Effects of adding water on seasonal variation of soil nitrogen availability under sandy grasslands in semi-arid region

Water is usally thought of a limiting factor for the restoration of semi-arid ecosystem. In the growing season of 2006, a study was conducted to determine the effects of modeling precipitation on seasonal patterns in concentrations of soil-available nitrogen and to describe the seasonal patterns in soil nitrogen availability and seasonal variation in the rates of net nitrogen mineralization of topsoil at Daqinggou ecological station in Keerqin sand lands, Inner Mongolia Autonomous Region, China. Manipulation of water (80 mm) was designed to be added to experiment plots of sandy grasslands in dry season. Water addition (W) treatment and control (CK) treatment were separately taken in six replications and randomly assigned in 12 plots (4 m×4 m for each) with 2-m buffers betweens. Results showed that the content of soil inorganic nitrogen and net nitrogen mineralization rate were not affected by adding water in sandy grassland of Keerqin sand lands. Net nitrogen mineralization rates ranged from 0.5 μg·μg−1·month−1 to 4 μg−1g−1·month−1. The highest values of soil inorganic nitrogen and net nitrogen mineralization occurred on October 15 in control plots. The seasonal changes of soil inorganic nitrogen contents exhibited “V” shape pattern that was related to seasonal patterns of soil ammonium-N (ascending trend) and nitrate-N transformation (descending trend).

[1]  I. Burke,et al.  Influence of climate variability on plant production and N-mineralization in Central US grasslands , 2002 .

[2]  Cheng Guang-sheng,et al.  Effects of soil moisture and soil depth on nitrogen mineralization process under Mongolian pine plantations in Zhanggutai sandy land, P. R. China , 2005, Journal of Forestry Research.

[3]  I. Burke,et al.  Biogeochemistry in a shortgrass landscape: control by topography, soil texture, and microclimate. , 2000 .

[4]  M. Oorschot,et al.  Experimental manipulation of water levels in two French riverine grassland soils , 2000 .

[5]  S. Schaeffer,et al.  Responses of soil nitrogen dynamics in a Mojave Desert ecosystem to manipulations in soil carbon and nitrogen availability , 2003, Oecologia.

[6]  William K. Lauenroth,et al.  REGIONAL AND TEMPORAL VARIATION IN NET PRIMARY PRODUCTION AND NITROGEN MINERALIZATION IN GRASSLANDS , 1997 .

[7]  Robert W. Howarth,et al.  Nitrogen limitation on land and in the sea: How can it occur? , 1991 .

[8]  O. Sala,et al.  Differential Controls of Water Input on Litter Decomposition and Nitrogen Dynamics in the Patagonian Steppe , 2006, Ecosystems.

[9]  R. D. Evans,et al.  Pulse additions of soil carbon and nitrogen affect soil nitrogen dynamics in an arid Colorado Plateau shrubland , 2005, Oecologia.

[10]  D. Tilman,et al.  Species effects on nitrogen cycling: a test with perennial grasses , 1990, Oecologia.

[11]  A. Porporato,et al.  Water pulses and biogeochemical cycles in arid and semiarid ecosystems , 2004, Oecologia.

[12]  R. J. Raison,et al.  Methodology for studying fluxes of soil mineral-N in situ , 1987 .

[13]  R. Ryel,et al.  Root responses and nitrogen acquisition by Artemisia tridentata and Agropyron desertorum following small summer rainfall events , 2003, Oecologia.

[14]  W. Schlesinger,et al.  Nitrogen loss from deserts in the southwestern United States , 1990 .

[15]  I. Burke,et al.  Nitrogen availability through a coarse-textured soil profile in the shortgrass steppe. , 2000 .

[16]  J. Stark,et al.  Microbial dynamics and carbon and nitrogen cycling following re-wetting of soils beneath two semi-arid plant species , 2004, Oecologia.

[17]  P. Kuikman,et al.  Nitrogen availability and uptake by grassland in mesocosms at two water levels and two water qualities , 1997, Plant and Soil.

[18]  W. Parton,et al.  Primary Production of the Central Grassland Region of the United States , 1988 .

[19]  M. Caldwell,et al.  A large ephemeral release of nitrogen upon wetting of dry soil and corresponding root responses in the field , 1997, Plant and Soil.

[20]  D. Hooper,et al.  Nitrogen limitation in dryland ecosystems: Responses to geographical and temporal variation in precipitation , 1999 .