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CENTER PIVOT IRRIGATION WATER MANAGEMENT PLAN

NRCS Designated Conservationist – Soil Conservation District

The NRCS District Conservationist for _______________County S&WCD (South Carolina) has reviewed this Irrigation Water Management Plan and concurs that the plan meets requirements of NRCS practice standard 442, Sprinkler System.

Signature__________________________________________ Date: _____________

Name: ______________________________

Title: ______________________________ NRCS Contract Number: ______________________

Owner/Operator

As the owner/operator of this Irrigation Water Management Plan, I certify that I, as the decision maker, have been involved in the planning process and agree with the items/practices listed in this document. I understand that I am responsible for keeping all the necessary records associated with the implementation of this IWM Plan. It is my intent to implement/accomplish this IWM Plan in a timely manner as described in the plan.

Signature: _________________________________________ Date: ________________

Name: ________________________________

NRCS-SC 442 IWMP February 2017

Technical Service ProviderAs the developer of this Irrigation Water Management Plan, I certify that this plan meets the requirements of NRCS conservation standard 449 and/or CAP 118 checklist.

Signature: _________________________________________ Date: ________________

Name: ________________________________ TSP Number: ______________________________

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TABLE OF CONTENTS

SECTION 1 General Information SCDHEC Permit Information Clearance and Permits Location of Utilities

SECTION 2 Irrigation Water Management Plan (IWMP) - Definitions and Requirements

SECTION 3 Documentation/Statement of past water withdrawal and application by crop

SECTION 4 IWMP Worksheet

SECTION 5 Proposed and Potential Water Sources Worksheet

SECTION 6 IWMP Summary Equipment Summary Soil Moisture Monitoring Irrigation Schedule Conservation Practices

SECTION 7 System Components – Center Pivots Critical System Components

SECTION 8 Reference Materials

SECTION 9 System Evaluations Existing Irrigation System New Irrigation System

SECTION 10 Safety Issues

SECTION 11 Maintenance

SECTION 12 Cooperator’s System Layout Maps

SECTION 13 Cooperator’s Soils Description Map Unit Description Soils Data (including field boundaries, predominate soil list, and area qualified) Feel and Appearance Method for Estimating the Available Moisture in the Soil

NRCS-SC 442 IWMP February 2017

This 442 Sprinkler System IWMP has been updated to incorporate scheduling and maximum application rate information from the South Carolina Irrigation Guide (SCIG) 2016. See the next page for the website and download location of the SCIG Supplement Chapters.

SECTION 14 Cooperator's Documentation Soil test results Water Quality test result

Economics of Water Use Energy Consumption

SECTION 15 TSP Additional Documentation

Location of SCIG (2016) Supplement Chapters on eDirectives

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To access the updated South Carolina Irrigation Guide (2016) Supplement Chapters;

click the link https://directives.sc.egov.usda.gov/ , then follow the “red” boxes below to the folder

NRCS-SC 442 IWMP February 2017

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SECTION 1 - GENERAL INFORMATION

SCDHEC PERMIT

You may need to refer to the South Carolina Water Withdrawal, Permitting Use, and

Report Act under section 49-4-10. Irrigation use in excess of 3 million gallons in any

given month may require a permit.

SC DHEC Bureau of Water

2600 Bull Street

Columbia, S.C. 29201

Phone: (803) 898-4300

Fax: (803) 898-4215

CLEARANCE AND PERMITS

It shall be the responsibility of the cooperator to obtain all necessary clearances, permits, rights of way, and to comply with all ordinances and laws pertaining to the construction of this project. It shall be the responsibility of the cooperator to assure that the project is constructed according to the attached drawings and specifications. Any changes shall be submitted in writing to the NRCS 48 hours prior to implementation for approval. NRCS shall be notified 72 hours prior to construction.

LOCATION OF UTILITIES

NRCS-SC 442 IWMP February 2017

ECONOMICS OF WATER USEWater is an essential natural resource. It is both a renewable and exhaustible resource. Quality is often as large a concern as quantity for water. Everyday people use vast amounts of water for everything from drinking to production/agricultural inputs. The use of this water comes with a cost of which is too often overlooked by the public at large.

The natural water cycle has long been characterized by substantial variability. The uncertainty this induces plays a large role in how modern water systems are managed. It also influences other items such as agricultural prices and recreational facility uses. Climate change is expected to result in major alterations of the current hydrological cycle, which in turn will influence a whole range of activities.

ENERGY CONSUMPTION IN AGRICULTUREIn agriculture, energy consumption consists of the following areas; 1) energy efficiency: a ratio between an output of performance and an input of energy; 2) energy efficiency improvement: an increase in energy end-use efficiency as a result of technological, behavioral and/or economic changes; and 3) energy savings : an amount of saved energy determined by measuring and/or estimating consumption before and after implementation of one or more energy efficiency improvement measures. Is the operating pressure of the base pivot =< 35 psi ( Y / N ) _______. Is an end gun Booster pump included in this system ( Y / N ) ___________.

No representation is made as to the existence or non-existence of any utilities, public or private. The cooperator must obtain the exact location and depth of all utilities from the utility companies prior to excavation or construction activities. PUPS (Public Utility

Protection Service) 1-888-721-7877.

RESOURCE CONCERNS

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SECTION 2 - DEFINITION AND REQUIREMENTS

What is Irrigation Water Management (IWM)?

IWM is simply defined as the act of timing and regulating irrigation applications to satisfy crop water requirements, without wasting water, nutrients, energy, and soil. This means scheduling water applications to meet specific crop needs based on plant growth and maturity, and the available water holding capacity of the soil. This system designed for

What does a farmer need to do to implement IWM?

Install an irrigation system and operate according to a certified system design and irrigation water management plan. Design must meet crop water requirements for total irrigated acres and peak application rate must not exceed soil intake rates (pg 14, Table SC2-18).

After installation and prior to season startup, evaluate irrigation system and pump

operation to maintain high efficiency. Monitor and record flow rates, pressure, water distribution, and uniformity in the field, and correct malfunctions to meet design standards.

Schedule irrigations through field record keeping procedures. This includes:

Soil moisture monitoring using tensiometers, watermark sensors (resistant meters), the“feel method” (determining soil texture and water availability by feel) or other approvedmethod to determine available water in lie soil and root zone area.

Recording rainfall through the use of rain gauges.

Recording total hours of irrigation and amount of water applied.

Use weather station data to record daily evapotranspiration to meet crop water userequirements during the growing season.

Submitting seasonal water use records and scheduling data to NRCS for certification andincentive payment (if enrolled in EQIP or AMA cost share program)

Install management tools such as soil moisture monitoring devices, and backflow

preventers.

Requires water quality testing of water source for irrigation system.

NRCS-SC 442 IWMP February 2017

What are the objectives of this Irrigation Water Management for FARM No: ___________(place on all objectives addressed by this IWMP) Conserves water through efficient application and scheduling Improves crop yield and quality by managing according to crop requirements Reduces runoff resulting in soil erosion control Decreases deep percolation and leachate contaminates into ground water Improves water quality (surface and subsurface) Saves energy through efficient pumping. Reduces nutrient movement past root zone. Manage salts in the crop root zone Manage air, soil or plant micro-climate

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SECTION 3 – IRRIGATION WATER MANAGEMENT PLAN

Provide an overview of the existing irrigation system and watering schedule (including past water withdrawal and application by crop) in-place prior to this IWMP.

The information contain within this plan will guide the grower in the use of supplemental irrigation to achieve a higher quality crop and increased total yields. Healthy plants that are not stressed by drought are better able to resist disease. Inconsistent application of water can cause plant stress and misshapen tuber and excessive soil moisture can cause root or tuber rot.

This plan will recommend that the grower allow some moisture stress to the crop, by applying less irrigation water than required to keep moisture near field capacity. This will allow capacity for natural rainfall between irrigation applications and reduce the chance of excess moisture. It will also reduce the volume of water that needs to be pumped and stored for irrigation.

Areas that experience dry summers and extended periods of limited rainfall have significant effects on crop quality and yield. In some growing seasons, no supplemental irrigation is required, and in others, only two or three applications are necessary. The Supplemental Irrigation or Seasonal Gross Water Needs will be based on all but the driest years and will come from the grower’s own experience, rainfall records, and consultation with local irrigation specialists. If the supplemental irrigation water is coming from an irrigation reservoir or river system, the grower should understand the risk that in some very dry years, both the river and irrigation reservoir might not provide adequate water volume to insure the desired crop quantity and quality.

The grower’s specific crops and rotation schedule will be used to insure the most efficient use of supplemental irrigation water. Theoretically an application depth of 50% of the available water capacity could be applied per irrigation, but some crops respond to lesser amounts (inches), but more frequent applications, thus keeping the soil moisture level below field capacity. Depending on the soil type, the latter procedure could cause plants to develop shallow root systems. The time to irrigate within this system shall be based on the soil moisture levels at the root zone, as determined by

NRCS-SC 442 IWMP February 2017

The following pages require data input from the Owner/Operator, Irrigation Designer, and NRCS staff. Please note the "symbols" in the left margin of this document, which identify who is to supply the data. All items must be completed for this plan to be considered valid. Use "N/A" to identify items not incorporated in this irrigation system design or scheduling plan.

To be completed by NRCS (pages 4, 6, 11, 14 and 23)

To be completed by the Designer (pages 3, 4, 5, 6, 7, 9, 12, 13, 16 and 23)

To be completed by the Operator or Designer (pages 6, 12 and 26)

SECTION 4 – IRRIGATION WATER MANAGEMENT PLAN

WORKSHEET Cooperator / County Planner

Tract Location (UTM-X) ft Date

Tract Location (UTM-Y) ft Total Acres in Field (ac)

TRACT NO. / FIELD NO.CROP TO IRRIGATE (if multiple

crops then enter in next column)

EFFECTIVE ROOT DEPTH AVAILABLE WATER CAPACITY

FOR EFFECTIVE ROOT DEPTH (in.) PEAK CROP ET (in/day)

MGT ALLOWED DEPLETION (MAD %) COEFFICIENT of UNIFORMITY [CU] or

DISTRIBUTION UNIFORMITY [DU] (%) GROSS WATER APPLIED PER

IRRIGATION (in.) NET DEPTH APPLIED PER

IRRIGATION (in) Will nozzles operate in canopy for 50% or

more of the growing season? (Y / N) Does nozzle spacing exceed every other

crop row? ( Y / N)SEASONAL NET WATER NEEDS (in) SEASONAL GROSS WATER NEEDS

(ac-ft)

FIELD MOISTURE METHOD

TYPE OF IRRIGATION SYSTEM

SYSTEM EFFICIENCY (%)

WATER SOURCES 1/

1_/ EWW = Existing Water Well Sys PWW = Proposed Water Well Sys EIR = Existing Irrigation Reservoir PIR = Proposed Irrigation Reservoir R = River System

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NRCS-SC 442 IWMP February 2017

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CU/ DU CU/ DU CU/ DU

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SECTION 5 – PROPOSED & POTENTIAL WATER SOURCES WORKSHEET

Cooperator/Farm Name

Planner

Date

WATER SOURCE 1_/

DRAINAGE AREA PUMPING RATE (cfsm)

(river or stream only STORAGE CAPACITY (ac-ft)

(reservoirs only) MAXIMUM DEPTH (ft)

POOL AREA (ac)

MAXIMUM FILL HEIGHT (ft)

EMBANKMENT HEIGHT (ft)

VOLUME OF FILL (cy)

BASIN SOIL TYPE

WETLAND ACRES IMPACTED (ac) DESIRED ORDER OF WATER

SUPPLY (1st, 2nd, etc)1_/ EWW = Existing Water Well System

PWW = Proposed Water Well System EIR = Existing Irrigation Reservoir (Embankment/Excavated) PIR = Proposed Irrigation Reservoir (Embankment/Excavated) R = River System

Describe potential Water Source(s): (Existing Technical Criteria & Potential Restrictions)

NRCS-SC 442 IWMP February 2017

TRACT NO. / FIELD NO. // /

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SECTION 6 – IWMP SUMMARY [CENTER PIVOT SYSTEM]

This plan addresses irrigation water management for the grower’s operation and includes a system design and installation procedures to meet the peak water requirements of your crop, without causing erosion, runoff, and losses to deep percolation.

All proposed irrigated acres for the grower have been included in this irrigation water management plan (IWMP), along with all available water sources. The supplemental irrigation water needs shown in this plan are the maximum amounts that would be needed for the specified crop rotation. The amount of supplemental irrigation water must be calculated separately for each unique crop rotation.

Evapotranspiration is the sum of the evaporation of water from the soil and plant surface plus the water that transpires through the plant tissue. Therefore, evapotranspiration equates to the total water needs or consumptive use for the plant growth. The effective precipitation is the amount of mean rainfall that is stored in the root zone and is useable by the crop. The net irrigation requirement is the difference between the average evapotranspiration and the effective precipitation. The grower needs to understand that the planned supplemental irrigation water needs may not meet the theoretical consumptive use requirements of the crop, but it will help to minimize the effects on surface streams, wetlands, and/or ground water supplies.

Each water source has an optimum working condition that will be utilized by the grower when scheduling application events through the center pivot irrigation system.

Water Well – if available, shall be the main source of supplemental irrigation water.

Irrigation Reservoir – if available, this source should be used during periods of low river flow.

River System – if available, this source should be used during high flow periods when irrigation withdrawals will not cause an adverse impact on the stream habitat.

Other water sources not mentioned in this plan would have to be found if the existing source does not meet the grower’s crop production objectives.

NRCS-SC 442 IWMP February 2017

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SYSTEM & EQUIPMENT SUMMARY

TRACT NO. / FIELD NO.

SYSTEM MANUFACTURER:

CHOOSE PIVOT TYPE: DISTANCE OUT FROM PIVOT TO

LAST TOWER (ft) PIVOT SYSTEM GAUGE PRESSURE (psi)

SYSTEM INLINE END PRESSURE (psi)

TOTAL SYSTEM FLOW (gpm)

FULL CIRCLE GPM / ACRE

ADJUSTED END GUN RADIUS (ft)

IRRIGATED ACRES UNDER PIVOT

SPRINKLER GROUND CLEARENCE (in)

NUMBER OF TOWERS

SPAN LENGTH (ft)

SPAN PIPE MATERIAL

SPAN PIPE DIAMETER (in)

ELECTRICAL PANEL

PUMP POWER SOURCE

PUMP POWER RATING (HP)

MOTOR SPEED (RPM)

CENTER GEAR RATIO

CENTER DRIVE SPEED (RPM) LAST TOWER GROUND SPEED @ 100%

TIMER SETTING (ft/min) SUPPLY PIPE MATERIAL / DIAMETER (in)

SUPPLY PIPE LENGTH FROM SOURCE (ft)

NOZZLE or SPRINKLER MODEL NO:

SOLID SET - ROW X SPRINKLER (ft x ft)

TRAVELER - SPRINKLER DIAMETER (ft)CENTER PIVOT - TOTAL WETTED

RADIUS OF PIVOT TO LAST TOWER (ft) CENTER PIVOT - WETTED RADIUS OF

LAST SPRINKLER ON BASE TOWER (ft)

NRCS-SC 442 IWMP February 2017

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x x x

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SOIL MOISTURE MONITORING

The number of soil moisture monitoring devices planned for a field or farm is dependent upon

the following criteria:

1. Different soil types and topography within the irrigated acreage.

2. Crop type and growth stage within the irrigation zone.

3. Crop varieties or diversity within the irrigation zone.

4. Changes in the system design - different flow rates, pressure etc. which will affect

application rates.

5. Number of irrigation zones.

If the above criteria is uniform throughout the irrigated area, as a rule of thumb plan about 2 - 4

sensors per irrigation zone.

For this center pivot system, locate the station within the limiting soil type. Increase the number

of stations as determined by the above criteria. The sensors may be tensiometers installed at

depths specific to the planned crop. See Section 8 for specific crop reference materials.

Field monitoring techniques can be used to establish when and how much to irrigate. Most crops

should be irrigated before more than half of the available soil water in the crop root zone has

been used. Tensiometers or other moisture monitoring instruments should be used to record

moisture readings within the root zone for proper irrigation scheduling.

Tensiometers give soil moisture readings in terms of centibars. These readings indicate how

tightly water is being held by the soil, and is a measure of soil moisture depletion. The graph

below shows the relationship between percent depletion and centibar readings for various soil

textures. The sensors are to be placed in the root zone. Percent depletion allowed depends on the

crop and growth stage. The table gives general recommendations based on sensor readings in

centibars. Read sensors a minimum of 3 times per week and plot readings on graph to show soil

moisture trends which will aid in irrigation planning. Monitor applications based on the crop

ET, rainfall and sensor readings.

Sensor reading

(centibars)

Description Available Moisture

(percent)

0-10 Saturated soil 100

10-20 Adequately wet 70-90

30-60 Irrigation range 40-70

60-100 Critical moisture level 20-40

NRCS-SC 442 IWMP February 2017

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SOILS DATA - to be completed by NRCS staff (Data shall be for Predominant Soil under Pivot)

TRACT NO. / FIELD NO.

PREDOMINANT SOIL TYPE (show top two soils and % under pivot)

PERCENT OF ACRES TO BE IRRIGATED (%)

DEPTH OF 1ST LAYER

TEXTURE OF 1ST LAYER1/

DEPTH OF 2ND LAYER

TEXTURE OF 2ND LAYER

NRCS-SC 442 IWMP February 2017

1/ "surface soil texture" -- To be used with Table SC2-18 (pg 14) in the determination of maximum application rate

/ / /

dry

wet

SOIL TEXTURE @ 24 inches DEEP (see pg 12 Footnote 2 /)

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IRRIGATION SCHEDULE

Submit irrigation scheduling data as required if you have an EQIP contract. This includes soil

moisture readings, irrigation applications, available water holding capacity (AWHC), rainfall and

evapotranspiration. Use Irrigation Water Management Workbook or an equivalent alternative to

record the required data.

SURFACE STORAGE (inch) based on soil intake family 2a /

PERCENT RESIDUE ON SURFACE (%)

FIELD MOISTURE METHOD# OF TENSIOMETERS PER

IRRIGATION ZONE 3_/ TENSIOMETER DEPTHS (in & in)

IRRIGATE WHEN: MAD REACHES (%) or DEEPEST TENSIOMETER READS (centibars)

NET DEPTH OF APPLICATION or WATER APPLIED (inch)

TIME TO IRRIGATE EACH ZONE (hrs)

REVOLUTION TIME (hrs)

PEAK NET APPLICATION (in/wk)

TEXTURE 2_/ CS = coarse sand 2a_/ CS = 3.0

S = sandFS = fine sandLS = loamy sandLFS = loamy fine sand LVFS = loamy very fine sand SL = sandy loamFSL = fine sandy loam VFSL = very fine sandy loam L = loamSIL = silty loamSCL = sandy clay loamCL = clay loamSICL = silty clay loamSC = sandy claySIC = silty clayC = clay

3_/ Proposed Tensiometer locations shall be shown on the Soil Map

See Figure SC2-11on page 11 to determine your tensiometer readings (centibars) at your planned Available Soil Moisture (percent) and soil texture at the 24 inch root zone [footnote 2/].

Available Soil Moisture (%) = 100 - MAD (%)

NRCS-SC 442 IWMP February 2017

%

centibars

%

centibars

%

centibars

CROP

SOIL INTAKE FAMILY (University of Nebraska Extension, pg 34)

S = 3.0FS = 3.0LS = 3.0LFS = 2.0LVFS = 2.0SL = 1.0FSL = 1.5 VFSL = 1.0 L = 1.5SIL = 0.5SCL = 0.5CL = 0.3SICL = 0.3SC = 0.1SIC = 0.1C = 0.1

TRACT / FIELD No // /

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MAXIMUM IRRIGATION APPLICATION RATES

Sprinkler irrigation application rates and amounts should be related to the temporary surface storage and soil intake rate – the capacity of a soil to absorb irrigation water from the surface and move it into and through the soil before runoff or redistribution occurs.

Solid-Set Sprinkler Intake Rate - The approximate application rate (AR) for solid-set, hand move or wheel line may be calculated, as follows:

Center Pivot Intake Rate - Center pivots create the greatest challenge for designs that must keep application rates below soil intake rate to avoid runoff or redistribution of water.

Use the following information from the South Carolina Irrigation Guide (SCIG 2016), Chapter 2 to determine if the designed "system" application rate (AR or PAR) is greater than the values in SCIG 2016, Table SC2-18 (pg 14) and has the potential to cause water runoff or redistribution.

NRCS-SC 442 IWMP February 2017

Tract # ( __________); AR = _______ in/hr

Tract # ( __________); AR = _______ in/hr

If we assume the maximum peak rate (based on an ellipitcal pattern) is going to occur at the end of the pivot, which it will, that will cancel out the r and one of the L values, leaving the following equation for peak application rate (PARcp):

Evaluate the PARcp against the maximum sprinkler application rate Table SC2-18 (next page) for the appropriate surface texture. There might be potential for redistribution or runofff of the applied irrigation water if (PARcp > Table SC2-18 value, based on your planned Net Water Applied (pg 12), slope, and surface texture). Is PARcp > Table SC2-18 value: (Y / N) _______. If yes, CP Nozzle can be used to determine Max Application Depth before runoff occurs [CP Nozzle download]. Does CP Nozzle indicate any "runoff" potental: (Y / N) ______. If yes, reduce CP Nozzle "Application Amount" to _______ inch so that Percent Potental Runoff on Results tab shows zero.

Tract # ( __________); AR = _______ in/hr

Tract # ( _______); PARcp = _______ in/hr

Tract # ( _______); PARcp = _______ in/hr

Tract # ( _______); PARcp = _______ in/hr

where:

_______________ ft x ______ ft

_______________ ft x ______ ft

_______________ ft x ______ ft

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CONSERVATION PRACTICES

Does the Conservation Plan include planned practices, implementation schedule, and a appropriate site specific construction specicications and job sheets? ( Y / N ) _________Place a next to all existing and planned conservation practices to be maintained under this IWMP.

TRACT NO. / FIELD NO.

330 CONTOUR FARMING

340 COVER CROP

442 IRRIGATION SYSTEM, SPRINKLER

430 IRRIGATION PIPELINE

449 IRRIGATION WATER MANAGEMENT

590 NUTRIENT MANAGEMENT

595 PEST MANAGEMENT

Contour Farming (330)

Tillage, planting, and other farming operations performed on or near the contour of the field slope in order to reduce sheet and rill erosion and reduce transport of sediment and other waterborne contaminants.

NRCS-SC 442 IWMP February 2017

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Footnotes are defined in the South Carolina Irrigation Guide (SCIG) 2016, Chapter 2 (pgs.2-50 & 2-51) 5/ Net Irrigation (Depth) Applied per Irrigation (inches) [see page 6 for input values] = AWC x MAD/100

5/NOTE: this table does not factor in surface storage, residue, or nozzle wetted diameter

PARcp ( )

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Irrigation Pipeline (430)

A pipeline and appurtenances installed in an irrigation system to prevent erosion or loss of water

quality or damage to the land, to make possible the proper management of irrigation water, and to

reduce water conveyance losses.

Nutrient Management (590)

Precision application equipment and methods are being utilized to perform nutrient management

activities, including managing the amount, source, placement, form and timing of the application

of plant nutrients and soil amendments.

Pest Management (595)

Utilizing environmentally sensitive prevention, avoidance, monitoring and suppression

strategies, to manage weeds, insects, diseases, animals and other organisms (including invasive

and non-invasive species), that directly or indirectly cause damage or annoyance.

SECTION 7 – SYSTEM COMPONENTS

All center pivot systems include the following general components: 1) structural components,

2) drive train, 3) controls, 4) electrical components, 5) sprinklers, and 6) water distribution

components. The following section details some critical system components for center pivot

irrigation systems.

Note: A pressure gauge shall be installed on each system under this Irrigation Water

Management plan.

Note: A flow meter shall be installed on each system under this Irrigation Water

Management plan.

I. BACKFLOW AND ANTI-SIPHON PREVENTION DEVICES:

If the irrigation system is not set up for chemical/fertilizer injection then this is not

needed. However if fertilizers or chemicals are injected through the irrigation system

then it is a necessary to have a backflow and anti-siphon prevention device.

Irrigation System, Sprinkler (442)

A planned irrigation system in which all necessary facilities are installed for efficiently applying

water by means of perforated pipes or nozzles operated under pressure for the purpose of

uniformly applying irrigation water to maintain adequate soil moisture for optimum plant growth

without causing excessive water loss, erosion, or reduced water quality.

Irrigation Water Management (449)

The process of determining and controlling the volume, frequency, and application rate of irrigation

water in a planned, efficient manner to manage soil moisture to promote desired crop responses,

optimize use of available water, minimize irrigation induced soil erosion, decrease non-point source

pollution of surface and groundwater resources, manage salts in the crop root zone, and manage air,

soil, or plant micro-climate.

Cover Crop (340)

Grasses, legumes, forbs, or other herbaceous plants established for seasonal cover and

conservation purposes including, but not limited to, reduction of water and wind erosion, manage

excess nutrients in the soil profile, and influence soil moisture management.

NRCS-SC 442 IWMP February 2017

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CRITICAL SYSTEM COMPONENTS

FIELD NUMBER WILL CHEMIGATION / FERTIGATION BE

UTILIZED IN THIS SYSTEM? (Y/N) IF YES, DIAMETER OF CHEMIGATION

VALVE TYPE OF FILTER SYSTEM

MESH / DIAMETER OF FILTER WILL WATER QUALITY ISSUES REQUIRE ADDITIONAL FILTER CONSIDERATION?

(Y/N)

IF APPLICABLE, DESCRIBE ADDITIONAL FILTER CONSIDERATION UTILIZED IN

THIS IRRIGATION SYSTEM:

Filters: If water quality is poor or a double dripline is installed, a two tank filtration system may

backflush more frequently resulting in high pressure losses throughout system during

backflushing and inadequate filtration. Therefore an additional tank may be necessary or reduce

pumping capacity (number of zones per irrigation). Refer to attached manufacturer sheets.

FLOW

A backflow and an anti-siphon prevention device are required to prevent pesticide

contamination of surface water supplies as well as groundwater. A Chemigation valve

which includes a Check Valve, Vacuum Relief Valve, Low Pressure Drain Valve and

Chemical Injection Port is required on Center Pivot Systems to prevent any back flow into

the water supply line and/or water source (see pictures on next page)..

NRCS-SC 442 IWMP February 2017

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/ / /

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SECTION 8 – REFERENCE MATERIALS

Crop Water Use and Growth Stages – Row Crops

Quick Facts...

Water stress during critical growth periods reduces yield and quality of Crops.

Crop water use (ET) at critical growth stages can be used in irrigation scheduling to avoid

stressing Crops.

Crop water use (ET) is weather dependent as well as soil, water and plant dependent.

Periodically check soil water at different depths within the root zone and at different

growth stages to avoid stressing the crop during critical growth stages.

Managing Irrigation According to Growth Stages (Row Crops)

Crops are different in their response to water stress at a given growth stage. Crops summarized

according to their sensitivity to water stress at various growth stages (Tables 1 and 2) reveal the

importance of these stages in making the irrigation decision.

Crops that are in the sensitive stage of growth should be irrigated at a lower soil water depletion

level than those that can withstand water stress. If a crop is last in the irrigation rotation and is at

a sensitive stage of growth, the recommended strategy may be to apply partial or lighter

irrigations in order to reach the end of the field before the sensitive crop is subjected to water

stress.

Such a strategy can be used with sprinkler systems, but this may lead to unfavorable soil

moisture conditions at the lower soil depths. When soil is repeatedly watered to only shallow

depths, the lower soil depths tend to develop a soil moisture deficit that exceeds the allowable

soil moisture depletion level at that particular growth stage. Therefore, quick soil moisture

assessment at various soil depths to determine the actual water use is essential in irrigation

scheduling as related to growth stages.

Crop appearance is considered one of many field indicators that can be used in irrigation

scheduling. A crop suffering from water stress tends to have a darker color and exhibits curling

or wilting. This is a physiological defense mechanism of the crop that is evident on hot, windy

afternoons when the crop cannot transpire fast enough, even if the water is readily available in

the soil. If the crop does not recover from these symptoms overnight, the crop is suffering from

water stress. Any changes in crop appearance due to water stress may mean a reduction in yield.

However, using this indicator alone for irrigation scheduling is not recommended if a maximum

yield is desired.

This indicator is inferior for modern agriculture due to the inability to determine the actual crop

water use. However, ignoring it at the critical growth stages may lead to yield reduction. Using

the growth stage as a field indicator in irrigation scheduling should be coupled with more

sensitive and accurate methods of determining the crop water use such as soil moisture

measurements and ET data. The main advantage of this indicator is to provide direct and visual

feedback from the crop.

Different Crops have different water requirements and respond differently to water stress. Crop

sensitivity to water stress varies from one growth stage to another. Table 1 is a summary of

NRCS-SC 442 IWMP February 2017

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critical growth stages during which major Crops in South Carolina which are especially

sensitive to water stress.

A good irrigation scheduling scheme should consider sensitivity of the crop to water stress at

different growth stages. This is accomplished by using a coefficient termed the Management

Allowable Depletion (MAD), which is the amount of water allowed to be depleted from the root

zone before irrigation is scheduled. At the time of irrigation, the soil water deficit should be less

than or equal to the MAD.

The goal of any irrigation scheduling scheme is to keep the water content in the root zone above

this allowable depletion level. This ensures that the crop will not suffer from water stress and

will produce maximum potential yield. In Table 2, suggested MADs for selected Crops are given

for different growth stages along with suggested Tensiometer lengths and placement depths for

various crops. This information can be used in an irrigation scheduling scheme by using the

appropriate MAD for each growth stage to trigger irrigation.

Table 1: Critical growth stages for major Crops.

Crop Critical period Symptoms of water

stress

Other considerations

Corn Tasseling, silk stage

until grain is fully

formed

Curling of leaves by

mid-morning,

darkening color

Needs adequate water from

germination to dent stage for

maximum production

Sorghum Boot, bloom and

dough stages

Curling of leaves by

mid-morning,

darkening color

Yields are reduced if water is

short at bloom during seed

development

Small grain Boot and bloom

stages

Dull green color, then

firing of lower leaves

Last irrigation at milk stage

Cool

season

grass

Early spring, early

fall

Dull green color, then

wilting

Critical period for seed

production is boot to head

formation

Table 2: Management allowable depletion (MAD) at the root zone of selected Crops at

different growth stages.

Crop Growth stages MAD(%) in root

zone

Tensiometer lengths

and placement depths

Effect of

water

stress

Shallow

Instrument1

(Inches)

Deep

Instrument1

(Inches)

Corn, grain

Emergence-12 leaf

12 leaf-dough

Dough-maturity

5050 50

18 36 Yield

reduction

of 11.5

bu/A-in

water

NRCS-SC 442 IWMP February 2017

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deficit

Small

grains

Emergence-first

node

First node-

flowering

Milk ripe-maturity

50

60

18 36 Yield

reduction

of 6-8

bu/A-in

of water

deficit

Soybeans Before flowing

First flower-first

pod

First pod-maturity

5050

50

18 36 Yield

reduction

1 Suggested placement depths for various row crops based on deep well drained soils.

Instruments can be angled or set more shallowly in lighter or shallow soil. With

microirrigation, 12” & 18” depths are recommended, with an added 24” depth on

deeper rooted crops.

For a complete guide to current irrigation information, including new techniques, soils,

climate, irrigation technical data including irrigation water requirements for crops, visit the

NRCS Irrigation Homepage link below:

https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/water/manage/irrigation/

INSTALLATION PROCEDURE OF TENSIOMETERS

• Soak tensiometer over night in a bucket of clean water. Fill with water and leave cap off.

• When ready to install, mix 1 capful of field solution in 1 gallon of distilled water. Fill

tensiometer with this mixture.

• Protect ceramic tip from air drying when transporting to field. Transport in bucket half filled

with water.

• De-air in bucket with hand vacuum pump to remove air bubbles in tube and air free gauge.

Pump to a reading of 80 - 85 cb. Repeat 2 - 3 times and replace filler cap by tightening

until neoprene stopper makes contact with reservoir bottom, then turn cap ¼ turn. Do Not

Overtighten.

• Install hole 12” - 18” from emitter but within root zone mass. Locate on sunny side of row.

Install using a ‘/z” galvanized pipe or 7/8” steel rod. Install to depth of ceramic tip within

root zone depth, (12” depth for vegetables and blueberries under drip). Hole should not be

deeper than depth of ceramic tip to prevent water accumulation and false readings.

• Install tensiometer pushing straight down on cap and maintain a minimum clearance of 1”

between the bottom of the gauge and the soil surface. Not more than 6” of the tube should

project above the ground.

40

NRCS-SC 442 IWMP February 2017

Additional Reference Material is available in NEH Part 652; NEH Part 652 State Supplement - South Carolina Irrigation Guide (2016); NEH Section 15 - Chapter 11 Sprinkler.

20

• Bank soil around plastic tube and pack to a depth of 3-4” for good soil contact, and drainage

for surface water.

• Within a few hours, accurate soil moisture content can be read.

• De-air tensiometer by pumping for a period of 4 to 5 days after installation until no further

air bubbles appear. This will increase the sensitivity and result in accurate readings. Refill the

reservoir as necessary and replace cap as discussed.

SECTION 9 – SYSTEM EVALUATIONS

A system evaluation is recommended under the IWM Program. At least one evaluation should

be performed during the contract period to check system flow rates and pressures. This provides

a check that the system is operating according to the design.

There are two evaluations that shall be recognized as satisfactory under the program. These

include:

Existing Irrigation Systems

A detailed evaluation for distribution uniformity /emission uniformity, and flow rate /pressure

variation within the irrigated acreage. If this evaluation is chosen, it is recommended that it is

completed within the first 3 years of the contract. *Recommended for existing systems that have

been operating for more than one season and may have a higher potential risk of emitter clogging

or worn sprinkler nozzles.

Newly Installed Irrigation Systems

A Basic “As Built” evaluation to check the installed system flow rates, pressure, and spacing

against the design flow rates. Flow rates and pressures shall be taken at inlets and outlets of

laterals and submain or mains, (the beginning and ends of main and lateral lines within a zone so

that the first outlet checked and last outlet checked are diagonal within that zone). If this

evaluation is used, it shall be completed within the irrigation season that it is installed.

*Recommended for newly installed irrigation systems.

SECTION 10 – SAFETY ISSUES

Make certain only well-trained people familiar with the National Electrical Code and the new

irrigation standard are allowed to work on the wiring.

When servicing the machine, personally shut off and lock the master control switch.

Stay away from the machine during lightning storms. A properly installed machine is an

ideal lightning receptor and will carry the current for long distances.

NRCS-SC 442 IWMP February 2017

21

Install lightning arresters to protect equipment. Place these outside the control box as they

explode when lightning strikes the system.

Mark the location of all buried electrical lines.

As with any electrical system, do not over-fuse. Instead, find out why the fuses are blowing

and correct the problem.

Don't cut corners on the electrical installation to save money.

Avoid contact with overhead lines when moving equipment.

Use the disconnect switch located at each tower when working on the system. It is there to

protect a person from injury if someone accidentally energizes the system or if the system

automatically restarts after a power outage. The Occupational Safety and Health Act (OSHA)

requires the switch to be within 15 feet of the motor.

If you feel a tingle when you contact any part of the system, shut it down until a competent

electrician can troubleshoot the system.

SECTION 11 – MAINTENANCE

A properly operated and maintained sprinkler irrigation system is an asset to the farm. This

irrigation system was designed and installed to apply irrigation water to meet the water

requirements of the crops. The estimated life span of this installation is approximately 15 years.

The life of this system can be assured and usually increased by developing and carrying out a

good operation and maintenance program. Failure to Operate and Maintain this system could

result in actions to reclaim cost share and/or loss of any future financial or technical assistance.

This practice will require performance of periodic maintenance and also require operational

items to maintain high distribution uniformity, emission uniformity, and application efficiency of

these systems. A good operation and maintenance program includes:

Monitor crops regularly noting areas of moisture stress and repair or adjust system operation

as needed.

Only operate the system when needed to furnish water for plant growth, salt management or

to store moisture within the rooting depth of the plant.

Operate the system at the pressure, discharge rate, speed, duration and frequency as designed.

Periodically examine each sprinkler and spray head, etc., for proper operation. Clean plugged

nozzles, and replace if defective and worn. Use shank end of steel drill bits to check

diameters.

Make sure all components of this system are checked periodically and worn or damaged parts

are replaced as needed.

NRCS-SC 442 IWMP February 2017

22

Always replace with the design size and type.

Install a flow meter at the water supply to monitor flow rates, detect leaks, and clogs in the

system.

Operate each zone at the planned pressures to allow for good distribution uniformity.

Maintain all pumps, valves, piping, regulators, chemical injectors, screens, filters, timers and

other electrical and mechanical equipment in accordance with manufacturer

recommendations.

Automatic disc filters or sand media tanks can be used if iron precipitant is a problem.

Filters need to be checked and cleaned periodically to prevent unnecessary friction losses and

to maintain water flow for efficient pump operation.

During non-seasonal use, place appurtenances in an area where it they will not be damaged

but are secure, if necessary.

Immediately repair any vandalism, vehicular or livestock damage. Do not allow livestock

near equipment during operation.

Drain and protect system and components from freezing, as necessary.

Eradicate or otherwise remove all rodents and/or burrowing animals that have

or can potentially damage any part of the delivery, or application facilities.

Immediately repair any damage caused by their activity.

Have system and pump evaluated to check for proper flow rates, pressure and distribution

uniformity (see Section 8).

Water treatment is recommended if using recycled tailwater. Recommendations include

diluting the tailwater and allowing a period of time for settlement, and treating the recycled

water through chlorination or copper ionization. Recycled water may need filtration prior to

pumpback. A major concern is the spread of phytopthora. Tailwater shall be tested for such

pathogens. Contact Clemson Cooperative Extension for assistance with monitoring and

analyzing for disease spores in tailwater.

NRCS-SC 442 IWMP February 2017

23

SECTION 12 – COOPERATOR’S SYSTEM LAYOUT MAPS

insert IRRIGATION SYSTEM LAYOUT MAP(s) behind this sheet

(to include the size, materials, and location of mains, laterals and all appternances required for the proper operation of the system)

insert SOIL MAP(s)(to include field boundaries, with the predominate soils listed and area qualified)

NRCS-SC 442 IWMP February 2017

24

SECTION 13 – COOPERATOR’S SOILS DESCRIPTIONS

SOIL DESCRIPTIONS

Map Unit Description (Brief)

The map units delineated on the detailed soil maps in a soil survey represent the soils or

miscellaneous areas in the selected area. The map unit descriptions in this report, along with

the maps, can be used to determine the composition and properties of a unit. A map unit

delineation on a soil map represents an area dominated by one or more major kinds of soil or

miscellaneous areas. A map unit is identified and named according to the taxonomic

classification of the dominant soils. Within a taxonomic class there are precisely defined limits

for the properties of the soils. On the landscape, however, the soils are natural phenomena, and

they have the characteristic variability of all natural phenomena. Thus, the range of some

observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils

of a single taxonomic class rarely, if ever, can be mapped without including areas of other

taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas

for which it is named and some minor components that belong to taxonomic classes other than

those of the major soils.

The "Map Unit Description (Brief)" report gives a brief, general description of the major soils

that occur in a map unit. Descriptions of non-soil (miscellaneous areas) and minor map unit

components may or may not be included. This description is written by the local soil scientists

responsible for the respective soil survey area data. A more detailed description can be

generated by the "Map Unit Description" report on the Soil Data Mart website. Other reports,

which give properties of the soils and the limitations, capabilities, and potentials for many uses

is also available for download.

Web Soil Survey - Home. (link to website)

(soil unit descriptions behind this sheet)

NRCS-SC 442 IWMP February 2017

25

FEEL AND APPEARANCE METHOD FOR ESTIMATING THE

AVAILABLE MOISTURE IN THE SOIL

Available Moisture

Feel, Appearance, and Texture of Soil

AWC (In/Ft)

Coarse textured soils Moderately coarse

textured soils

Medium textured

soils

Fine & very fine

textured soils

0.5-1.25 1.25-1.75 1.5-2.3 1.6-2.5

0 - 25 %

Dry, loose, and single

grained; flows through

fingers

Dry and loose; flows

through fingers

Powdery dry; in some

places slightly crusted

but breaks down easily

into powder

Hard, baked, &

cracked; has loose

crumbs on surface in

some places

25 - 50% Appears to be dry; does

not form a ball under

pressure*

Appears to be dry; does

not form a ball under

pressure*

Somewhat crumbly but

holds together under

pressure

Somewhat pliable;

balls under pressure*

50 - 75%

Appears to be dry; does

not form a ball under

pressure*

Balls under pressure

but seldom holds

together

Forms a ball under

pressure; somewhat

plastic; slicks slightly

under pressure

Forms a ball; ribbons

out between thumb &

forefinger

75 - 100%

Sticks together slightly;

may form a very weak

ball under pressure

Form weak ball that

breaks easily; does not

slick

Forms ball; very

pliable; slicks readily if

realatively high in clay

Ribbons out between

fingers easily; has a

slick feeling

At Field Capacity

On squeezing, no free

water appears on soil

but wet outline of ball

is left on hand

Same as for coarse

textures soils at field

capacity

Same as for coarse

textured soils at field

capacity

Same as for coarse

textured soils at field

capacity

Above Field Capacity

Free water appears

when soil is bounced in

hand

Free water is released

with kneading

Free water can be

squeezed out

Puddles; free water

forms on surface

Irrigation Range

30% - 60%

NRCS-SC 442 IWMP February 2017

SECTION 14 – COOPERATOR’S DOCUMENTATION

NRCS-SC 442 IWMP February 2017

26

insert SOIL TEST RESULTS (behind this sheet)

insert WATER QUALITY TEST RESULTS (behind this sheet)