Irrigation can be specified based on actual field records of irrigation application events, or on rules for automatic management. Field records consist of a date (or days after planting), the type of application (sprinkler, drip, etc.), and an amount of water applied. The irrigation efficiency can be specified for estimating total water supply requirements.

DSSAT-CSM provides several classes of rules for specifying how to trigger an irrigation event based on simulated state and process values.

Automatic irrigation rules may be specified separately for various plant growth stages. The two main classes of automatic irrigation are triggered by soil moisture and by evapotranspiration demand. Irrigation amounts can be calculated based on deficit or a user-supplied fixed amount. Irrigation events may be further limited by a total available water (by plant growth stage or for the entire season) and by a minimum duration between irrigation events.

Refer to the User’s Guide to Automatic Irrigation using Growth Stage Controls for details on these routines.