This data set was collected to provide data for comparison of the losses of dissolved nitrogen and phosphorus in the runoff from grass- and shrub- dominated plots in the Jornada Basin of southern New Mexico. This summary dataset contains the following columns for the intershrub plots: Plot: the identification number for the 6 grassland plots. Q: the mean rate of discharge during the entire experiment, obtained by dividing the total runoff by l800 sec. The units are cubic centimeters per second. Total N yield: the total yield of dissolved nitrogen discharged from the plot during the duration of the experiment. The units are grams per square meter per l800 sec. This yield has been adjusted, by subtracting the content of total dissolved N applied in the simulated rainfall. Organic N yield: the yield of dissolved organic N, as above. Inorganic N yield: the yield of NH4-N plus NO3-N discharged from the plot during the duration of the experiment, as above. Total P yield: the yield of total dissolved P discharged from the plot during the duration of the experiment. The units are grams per square meter, per l800 sec. Organic P yield: the yield of dissolved organic P, as above. Inorganic P yield: the yield of PO4-P discharged from the plot during the duration of the experiment. Fines: the percent of the plot surface covered by materials < 2.0 mm diameter Gravel: the percent of the plot surface covered by materials > 2.0 mm diameter Vegetation: the percent of the plot surface covered by vegetation. Litter: the percent of the plot surface covered by plant litter. Slope: the plot in degrees

This data set was collected to provide data for comparison of the losses of dissolved nitrogen and phosphorus in the runoff from grass- and shrub- dominated plots in the Jornada Basin of southern New Mexico. This dataset contains the following columns: Plot: the identification number for the plots, which are grouped for grass, shrub or intershrub areas. Fill Time: the time in seconds used to collect an individual sample of discharge from the plot. Time: the time in minutes (from the beginning of the rainfall simulation) at which each individual collection of discharge began. In each case, the first time listed is the time at which discharge was first observed. Time b/w samples: the time in seconds between the beginning the collection of a given sample of discharge and the beginning of the next collection. Q: the rate of discharge during each collection, in cubic centimeters per second. AveQ/time: the total discharge during an interval in cubic centimeters. For example, the discharge between 16 and 20 minutes is calculated as the mean of the discharge at l6 and 20 minutes multiplied by 4 minutes. InorgN-rain (adjusted inorganic N): the concentration of NH4-N + NO3-N in the discharge sample collected, corrected for the sum of the concentration of these ions in the simulated rainfall applied. Concentration is given in milligrams per liter for N contained in the sum of these forms. Analysis for NH4-N and NO3-N was performed using the Bran-Luebbe Traacs 800 Autoanalyzer, as detailed in Schlesinger et al. (l999). Total N-rain (adjusted total N): the concentration of total dissolved N in the discharge sample collected, corrected for the concentration of total dissolved N in the simulated rainfall applied. Concentration is given in milligrams per liter of total dissolved N in the sample. The concentration of total dissolved N was performed using the Traacs 800 Autoanalyzer, following a persulfate digestion of the sample, as detailed in Schlesinger et al. (l999). OrgN-rain (adjusted organic N): the concentration of N contained in dissolved organic forms, corrected for the concentration of dissolved organic N in the simulated rainfall applied. Dissolved organic N is calculated as the difference, in any sample, between the total dissolved N and the sum of NH4-N and NO3-N. Values are in milligrams per liter. Total P-rain (adjusted total P): the concentration of total dissolved phosphorus, corrected for the concentration of total dissolved phosphorus in the simulated rainfall applied, both in milligrams per liter. Org-P-rain (adjusted org P): the concentration of dissolved organic phosphorus, corrected for the concentration of dissolved organic phosphorus in the simulated rainfall applied, both in milligrams per liter. Inorg-N-rain (adjusted inorganic N), the yield in grams of NH4-N plus NO3-N in the discharge collected. TotalN-rain (adjusted total N), the yield in grams of total dissolved N in the discharge collected. OrgN-rain (adjusted organic N), the yield in grams of forms of dissolved organic N in the discharge collected. Total P-rain (adjusted total P), the yield in grams of total dissolved phosphorus in the discharge collected. OrgP-rain (adjusted organic P), the yield in grams of forms of dissolved organic phosphorus in the discharge collected. InorgN-rain (adjusted inorganic N) load, is the rate of loss, in grams per second, of the sum of NH4-N plus NO3-N during the period of the sample collection. Total N-rain (adjusted total N) load, is the rate of loss, in grams per second, of total dissolved N during the period of the sample collection. OrgN-rain (adjusted organic N) load, is the rate of loss, in grams per second, of dissolved organic N during the period of the sample collection. Total P-rain (adjusted total P) load, is the rate of loss, in grams per second, of total dissolved P during the period of the sample collection. Org-P-rain (adjusted organic P) load, is the rate of loss, in grams per second, of dissolved organic P during the period of the sample collection.

**The objective of the present research was to determine whether there have been changes in the structure and function of the surface (0-20cm) soil system, the zone most affected by litter decomposition, which is associated with the rapid movement of mesquite from historical habitats (arroyo and playa fringe) into recent habitats (grassland and dunes). We hypothesized that the soil biotic communities would be poorly developed in the recent mesquite habitats because of lower soil C and nutrient concentrations. As a result of these differences we predicted lower rates of net N mineralization in the soils from recent mesquite habitats. Data set contains analyses for gravimetric soil moisture, pH, phosphate, total Kjeldahl nitrogen, total phosphorus, NO3-N nitrogen mineralization, total inorganic nitrogen, NH4-N nitrogen mineralization, organic carbon, inorganic carbon, total roots, tap roots, intermediate roots, and fine roots.

In the spring of 1982, as part of the establishment of the Jornada Long-Term Ecological Research site in southern New Mexico, a 135 ha portion of a 1500 ha, internally drained, watershed was exclosed from grazing by domestic livestock. Prior to exclosure the watershed, as well as the rest of the Jornada basin, had been moderately to heavily grazed for the past 100 years. Concurrent with grazing, the vegetation had undergone a dramatic change from desert grassland, with an almost continuous cover of C4 perennial grasses, to isolated patches of the original grassland in a mosaic with desert shrub dominated plant communities (Buffington and Herbel, 1965). Three parallel transects (2.7 km in length) run from the middle of the College Playa up into the foot of Mt. Summerford. The Control transect is to the west, the Treatment transect on the east side of the Control transect, and the Alternate Control to the east of the Treatment transect. Each transect is 30 meters wide with a 45 meter buffer zone between each transect. The Treatment transect was treated annually until 1987 with NHNO3 in a concentration equal to 10g N/m2.Soil mineralization was examined on the control and fertilized treatment transects in association with the vegetation biomass study. In 1989, soil properties were measured. This Dataset contains soil moisture correction factor, sample weight, total inorganic nitrogen (NO3+NO2-N), and nitrogen in ammonium (NH4-N) for Week 0 of nitrogen mineralization potentials. This sampling is complete.

Soil water potential recorded on data sheets for psychrometers along treatment and control transects every 5 stations at 5cm, 15cm and 30cm depths. Soil temperatures at these depths and calibration slope and intercept for each psychrometer are included in order to convert microvolt readings to -bar readings.