msu-ceco/aec_v1 · Datasets at Hugging Face

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Stage development to mature 2,3
R4 End of pod elongation 50-60
R5 enlargement 40-50 10.0
End of seed enlargement to
R6 R6.5 leaves beginning to yellow 30-40 4.71
R6.5 R7 Leaves begin to yellow 20-30 2.9
R7 Beginning maturity 10-15 0.75
R8 Maturity 0 0.27
layer).
That crop requires 1 inch of water in the soil profile to reach black layer.
To determine amount of water needed for the final irrigation, an irrigator should determine soil water availability.
If there is more than 1 inch available in the profile, then additional irrigation or rainfall is not needed.
For soybeans that have reached the R6.5 growth stage, there are 20 to 30 days left to reach maturity , and at that point approximately 2.9 inches of water are needed for optimal development.
Step 2.
Determine the amount of water available in the effective root zone.
It is recommended that irrigation managers deploy sensors at 6-", 12-", 18-" and 30-inch" depths to provide soil moisture information from different portions of the plant rooting zone.
These depths correspond to the top, middle and lower portions of the theoretical rooting profile.
The effective rooting zone can be determined from direct field sampling using a soil probe and inspecting roots.
However, estimating the effective rooting depth from the sensor responses from the season is more practical.
The upper 6and 12-inch sensors represent the most active area of the rooting profile.
Determining Plant Available Water : Use Table 1 and the following equation to convert readings from Watermark sensors to soil water holding capacity.
The calculations are simplified by using the UAEX Arkansas Soil Sensor Calculator mobile app.
Plant Available Water
= WHC X MAD X Effective Rooting Depth
Example: Assume the average readings from four Watermark sensors is 40 cb.
For a silt loam soil with a hard pan at 50% MAD, the plant available water would be 0.72 inches/ft, as read from Table 1.
If the effective root zone is 3 feet, then the calculation would be:
PAW = 0.72 in/ft ft = 2.4 inches of plant available water.
If this were a corn field, checking back to the information listed in Table 2, the PAW calculation would indicate that no further irrigations will be required because only 2.2 inches of water are needed to mature the crop.
If this were a soybean field at R6 , then the 2.4 inches PAW calculated value indicates that an addition irrigation would be required.
Step 3.
Account for any potential rainfall that may occur before the crop matures.
If rainfall occurs, this amount can be added to the water balance.
For example, if 0.5 inches of water are needed to finish the crop, and that much or more falls on the field without runoff, then no additional irrigation need be applied.
Step 4.
Determine the irrigation need.
If rainfall does not provide enough to finish the crop, then a last
Table 4.
Typical Irrigation Efficiencies for Arkansas Systems
Furrow Irrigation 60-80% 70%
Center Pivot 65-85% 80%
irrigation is necessary.
The irrigation need is the difference between what is available in the soil and what is needed.
Irrigation is not 100% efficient.
Losses may be due to tail water runoff and deep percolation, or there may be uneven infiltration along the row.
All of the water applied to a crop does not reach all of the plants equally.
Furrow irrigation systems generally are only about 60-70% efficient, and center pivot systems are between 65-85% efficient depending upon condition and sprinkler package.
If the crop needs 1.0 inch of water to finish, and the irrigation system is only 70% efficient, then 1.4 inches of water are needed to provide that inch of water.
Also, if only 1.0 inch of water is needed to finish out a furrow irrigated crop, then reduce the irrigation time or depth accordingly rather than apply a full irrigation.
This should be adequate to provide an inch of water to the lower reach of the field.
For sprinklers, the irrigator should adjust the percent run time based on the pivot's operation chart to match the application depth needed.
Run time calculations should also account for irrigation efficiency.
Irrigation application efficiency is defined as Ea = 100.
A simplified net irrigation equation is below.
Applied Irrigation Depth =
Thus, to apply an inch of irrigation, using an irrigation system that is 70% efficient, it is necessary to apply 1.4 inches.
Table 5.
Applied Irrigation Depth Needed for Plant Water Needs for Different Irrigation Efficiencies
0.5 0.7 0.6 0.6
1.0 1.4 1.3 1.1
1.5 2.1 1.9 1.7
2.0 2.9 2.5 2.2
2.5 3.6 3.1 2.8
3.0 4.3 3.8 3.3
Readers are encouraged to use the mobile app designed for phones and tablets, "Arkansas Soil Sensor Calculator" to determine the water available in the profile.
If the amount available is more than is needed, no additional irrigation is necessary.
The difference is the net irrigation required.
Crop Stage: Corn at R5 with the starch line at 50% and rooting depth of 3 ft.
Watermark sensor readings: 40, 63, 60, and 85 cb for 6-, 12-, 18and 30-inch depths.
Irrigation and soil: Furrow irrigated field with clay soil.
Rainfall: 0.15 inches rainfall occurred within 12 hours of making the readings.
Managed Allowable Depletion : 50%
Step 1.
Determine crop stage and water needed to finish the crop.
Amount of water needed to finish the corn is determined from Table 2 = 2.2 inches.
Step 2.
Determine the amount of water available in the effective root zone.
The average of watermark
Figure 1.
Apple version of Arkansas Watermark Tool, Soil Sensor Calculator result for the example.
The app does all of the calculations except adjusting for rainfall.
The app can be downloaded at the Apple App Store.
readings is 62cb [= 4 = 62 cb].
It is assumed the rooting depth is 3 feet because all the sensor readings moved during the season, and the irrigation manager used a shovel to visually inspect roots.
From Table 1, for a clay soil at 60 cb the plant available water per foot is 0.30 inches per foot.
PAW = 0.30 X 3 ft.
= 0.90 inches.
This is the plant available water in the effective rooting zone.
Step 3.
Account for any potential rainfall that may occur before the crop matures.
There were 0.15 inches of rainfall that occurred after the readings were taken, SO the total plant available water is 0.90 inches + 0.15 inches = 1.05 inches of plant available water.
Step 4.
Determine the irrigation need.
The irrigation need is 2.2 inches.
PAW is 1.05 inches.
The difference between PAW and the amount of water needed is = 1.15 inches.
So, for this example, another irrigation is necessary to meet crop water demand.
This furrow irrigation system is at least 70% efficient, SO the depth to apply is 1.65 inches of water to get 1.15 inches.
If a normal irrigation is 2 inches, irrigation can be reduced after the advance has occurred about 20% earlier than a normal irrigation to finish the corn crop.
Figure 2.

Stage development to mature 2,3

R4 End of pod elongation 50-60

R5 enlargement 40-50 10.0

End of seed enlargement to

R6 R6.5 leaves beginning to yellow 30-40 4.71

R6.5 R7 Leaves begin to yellow 20-30 2.9

R7 Beginning maturity 10-15 0.75

R8 Maturity 0 0.27

layer).

That crop requires 1 inch of water in the soil profile to reach black layer.

To determine amount of water needed for the final irrigation, an irrigator should determine soil water availability.

If there is more than 1 inch available in the profile, then additional irrigation or rainfall is not needed.

For soybeans that have reached the R6.5 growth stage, there are 20 to 30 days left to reach maturity , and at that point approximately 2.9 inches of water are needed for optimal development.

Step 2.

Determine the amount of water available in the effective root zone.

It is recommended that irrigation managers deploy sensors at 6-", 12-", 18-" and 30-inch" depths to provide soil moisture information from different portions of the plant rooting zone.

These depths correspond to the top, middle and lower portions of the theoretical rooting profile.

The effective rooting zone can be determined from direct field sampling using a soil probe and inspecting roots.

However, estimating the effective rooting depth from the sensor responses from the season is more practical.

The upper 6and 12-inch sensors represent the most active area of the rooting profile.

Determining Plant Available Water : Use Table 1 and the following equation to convert readings from Watermark sensors to soil water holding capacity.

The calculations are simplified by using the UAEX Arkansas Soil Sensor Calculator mobile app.

Plant Available Water

= WHC X MAD X Effective Rooting Depth

Example: Assume the average readings from four Watermark sensors is 40 cb.

For a silt loam soil with a hard pan at 50% MAD, the plant available water would be 0.72 inches/ft, as read from Table 1.

If the effective root zone is 3 feet, then the calculation would be:

PAW = 0.72 in/ft ft = 2.4 inches of plant available water.

If this were a corn field, checking back to the information listed in Table 2, the PAW calculation would indicate that no further irrigations will be required because only 2.2 inches of water are needed to mature the crop.

If this were a soybean field at R6 , then the 2.4 inches PAW calculated value indicates that an addition irrigation would be required.

Step 3.

Account for any potential rainfall that may occur before the crop matures.

If rainfall occurs, this amount can be added to the water balance.

For example, if 0.5 inches of water are needed to finish the crop, and that much or more falls on the field without runoff, then no additional irrigation need be applied.

Step 4.

Determine the irrigation need.

If rainfall does not provide enough to finish the crop, then a last

Table 4.

Typical Irrigation Efficiencies for Arkansas Systems

Furrow Irrigation 60-80% 70%

Center Pivot 65-85% 80%

irrigation is necessary.

The irrigation need is the difference between what is available in the soil and what is needed.

Irrigation is not 100% efficient.

Losses may be due to tail water runoff and deep percolation, or there may be uneven infiltration along the row.

All of the water applied to a crop does not reach all of the plants equally.

Furrow irrigation systems generally are only about 60-70% efficient, and center pivot systems are between 65-85% efficient depending upon condition and sprinkler package.

If the crop needs 1.0 inch of water to finish, and the irrigation system is only 70% efficient, then 1.4 inches of water are needed to provide that inch of water.

Also, if only 1.0 inch of water is needed to finish out a furrow irrigated crop, then reduce the irrigation time or depth accordingly rather than apply a full irrigation.

This should be adequate to provide an inch of water to the lower reach of the field.

For sprinklers, the irrigator should adjust the percent run time based on the pivot's operation chart to match the application depth needed.

Run time calculations should also account for irrigation efficiency.

Irrigation application efficiency is defined as Ea = 100.

A simplified net irrigation equation is below.

Applied Irrigation Depth =

Thus, to apply an inch of irrigation, using an irrigation system that is 70% efficient, it is necessary to apply 1.4 inches.

Table 5.

Applied Irrigation Depth Needed for Plant Water Needs for Different Irrigation Efficiencies

0.5 0.7 0.6 0.6

1.0 1.4 1.3 1.1

1.5 2.1 1.9 1.7

2.0 2.9 2.5 2.2

2.5 3.6 3.1 2.8

3.0 4.3 3.8 3.3

Readers are encouraged to use the mobile app designed for phones and tablets, "Arkansas Soil Sensor Calculator" to determine the water available in the profile.

If the amount available is more than is needed, no additional irrigation is necessary.

The difference is the net irrigation required.

Crop Stage: Corn at R5 with the starch line at 50% and rooting depth of 3 ft.

Watermark sensor readings: 40, 63, 60, and 85 cb for 6-, 12-, 18and 30-inch depths.

Irrigation and soil: Furrow irrigated field with clay soil.

Rainfall: 0.15 inches rainfall occurred within 12 hours of making the readings.

Managed Allowable Depletion : 50%

Step 1.

Determine crop stage and water needed to finish the crop.

Amount of water needed to finish the corn is determined from Table 2 = 2.2 inches.

Step 2.

Determine the amount of water available in the effective root zone.

The average of watermark

Figure 1.

Apple version of Arkansas Watermark Tool, Soil Sensor Calculator result for the example.

The app does all of the calculations except adjusting for rainfall.

The app can be downloaded at the Apple App Store.

readings is 62cb [= 4 = 62 cb].

It is assumed the rooting depth is 3 feet because all the sensor readings moved during the season, and the irrigation manager used a shovel to visually inspect roots.

From Table 1, for a clay soil at 60 cb the plant available water per foot is 0.30 inches per foot.

PAW = 0.30 X 3 ft.

= 0.90 inches.

This is the plant available water in the effective rooting zone.

Step 3.

Account for any potential rainfall that may occur before the crop matures.

There were 0.15 inches of rainfall that occurred after the readings were taken, SO the total plant available water is 0.90 inches + 0.15 inches = 1.05 inches of plant available water.

Step 4.

Determine the irrigation need.

The irrigation need is 2.2 inches.

PAW is 1.05 inches.

The difference between PAW and the amount of water needed is = 1.15 inches.

So, for this example, another irrigation is necessary to meet crop water demand.

This furrow irrigation system is at least 70% efficient, SO the depth to apply is 1.65 inches of water to get 1.15 inches.

If a normal irrigation is 2 inches, irrigation can be reduced after the advance has occurred about 20% earlier than a normal irrigation to finish the corn crop.

Figure 2.