|Author:||Dogan, E. ; Martin, V. ; Vanderlip, R.L. ; Clark, G.A. ; Rogers, D.H.|
|Book Group Author:||NA|
A field study was conducted to evaluate an irrigation scheduling model (KanSched) using seven center pivot irrigated corn sites in south central Kansas from 1999 to 2001. Portions of each center pivot irrigation system were modified to apply various irrigation amounts. Site-specific irrigation, weather, and field data were used in KanSched to create comparative irrigation schedules for each test zone of each site. Those schedules were also used in the CERES-Maize corn growth simulation model. Irrigation treatments included deficit amounts ranging from 10 to 180 mm while excess irrigation amounts ranged from 8 to 139 mm. KanSched calculated crop evapotranspiration (ET(ks)) ranged from 370 to 488, 356 to 426, and 386 to 566 mm, while CERES-Maize simulated crop ET ranged from 418 to 585, 398 to 699, and 409 to 712 mm for all sites in 1999, 2000, and 2001, respectively. Analyses of measured corn grain yield versus a KanSched water balance ratio [R(w) = (Net irrigation + Effective rain + Soil water depletion) / ET(ks)] indicated that crop yield was highest at a water balance ratio of 1.0 (full irrigation). Measured yield from all treatments ranged from 9.5 to 13.1, 7.4 to 14.4, and 3.8 to 16.1 Mg ha -1 while CERES-Maize simulated corn yield ranged from 7.9 to 13.8, 6.9 to 17.1, and 6.6 to 13.8 Mg ha -1 in 1999, 2000, and 2001, respectively. In general, substantial deficit irrigation amounts reduced measured grain yield especially in drier years on south central Kansas farm sites. While the CERES-Maize model simulated average yield from all sites and years was equal to the average measured yield, the model over-predicted measured yields in the lower end of the measured yield range and under predicted yield in the upper end of the measured yield range. Thus, the CERES-Maize model may be adequate for large spatial and temporal simulations, but may not be adequate to simulate individual sites and deficit yield conditions.
|Pages:||509 - 516|
|Journal:||Applied engineering in agriculture|
grain yield, irrigation rates, deficit irrigation,agricultural management models, evapotranspiration, irrigationmanagement, irrigated farming, corn, Zea mays, center pivot irrigation,crop models, irrigation scheduling, Kansas