Some techniques for predicting winter wheat yields in major wheat-producing crop districts of Texas and Oklahoma
✍ Scribed by Obi L. Odumodu; John F. Griffiths
- Publisher
- Elsevier Science
- Year
- 1980
- Weight
- 741 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0002-1571
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✦ Synopsis
Odumodu, O.L. and Griffiths, J.F., 1980. Some techniques for predicting winter wheat yields in major wheat-producing crop districts of Texas and Oklahoma. Agric. Meteorol., 22: 267--279.
Wheat yields are analyzed as a differential time function of agricultural technology and the fluctuating environmental conditions as indicated by the Palmer Drought Index severity variables. The use of arctangent curves is introduced to represent the three time trends in agricultural technology in the recent history (1931--1975) of the area. Multiple regression equations for estimating and predicting deviations of wheat yields from the technological curves using weather (environmental) variables were generated and critically studied. In several instances, the partial regression coefficients for estimating and predicting the weather component of the wheat yields were found to be inconsistent in sign and magnitude, and to be agronomically meaningless. Idealized estimators of the same form are presented which have virtually the same correlation coefficients, standard error of estimates and predictiveness. The rationale and a probable method for obtaining the ultimate parameters (similar to the idealized estimators) £or forecasting the winter wheat yields are suggested and discussed.