Six Warm Season Grasses Grown Under Three Irrigation Levels in the Texas Panhandle.

The Ogallala Aquifer is declining each year, with agriculture as the major consumer of water. With increasing concerns of water availability in the region, alternatives to corn and other high water use crop production are needed. The objective of this study was to determine yield, water use efficiency, and nutrient composition of six warm-season grasses produced under dryland, limited, and full irrigation conditions. The study was initiated in 2007 at the Texas AgriLife Research field lab near Etter, TX. Six grass species were planted: Texoka buffalograss, Haskell sideoats grama, WW Spar old world bluestem, Blackwell switchgrass, Hatchita blue grama and Wrangler bermudagrass. Each treatment combination appeared in three replicated plots arranged in a split-plot randomized complete block design with irrigation level as the main plot and grass species as the sub-plot. Irrigation level was determined using the reference evapotranspiration (ET) value of bermudagrass estimated by the North Plains ET Network for the Etter location. Full irrigation plots received water equal to the bermudagrass ET value minus rainfall in the preceding seven days. Limited irrigation plots received one-half of the amount of water for full irrigation plots. During the growing season, irrigation water was applied in one or two applications each week as needed. Plots were fertilized as needed based on soil sample analysis. Each year, plot were harvested four times during the growing season to estimate dry matter yield. A subsample from each plot was collected for nutrient analysis. Soil core samples were collected at the beginning of the growing season and after the last harvest to determine total water use and water use efficiency. Total water use (ET) was calculated as the sum of soil water balance, irrigation, and rainfall values. Water use efficiency (WUE) was determined as the ratio of dry matter yield and seasonal ET. An irrigation by grass interaction was detected for total season dry matter yield (P = 0.003). WUE differed among irrigation levels (P = 0.01) and grass species (P < 0.0001).