Resource Gradient Experiment: Irrigation Scheduling

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In use from 2011-05-01

Protocol

Irrigation events in the Resource Gradient Experiment will be scheduled by employing a soil water budget that balances the amount of plant available water. In this budget, rainfall and irrigation amounts represent a credit to the soil, whereas evapotranspiration (ET) is recorded as a debit to the soil. Daily values of ETmax were generated by running a 100 year simulation with the SALUS model that incorporated site-specific historical weather data (1984-2010) and crop-specific data from T1 (Basso, unpublished data).

Starting on May 1, LTER staff will record rainfall and irrigation events and these values will be entered daily into the corn-specific soil water budget spreadsheet. This spreadsheet is located in the shared folder “LTER Irrigation”, which is located in the “data entry” folder on the lter (\\lterfiles) server. Based on these inputs and modeled values of daily ETmax, the spreadsheet calculates a daily estimate of plant available water (mm). Negative values indicate that soil water is not available for plant uptake. When a negative value is observed for two consecutive days, an irrigation event will be scheduled for the next day unless there is a rainfall event that results in net plant available water. The amount of water to be applied during irrigation events will be determined by the value of the plant available water deficit on the day prior to the scheduled irrigation event. Communication of scheduled irrigation events to key investigators and LTER staff will occur via e-mail and will be coordinated by Joe Simmons. During the 2011 growing season, the following individuals will be included on these e-mails: Stacey Vanderwulp, Kevin Kahmark, Neville Millar, Iurii Shcherbak, Justin Kunkle, Bruno Basso and Phil Robertson.

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