Sensitivity analysis of soil hydrologic parameters for two crop growth simulation models

Soil characteristics are some of the most important inputs in crop simulation models like CERES-Maize and MACROS models under field conditions. A sensitivity analysis of these models was carried out for 1995 and 1996 by incorporating changes (+2, +4, +6, −2, −4, and −6%) of the measured values of three basic soil input parameters: wilting point (WP), saturated soil water content (FS) and field capacity (FC). For this purpose, eight soil profile layers were chosen for CERES-Maize and three for the MACROS model. The MACROS model was found to have a higher degree of sensitivity to changes in the relevant soil parameters than the CERES-Maize model, especially for WP. For the MACROS model, an earlier end of the growing period (75 days) for maize at the +6% level for WP was simulated in 1995 as against 152 days for the CERES-Maize model. The yield in 1995 due to 6% increase in WP resulted in a decrease of about 35% yield when CERES-Maize model was used. In 1996 the increase in WP by 6% resulted in decrease of yield by 22.5 and by 0.9% for MACROS and CERES-Maize models, respectively. When WP was decreased by 6% then the yield was found to increase by about 20.4 and 12.0% for MACROS and CERES-Maize models, respectively in 1995. In 1996 the same alteration of WP caused the yield to increase by about 5.7 and 0.7% for MACROS and CERES-Maize models. Alteration of the model's remaining parameters showed a negligible influence on yields for both the models.