Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2020
Publication Date: 10/30/2020
Citation: Baumhardt, R.L., Marek, G.W., Brauer, D.K. 2020. Trends in runoff from dryland, cropped fields on the Texas High Plains, and implications for their management. Frontiers in Sustainable Food Systems. 4. Article 529319. https://doi.org/10.3389/fsufs.2020.529319.
Interpretive Summary: As water available for irrigation from the Ogallala Aquifer decreases, dryland farming will need to be more productive and capturing precipitation as soil moisture is essential for successful dryland farming in semi-arid regions. However, runoff is a loss of precipitation that is not an input to increase soil moisture. Therefore, understanding the factors affecting runoff from cropped fields is important. ARS scientists from Bushland, TX, analyzed runoff frequency and volume using data from 1990-2009 from a long-term wheat-sorghum-fallow rotation. The likelihood that a rainfall will generate runoff increased with increasing rainfall depth such that all storms in excess of 50 mm induced runoff. Fortunately such storms only occur about once every 18 months. These results are of interest to hydrologists and crop related scientists trying to minimizing runoff.
Technical Abstract: Capturing precipitation as soil moisture is essential for successful dryland crop production, especially in semi-arid regions. Runoff is a loss of precipitation that does not result in increased soil moisture. Therefore, understanding the factors affecting runoff from cropped fields is important to successful farming. Runoff frequency and volume were assessed using data from 1990-2009 from a long-term wheat-sorghum-fallow rotation near Bushland, Texas (USA), an area with an annual precipitation of approximately 500 mm and pan evaporation rate of over 2,000 mm. The likelihood that a rainfall event will generate runoff increased with increasing rainfall volume such that all storms in excess of 50 mm yielded runoff. Runoff volume also increased with storm intensity. Rainfall in the preceding week was positively related to runoff volume. Runoff tended to be greater in no-till plots as compared to stubble mulched plots. During El Nino and La Nina phases of the El Nino-Southern Oscillation the number of precipitations during the months of December through February and November through January, respectively tended to be higher and lower, prospectively. There also was a tendency for rainfall events during the EL Nino phase to be of greater volume. However, the data did not support the hypothesis that greater winter rainfall with the El Nino event was associated with greater runoff. Therefore, greater rainfall during the El Nino phases should have been available for crop production. These results are discussed with regarding crop management practice for the Texas High Plains.