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Determining Cotton Water Use in a Semiarid Climate with the GOSSYM Cotton Simulation Model
Author(s) -
Staggenborg Scott A.,
Lascano Robert J.,
Krieg Daniel R.
Publication year - 1996
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1996.00021962008800050010x
Subject(s) - evapotranspiration , environmental science , irrigation scheduling , transpiration , irrigation , leaf area index , potential evaporation , hydrology (agriculture) , soil water , soil science , atmospheric sciences , agronomy , ecology , physics , chemistry , geology , biochemistry , photosynthesis , geotechnical engineering , biology
Simulation models are useful tools that provide information about potential changes to production systems before committing time and resources. GOSSYM, a physiologically based cotton ( Gossypium hirsutum L.) simulation model, was developed as an experimental tool but has been modified and adapted as a crop management tool. For GOSSYM to be used successfully in crop management, especially as an irrigation scheduling predictor, its ability to accurately calculate and partition total water use between transpiration ( T ) and soil water evaporation ( E ) must be evaluated. A field study with cotton was conducted at Lubbock, TX, in 1994 in an Olton soil (fine, mixed, thermic Aridic Paleustoll) to compare GOSSYM's calculations of E , T , and evapotranspiration (ET = E + T ) with values measured by neutron attenuation, microlysimetry, and stem flow gauges. During a 12‐d period when E and T were measured separately, GOSSYM underestimated cumulative E by 18%, while cumulative T was in close agreement with measured values. Underestimation of E was due to overestimation of leaf area index (LAI), thus reducing simulated incident irradiance at the soil surface. A comparison of calculated and measured values of daily T over 60 d showed that calculated daily T 's were 40% greater than measured values during the initial 10 d, 50% less during the last 10 d, and in close agreement in between. Differences between calculated and measured daily T ‐values were attributed to GOSSYM underestimating potential ET and overestimating LAI. However, ET over 102 d was calculated within 10% at the end of the measuring period. These data suggest that GOSSYM can be used to assess water use in cotton, and as a tool for scheduling irrigations in a semiarid region, provided that current algorithms used to calculate potential ET are modified to include air humidity.