walter G Whitford, Field simulation of wet and dry years in the Chihuahuan desert: soil moisture, N mineralization and ion-exchange resin bags: .
Summary
Irrigation and rain-out shelters were used to simulate precipitation patterns of wet and dry years in the northern Chihuahuan Desert. Irrigation provided approximately double the long-term average monthly precipitation. Rain was excluded during the wet season, July-October, to simulate a dry year. N net mineralization in laboratory incubations was undectable at calculated water potentials less than -1 MPa. Witb increasing moisture, mineralization gradually rose to the highest observed rates near field capacity. There was no mineralization maximum at moisture contents below field capacity. Irrigation significantly increased the water potential and rainfall exclusion reduced water potentials to less than-8 MPa. The general absence of [...]
Summary
Irrigation and rain-out shelters were used to simulate precipitation
patterns of wet and dry years in the northern Chihuahuan Desert.
Irrigation provided approximately double the long-term average monthly
precipitation. Rain was excluded during the wet season, July-October, to
simulate a dry year. N net mineralization in laboratory incubations was
undectable at calculated water potentials less than -1 MPa. Witb
increasing moisture, mineralization gradually rose to the highest
observed rates near field capacity. There was no mineralization maximum
at moisture contents below field capacity. Irrigation significantly
increased the water potential and rainfall exclusion reduced water
potentials to less than-8 MPa. The general absence of important
irrigation effects may have resulted from the high natural precipitation
during the experiment or because irrigation inputs were insufficient to
increase microbial activity during very dry periods. Precipitation
exclusion reduced ion capture during the warm-wet season. After allowing
precipitation inputs to resume, NH4+-N capture was increased in the
cool-dry seasons of both 1987–1988 and
1988–1989. NH4+-N capture more than doubled that
predicted from the overall covariance of moisture input and ion capture,
suggesting increased availability of N. An unusually hot, dry period in
May and June 1989 was followed by a threeto fourfold increase in the
warm-wet season NO3-+NO2-N capture compared to 1988. These data suggest
that short droughts of about 3 months in length (both simulated and
natural) increased N availability relative to moisture availability.
Published in Biology and Fertility of Soils, volume 20, issue 2, on
pages 137 - 146, in 1995.
