Soil water content data for The Bushland, Texas large weighing lysimeter experiments

Authors: Evett, Steven - Steve; Marek, Gary; Copeland, Karen; HOWELL, SR, TERRY - Retired ARS Employee; Colaizzi, Paul; BRAUER, DAVID - Retired ARS Employee; Ruthardt, Brice

Submitted to: Ag Data Commons
Publication Type: Database / Dataset
Publication Acceptance Date: 7/29/2023
Publication Date: 7/31/2023
Citation: Evett, S.R., Marek, G.W., Copeland, K.S., Howell, Sr, T.A., Colaizzi, P.D., Brauer, D.K., Ruthardt, B.B. 2023. Soil water content data for The Bushland, Texas large weighing lysimeter experiments. Ag Data Commons. https://doi.org/10.15482/USDA.ADC/1526332.
DOI: https://doi.org/10.15482/USDA.ADC/1526332

Interpretive Summary: The scarcity of water resources in the U.S. Southern High Plains is of regional, national and even international concern due to the fact that the region acts as a breadbasket for the nation and world. The majority of agricultural production in this region depends on irrigation, largely dependent on pumping from the Ogallala or High Plains Aquifer, which are yielding less water every year. From 1989 through 2021, scientists at the USDA ARS Conservation & Production Research Laboratory at Bushland, Texas, collected data on water content changes in the soil that can be used to calculate crop water use under irrigated and dryland conditions in the region’s climate, and regionally specific crop coefficients for irrigation scheduling, including reduced coefficients for subsurface drip irrigation that can save water. Crops grown include alfalfa, corn (maize), cotton, sorghum, sunflower, soybean, and winter wheat. However, these data have not been previously publicly available in a readily useable format. Thus, the scientific team has prepared these unique water content data sets for sharing with other scientists and the general public on the USDA National Agricultural Library online data sharing library. These data sets have already been used along with crop growth and yield data, to calculate water use, crop water productivity, and crop coefficients to guide irrigation scheduling and water planning locally and regionally. Public accessibility via the USDA National Agricultural Library will increase their use by other researchers developing more capable water management tools and crop water use and yield computer models.

Technical Abstract: Accurate ET is important for effective irrigation scheduling to improve crop water productivity, irrigation scheme management, long term water resource planning and management, and for use in crop simulation models to improve accuracy of yield estimates. However, all crop ET estimation methods must be tested against ground truth – ET as measured by mass balance in crop fields – and improved so as to estimate ET as accurately as possible. Mass balance measurement of ET depends on solving the soil water balance for a period during which ET is the sum of the change of water stored in the soil profile to well below the root zone, irrigation, precipitation, the sum of any runon and runoff, and any soil water flux into or out of the soil profile. Effective means of measuring the profile change in water storage include the neutron probe and large weighing lysimeters. The USDA ARS weighing lysimeter team at Bushland, Texas, measured ET of various crops beginning in 1989 and continuing to present. These data represent field and lysimeter soil water contents from 1989 through 2021. Data from 2013 through 2021 were from fields under both sprinkler and subsurface drip irrigation. Earlier data represent sprinkler or dryland conditions. This dataset contains soil water content data developed from neutron probe readings taken in access tubes in each of the four large, precision weighing lysimeters and in the fields surrounding each lysimeter 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) beginning in 1989. Readings were taken periodically with a field-calibrated neutron probe at depths from 10 cm to 230 cm (maximum of 190 cm depth in the lysimeters) in 20-cm depth increments. Periods between readings were typically one to two weeks, sometimes longer according to experimental design and need for data. Field calibrations in the Pullman soil series were done every few years. Calibrations typically produced a regression equation with RMSE <= 0.01 m3 m-3. Data were used to guide irrigation scheduling to achieve full or deficit irrigation as required by the experimental design. Data may be used to calculate the soil profile water content in mm of water from the surface to the maximum depth of reading. Profile water content differences between reading times in the same access tube are considered the change in soil water storage during the period in question and may be used to compute evapotranspiration (ET) using the soil water balance equation: ET = (change in storage + P + I + F + R, where P is precipitation during the period, I is irrigation during the period, F is soil water flux (drainage) out of the bottom of the soil profile during the period, and R is the sum of runon and runoff during the period. Typically, R is taken as zero because the fields were furrow diked to prevent runon and runoff during most of each growing season. ET was measured using both weighing lysimeters and the neutron probe. Water management ranged from full irrigation to deficit irrigation and dryland production. Along with those measurements, the team measured crop growth and yield, weather, and irrigation applied. These data are presented, along with cropping calendars for each season, as machine readable files available to the public via the USDA ARS National Agriculture Library (NAL) Ag Data Commons internet site. The cropping calendars contain dates of important field operations, including dates, amounts, and kinds of fertilizers and pesticides applied, harvests and irrigations. The weather data include daily sums and averages as well as 15-minute mean data for all days of the year, and include solar irradiance, air temperature and humidity, wind speed, air pressure, and precipitation. The Bushland data have already been u