July 19, 2013

A new CropWatch web app can help you better use your irrigation flow meter as a management tool.

Irrigation Meter Calculator

Calculate the number of inches of water applied per acre for each irrigation. Try out this new UNL Web app.

Many growers installed flow meters in response to NRD regulations, but rarely look at them during the growing season. Having a flow meter on your irrigation system and not using it is like driving a car and not looking at the speedometer or odometer. Without periodically checking your irrigation meter, you don’t really know how fast you are pumping water and how much you have pumped.

Using your flow meter as a management tool will allow you to keep track of your NRD allocation, check your irrigation efficiency, determine pumping plant efficiency, and detect any well or pump problems before they become severe.

Keeping track of your water meter during the growing season can help you determine how close you are getting to the annual NRD allocation and track how much of your multiple year allocation you have already used this growing season. This can keep you from being penalized for using too much water in a given year. In a multi-year allocation, it can help you decide whether that last inch or two of the current year’s allocation would be worth more in future years. For example, the yield response for the last inch applied is usually less than the response to water applied during corn’s early grain-fill period.

You can improve your irrigation efficiency by keeping track of how much water was applied the previous week and comparing that number to the crop water use as determined by an ET gage. (See the CropWatch article Cost Effective Tools to Improve Water Use Efficiency.) If you applied more water than the crop used the previous week, you may not be making room to store potential rainfall or water may be leaching below the active root zone.

You also can use a flow meter to estimate pumping plant efficiency. The brochure, Estimating the Savings from Improving Pumping Plant Performance, guides you through how to estimate the cost of pumping water and how to compare the energy your pump is using with that of a well maintained and designed pump. Simply record how much fuel you used to pump a given amount of water and compare it to the Nebraska Pumping Plant Criteria to determine if your pumping plant is operating at peak efficiency. Noted differences can reduce fuel costs.

Also, keeping a record of how much water you pump for a given time period can help determine if your pump is delivering the planned amount of water. Compare pumping rates from previous periods to determine if your pump is experiencing problems and you can plan to correct the problem at a less critical time.

Chuck Burr, UNL Water/Cropping Educator
Bill Kranz, Extension Irrigation Specialist
Derrel Martin, Extension Irrigation Specialist