Pivot Irrigation. How much water per pass?

[Otha]

I have one pivot leased this year and am managing another. Neither make full circles so there is some challenge there.
The leases pivot is on very sandy ground and has sudan planted under it. I'm not sure the gpm from the wells but it isn't enough to water as much as I would like. Wells pump into a pit and pumped out to pivot.

The managed pivot is on Coastal Bermuda. Same story, not enough water from wells so takes a while to fill pit.

What is the most efficient way to water? I know watering only at night can help but I'm not sure how much water to apply per pass. Some people have told me to fill the pond up and set the pivot to apply the total volume of the pond in one pass. Others have told me to set the pivot to apply .3 to .4 inches and let it bounce back and forth till the pond is empty. I have been told applying too much per pass can risk getting the pivot stuck, although as dry as it is and as sandy as the soil is I don't think that is a high risk.

 

[Ebenezer]

Shallow irrigation (low total amounts per pass) will have about the same amount of loss of transpiration and evaporation as say enough water to allow a week's worth of growth, likely 1 to 1.5". Repeated shallow waterings can increase shallow rooting. But with sandy soil, you need someone to tell you the approximate water holding capacity of the effective root zone. On newly planted crops, that would be much shallower than mature plants or with coastal bermudagrass in general.

 

[wbvs58]

With the cost of power to pump water I would think it would need to be set to empty the pond in one pass.

Ken

 

[Otha]

Thanks for the input. The problem now is that empting the ponds on either case is and inch or less. Not ideal. It's always enough water to water in some fertilizer but never enough to make a good crop if it doesn't rain a little along.