A Comparison of GOSSYM-COMAX™ to Arkansas and Tennessee Recommendations for Cotton Production

D.D. Howard, T.C. Keisling, P.E. Hoskinson, and R.L. Maples


Gossym-Comax(TM) (G/C(TM)) simulation model/expert management system was utilized in six experiments in Arkansas and Tennessee to evaluate irrigation timing, nitrogen (N) management, crop termination and yield predictions. G/C(TM) was also compared with current recommended practices. G/C(TM) predicted water stress and recommended irrigation about one week earlier than was indicated by tensiometer in Arkansas. The model recommended 110 and 193 lb/ac N in two of the four experiments conducted in Tennessee, but lint yields were not higher than the yields produced by applying the current recommendation of 80 lb/ac N. Nitrogen nutrition of the plant was evaluated by comparing the petiole N and G/C(TM) N stress factor. These comparisons showed the two methods agreed 70% and 64% of the time in Arkansas and Tennessee, respectively. Maturity predictions by G/C(TM) were 3 to 11 days later compared to maturity based on 60% open bolls. In four Tennessee experiments involving various N rates and soil types, the G/C(TM) program predicted yields ran in from 28% over to 61% under actual yields. Actual lint yields ranged from 643 to 1567 lb/ac while G/C(TM) predicted yields ranged from 474 to 988 lb/ac. These results show the G/C(TM) growth simulation model needs further refinement to simulate cotton growth under these conditions.

Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pp. 488 - 489
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998