msu-ceco/aec_v1 · Datasets at Hugging Face

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Total dynamic head or operating pressure at the pump includes the sum of the following:
friction loss in the main line
friction loss in the lateral line
elevation difference between the water supply and the highest point in the field, and
height of sprinkler above the ground
Flow is the rate water is being delivered to the sprinklers.
After computing TDH, a pump efficiency should be assumed SO that horsepower can be computed using the above formula.
Refer to Extension Publication AG-452-6: Pumping Plant Performance Evaluation, for a discussion of recommended pump efficiencies to select.
Once the power requirements have been determined, the fuel cost can be computed.
By comparing costs of several operational and system alternatives the most energy efficient system can be identified for the given situation.
If proper design guidelines are used and sprinklers are operated at the manufacturers' recommended mid-range of operating pressures, these systems should be reasonably energy efficient.
Pump selection should include the use of high efficiency pumps and matched power units.
Hand-move, solid-set, and permanent irrigation system can be energy efficient.
Solid-set and permanent systems are normally more energy efficient than portable handmove systems.
Unfortunately, some of the older systems have sprinklers, pumps, and power units that are 20 or more years old and need replacing.
Many growers have replaced sprinklers and often have several sizes of orifices on the same system.
Growers often purchase used equipment and combine components from several systems to make one system.
When this is done, little opportunity exists to incorporate recommended design guidelines to properly size and match system components.
If your system is more than three years old, you should have it evaluated.
Contact your county Extension office or local irrigation dealer for more information and assistance.
Making a profitable decision about repairs like when to replace worn system components requires a complete economic analysis of existing system performance and the projected cost of alternatives.
erraticity n.
The quality or state of being erratic, characterized by the lack of consistency, regularity or uniformity.
That's correct, there is no such word, but you sure know it when you see it.
Unfortunately, we saw a lot of it this past season in sprinkler irrigated corn.
Figure 1.
Nonuniformity of sprinkler irrigated corn under extreme drought conditions in southwest Kansas in 2011.
These instances of erraticity resulted in low quality, lowor non-yielding corn production.
Crop water stress caused by the extreme drought in portions of the central and southern Great Plains is ultimately responsible for the erraticity.
However, there may be ways to reduce erraticity and its harmful effects by improvements in design and management of center pivot sprinklers for corn production that can minimize water losses.
SPRINKLER PACKAGE EFFECTS ON WATER LOSSES
Center pivot sprinkler management techniques to avoid water losses begin at the design and installation stages with selection of an appropriate sprinkler package.
Typical sprinkler packages in use to today are medium and high pressure impacts which are located on top of the sprinkler span , low pressure rotating spray nozzles which are typically located on the span or at least above the crop canopy, low pressure fixed spray applicators that are located above and within the crop canopy and LEPA that are located near the ground surface.
Commercial LEPA applicators often can apply water in multiple modes.
The popular low pressure fixed spray applicators have also been categorized by their location with respect to the canopy with the terms LESA and MESA .
Application with MESA is typically above the crop canopy for all or most of the crop season depending on the crop.
There are numerous water loss pathways using center pivot sprinklers and each type of sprinkler package has advantages and disadvantages as outlined by Howell that must be balanced against the water loss hazards.
Table 1.
Water loss components associated with various sprinkler packages.
Adapted from Howell.
Water Loss Component (Impact sprinklers, rotating or fixed MESA LESA LEPA
Canopy evaporation Yes
Impounded water evaporation No Yes
Wetted soil evaporation Yes Yes
Surface water redistribution No, Yes, Yes (not major unless Yes
Runoff Yes Yes surface storage is not used)
Percolation No No No No
Windy and hot conditions during the growing season affect center pivot sprinkler irrigation uniformity and evaporative losses.
As a result many producers in the southern and central Great Plains have adopted sprinkler packages and methods that apply the water at a lower height within or near the crop canopy height, thus avoiding some application nonuniformity caused by wind and also droplet evaporative losses.
In-canopy and near-canopy sprinkler application can reduce evaporative losses by nearly 15% , but introduce a much greater potential for irrigation nonuniformity.
These sprinkler package systems are often adopted without appropriate understanding of the requirements for proper water management, and thus, other problems such as runoff and poor soil water redistribution occur.
Table 2.
Partitioning of sprinkler irrigation evaporation losses with a typical 1 inch application for various sprinkler packages..
Sprinkler package Air Canopy Ground Total Application
loss, % loss, % loss, % loss, % efficiency, %*
= 14 ft height 3 12 -- 15 85
= 5 ft height 1 7 -- 8 92
= 1 ft height -- -- 2 2 98
* Ground runoff and deep percolation are considered negligible in these data.
Traditionally, center pivot sprinkler irrigation systems have been designed to uniformly apply water to the soil at a rate less than the soil intake rate to prevent runoff from occurring.
These design guidelines need to be either followed or intentionally circumvented with appropriate design criteria when designing and managing an irrigation system that applies water within the canopy or near the canopy height where the full sprinkler wetted radius is not developed.
Peak application rates for in-canopy sprinklers such as LESA and LEPA might easily be 5 to 30 times greater than above-canopy sprinklers.
Runoff from LEPA sprinklers was negligible on 1% sloping silt loam soils in eastern Colorado but exceeded 30% when slopes increased to 3%.
Runoff from LEPA with basin tillage was approximately 22% of the total applied water and twice as great as MESA for grain sorghum production on a clay loam in Texas.
Basin tillage created by periodic diking of crop furrow , rather than reservoir tillage created by pitting or digging small depressions , is often more effective at time averaging of LEPA application rates, and thus, preventing runoff.
Distance from nozzle centerline
Figure 2.
Application intensities for LEPA, LESA, MESA, rotating sprays on span and impact sprinklers on the span as related to the typical size of their wetting pattern.
Decreasing the application intensity is the most effective way to prevent irrigation field runoff losses and surface redistribution within the field When runoff and surface redistribution occurs using in-canopy sprinklers because of a reduced wetting pattern, one solution would be to raise the sprinkler height.
Figure.
3.
Illustration of runoff or surface water redistribution potential for impact and LESA sprinkler application packages for an example soil.
After Howell.
One might assume that the erraticity observed in sprinkler irrigated fields in 2011 was primarily associated with the evaporative water loss components shown in Table 1, but that is probably not the case.
When using fixed plate applicators near or within the canopy , the magnitude of field runoff and particularly surface redistribution within the field may overwhelm the evaporative loss reductions possible with these packages.
Surveys conducted by Kansas State University have indicated that approximately 90% of the center pivot sprinkler systems in western Kansas use fixed plate applicators and nearly 60% have sprinkler nozzle height less than 4 ft above the soil surface.
The erraticity can be caused by failure to follow appropriate guidelines for irrigation with nearand in-canopy sprinklers.
SOME GUIDING PRINCIPLES FOR IN-CANOPY APPLICATION
A prototype of the LEPA system was developed as early as 1976 by Bill Lyle with Texas A&M University.
Jim Bordovsky joined the development effort in 1978 and the first scientific publication of their work was in 1981.
Although, originally LEPA was used in every furrow, subsequent research demonstrated the superiority for alternate furrow LEPA.
The reasons are not always evident, but they may result from the deeper irrigation penetration , possible improved crop rooting and deeper nutrient uptake, and less surface water evaporation.
The seven guiding principles of LEPA were given by Lyle as:
1) Use of a moving overhead tower supported pipe system
2) Capable of conveying and discharging water into a single crop furrow
3) Water discharge very near the soil surface to negate evaporation in the air
4) Operation with lateral end pressure no greater than 10 psi when the end tower is at the highest field elevation
5) Applicator devices are located so that each plant has equal opportunity to the water with the only acceptable deviation being where nonuniformity is caused by nozzle sizing and topographic changes
6) Zero runoff from the water application point
7) Rainfall retention which is demonstrably greater than conventionally tilled and managed systems.
The other types of in-canopy and near-canopy sprinkler irrigation do not necessarily require adherence to all of these seven guidelines.
However, it is unfortunate that there has been a lack of knowledge or lack of understanding of the importance of these principles because many of the problems associated with in-canopy and near-canopy sprinkler irrigation can be traced back to a failure to follow or effectively "work around" one of these principles.
In-canopy and near-canopy application systems can definitely reduce evaporative losses
, but these water savings must be balanced against runoff and within field water redistribution, deep percolation and other soil water nonuniformity problems that can occur when the systems are improperly designed and managed.
PROVIDING PLANTS EQUAL OPPORTUNITY TO ROOT-ZONE SOIL WATER
The No.
5 LEPA guiding principle listed earlier emphasizes the importance of plants having equal opportunity to root-zone soil water.
Ensuring this equal opportunity requires sufficient uniformity of water application and/or soil water infiltration.
Key issues that must be addressed are irrigation application symmetry, Crop row orientation with respect to center pivot sprinkler direction of travel, and the seasonal longevity of the sprinkler pattern distortion caused by crop canopy interference.
SYMMETRY OF SPRINKLER APPLICATION

Total dynamic head or operating pressure at the pump includes the sum of the following:

friction loss in the main line

friction loss in the lateral line

elevation difference between the water supply and the highest point in the field, and

height of sprinkler above the ground

Flow is the rate water is being delivered to the sprinklers.

After computing TDH, a pump efficiency should be assumed SO that horsepower can be computed using the above formula.

Refer to Extension Publication AG-452-6: Pumping Plant Performance Evaluation, for a discussion of recommended pump efficiencies to select.

Once the power requirements have been determined, the fuel cost can be computed.

By comparing costs of several operational and system alternatives the most energy efficient system can be identified for the given situation.

If proper design guidelines are used and sprinklers are operated at the manufacturers' recommended mid-range of operating pressures, these systems should be reasonably energy efficient.

Pump selection should include the use of high efficiency pumps and matched power units.

Hand-move, solid-set, and permanent irrigation system can be energy efficient.

Solid-set and permanent systems are normally more energy efficient than portable handmove systems.

Unfortunately, some of the older systems have sprinklers, pumps, and power units that are 20 or more years old and need replacing.

Many growers have replaced sprinklers and often have several sizes of orifices on the same system.

Growers often purchase used equipment and combine components from several systems to make one system.

When this is done, little opportunity exists to incorporate recommended design guidelines to properly size and match system components.

If your system is more than three years old, you should have it evaluated.

Contact your county Extension office or local irrigation dealer for more information and assistance.

Making a profitable decision about repairs like when to replace worn system components requires a complete economic analysis of existing system performance and the projected cost of alternatives.

erraticity n.

The quality or state of being erratic, characterized by the lack of consistency, regularity or uniformity.

That's correct, there is no such word, but you sure know it when you see it.

Unfortunately, we saw a lot of it this past season in sprinkler irrigated corn.

Figure 1.

Nonuniformity of sprinkler irrigated corn under extreme drought conditions in southwest Kansas in 2011.

These instances of erraticity resulted in low quality, lowor non-yielding corn production.

Crop water stress caused by the extreme drought in portions of the central and southern Great Plains is ultimately responsible for the erraticity.

However, there may be ways to reduce erraticity and its harmful effects by improvements in design and management of center pivot sprinklers for corn production that can minimize water losses.

SPRINKLER PACKAGE EFFECTS ON WATER LOSSES

Center pivot sprinkler management techniques to avoid water losses begin at the design and installation stages with selection of an appropriate sprinkler package.

Typical sprinkler packages in use to today are medium and high pressure impacts which are located on top of the sprinkler span , low pressure rotating spray nozzles which are typically located on the span or at least above the crop canopy, low pressure fixed spray applicators that are located above and within the crop canopy and LEPA that are located near the ground surface.

Commercial LEPA applicators often can apply water in multiple modes.

The popular low pressure fixed spray applicators have also been categorized by their location with respect to the canopy with the terms LESA and MESA .

Application with MESA is typically above the crop canopy for all or most of the crop season depending on the crop.

There are numerous water loss pathways using center pivot sprinklers and each type of sprinkler package has advantages and disadvantages as outlined by Howell that must be balanced against the water loss hazards.

Table 1.

Water loss components associated with various sprinkler packages.

Adapted from Howell.

Water Loss Component (Impact sprinklers, rotating or fixed MESA LESA LEPA

Canopy evaporation Yes

Impounded water evaporation No Yes

Wetted soil evaporation Yes Yes

Surface water redistribution No, Yes, Yes (not major unless Yes

Runoff Yes Yes surface storage is not used)

Percolation No No No No

Windy and hot conditions during the growing season affect center pivot sprinkler irrigation uniformity and evaporative losses.

As a result many producers in the southern and central Great Plains have adopted sprinkler packages and methods that apply the water at a lower height within or near the crop canopy height, thus avoiding some application nonuniformity caused by wind and also droplet evaporative losses.

In-canopy and near-canopy sprinkler application can reduce evaporative losses by nearly 15% , but introduce a much greater potential for irrigation nonuniformity.

These sprinkler package systems are often adopted without appropriate understanding of the requirements for proper water management, and thus, other problems such as runoff and poor soil water redistribution occur.

Table 2.

Partitioning of sprinkler irrigation evaporation losses with a typical 1 inch application for various sprinkler packages..

Sprinkler package Air Canopy Ground Total Application

loss, % loss, % loss, % loss, % efficiency, %*

= 14 ft height 3 12 -- 15 85

= 5 ft height 1 7 -- 8 92

= 1 ft height -- -- 2 2 98

* Ground runoff and deep percolation are considered negligible in these data.

Traditionally, center pivot sprinkler irrigation systems have been designed to uniformly apply water to the soil at a rate less than the soil intake rate to prevent runoff from occurring.

These design guidelines need to be either followed or intentionally circumvented with appropriate design criteria when designing and managing an irrigation system that applies water within the canopy or near the canopy height where the full sprinkler wetted radius is not developed.

Peak application rates for in-canopy sprinklers such as LESA and LEPA might easily be 5 to 30 times greater than above-canopy sprinklers.

Runoff from LEPA sprinklers was negligible on 1% sloping silt loam soils in eastern Colorado but exceeded 30% when slopes increased to 3%.

Runoff from LEPA with basin tillage was approximately 22% of the total applied water and twice as great as MESA for grain sorghum production on a clay loam in Texas.

Basin tillage created by periodic diking of crop furrow , rather than reservoir tillage created by pitting or digging small depressions , is often more effective at time averaging of LEPA application rates, and thus, preventing runoff.

Distance from nozzle centerline

Figure 2.

Application intensities for LEPA, LESA, MESA, rotating sprays on span and impact sprinklers on the span as related to the typical size of their wetting pattern.

Decreasing the application intensity is the most effective way to prevent irrigation field runoff losses and surface redistribution within the field When runoff and surface redistribution occurs using in-canopy sprinklers because of a reduced wetting pattern, one solution would be to raise the sprinkler height.

Figure.

3.

Illustration of runoff or surface water redistribution potential for impact and LESA sprinkler application packages for an example soil.

After Howell.

One might assume that the erraticity observed in sprinkler irrigated fields in 2011 was primarily associated with the evaporative water loss components shown in Table 1, but that is probably not the case.

When using fixed plate applicators near or within the canopy , the magnitude of field runoff and particularly surface redistribution within the field may overwhelm the evaporative loss reductions possible with these packages.

Surveys conducted by Kansas State University have indicated that approximately 90% of the center pivot sprinkler systems in western Kansas use fixed plate applicators and nearly 60% have sprinkler nozzle height less than 4 ft above the soil surface.

The erraticity can be caused by failure to follow appropriate guidelines for irrigation with nearand in-canopy sprinklers.

SOME GUIDING PRINCIPLES FOR IN-CANOPY APPLICATION

A prototype of the LEPA system was developed as early as 1976 by Bill Lyle with Texas A&M University.

Jim Bordovsky joined the development effort in 1978 and the first scientific publication of their work was in 1981.

Although, originally LEPA was used in every furrow, subsequent research demonstrated the superiority for alternate furrow LEPA.

The reasons are not always evident, but they may result from the deeper irrigation penetration , possible improved crop rooting and deeper nutrient uptake, and less surface water evaporation.

The seven guiding principles of LEPA were given by Lyle as:

1) Use of a moving overhead tower supported pipe system

2) Capable of conveying and discharging water into a single crop furrow

3) Water discharge very near the soil surface to negate evaporation in the air

4) Operation with lateral end pressure no greater than 10 psi when the end tower is at the highest field elevation

5) Applicator devices are located so that each plant has equal opportunity to the water with the only acceptable deviation being where nonuniformity is caused by nozzle sizing and topographic changes

6) Zero runoff from the water application point

7) Rainfall retention which is demonstrably greater than conventionally tilled and managed systems.

The other types of in-canopy and near-canopy sprinkler irrigation do not necessarily require adherence to all of these seven guidelines.

However, it is unfortunate that there has been a lack of knowledge or lack of understanding of the importance of these principles because many of the problems associated with in-canopy and near-canopy sprinkler irrigation can be traced back to a failure to follow or effectively "work around" one of these principles.

In-canopy and near-canopy application systems can definitely reduce evaporative losses

, but these water savings must be balanced against runoff and within field water redistribution, deep percolation and other soil water nonuniformity problems that can occur when the systems are improperly designed and managed.

PROVIDING PLANTS EQUAL OPPORTUNITY TO ROOT-ZONE SOIL WATER

The No.

5 LEPA guiding principle listed earlier emphasizes the importance of plants having equal opportunity to root-zone soil water.

Ensuring this equal opportunity requires sufficient uniformity of water application and/or soil water infiltration.

Key issues that must be addressed are irrigation application symmetry, Crop row orientation with respect to center pivot sprinkler direction of travel, and the seasonal longevity of the sprinkler pattern distortion caused by crop canopy interference.

SYMMETRY OF SPRINKLER APPLICATION