Location: Soil and Water Management ResearchTitle: Cotton irrigation timing with variable seasonal irrigation capacities in the Texas south plains. Author
|Bordovsky, James - Texas A&M Agrilife|
|Mustian, Joseph - Texas A&M Agrilife|
|Ritchie, Glen - Texas Tech University|
|Lewis, Katie - Texas A&M Agrilife|
Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2015
Publication Date: 8/30/2015
Citation: Bordovsky, J.P., Mustian, J.T., Ritchie, G.L., Lewis, K.L. 2015. Cotton irrigation timing with variable seasonal irrigation capacities in the Texas south plains. Applied Engineering in Agriculture. 31(6):883-897.
Interpretive Summary: Texas High Plains has become an important region for cotton production; however future production may be limited by dwindling water availability from the underlying Ogallala Aquifer. Irrigation capacity for a given field often changes within a growing season due to seasonal depletion of the aquifer, in season changes in crop irrigation needs in dry years, or consequences of irrigation volume limits imposed by irrigation district rules. Scientists from Texas A&M AgriLife Research and Texas Tech University in the ARS led Ogallala Aquifer Program conducted a field experiment to determine cotton productivity under irrigation capacities common to the Texas High Plains. Results indicated that attempting to store water in the soil profile by irrigating in excess of the evapotranspiration rate early in the growing season reduced seasonal irrigation water use efficiency. These results clearly indicate that irrigation water can be restricted early in the growing season with little effect on yield while improving irrigation water efficiency.
Technical Abstract: Within the Ogallala Aquifer Region of Texas, the irrigation capacity (IC) for a given field often changes within a growing season due to seasonal depletion of the aquifer, in season changes in crop irrigation needs in dry years, or consequences of irrigation volume limits imposed by irrigation district rules. Irrigation planning is further complicated by erratic seasonal rainfall. A field experiment was conducted from 2010 to 2013 to determine cotton (Gossypium hirsutum L.) irrigation productivity using a range of ICs common to the Texas South Plains during three irrigation periods. The treatments included in season ICs (maximums of 0, 3.2, and 6.4 mm per day) in combination with irrigation periods determined by accumulated growing degree days (GDD15.6) and were designated as period 1 (P1= emergence to 525 GDD15.6), period 2 (P2= 525 to 750 GDD15.6), and period 3 (P3 greater than 750 GDD15.6). Combinations of these factor levels resulted in 27 irrigation treatments with applications made by the low energy precision application (LEPA) method. Annual rainfall totals ranged from 137 to 557 mm over the four years. In all years, results indicated that attempting to store water in the soil profile, or irrigating in excess of the cotton evapotranspiration rate, early in the growing season reduced seasonal irrigation water use efficiency (SIWUE), and sometimes yield, compared to treatments with limited or no early irrigations. Treatments with 0 and 3.2 mm per day ICs during P1 used up to 20% less seasonal irrigation with minor yield loss (less than 2%) compared to treatments with ICs of 3.2 and 6.4 mm per day, respectively. This was attributed to water losses caused by evaporation in the region (high wind, low humidity, and high temperatures) from May through June as well as excessive early season vegetative growth resulting in elevated crop transpiration later in the season that could not be met with available IC. Cotton irrigation during the period beyond accumulative cotton GDD15.6 = 750 was critical for acceptable irrigated yield and high SIWUE. These results provide information to optimize cotton water use in an area with declining irrigation capacity, an advective climate, and increasing pumping restrictions.