Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Simulating Grass Productivity on Diverse Range Sites in Texas

Authors
item Kiniry, James
item Sanchez, H - NRCS
item Greenwade, J - NRCS
item Seidensticker, E - NRCS
item Bell, J - NRCS
item Pringle, F - NRCS
item Peacock, G Jr - NRCS
item Rives, J - NRCS

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2001
Publication Date: N/A

Interpretive Summary: Computer simulation models that are used to answer questions related to soil erosion and water quality on ran should realistically simulate grass dry matter for many soils and climate regimes. In this study we evaluated the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model's ability to simulate annual range grass biomass production under diverse weather conditions and soils in Texas. We compared range grass production at each rangeland ecological site, as reported in the USDA-NRCS soil surveys, with production simulated by ALMANAC using the most common grasses for each site. The model was run on twenty different soils from a diverse set of sites in Texas. Model inputs included parameters for the soil type, grass species characteristics, and locally measured weather data. Means for simulated production for the sites for 50 years were similar to reported means. Simulated production in high rainfall years and low rainfall years were also comparable to reported values. The soils, weather, and grass parameter data sets developed here can be useful in starting points for deriving data for additional range sites, giving model users examples of realistic input data. The model shows promise as a tool for realistically simulating grass production on a diverse group of soils and in diverse climatic conditions.

Technical Abstract: Simulation models addressing soil erosion and water quality issues on range sites should realistically simulate grass dry matter yields across a wide range of soils and climate regimes. This study was designed to evaluate the ability of the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model to simulate annual range grass biomass production under diverse weather conditions and soils in Texas. The objective was to compare range grass production at each rangeland ecological site, as reported in the USDA- NRCS soil surveys, with production simulated by ALMANAC using the most common grasses for each site. The model was run with 60 years of weather on twenty different soils from a diverse set of sites in Texas. Model inputs included parameters for the soil type, grass species characteristics, and locally measured weather data. After allowing 10 years for the model to equilibrate, means for simulated production for the sites for the next 50 years were similar to reported means. Simulated production in high rainfall years and low rainfall years were also comparable to reported values. The soils, weather, and grass parameter data sets developed here can be useful starting points for deriving data for additional range sites, giving model users examples of realistic input data. The model shows promise as a tool for realistically simulating grass production on a diverse group of soils and in diverse climatic conditions.

Last Modified: 8/22/2014
Footer Content Back to Top of Page