wAbstract
@Nitrate (NO3-1) accumulates in
Haplocambids and Torrifluvents in inset fan and fan skirt positions
in central Nevada. The soils store as much as 17,600 kg of NO3-1 N ha-1 within the upper
208 cm. This paper provides an explanation. These Holocene soils
receive NO3-1 N from mineralization
of organic matter and other NO3-1
N sources including snowmelt. The NO3-1
is delivered to soils in the first part of snowmelt in run-off
from the higher surfaces. The last part of the melt and the run-off,
when sufficient, serve to move the NO3-1
out of the root zone. Winter fat (Krascheninnikovia lanata),
the most valuable winter grazing plant in the Great Basin, is
the common plant on NO3-1 N rich
soils. The soils are loamy or sandy and lack horizons restricting
water penetration or biological denitrification zones. Hence,
some NO3-1 is free to leach deeply
past plant roots. Playas, wet floodplains, deeply gullied inset
fans and well-developed soils accumulate little NO3-1
except where the latter soils are capped by desert pavements and
rarely, if ever become saturated with water. Soils with argillic
or petrocalcic horizons or duripans on summits of alluvial fan
remnants loose NO3-1 through denitrification,
or incorporate it in plants, commonly accumulating less than 50
kg of NO3-1 N ha-1.
These soils however do accumulate salt as shown by their shadscale
saltbush Atriplex confertifolia, bud sagebrush Picrothamus
desertorum, and four-wing saltbush Atriplex conescens
shrub cover.
Keywords: Holocene soils; Nitrate accumulation; Desert soils;
Inset fans; Great Basin; Snowmelt; Denitrificationx
1. Introduction
2. Soils and methods
3. Results and discussion
@3.1. Relationship of NO3-1
accumulation to landform
@3.2. Relationship of NO3-1 accumulation
to soil morphology
@3.3. Relationship of NO3-1 accumulation
and the water added through run-on to kind of vegetation
@3.4. Importance of Snowmelt to NO3-1
accumulation in the soils and sediments of Central Nevada
@3.5. Environmental relationships
Acknowledgements
References