Optimizing Water Use for Three Old World Bluestems in the Texas High Plains

Project Overview

GS02-012
Project Type: Graduate Student
Funds awarded in 2002: $10,000.00
Projected End Date: 12/31/2004
Matching Non-Federal Funds: $6,000.00
Region: Southern
State: Texas
Graduate Student:
Major Professor:
Dr. Vivien Allen
Texas Tech University

Annual Reports

Commodities

  • Agronomic: general hay and forage crops, grass (misc. perennial), hay

Practices

  • Animal Production: feed/forage
  • Crop Production: irrigation
  • Education and Training: demonstration, focus group, workshop
  • Farm Business Management: budgets/cost and returns, agricultural finance
  • Soil Management: soil chemistry
  • Sustainable Communities: urban agriculture

    Abstract:

    Agriculture in the Texas High Plains is challenged by rapid depletion of ground water. Warm-season grasses offer opportunities for grazing but information is needed on comparative water use efficiencies. Three old world bluestems (Bothriochloa caucasica, ‘Caucasian’; B. ischaemum, ‘Spar’; and B. bladhii, ‘Dahl’) were grown under dryland and low, medium, and high irrigation levels to determine water use efficiency, yield, and nutritive value during 2001 to 2003. Amount of water applied in the high treatment was 100% replacement of potential evapotranspiration (PET) minus precipitation. Medium and low treatments were spaced evenly and calculated as 66 and 33% of the high treatment; the dryland treatment received no irrigation (0%). In 2003, Caucasian was more water use efficient than Spar; no differences were observed among species in 2001 and 2002. Caucasian and Dahl consistently outyielded Spar by about 30%. Maximum yields resulted from a high irrigation level but forage nutritive value was higher under low irrigation. These data provide information for optimizing water use, nutritive value, and for selecting an optimum between irrigation water invested and total nutrient yield.

    Introduction

    Water use efficiency (WUE) of forage grasses is crucial in determining species suitable for implementation into forage/livestock systems in semi-arid environments. Previous researchers have defined WUE as dry matter (DM) yield per ha divided by the amount of water added to achieve that yield. Other authors have inferred WUE from plant-physiological parameters such as gas exchange and leaf water relations. Old world bluestem species are widely grown in the semi-arid Texas High Plains but information is lacking concerning their water use – yield relationships under semi-arid conditions when compared at one location.

    Previous research has suggested a 10 to 20% higher productivity of Caucasian bluestem compared with B. ischaemum types. The more recently released old world bluestem WW-B. Dahl showed higher DM yields under dryland conditions than a variety of warm-season grasses in central Texas. With rising concerns regarding sustainability of agricultural systems dominating the Texas High Plains due to a declining supply of irrigation water, introduced warm-season grasses such as Bothriochloa species may offer alternatives for designing viable crop/forage/livestock systems. A variety of old world bluestem species, primarily B. ischaemum types, were grown widely on Conservation Reserve Program (CRP) land to minimize soil erosion and degradation. Previous research showed that Dahl can serve as a key component in functioning crop/forage/livestock systems while reducing water and fertilizer needs. This species has been shown to support higher animal gains than B. ischaemum types (unpublished data, Texas Tech University). Also, Caucasian is perhaps more cold tolerant given its origin and could be an alternative for areas further north in the Southern High Plains.

    Declining water reserves in the Ogallala Aquifer require research efforts to find solutions for alternative agricultural systems. The Southern High Plains of Texas may be environmentally well suited to establish forage-based systems while reducing overall water use. However, little is known regarding the water use of old world bluestems grown under conditions of the Texas High Plains. Thus, our objective was to test Caucasian, Spar, and Dahl regarding their WUE, DM yield, and nutritive value.

    Project objectives:

    The overall objective was to determine forage growth and nutrient yield per unit of added water (water use efficiency) for three warm-season perennial grasses in Southern High Plains.

    Specific objectives included:
    To determine the influence of dryland, and low, medium, and high irrigation levels on dry matter (DM) yield, water use efficiency (WUE; kg DM ha-1 mm-1 water), nutritive value, plant morphology including percentage live/dead and leaf/stem ratio of Caucasian, Spar, and Dahl bluestems.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.