msu-ceco/aec_v1 · Datasets at Hugging Face

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The balance sheet approach assumes that a plant can equally access all available moisture between saturation and permanent wilting point.
This is an accurate assumption when soils are wet.
However, as soil dries, plants have more difficulty extracting water, which decreases growth rates.
Salinity and Crop Production
Salinity is measured in millimhos per centimeter.
Water from the Rio Grande has moderate salinity, ranging between 1.0 to 1.65 mmhos/cm.
At Rio Grande City, the salinity is less than 1.2 mmhos/cm, with the highest values of 1.2 mmhos/ cm occurring between April and June.
The levels drop below 1.0 mmhos/cm during the rest of the year.
Downstream, salinity levels increase: At the Mercedes Irrigation District, salinity ranges from 1.0 to 1.5 mmhos/ cm, reaching 1.6 mmhos/cm during part of November.
Good soil drainage minimizes the effects of salinity.
Heavy, slow-draining soils are poor for citrus production.
To help the salt leach from the soil and improve drainage, some Lower Rio Grande Valley producers practice deep chiseling between citrus rows.
Bad drainage also can cause the accumulation of sodium or other salts including boron and chlorine.
Citrus is sensitive to boron concentrations of 0.3 to 1.0 parts per million.
Citrus yields drop by 10 percent when soil salinity increases to 2.3.
The soil salinity is measured by extracting water from a soil saturated paste.
At higher soil salinity levels, the yields drop even more: by 25 percent at the 3.3 salinity level, 50 percent at the 4.8 level and 100 percent at 8 mmhos/cm.
Saline irrigation water also reduces citrus yields by 10 percent at 1.6 mmhos/cm.
Irrigation for Freeze Protection
Citrus trees grow best when the temperature is 73.4 degrees F to 86 degrees F.
Growth
Table 5.
Number of irrigations for citrus with 70 percent canopy in a Hidalgo sandy clay loam soil with 60 percent management allowable depletion and holding capacity of 8.2 inches in 4 feet of soil depth.
Figure 2.
Traditional irrigation with sloping borders and earth canals.
One of the main problems of earth ditches is that they can break, spilling water out of the area to irrigate.
slows in temperatures above 100.4 degrees F and below 55.4 degrees F.
Active root growth occurs when soil temperatures are higher than 53.6 degrees F.
Most citrus species tolerate light frost for short periods only and can be injured by temperatures of 26.6 degrees F over several hours.
Temperatures of 17.6 degrees F cause branches to wither, and 14 degrees F generally kills the tree.
Flowers and young fruits, which are particularly sensitive to frost, are shed after very short periods of temperatures slightly below freezing.
Dormant trees are less susceptible to cold injury.
Strong wind causes flowers and young fruits fall to easily; provide windbreaks when necessary.
Microsprinklers can protect young trees during freezing nights, especially when water is continuously applied to the lower part of the trunk, because as water freezes, heat is released.
When the application rate is high enough, the freezing water will maintain the trunk, the bud union and lower branches at temperatures near freezing.
To protect trees using microsprinklers, place the sprinklers 1 to 2.5 feet from the trunks in the upwind side of the trees.
Place insulating tree wraps around the trunks of young trees to slow the rate of temperature decline and protect the trunks; use the wraps in combination with sprinkler irrigation.
A microsprinkler irrigation rate of 20 gallons per hour is more effective for cold protection.
Turn on the water before the temperature reaches 32 degrees F , making sure the microsprinkler is placed correctly.
Continue running the microsprinkler all night during the freeze.
Evaporative cooling will cause greater damage if the irrigation system fails when the temperature is below freezing.
Therefore, do not to turn on the system if the pumping system is unreliable.
The system can be stopped once temperatures rise above 33.8 degrees F.
Irrigation Practices in the Lower Rio Grande Valley
Historically, producers in the Valley have used flood irrigation to water citrus crops.
An extensive network of canals and large-diameter underground pipelines use
gravity flow to deliver large volumes of water from the Rio Grande to fields over short periods of time.
Because the Valley generally slopes toward the northleast, away from the river, little pumping is necessary except to lift the water from the river to the canals.
Present water restrictions are causing interest in more efficient irrigation technologies.
Properly managed flood irrigation can be efficient.
During delivery, losses occur because of evaporation and leaks in canals and pipelines.
Irrigation canals that are unlined earthen ditches allow water to seep out.
Lining canals and using pipe to deliver water can reduce these losses and provide better control of the irrigation.
The most common irrigation method for citrus on the farm is flood irrigation with graded borders.
To irrigate efficiently with flood irrigation, level the land to the appropriate grade before establishing the orchard and control water applications with valves or structures.
Citrus groves that are bordered and properly graded do not produce runoff.
To distribute water faster and more efficiently, install alfalfa or orchard valves at different locations in the orchard use gated or flexible pipes.
Build permanent borders every two rows, with an irrigation valve between each pair.
Temporary borders may be single or double row, depending on the grower's preferences.
For better control and faster irrigation, build one border per row of trees.
The border edge is about 1 foot high.
To reduce the irrigated area, place temporary borders along one side of the rows of young trees.
This method, called strip flooding or narrow-border flood, allows faster water advancement.
A farmer can receive 1,346 gallons of water per minute or more to irrigate a field of 40 acres.
One "head" of water per outlet is equivalent to 3 cubic feet per second, or 1,346 gallons per minute.
Weed control methods affect the choice of irrigation method.
Permanent borders need trunk-to-trunk herbicidal weed control, while temporary border irrigation requires tillage to control weeds in the row middles.
In both cases, apply the herbicides beneath the tree canopies.
Use herbicides or tillage implements to control weeds in the row middles of orchards that are irrigated with microsprayer or drip irrigation systems.
Figure 3.
Border irrigation with alfalfa valves.
Each valve covers one border with two rows of trees.
Figure 4.
Using a narrow-border flood can conserve more water than can traditional flood practices in the orchard.
Figure 5.
Irrigation of citrus crops with drip irrigation.
The top photo shows two drip lines per tree row and weeds that are climbing the tree.
The bottom photo shows an implement used to apply herbicide close to the tree to control weeds.
In deciding when to irrigate, producers also must consider the need to order water several days in advance and the wait for the water delivery.
Depending on the location and the irrigation district, a reservoir may be needed to store water for frequent irrigations using microsprinkler irrigation or drip irrigation systems.
Improving Citrus Irrigation Efficiency
Periods of drought have reduced some water allocations in the Lower Rio Grande Valley.
Pressurized irrigation systems can be used to increase production per unit of water applied and to maintain orchards during droughts.
These pressurized systems have one or more emitters at each tree, which allows for the uniform injection of fertilizers and some agrochemicals.
This improves plant nutrition and increases productivity per unit of water applied, partly compensating for the higher initial cost of the system and the variable costs such as energy and maintenance.
The most common pressurized systems are drip and micro-irrigation.
On Lower Rio Grande Valley farms with drip irrigation systems, the most common method is to run the drip lines parallel to the tree rows.
Young orchards can be irrigated with a single line per row, but older trees require two lines-one on each side of the row-because they need more water.
The initial system design must allow for the additional line of emitters to ensure that enough water can be supplied to both lines in the future.
The drip emitters are generally spaced every 3 feet and apply about 1 gallon per hour per emitter.
Drip irrigation systems require filtration to prevent emitter clogging.
Many farms have settling ponds, where sediments and small particles from the pumped canal water can settle out.
The water is then filtered before entering the irrigation lines.
A drip irrigation system can save water because it wets only about 33 percent to 50 percent of the surface area.
In addition, a drip system can apply fertilizer quickly, efficiently and uniformly.
Weed control in the wetted area can be difficult because frequent irrigations cause the herbicides to leach below the soil surface, where they are needed.
Vines growing into and covering the tree are a serious problem.
A good
herbicide program is especially vital with these systems, and growers should include less soluble herbicides in the weed control program.
Fortunately, some herbicides with reduced solubility can be applied through the irrigation system, placing the herbicide where it is most needed.

The balance sheet approach assumes that a plant can equally access all available moisture between saturation and permanent wilting point.

This is an accurate assumption when soils are wet.

However, as soil dries, plants have more difficulty extracting water, which decreases growth rates.

Salinity and Crop Production

Salinity is measured in millimhos per centimeter.

Water from the Rio Grande has moderate salinity, ranging between 1.0 to 1.65 mmhos/cm.

At Rio Grande City, the salinity is less than 1.2 mmhos/cm, with the highest values of 1.2 mmhos/ cm occurring between April and June.

The levels drop below 1.0 mmhos/cm during the rest of the year.

Downstream, salinity levels increase: At the Mercedes Irrigation District, salinity ranges from 1.0 to 1.5 mmhos/ cm, reaching 1.6 mmhos/cm during part of November.

Good soil drainage minimizes the effects of salinity.

Heavy, slow-draining soils are poor for citrus production.

To help the salt leach from the soil and improve drainage, some Lower Rio Grande Valley producers practice deep chiseling between citrus rows.

Bad drainage also can cause the accumulation of sodium or other salts including boron and chlorine.

Citrus is sensitive to boron concentrations of 0.3 to 1.0 parts per million.

Citrus yields drop by 10 percent when soil salinity increases to 2.3.

The soil salinity is measured by extracting water from a soil saturated paste.

At higher soil salinity levels, the yields drop even more: by 25 percent at the 3.3 salinity level, 50 percent at the 4.8 level and 100 percent at 8 mmhos/cm.

Saline irrigation water also reduces citrus yields by 10 percent at 1.6 mmhos/cm.

Irrigation for Freeze Protection

Citrus trees grow best when the temperature is 73.4 degrees F to 86 degrees F.

Growth

Table 5.

Number of irrigations for citrus with 70 percent canopy in a Hidalgo sandy clay loam soil with 60 percent management allowable depletion and holding capacity of 8.2 inches in 4 feet of soil depth.

Figure 2.

Traditional irrigation with sloping borders and earth canals.

One of the main problems of earth ditches is that they can break, spilling water out of the area to irrigate.

slows in temperatures above 100.4 degrees F and below 55.4 degrees F.

Active root growth occurs when soil temperatures are higher than 53.6 degrees F.

Most citrus species tolerate light frost for short periods only and can be injured by temperatures of 26.6 degrees F over several hours.

Temperatures of 17.6 degrees F cause branches to wither, and 14 degrees F generally kills the tree.

Flowers and young fruits, which are particularly sensitive to frost, are shed after very short periods of temperatures slightly below freezing.

Dormant trees are less susceptible to cold injury.

Strong wind causes flowers and young fruits fall to easily; provide windbreaks when necessary.

Microsprinklers can protect young trees during freezing nights, especially when water is continuously applied to the lower part of the trunk, because as water freezes, heat is released.

When the application rate is high enough, the freezing water will maintain the trunk, the bud union and lower branches at temperatures near freezing.

To protect trees using microsprinklers, place the sprinklers 1 to 2.5 feet from the trunks in the upwind side of the trees.

Place insulating tree wraps around the trunks of young trees to slow the rate of temperature decline and protect the trunks; use the wraps in combination with sprinkler irrigation.

A microsprinkler irrigation rate of 20 gallons per hour is more effective for cold protection.

Turn on the water before the temperature reaches 32 degrees F , making sure the microsprinkler is placed correctly.

Continue running the microsprinkler all night during the freeze.

Evaporative cooling will cause greater damage if the irrigation system fails when the temperature is below freezing.

Therefore, do not to turn on the system if the pumping system is unreliable.

The system can be stopped once temperatures rise above 33.8 degrees F.

Irrigation Practices in the Lower Rio Grande Valley

Historically, producers in the Valley have used flood irrigation to water citrus crops.

An extensive network of canals and large-diameter underground pipelines use

gravity flow to deliver large volumes of water from the Rio Grande to fields over short periods of time.

Because the Valley generally slopes toward the northleast, away from the river, little pumping is necessary except to lift the water from the river to the canals.

Present water restrictions are causing interest in more efficient irrigation technologies.

Properly managed flood irrigation can be efficient.

During delivery, losses occur because of evaporation and leaks in canals and pipelines.

Irrigation canals that are unlined earthen ditches allow water to seep out.

Lining canals and using pipe to deliver water can reduce these losses and provide better control of the irrigation.

The most common irrigation method for citrus on the farm is flood irrigation with graded borders.

To irrigate efficiently with flood irrigation, level the land to the appropriate grade before establishing the orchard and control water applications with valves or structures.

Citrus groves that are bordered and properly graded do not produce runoff.

To distribute water faster and more efficiently, install alfalfa or orchard valves at different locations in the orchard use gated or flexible pipes.

Build permanent borders every two rows, with an irrigation valve between each pair.

Temporary borders may be single or double row, depending on the grower's preferences.

For better control and faster irrigation, build one border per row of trees.

The border edge is about 1 foot high.

To reduce the irrigated area, place temporary borders along one side of the rows of young trees.

This method, called strip flooding or narrow-border flood, allows faster water advancement.

A farmer can receive 1,346 gallons of water per minute or more to irrigate a field of 40 acres.

One "head" of water per outlet is equivalent to 3 cubic feet per second, or 1,346 gallons per minute.

Weed control methods affect the choice of irrigation method.

Permanent borders need trunk-to-trunk herbicidal weed control, while temporary border irrigation requires tillage to control weeds in the row middles.

In both cases, apply the herbicides beneath the tree canopies.

Use herbicides or tillage implements to control weeds in the row middles of orchards that are irrigated with microsprayer or drip irrigation systems.

Figure 3.

Border irrigation with alfalfa valves.

Each valve covers one border with two rows of trees.

Figure 4.

Using a narrow-border flood can conserve more water than can traditional flood practices in the orchard.

Figure 5.

Irrigation of citrus crops with drip irrigation.

The top photo shows two drip lines per tree row and weeds that are climbing the tree.

The bottom photo shows an implement used to apply herbicide close to the tree to control weeds.

In deciding when to irrigate, producers also must consider the need to order water several days in advance and the wait for the water delivery.

Depending on the location and the irrigation district, a reservoir may be needed to store water for frequent irrigations using microsprinkler irrigation or drip irrigation systems.

Improving Citrus Irrigation Efficiency

Periods of drought have reduced some water allocations in the Lower Rio Grande Valley.

Pressurized irrigation systems can be used to increase production per unit of water applied and to maintain orchards during droughts.

These pressurized systems have one or more emitters at each tree, which allows for the uniform injection of fertilizers and some agrochemicals.

This improves plant nutrition and increases productivity per unit of water applied, partly compensating for the higher initial cost of the system and the variable costs such as energy and maintenance.

The most common pressurized systems are drip and micro-irrigation.

On Lower Rio Grande Valley farms with drip irrigation systems, the most common method is to run the drip lines parallel to the tree rows.

Young orchards can be irrigated with a single line per row, but older trees require two lines-one on each side of the row-because they need more water.

The initial system design must allow for the additional line of emitters to ensure that enough water can be supplied to both lines in the future.

The drip emitters are generally spaced every 3 feet and apply about 1 gallon per hour per emitter.

Drip irrigation systems require filtration to prevent emitter clogging.

Many farms have settling ponds, where sediments and small particles from the pumped canal water can settle out.

The water is then filtered before entering the irrigation lines.

A drip irrigation system can save water because it wets only about 33 percent to 50 percent of the surface area.

In addition, a drip system can apply fertilizer quickly, efficiently and uniformly.

Weed control in the wetted area can be difficult because frequent irrigations cause the herbicides to leach below the soil surface, where they are needed.

Vines growing into and covering the tree are a serious problem.

A good

herbicide program is especially vital with these systems, and growers should include less soluble herbicides in the weed control program.

Fortunately, some herbicides with reduced solubility can be applied through the irrigation system, placing the herbicide where it is most needed.