The Bushland, Texas, Alfalfa Datasets

This parent dataset (collection of datasets) describes the general organization of data in the datasets for each growing season (year) when alfalfa (Medicago sativa L.) was grown as a reference evapotranspiration (ETr) crop at the USDA-ARS Conservation and Production Laboratory (CPRL), Soil and Water Management Research Unit (SWMRU), Bushland, Texas (Lat. 35.186714°, Long. -102.094189°, elevation 1170 m above MSL). Alfalfa was grown on two large, precision weighing lysimeters, calibrated to NIST standards (Howell et al., 1995). Each lysimeter was in the center of a 4.44 ha square field on which alfalfa was also grown (Evett et al., 2000). The two fields were contiguous and arranged with one (labeled northeast, NE) directly north of the other (labeled southeast, SE). See the resource "Geographic Coordinates, USDA, ARS, Bushland, Texas" for UTM geographic coordinates for field and lysimeter locations. Alfalfa was planted in Autumn 1995 and grown for hay in 1996, 1997, 1998, and 1999. The resource "Agronomic Calendar for the Bushland, Texas Alfalfa Datasets", gives a calendar listing by date the agronomic practices applied, severe weather, and activities (e.g. planting, thinning, fertilization, pesticide application, lysimeter maintenance, harvest) in and on lysimeters that could influence crop growth, water use, and lysimeter data. These include fertilizer and pesticide applications. There is one calendar, from before planting in autumn 1995 to after final harvest in 1999, for the NE and SE lysimeters and fields. There were 4 harvests each year except 1998 when 5 harvests were taken. Irrigation was by linear move sprinkler system equipped with pressure regulated low pressure sprays (mid-elevation spray application, MESA). Irrigations were managed to replenish soil water used by the crop on a weekly or more frequent basis as determined by soil profile water content readings via field-calibrated (Evett and Steiner, 1995) neutron probe from 0.10- to 2.4-m depth in the field. Lysimeters and fields were planted to the same plant density, row spacing, tillage depth (by hand on the lysimeters and by machine in the fields), and fertilizer and pesticide applications. Weighing lysimeters measured relative soil water storage to 0.05 mm accuracy at 5-min intervals, and the 5-min change in soil water storage was used along with precipitation, dew and frost accumulation, and irrigation amounts to calculate crop evapotranspiration (ET), reported at 15-min intervals. Each lysimeter was instrumented to sense wind speed, air temperature and humidity, radiant energy (incoming and reflected, typically both shortwave and longwave), surface temperature, soil heat flux, and soil temperature, all at 15-min intervals. Instruments used changed from season to season, thus subsidiary datasets and data dictionaries for each season are required. The Bushland weighing lysimeter research program is described by Evett et al. (2016), and lysimeter design is described by Marek et al. (1988). Important conventions concerning the data-time correspondence, sign conventions, and terminology specific to the USDA ARS, Bushland, TX, field operations are given in the resource "Conventions for Bushland, TX, Weighing Lysimeter Datasets".

There are 5 datasets in this collection. Common symbols and abbreviations used are defined in the resource "Symbols and Abbreviations for Bushland, TX, Weighing Lysimeter Datasets". Datasets consist of Excel (xlsx) files. Each xlsx file contains an Introductory tab that explains the other tabs, lists the authors, describes conventions and symbols used, and lists instruments used. The remaining tabs in a file consist of dictionary and data tabs. The 5 datasets are:

• Growth and Yield Data for the Bushland, Texas Alfalfa Datasets
• Weighing Lysimeter Data for The Bushland, Texas Alfalfa Datasets
• Soil Water Content Data for The Bushland, Texas, Large Weighing Lysimeter Experiments
• Evapotranspiration, Irrigation, Dew/frost - Water Balance Data for The Bushland, Texas Alfalfa Datasets
• Standard Quality Controlled Research Weather Data – USDA-ARS, Bushland, Texas

See README for descriptions of each dataset.

The soil is a Pullman series fine, mixed, superactive, thermic Torrertic Paleustoll. Soil properties are given in the resource titled "Soil Properties for the Bushland, TX, Weighing Lysimeter Datasets". Land slope in the lysimeter fields is <0.3% and topography is flat. Mean annual precipitation is ~470 mm, the 20-year pan evaporation record indicates ~2,600 mm Class A pan evaporation per year, and winds are typically from the South and Southwest. Climate is semi-arid with ~70% (350 mm) of the annual precipitation occurring from May to Sep, during which period the pan evaporation averages ~1520 mm. These datasets originate from research on crop water use (ET), reference ET methods for irrigation scheduling, crop coefficients for use in ET-based irrigation scheduling based on a reference ET, crop growth, yield, harvest index, and crop water productivity as affected by irrigation method, timing, amount (full or some degree of deficit), agronomic practices, cultivar, and weather. Prior publications have described the facilities and research methods (Evett et al., 2016), and have focused on alfalfa ET (Todd et al., 1998), the Bowen ratio method applied to alfalfa ET (Todd et al., 2000), comparison of alfalfa ET to ETr calculated from weather data (Evett et al., 1998, 2000), new methods of calculating ETr (Evett et al., 2010, 2012; Lascano and Evett, 2007, 2010; Lascano et al, 2010), and crop water productivity. Crop coefficients (Howell et al., 2006) have been used by ET networks for irrigation management. The data have utility for testing simulation models of crop ET (Colaizzi et al., 2005; Thorp et al., 2019), growth, and yield by several universities and for testing, and calibrating models of ET that use satellite and/or weather data.

Resources in this dataset:

• Resource Title: Geographic Coordinates of Experimental Assets, Weighing Lysimeter Experiments, USDA, ARS, Bushland, Texas. File Name: Geographic Coordinates, USDA, ARS, Bushland, Texas.xlsx Resource Description: The file gives the UTM latitude and longitude of important experimental assets of the CPRL. Locations include weather stations (SWMRU and CPRL), large weighing lysimeters, and corners of fields within which each lysimeter was centered. There were four fields designated NE, SE, NW, and SW, and a weighing lysimeter was centered in each field. The SWMRU weather station was adjacent to and immediately east of the NE and SE lysimeter fields.

• Resource Title: Conventions for Bushland, TX, Weighing Lysimeter Datasets. File Name: Conventions for Bushland, TX, Weighing Lysimeter Datasets.xlsx Resource Description: Descriptions of conventions and terminology used in the Bushland, TX, weighing lysimeter research program.

• Resource Title: Symbols and Abbreviations for Bushland, TX, Weighing Lysimeter Datasets. File Name: Symbols and Abbreviations for Bushland, TX, Weighing Lysimeter Datasets.xlsx Resource Description: Definitions of symbols and abbreviations used in the Bushland, TX, weighing lysimeter research datasets.

• Resource Title: Agronomic Calendar for the Bushland, Texas Alfalfa Datasets. File Name: 1995-1999 Alfalfa Calendar.xlsx Resource Description: The calendar lists by date the agronomic practices applied, severe weather, and activities (e.g., planting, thinning, fertilization, pesticide application, lysimeter maintenance, harvest) in and on lysimeters that could influence crop growth, water use, and lysimeter data. These include fertilizer and pesticide applications. There is one calendar, from before planting in autumn 1995 to after final harvest in 1999, for the NE and SE lysimeters and fields.

• Resource Title: Soil Properties for the Bushland, TX, Weighing Lysimeter Datasets. File Name: Bushland_TX_soil_properties.xlsx Resource Description: Soil properties useful for simulation modeling and describing the soil are given for the Pullman soil series at the CPRL. For each soil layer, soil horizon designation and texture according to USDA Soil Taxonomy, bulk density, porosity, water content at field capacity (33 kPa) and permanent wilting point (1500 kPa), percent sand, percent silt, percent clay, percent organic matter, pH, and van Genuchten-Mualem characteristic curve parameters describing the soil hydraulic properties are given. A separate table describes the soil horizon thicknesses, designations, and textures according to USDA Soil Taxonomy. Another table describes important aspects of the soil hydrology and rooting behavior.

• Resource Title: README - Bushland Texas Alfalfa collection. File Name: README_Bushland_alfalfa_collection.pdf Resource Description: Descriptions of the datasets in the Bushland Texas Alfalfa collection.