Investigating DSSAT: Bermudagrass Response to Nitrogen as Influenced by Soil and Climate

Abstract

Core Ideas The DSSAT perennial forage model predicted bermudagrass response to N reasonably well.The model prediction accuracy was linked mainly to soil water holding capacity.Bermudagrass production in the southern United States could be impacted by El Niño‐Southern Oscillation.The La Niña (El Niño) phase was associated with above (below) normal production.The impact of El Niño‐Southern Oscillation was greater on a soil with a coarser texture. The perennial forage model in the Decision Support System for Agrotechnology Transfer (DSSAT) suite is a newly developed model. Studies involving the use of the forage model for predicting biomass production for a perennial grass such as bermudagrass [Cynodon dactylon (L.) Pers.] are few. By conducting a series of simulation investigations, we examined the DSSAT forage model for simulating ‘Coastal’ bermudagrass biomass response to N as affected by soil and climate variability in the southern United States. The simulation results indicated that the DSSAT forage model predicted the biomass response to N reasonably well. However, the accuracy of simulations was linked primarily to the water holding capacity (WHC) of the soil used. A seemingly small difference in WHC, such as 0.03 mm mm−1, made a significant difference in the biomass response to N rate by a margin of about 3 Mg ha−1. These results indicated that providing more leverage to WHC than to the soil name, texture, or type being used for simulations could provide more accurate results. The simulations further indicated that bermudagrass production in the southern United States could be impacted by El Niño‐Southern Oscillation (ENSO), with the La Niña and El Niño phases providing above‐normal and below‐normal production, respectively. The rate of increase in biomass with an increase in N rate was higher under La Niña than under El Niño. The impact of ENSO was greater on a soil with a coarser texture.