Modeling corn growth and root zone salinity dynamics to improve irrigation and fertigation management under semi-arid conditions

Modeling is an advanced technique to study the effects of crop management practices as management scenario simulations in a convenient and economical way. A multi seasonal study was conducted on corn, sown under drip irrigation, to assess its growth under three irrigation intervals (I-1: irrigation on daily basis, I-2: irrigation on 3rd day and I-3: irrigation on 5th day) and three fertigation levels [F-1:100 % RFA (recommended fertigation applications), F-2:75 % RFA and F-3:50 % RFA)] of two types of fertilizers (M-1: Imported and M-2: Indigenous). The SALTMED model was calibrated and validated, using data collected from experiments, to explore different management scenarios of corn production. The accuracy of the validation process was examined by root mean square error (RMSE), percentage of difference (%D), coefficient of residual mass (CRM) and coefficient of determination (R-2). The results showed that corn produced statistically highest plant height (183.7 cm), dry matter (16.9 t/ha), grain yield (8.57 t/ha) and water productivity (1.52 kg/m(3)) under I-l in comparison to that under other irrigation intervals. Similarly, M-1 and F-1 produced statistically highest plant height, dry matter, grain yield and water productivity as compared to M-2 and other fertigation levels, respectively. SALTMED simulated soil moisture and soil salinity accurately with average values of RMSE, R-2 and CRM as 0.013, 0.850 and -0.002, respectively for soil moisture and 0.479, 0.864 and 0.130, respectively for soil salinity. The SALTMED simulations showed good results also for grain yield (RMSE = 0.475, R-2 = 0.873, CRM = -0.0013 and highest %D = -4.9 %) and dry matter (RMSE = 0.596, R-2 = 0.909, CRM = -0.027 and highest %D = 4.2 %). Overall, it was concluded that corn should be irrigated on daily basis under drip irrigation and fertilized with 100 % RFA. Moreover, the SALTMED model proved to be a useful tool for simulations of different management scenarios regarding corn growth and root zone salinity dynamics with reliable results under semi-arid conditions.