To irrigate or not to irrigate? 3 tips and signals to help you decide
Updated: Aug 11, 2022
Now, when many of the fields in Kansas and Nebraska are done pollinating and are getting closer to R4-R5, irrigation should be managed more carefully. Though many areas still face drought conditions with hot and dry weather, crop water use is beginning to decline, plants tend to get into stress less frequently, and crops are less sensitive to water stress. Closely monitoring field conditions allows you to plan irrigation more efficiently, avoid unnecessary irrigation, save water and energy, and maintain the required moisture to finish the crop without potential yield loss.
Plant Status and MDS
Dark green plant status or green plant status and low MDS (Maximum Daily Shrinkage, lower than 180 in Corn and lower than 100 in Soybean) means that fields are currently out of stress. When those conditions exist consistently over time, it is safe to assume that stress will not suddenly build-up in the field, and it is safe to reduce irrigation amounts at this stage.
Days to Refill and the Refill Line
High days to refill prediction means that the probability of developing water stress conditions in the field is low within the predicted days to refill period, allowing to plan irrigation more efficiently. While predictions may be challenging during the early part of the season, days to refill prediction in the later part of the season is usually stable and reliable. At this point, most fields have already gone through several soil moisture depletion and wetting events, as well as stress conditions measured by the plant sensors. This allows us to accurately identify the critical soil moisture zone and adjust the refill line accordingly. A stable refill line and good soil moisture history result in reliable days to refill prediction.
Moisture Accumulation Trend
Moisture build-up and accumulation in the root zone and profile is a good signal that crop water use is dropping and irrigation can be reduced or stopped. Trends are usually visible on long periods; therefore, 5 weeks view is usually the recommended way to view moisture accumulation trends. In addition to accumulation trends in the root zone (the average moisture level in the 0.5ft and 1ft), it is recommended to watch the moisture on the complete 3ft profile as well. Corn and Soybean plants in most fields have already depleted a significant amount of the available moisture in the deeper profile. Moisture increases in 2ft, 2.5ft, and 3ft during irrigation or rain events could indicate decreasing crop water use and (explain?) moisture accumulation trends in the profile.
That's it for the tips. We also would like to remind you to: