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Water management strategies to keep in mind while making irrigation decisions

irrigation water management strategies

By: Vasudha Sharma, Extension irrigation specialist

When making irrigation decisions, it is important to consider various water management strategies to ensure that water is used efficiently and sustainably. Also, to reduce nonpoint source pollution of ground and surface waters caused by irrigation it is important to operate the irrigation system so that the timing and amount of irrigation water applied match crop water needs. Here are some strategies to keep in mind:

Early season strategies

In the spring, always make sure the soil in the germination and early-growth root zone is moist when planting. In Minnesota, spring rains usually provide this moisture and irrigation at planting is not required but, if necessary, irrigate to wet this zone. As the plant grows, moist soil is necessary for proper root development, as roots will not grow through a dry layer of soil. A dry layer will result in a shallower rooting depth than desirable. For corn, experience shows that the soil water deficit can be as high as 60 to 65 percent in the early vegetative growth stage (germinating to 10th leaf) without affecting plant development (more information about management allowable deficit for different crops can be found here: Basics of irrigation scheduling). Root zone at this time may only be half to two-thirds of the crop's potential. Holding back on irrigating during the early vegetative growth stages promotes deeper root growth, increases the opportunity to store rainfall when it occurs and decreases the risk for leaching valuable nutrients.

Mid-season strategies

As the crop nears its critical growth period or its usual peak water-use period, reduce the selected allowable soil water deficit to minimize the risks of not meeting the crop's water needs and causing yield losses. For most crops, this may mean changing soil water deficit limit to a 30 to 40 percent before entering the critical growth stage - such as the 10th to 12th leaf stage for corn, or early flower for soybeans. During these critical periods of high-water use, regularly project the next two to three days of water needs to plan ahead and avoid stressing any part of the field before it’s irrigated. For example, when using a center pivot, which takes three days to cover the field, project what the water deficit will be after three days and use that to determine when to start irrigating. To reduce the leaching potential of a rainfall event, always consider the weather forecast when scheduling the next irrigation.

Increase allowable soil water deficit

Another possible irrigation water management plan is to set the allowable soil water deficit equal to, or slightly greater than, the irrigation system’s normal net application amount. For example, if the typical application is 0.75 inches net, then choose a planning deficit limit of 0.75 to 1 inch. If this is greater than 50 percent of the available water capacity in the root zone, make the amount smaller, especially during the critical stages of crop growth, to reduce the risk of moisture stress. This strategy will require more irrigation applications than the variable deficit strategy described earlier.

Use water budgeting approach

This method involves calculating the water needs of the crops and the amount of water available for irrigation. Estimating soil water using the water-budgeting approach is done by accounting for all the incoming and outgoing water from the soil root zone. Major inputs include precipitation (P) or rainfall and irrigation (Irr). Major outputs is crop water use or evapotranspiration (ETc). Daily soil water depletion in the rooting zone is calculated using the equation below:

Dc = Dp + ETc - P – Irr

Various water budgeting tools are available for irrigation scheduling such as:

Use soil moisture sensors

One of the easiest and most effective ways to improve irrigation efficiency is to implement soil moisture sensor technology in irrigation scheduling. This involves measuring the moisture level in the soil to determine when and how much water to apply. This ensures that water is applied only when necessary and in the right amount. More details about soil moisture sensors, their use and installation is can be found here: Soil moisture sensors for irrigation scheduling.


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  1. Irrigator AssociationJune 7, 2023 at 8:14 AM

    Great advice, it’s gonna be a long season if doesn’t start raining soon


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