Use of Guar (Cyamopsis tetragonolaba (L.) Taub) for cover crop rotation and green manuring

Project Overview

Project Type: On-Farm Research
Funds awarded in 2006: $15,000.00
Projected End Date: 12/31/2007
Region: Southern
State: Texas
Principal Investigator:
Dr. Russell Wallace
Texas A&M University AgriLife Extension

Annual Reports


  • Agronomic: general silage crops


  • Crop Production: cover crops, crop rotation, nutrient cycling
  • Production Systems: general crop production
  • Soil Management: green manures, organic matter, soil quality/health

    Proposal abstract:

    Sustainable practices help to maintain an owner- operated farming system by optimizing management of natural resources. Crops which have multiple uses (i.e. as cover crop rotations and green manure crops) are an integral part in sustainable farming systems allowing farms to be more efficient (Sullivan, 2003). Environmental and economic concerns for introducing new multi-use crops into production on the Texas High Plains are crop monoculture, soil erosion, limited water, and fields low in fertility and organic matter. An associated economic concern is limited income markets for the farmer. The main crop on the Texas High Plains is cotton; annual production is approximately 3.7 million acres grown as cotton following cotton (Plains Cotton Cooperative Association, 2004). Monocultures contribute to disease and insect buildup. The lack of crop rotation with green manure crops increases soil erosion, leaves low organic matter, poor tilth, and increased salinity in the soil (Blackshaw et al., 2001). Crops monocultured (without rotation) are usually fertilized with inorganic nutrient source. Anhydrous ammonia is a commonly used nitrogen source in the Texas High Plains. Prices of this fertilizer have risen consistently over the last five years from $80.00/ ton in 2000 to $240/ ton in 2005 (McQuaid, 2005). Because cost of inorganic Nitrogen (N) fertilizer is rising alternative sources of fertility are sought (Auld et. al., 1982). Inorganic fertilizers while adding nutrients to the plants do not add organic matter (OM) to the soil. Green manure crops meet this need; amending soil with green manure crops adds OM and nutrients to the soil. Organic matter improves soil tilth and maintains nutrients in an exchangeable form for plants while increasing water holding capacity. (McKaig et al., 1938 ). Lubbock County is in a semiarid region receiving approximately 18 inches of rain yearly. Sandy soils of the High Plains have low water holding capacity. Expanding urban areas across the Southwest demand more of the available water. With limited water resources it is critical to identify agricultural crops tolerant to drought with low water requirements (Alexander et al., 1986). The rising costs of fertilizers and other non-renewable resources and declining water are primary in the decreased income of farmers. Variability in production was lowest in crop rotations with the most diversity (Smolik, 1995). In summary, multi-use crops can stabilize income and stresses by opening alternative markets. Cover crop rotation and green manure crops not only add OM, improve soil tilth, increase water holding capacity, and replace lost fertility, they can also maximize profits in uncertain market cycles.

    Project objectives from proposal:

    The objective of this research is to examine if guar [Cyamopsis tetragonolaba (L.) Taub.] is suitable as a summer cover crop rotation or green manure crop and provide a marketable unit (dry bean or immature pod). A field trial will be conducted to test different ways of land management using guar. A second rotation using a summer squash variety as a follow-up study in 2007 will analyze soil quality and yield data between the guar and southern pea treatments. Accomplishments to date - Two trials at separate locations in Lubbock county, Texas have been inititated and crop growth is very good. Preplant soil samples have been taken, guar and blackeye pea harvesting is underway, and mid-season soil samples have also been taken at one of the test sites. However, the data is still to be tabulated and analyzed yet for the 2006 growing season. Trials for 2006 are expected to be complete by the end of September 2006.

    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.