Campbell Scientific Sentek EnviroSCAN Access Tube User Manual

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ACCESS TUBE INSTALLATI ON GUIDE

Version 1.0

for

EnviroSCAN

EnviroSMART

Diviner 2000

Access Tube Installat ion Guide

EnviroSCAN EnviroSMA RT Diviner 2000

Al l ri ghts re s erved. No part of this document may be reproduced, transcribed, translated into any language or transmitted in any form electronic or mechanical for any purpose whatsoever without the prior written

consent of Sentek Pty Ltd. Al l intellectual an d pro per t y r ig hts remain with Sentek Pty Ltd. All information presented is subject to change wi thout notice. Names of programs and com puter systems are registered trademarks of their respective companies.

EnviroSCAN, EnviroSMART and Diviner 2000 are trademarks of Sentek Pty Ltd which may be registered

in ce rt ain jurisdictions. Env iroSCAN, Env iroSMART and Diviner 2000 ar e pr otecte d int er nat i onally by various patents (and/or patents pending).

Sentek Pty Ltd 77 Ma gil l R o ad

Stepney, South Australia 5069 Phone: +61 8 8366 1900

Fac simile: + 61 8 836 2 8400 Internet: www.sentek.com. au

Email: Sentek@sentek.com.au

Access Tube Installat ion Guide Low Res

Contents

Access Tub e Installation Guide i Contents i

Ab o u t thi s man u al 1

Document Conventions 1

Introduction 2 Site Selection 3

W hat is site selection? 3 Relationship between macro and micro zones i n the field 3

Important factors you should know that affect crop water use 4 A general view of macro scale zone selection 7

Micro scale zone selection 10 Micro zone selecti on guidelines 10

Installing access tubes f or Diviner 2000, EnviroSCAN and EnviroSMART probes 13

Introduction 13 Safety 14

Good versus poor inst allation 14

Standard manual installation method 16

Introduction 16 Items required for standar d manual installations 16

Installati on procedure 18 Troubl eshooting the standard manual installation method 30

S l urry I ns ta l lat i on Meth o d 35

W hat are the different slurry methods? 35 Installati on procedure 38

Removing Access Tubes 45

Items required for access tube removal for EnviroSCAN, EnviroSMART and Diviner 2000 45 Removing EnviroSCAN, EnviroSMART and Diviner 2000 Access Tubes 45

Toolkit Items 48

Sentek access tube items 48 Standard Access Tube Installation Kit Complete (Part No. 07000) 49

Slurry Access Tube Installati on Ki t ( Part No. 07250) 51 Optional T ools for Access Tube Installation 52

Recommended Reading 54

Access Tube Installat ion Guide Low Res

About this manual

This guide describes the principles of site selecti on and the materials and methods that are used to install Sentek access tubes .

Document Conventions

Before you start it is important that you understand the conventions used in thi s manual .

Conventions Type of Inform ation

Bold text

This font face This font face is used for the names of tools, methods and miscellaneous i tems, for

Text presented under the heading:

‘Note:’ ‘Hint:’

Text presented under the heading:

‘Warning:’

‘Disclaimer:’

‘Caution:’ Information whi ch, if not strictly observed, could result i n dam age to, or destruction

desi gned to be used together. Other brands of probe and access tubes are not

co mpa tible wit h t he Sentek products and shoul d not be used as they m ay damage

Sentek has developed precision i nstallation tools are to be used for the installati on

of Sentek access tubes. The precision of the access tubes and tools is designed

to complement the value of the readings taken by Sentek sensors. The value of

readings is compromised when poor and hasty installation methods are used.

Sentek does not accept any responsibility for damage caused by incorrect site

Bold text is used to highlight names of products and companies, for example Sentek or an emphasized word, for example, ‘Note:’ or ‘Warning’

example Regu lar T-Ha ndle.

Important information that should be considered before completing an action Information that makes a process easier or saves ti me

Information whi ch, if not strictly observed, could lead to misleading moisture trends and wrong irrigation management deci sions.

Cri ti cal information that m ust be considered before completing an action. Cri ti cal information regarding the liability of Sentek and the responsi bility of the client

to use the equipment responsibly and as described in the manual.

of, equ i pm ent.

Disclaimer:

The access tubes, probes and sensors supplied by Sentek are speci fically

Sentek equipmen t. Damage to Sentek equipme nt th rou gh incorrec t u se will

inva lidate warra nty agreements.

s elec t io n, poor insta l lat io n or inappropria te use of Se nt ek prod uc ts.

Introduction

The Access Tube Installati on Guide provides important inform ation about how to select m onitoring sites and install access tubes. Please read this information prior to installing access tubes.

Site selection and access tube installation have a significant impact on the value of the soil moisture data that can be gathered on your property.

Warni ng: Good Site Sel ec tion is Critical

To obtain representative soil moisture readings, the site where the access tube is

installed must reflect changes in soil moisture and crop water use trends which can

then be used to representatively schedule irrigati ons over a defined area.

This area may be an entire field or a subsection of a field where irrigation water is

appli ed during a watering shift.

The quality of acc ess tube insta llation is cr itic a l. T he acc ess tube must f it ti ghtly

against the soil and cause the least possible di sturbance to the surrounding soil

profile.

To take soil moisture readings, access tubes are installed at m onitoring sites, which should be chosen using a series of proven evaluation methods described in the section on Site Sel ect ion .

It is important to select monitoring sites so that the information that is gathered from them is representative of the surrounding crop water use and soil water holding capacity. At each site, one or several PVC access

tubes may be driven into the soil. The access tube prevents the direct contact of the Sentek probe with the soi l. The bottom stopper and top cap prevent moisture and dirt from enteri ng the tube.

The access tube installati on process is described in the section on Access Tube Installation for Diviner

2000, EnviroSCAN and Enviro SMART .

Warning: If you do not understand any of the inform ation presented here on Site

Selecti on, consult a trai ned Sentek reseller or agronomist. Incorrect site selection

can result in m is lea din g data and/or cr o p damage.

Access tubes are installed using Se ntek precision i nstallation tools designed to install access tubes in a range of soil types. It is recommended that you always try the Standard manual installation method first. A

slurry method is available for i nstallations in soils with high stone and gravel content.

Note: To identify the tools you require to install the access tube, examine the soil

profile with a shovel or backhoe close to the nominated monitoring si tes. Read the

section on Access T ube Installation for Diviner 2000, EnviroSCAN and

Envi roSM ART to work out which toolkits and additi onal tools will be required for

your install atio ns.

When the monitori ng of a soil profile is no longer required, the access tubes can be removed, cleaned and stored. T his process is described in the section on Removing Access Tube s.

If you have any questions, Sentek recommends consultation with a trained reseller or agronomist prior to installation. Trained resellers and agronomists understand the complexity of site selection for irrigation

s c hedu li ng an d the need f or pr o per ins t a l lat io n of the access tubes .

Site Selection

The key to effective soil moi sture monitoring is to select monitoring sites which truly represent irrigation management areas. The same basi c site sel ection principles appl y to the full range of Sentek soil moisture

monitoring devi ces. Many variables influence the spatial distribution of water across an area of land. These variables and their impact on site selection are di scussed in more detail below.

What is site selection?

A si te is defined here as:

“The location of the access tube within a field or i rrigation shift, where soil water readings are taken at dif fer e nt dep th l ev e ls wit h in th e so i l profile.”

Note:

If readings are to be used as a basis for scheduling irrigati ons over larger defined

areas, it is imperative that m oni tori ng sites are representati ve of these areas.

Soil moisture data can provide information about the:

• Quality and depth of irrigations

• Level s of soil moisture retention

• Depth of the crop root zone

• Impact of weather and rainfall events on an area

Warning:

Do not sel ect irrigation scheduling si tes at random on your property. Poor site

se lection will re sult in soil moisture data tha t is unrep resenta tive of soil water

changes and crop water use in that field.

Site selection i s carried out in two stages:

• M a cro zone selection

• Micro zone selection

Relationship between macro and micro zones i n the field

Traditional practice within the field and across the whole farm has been for i rrigation to be applied on a hypothetical “farm average” – i n a similar way to traditional broad acre management practices.

Uniform application of irrigation across areas with highly variable soils and di fferent levels of crop water use causes signi ficant differences in yield and quality, creating commercial losses and environm ental harm

through increasing problems with rising water tables and increasing salinity. If di fferent soil types are ignored in terms of thei r different irrigation scheduling requirements, crop setbacks

or failures may occur. Macro zone selection defines the number of zones on a property where the amount of timing of irrigation

applications can be specifi cally tailored to match soil and crop variability – a macro zone comprises areas with simila r c rop wat er u se.

Crop water use i s governed by many factors such as soil properties, water quality, weather patterns and type of irri gati on system. These factors need to be consi dered when defining the macro zones on your property

and are descri bed in the following pages.

Site Selection

Micro zone selection determines the posi tion of access tubes in rel ation to the crop and irrigation system. Micro zone selection consi ders the:

• Area of root zone and canopy spread

• Water distribution uniformity (sprinkler pattern)

• Moisture pattern of drip irrigation

• Su rf ace, topographic and soil anomalies

The consi deration of these factors will assist in finding the best representative posi tion or si te for access tube plac e me nt withi n th e macr o an d micro zones .

Macro and micro zone selection i s described in greater detail in the following pages. If you require further information, consul t your Sentek reseller and/or a trained agronomist.

Important factors you should know t hat affect crop water use

All the factors li sted below can have an impact on the way the water is stored in the soil and on the way that plants use that water. They affect transpiration and evaporation rates and have a di rect impact on irrigation

scheduling. In macro zone selection, it is important to consider the way these factors i nfluence water use in a particular area or zone:

• Climate

• Soils

• Crop

• Cultural management

• Irrigation system

Climate

The most com monly recognized factor infl uencing the amount of crop transpiration is the weather.

Temperature

Crops need to draw up water to compensate for water use through transpiration (water loss through the leaves) and evaporation (water loss from the surface of soil and leaves). The demand increases with

increasing temperature up to a maximum threshold for each crop (when the stomata close and photosy nth esis stops).

Humidity

Atmospheric demand for transpiration and evaporation is relative to the humidi ty (amount of water vapour in the air). The higher the humidity level, the lower the demand.

Wind speed

Crop transpiration and evaporation i ncrease with increasing wind speed, creating an increased water demand. At higher wind speeds, transpirati on eventually decreases due to stomata cl osure, but evaporation

increases.

Solar radiation

On sunny days, crops can synthesize more basic sugars and more complex plant food compounds, through the combi nation of atmospheric carbon dioxide and soil-derived water, than on cloudy days. Although crops

vary in thei r sensitivity of photosynthetic response, they all require access to greater amounts of soil water.

Rainfall

Rain is generally associated with higher humidity level s and lower solar radiation and temperatures. It follows that days on which rai nfall occurs are associated with lower water demand and use than dry sunny

days.

Site Selection

Notwithstanding the care taken to delineate macro zones, som e variability in soil moisture level s is inevitable. For example: on lar ge pr oper tie s, r ain events may cov er only a porti on of the land area, replen ishi ng some

soi l reservoi rs and leaving others dry. The aspect or orientation of slopi ng fields can subject the crop to more or less solar radiation, wind exposure

or water run-off – all affecting crop water use.

Soils

An understanding of how soil type influences plant-soil-water-dynamics, and hence irrigation scheduling is important. Intrinsic soil properties are texture, structure, depth, chemistry, organic matter content, rocks and

stones and clay mineralogy. Influencing factors include compaction, salinity, water-table development, drainage rate dynamics and topography.

Soil textur e

Water storage in the soil profile and the rate it dries out, depends on the soil texture. At one end of the spectrum, sandier soils fill up and drain quickl y. Hence these soils, in general, require sm aller and more

frequent irrigations. In contrast, heavier clay soils replenish and drain slowly and to a higher total water content than lighter (sandier) soils. An infi nite range of textures exist between the two extremes. Textures

often change wi thin a profile, with the layering of different textural bands playing a large part in determining the water holding capacity of a soil.

Soil structure

Water infiltration rates and ai r and water permeability within the soil profile are closely related to the size and distribution of soil pores. Porosi ty in turn, is dependent upon the arrangement and aggregati on (binding) of

sand, silt and clay particles (soil structure). Soil structure is as important as soil texture in governing how much water and air move in the soil and their availability to crops. Roots penetrate more easi ly and rapidly in

soi ls that have stable aggregates than i n similar soil types that have no or highly devel oped structures. The effectiveness of soil moisture, air and nutrient utilization i s related to the effi ciency of root colonization of the

entire soil profile.

Soil depth

The effective depth of soil affects the extent of root penetration. The deeper the soil, the greater the vol ume of soil that is availabl e for gaseous exchange and water uptake. Drainage is al so influenced by effective

depth.

Soil compaction

Soil compaction from farm machinery can change pore size and distribution resulting from the natural arrangement of the sand, silt and clay particl es. This can cause reducti ons in water i nfiltration rates, and air

and water perm eabi lity within the soil profile. The resultant impact upon the effectiveness of root penetration, air exchange and water uptake affects plant growth effi ciency and hence water demand.

Salinity

Salini ty lowers the osm otic potential, reducing the effici ency with whi ch water and nutrients are taken up by the p lan t. The domina nc e of the co ntr i buting i ons can r esu lt in a nutr ie nt imba l anc e ca using de f ic i encies of

essential macro and micro nutrients. The reduced plant health and vigor affect crop water use.

Water tables and drai nage rate

Poor drainage can lead to the development of water tables and/or cause a temporaril y saturated soil profile. The presence of impermeable soil layers can cause the formation of perched water tables, which saturate

parts of the root zone. Efficient gaseous exchange becomes restricted and pl ant health and water use is reduced.

Site Selection

Organic Matte r

The presence of organic matter and humus increases the cation exchange capacity (CEC), water holding capacity and structural stability of soils.

Soil chemistry

Acid, al kaline, sodic (soils characterized by a dominance of sodium ions) or nutrient deficient conditi ons impact on expected soil chemical properties. For exampl e:

• pH conditions change CEC and the availability of nutrients (by changing their form). Nutrient deficient plants have a lower water uptake rate

• high levels of sodium can lead to structural collapse, infiltration problems and reduced water availability

Rocks and stones

Stones and rocks and other coarse fragments within a soil profile occupy part of the soil volume and hence reduce the soil water storage capacity. Very stony soils have a substantially lower water holding capacity

than soils of the same texture that are free of stones.

Topography

Topography relates to the configuration of the land surface and is described in terms of differences in aspect, elevation and sl ope. This has an impact on plant-soil-water dynamics via influencing climati c conditions

including:

• rain shadows and sunshine hours

• rainfall and temperature patterns up slopes

• elluviation (washing-out) of cl ays from higher elevations and illuviation (washing-i n and

accumulation) of clays at lower elevations

• r elat iv e ly p oor er dr ai na ge i n low lying are as

Crop

Crop differences have an impact on crop water use and i rrigation scheduling requirements. While all require management between field capacity and wilting point at most times, the depth of root extraction varies, as do

specialized requirements, e.g. the deliberate stressing of wi ne grapes. Most pl ant tissues contai n about 90% water and the rate of uptake of water from the soil solution by plant

roots i s largely controlled by the rate of water loss through transpiration. Plant characteristics such as crop type, si ze, age, vigour, variety, rootstock, developm ent stage, leaf area, nutriti onal status, crop load and

harvest all affect crop water use. Specialized advi ce should be sought in this regard. A rough guide to water use can be obtained from crop coefficients, which are wi dely available in the literature for different growth

stages of most crops. These express evapotranspiration as a ratio of reference evaporation.

Cultural Managemen t

The i mpacts of cultural management (agronomi c/horticultural practices) also need to be understood for pr oper irr i gation sche du li ng .

Soil preparation

Culti vation increases evaporation from the topsoil, reducing the amount of soil water availabl e to the plant. It may also reduce water run-off and improve the infiltration of rain and irrigation water, improving plant water

availability.

Site Selection

Cover crop and mulch

Cover crops provide more competition for water, but reduce evaporation and facilitate infiltration of rain and irrigation water, reducing run-off.

Mulch can improve the infiltrati on rate of the soil, reduce water run-off, encourage root growth near the soil surface and increase the soil water holdi ng capaci ty over time, through the accumulation of soil organic

matter, and reduce soil tem perature.

Oil spraying

Oily substances on leaves reduce water use by temporarily cl osing stomata. An example of this is mite contr ol in c it r us.

Fertilizer management

In order to ensure that no nutrients are deficient, fertilizer applications are normally based on soil and/or leaf sam ple analyses. The degree of precision varies from a rough averaging approach to precision farming

where sample points are matched to requirements usi ng satellite tracking technology. Healthy crops require more water and have different nutrient dynamics to crops that have been stunted or diseased through

inefficient fertilizer management.

Pest/disease management

Good pest/disease management keeps the crop protected and in good health, sustaining its potential growth and transpiration rates. Infe stations can resul t in lower tha n normal water uptake.

Irrigation S ystem

The effectiveness of an irrigation system to deliver water affects crop water use. Variations in irrigation system pressure, flow and water di stribution uniformity cause variations in irrigation application. This affects

root zone wetti ng patterns and therefore crop water use. The preceding crop water use factors should be taken into account when matching your irrigations to areas

of similar crop water use. These areas are then represented by soil water monitoring sites and the data collected at these sites is used for irrigation scheduling purposes.

Water Quality

The source and constituents of irrigation water impact on osmoti c potential and hence plant water uptake. Water quality can vary both within and between seasons and between water sources. Hi ghly sodic waters

can al so affect soil structural properties, reducing water infiltrati on rates.

A general view of macro scale zone selection

Macro zone selection is used to identify the total number of required zones and their locations on your property. A macro zone com prises areas of sim ilar crop water use. The aim of good site selection i s to

sel ect a monitoring si te that reflects changes in soil water content and crop water use trends. The representative data gained from monitoring si tes is used to schedule i rrigations over a larger defined

area. This area (or macro zone) may be an entire fi eld, or a sub-section of a field, where irrigation i s applied during a watering shift.

As an i rrigator, you want to replenish the soil water used by plants for growth and transpiration. So, it is important to understand the many factors that affect crop water use or transpi ration, and how these factors

may vary on your farm . A primary goal of good irrigation management is to match irrigations to areas with similar crop water use,

withi n the limits of your i rrigation system flexibility. This consi deration will ultimately determine how many monitoring si tes you will need and where you should l ocate them.

Site Selection

The diagrams on the following pages show an exampl e of how ‘factors that affect crop water use’ can be used to determine macro zones. Consult your local soil specialist for further information on the soils at your

si te. Firstl y the soil properties and types are considered, to differentiate between areas of varying soil-water properties:

Then the soil limitations and suitability for the proposed use are identified i n order to determine the need for s oil impr ovem ents and am elior at io n:

From this the requirements for soil improvements and amelioration are outlined:

Site Selection

Once the soil has been ameliorated and improved, then the altered soil properties are considered in conj unction with the topography, irri gati on system and crop types to delineate irrigation management units.

Site Selection

Overlaying all this information makes it possible to identify, wi thin a property, areas (zones) that have si gnificantly different requirements.

In the example used, the property has been divided into eight macro zones. Each m acro zone requires a monitoring si te. Potential sites are shown by the dots, but final posi tioni ng can be determined by the

information in the micro scale zone sel ection.

Micro scale zone selection

With macro zone selection you have identi fied the i rrigation management units on your property. Micro scale zone selection is used to target the actual site of the access tube in relation to crop, micro-scale soil

var iability and ir r iga tion deliver y point.

Note: Micro zone selection is equally as important as macro zone selection and

has a direct effect on the representati ve value of the data.

In soil-based monitoring the measurements are taken from a small part of the root zone. Sentek sensors record the dynamics of m oisture i n the part of the soil profile where the access tube has been installed. If

you miss the root system or install the access tube i n dry or wet irrigation spots, the data wi ll not make sense and cannot be used for irrigation scheduling, as it will not be representati ve of an entire i rrigation

management unit. So il moisture m onitorin g ins t r um ents are of t en bl a med if there is no inc rease in moistur e c ontent aft er a n

irrigation, but testing will al most always show that the si ting of the equipment i s wrong. For example i t is common to fi nd that the access tube is placed in a dry spot, cause by a sprinkler system havi ng a poor

distribution uniform ity. Also, on slopi ng ground, the lateral movem ent of water needs to be taken into consideration when si ting the access tube.

Where there are variations in the micro relief or soil properties and depth over very small distances that affect the root di stribution and growth of the plant (e.g. in gilgai soils), it may be necessary to i nstall more

than one soil moisture probe in the same area to represent these variations.

Micro zone selection gui delines

Followi ng i s a set of guidel ines for selecti ng access tube i nstallation sites within irrigati on m anagement units. Thre e ma jor fac t or s need to be taken in to ac co unt; irr ig ation, pl ant health and s oi l type.

Irrigation sy ste m

It is important to check that your irrigation system is performing as per the design specifi cations prior to installation. Variations in sprinkler pressure and flow, pump performance, distribution uniformity and wind

can result i n uneven patterns of watering and irrigation depths. This can lead to salinity problems, development of water tables, water logging, root death and an overall decline in crop health, yield and

quali ty. Before you commence irrigation scheduling make sure your irrigation system performance is at an

acceptable level. Read the recommended l iterature (Merriam & Keller, 1978) to perform detailed checks on irrigation systems or contact your irrigation consultant or Department of Agriculture for further advice. It is

important to check your i rrigation system at least once a year.

Conducting a distribution uniformity (DU) test

Prior to installing the site, it is also necessary to check the distribution uniformity of the system. The uniformity of water distribution from sprinkl ers can be checked with a simple can test. The method involves

arrangi ng cans in a grid pattern withi n the wetted area and measuring the volume of water i n each can.

Site Selection

In the example illustrated below, cans in the blue shaded area received above average water; those in the red shading below average; while those in the green shaded area received an average amount.

Due to the specific nature of each site in terms of irrigation system, it is inappropriate to give prescriptive adv ic e on tu be pl ac e me nt. For soil mo is tur e mo ni tor i ng, tu be placement s hou ld how ever, be re pr esenta t iv e

and consistent of the area being watered. General guidelines for commonl y used systems and principles of sample site sel ection fol l ow.

For sprinkler systems, it is preferable to use two access tubes per site, placing one into an area receiving average precipitation and the other one into a wet or dry spot, depending on a soil salinity or water table

problem. In centre pivots, if the distribution uniformity tests show si gnificant variation between booms, two or more

access tubes should be installed, with at l east one tube in each different area. For high pressure rain guns, measure the water application pattern under di fferent wind conditions to ensure that you don’t pick on area of

extremely l ow or high water application. Installation of probes in drip irrigated crops needs consideration of the extent of the ‘wetting onion.’ Use at

least two probes to moni tor soil moisture of drip irrigated crops to measure both the vertical and the lateral spread of water. The schematic below shows an example of the variation i n the wetting pattern below a

dripper. The darker blue colour signi fies wetter soil conditions, while the lighter blue colour signifi es drier soil condi tions. The pl ant roots will utilize the water from di fferent locations under the dripper at different

intervals; therefore it is very important to measure these differences using more than one probe.

Site Selection

In addition, in drip irrigation, the slope needs to be taken into consideration, to account for movement of wate r do wn slop e.

In furrow irrigated fields, access tubes should be installed 50 to 100 metres away from the head ditch. Access tubes should not be installed solely at the opposite side to the head ditch, as tail water from the

irrigation may back up the furrows and give unrepresentative readings. Placement of tubes here may be considered when measurement of deep percolation below an irrigation field is required. Consideration

should also be given to placing another tube in the middle of the field to measure the depth of irrigation there.

Plant h ealth

Select a site next to an average-sized, heal thy plant representing the Irrigation management unit. Avoid:

• Stunted or sick plants

• Unusual ly l ar ge p lan ts or trees

• Spots where plants are missing

General guidelines for key crops include:

• In fi eld crop and vegetable production, choose a uniform crop stand, and ensure that the probes are inserted within the actively growing root zone.

• In orchards, use two access tubes to monitor the site. Place one access tube under the canopy of the trees and another outsi de the canopy – there will be some interception of rainfall

by the canopy so less rain water will penetrate the ground directly under the canopy. Select a si te that represents dynamic data trends (more root activity) and again consi der irrigation

dist r ibu tion unif ormity.

Soil p roperties

Soil properties influence probe placement in drip irrigati on, as the wetti ng pattern is highl y dependent upon the soil. In uni form sands, most of the water applied under the dri pper will tend to move vertically through

the profile, with minimal lateral spread. Conversely, i n uniform clay soils, the water will tend to spread laterally as well as vertically. In soils of contrasting textures, there will be varyi ng wetting patterns that need

to be taken into consideration. In many soils there are substantial variati ons in the thickness of horizons and in the potenti al rooting depth.

This can lead to si gnificant variations in soil water storage capaci ty and plant growth over relatively short distances. Under these conditions, it is recomm ended to install to two access tubes to ensure that this

variability is taken into accou n t.

Other micro zone selection considerations

There are several other factors when considering micro zone selecti on that also need to be taken into consideration. These are:

• Do not install access tubes in outsi de rows. These locations are usually exposed to wind and dust, particularly in the vicinity of roads or adjoining broad-acre properties.

• Avoi d the ‘drip ring’ in, for example, citrus orchards, where sprinkler irrigation water is channeled by the canopy to the outside bottom edge of the foliage creating wetter soil

condi tions at the edge of the canopy.

• Avoi d wheel tracks (and wheel track rows) as the soil is more compacted in these areas and stores less readily available water than the rest of the field (non wheel track rows).

I nstalling EnviroSCAN, Enviro SMART & Diviner 2000 access t ub es

Installing access tu b es for Divin er 2000, EnviroS C AN and EnviroSMART probes

Introduction

It is ne cessary to install Sentek access tubes before Sentek sensors can be used to measure vol umetric soil water content. Access tubes are installed at sel ected sites usi ng Sentek instal lation tools. The tools are

specific to the installation method so it i s important to understand the installati on method before purchasing your installation tools. A slurry installation method may be used for soil with a high gravel and stone content.

Note:

Inspect the soil types on your property prior to undertaking an installation to

ensure that you have the correct tools. The standard installation kit is designed for

installation i n most soi l types, but in some situations such as very heavy clay or

roc ky soils, additional tools may be require d.

Once you have i dentified your soil properties, read the rel evant section of this

manual to determine what tools you require.

If yo u ar e unsure about any aspect of t he i nstalla t ion m et h od, c on tac t y our Sen tek

reseller and discuss the sites you have selected and your installation needs.

The aim of the installation process is to cause minimum disturbance to the surroundi ng crops and soil profile. Disturbances to the soil may introduce pockets of air and loosely packed soil material. The disturbances

affect the contact of the outer surface of the access tube wi th the surrounding soil profile and may lead to preferential flow of irrigation water or rain to a greater depth compared with the rest of the field. If readings

are taken under disturbed soil conditions they m ay by i ncorrect or misleadi ng.

Warning:

Access tubes must be installed so that they fit tightly in the soil along their entire

length. Permanent errors can be introduced into the readings through poor or

hasty installations. Any air gaps between the length of the access tube and the soil

will cause data deviations.

For exa mp le , the penet r at i on de pt h of an ir r i ga ti on appear s to be m uc h de eper if

there is an air gap next to the access tube. This misrepresents the depth of the

irrigation in the field at that site.

The addition time taken i n careful installati on ensures access to accurate and

me an in gfu l dat a.

I nstalling EnviroSCAN, Enviro SMART & Diviner 2000 access t ub es

Disclaimer:

The access tubes, probes and sensors supplied by Sentek are speci fically

desi gned to be used together. Other brands of probe and access tube are not

compati ble with the Sentek products and should not be used as they may damage

Sentek equipm en t thro ug h inco rrect use a nd will invalida te warranty agreement s. Sentek has developed precision i nstallation tools to be used for the installation of

Sentek access tubes. The precisi on of the access tubes and tools is designed to

complement the high value of readings taken by the Sentek sensors. T his value of

both relative and absolute readings is compromised when poor and hasty

installation methods are used.

Safety

Sentek encourages the use of safe practices that minimize the risk to users, their machinery and their property. The following safety information i s provided to help you prevent acci dents on your property.

Carrying equip ment into th e field

An access tube installation requires access tube kits, toolkits, miscell aneous tools and duck boards. Often yo u can not drive a vehi cl e al ongsi de the installation si te so it is i mpo rtant to conside r ho w y ou will ge t the

required equipment to the site. The toolkits come i n cases that protect them from the elements and from general damage. T hese ki ts have

handles to help you carry them into the field. It is important to carry the longer kits in a way that does not place undue stress on your body nor damage crops.

When carrying equipment into the field remember to:

• Bend your knees and keep your back straight when lifting

• Make several small trips rather th an trying to carry too much at one time

Wor k ing with in sta lla tio n e quipm e nt

It is important that you wear gloves and safety goggles to protect your hands from burns and to prevent your eyes from penetration injuries caused by splinters of metal or soil.

When using motors to drive augers, ensure you wear ear protectors to minimize the affects of the motor on your hearing.

Protect ing and caring for equipment

There are numerous items in the various toolkits. It is important to keep all of the items clean and to put the m away in the ir pr otectiv e cas es when not in use.

Good versus poor installation

The aim of any installati on i s to cause as little disruption to the normal soil structure as possi ble, and provide an envi ronment where the soil moi sture may be detected repeatedly and accurately over an extended period

of time. If the surrounding soil is disturbed during the installation process, then air gaps m ay form down the side of

the tube, which can lead to preferential flow of water between the soil and the access tube. Water will travel dee per t han in the s ur r ound in g s oi l, lea di ng t o a mis l ea di ng r e pr esent at ion of wat er mov emen t in the soil.

I nstalling EnviroSCAN, Enviro SMART & Diviner 2000 access t ub es

The figure below shows preferential flow of water down the side of the access tube, where the wetting front moves to the bottom sensor almost instantaneously.

The movement of wetting front should match the hydraulic properties of the soil, such as shown in the exa mp le be l ow .

+ 39 hidden pages

Campbell Scientific Sentek EnviroSCAN Access Tube User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual