Jornada Basin LTER Research

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Dataset: Transect Soil Water Content


   File description including attribute definitions: data_Jornada_012002_transect_soil_water_content
   Original Investigator: Peter Wierenga
   Data contact: John Anderson
   Duration: 1982 - ongoing
   Dataset ID: 210012002
   DOI: 10.6073/pasta/80ba5570ee6c21847e07c2ef988df391
   Abstract:

Soil water content measurements (cm3 H2O / cm3 soil) at 5 depths at each of 89 (2" O.D. diameter) aluminum access tubes on the Control transect and at every 5th station on the nitrogen fertilized Treatment transect using a neutron probe (Campbell Model 503DR Hydroprobe). Access tubes are installed such that there are 6 inches of tube aboveground. Stations are 30 meters apart. Measurements are taken at 30cm, 60cm, 90cm, 110cm, and 130cm. Neutron probe readings taken in 6 lysimeters along transects are also included. 5 standard readings are taken at beginning and end of each transect, and after every 20 stations. Measurements taken at 2 week intervals from April 1982 to 1987, monthly since.


   Additional information:

LTER-I control and treatment transects (2.7 km long parallel transects) extending from College Playa to base of Mt. Summerford on NMSU College Range. Stations located at 30 meter intervals. Access tube within 1 meter of station marker.

   Methods:

Field data sheets : Week 18 - Week 214 (April 1982-January 1986) Datalogger : Week 216 - present (February 1986 - present) Campbell Model 503DR Hydroprobe (neutron probe with data logger)

   Methods:

Soil water content measurements are made at 5 depths at each of 90 (2" O.D. diameter) aluminum access tubes on the Control transect and at every 5th station on the nitrogen fertilized Treatment transect using a neutron probe (Campbell Model 503DR Hydroprobe). Stations are 30 meters apart. Measurements are taken at 30cm, 60cm, 90cm, 110cm, and 130cm. Measurements taken at 2 week intervals from April 1982 to 1987, monthly since. If any readings were not measured, the missing depths have a zero in the raw data set of count values. These are changed to "." in converted water content data set. Calculated water content values equal to less than zero are changed to zero in converted water content data set. Converted soil water content values are a volume/volume relationship and represent cm3 water/cm3 soil. Count rates are recorded for each depth and access tube. Five standard count rates are taken before and after, and after reading each 20 access tubes. Count rates are also taken in 6 lysimeters along the transect, at the above listed depths. If any readings were not made, the missing readings have a zero (0) in the raw data set of count values. These are changed to "." in converted water content data set. Calculated water content values equal to less than zero ( <0 ) are changed to zero in converted water content data set. Data from neutron probe data logger is dumped to disk. Raw count data is then converted to water content using a Fortran program called WC1#3900.FOR (water content for LTER-I transect using probe with serial # ending in 3900). Water content data is then sorted by i.d. number using a LOTUS 123 macro found in WC1_SORT.WQ1 which creates final version of water content data set for the month in a separate file. Two files per month are saved: raw count data (mmddyy-1.RAW; ex. 121189-1.RAW) and calculated/sorted data which is appended to the year's data (TRANSWCyy.DAT; ex. TRANSWC89.DAT).

   Maintenance:

Every 2 weeks: April 1982 - Feb 1987 Monthly: Mar 1987 - present

   Quality Assurance

1982 - Aug 1989. Raw data was processed with a LOTUS Symphony spreadsheet macro written by Dr. P. Wierenga's personnel. Raw data converted to soil water content values with macro. Sep 1989 - present. FORTRAN program used to convert raw data as downloaded from hydroprobe data logger to soil water content (cm3 water/cm3 soil). See attached for program (SWC#3900.FOR for probe serial #H32073900 and SWC#7085.FOR for probe serial #H36097085). Programs are same except for regression equation used in conversion.