To survey inorganic nitrogen concentrations of soils associated with
mesquite (Prosopis glandulosa) and several grass habitats, 10 sites
were established at the Jornada Basin in 1986. Sites include USDA
Mesquite Dunes (MD_USDA), USDA Between Dunes (BD_USDA), IBP Grama
Grassland (GG_IBP), USDA Grama Grassland (GG_USDA), LTER Arroyo
Mesquite (AM_LTER), LTER Fluff Grass (FG_LTER), LTER Grama Grassland
(GG_LTER), LTER Playa Mesquite (GG_LTER), USDA Sporobolus/ Gutierrezia
(SG_USDA), USDA Mesquite Grassland (MG_USDA). Soil samples were
collected to 20 cm or to hard pan, whichever came first. At FG_LTER,
samples were collected on the lower grassland control transect from
fluff grass clumps. At GG_LTER, GG_USDA, GG_IBP, samples were
collected from the upper grassland control transect from black grama
clumps. GG-USDA is classified as a grazed site, while GG_Ibp is
classified as a grazing exclosure. At SG_USDA, samples were collected
from sporobolus/Gutierrezia clumps. SG_USDA is dominated by these
grasses though mesquite was observed to be increasing in this site.
Mesquite samples were taken from AM-LTER and PM_LTER, which had few to
no detectable hardpans. Nitrogen mineralization of soils was measured
for up 28 weeks following Stanford and Smith, 1972, Nitrogen
Mineralization Potentials of Soils. Briefly, an incubation procedure
was utilized to describe the relationship between cumulative N and
incubation periods. Incubation continued for 28 weeks at 350 C, where
mineralized nitrogen was removed by leaching with 0.01 M CaCI2 at 0, 1
2, 4, 8, 12, 16, 20, 24, and 28-week intervals. The N value was then
estimated from the cumulative amounts of nitrogen mineralized under
these conditions. This data set contains the week of analysis, sample
number, site, and inorganic nitrogen (mg-N/kg-dry soil).