magazine tydskrif - sabi
TRANSCRIPT
IRRIG
ATION
BESPROEI
ING
MAGAZINE TYDSKRIFTHE MAGAZINE FOR THE SOUTH AFRICAN IRRIGATION INDUSTRY • DIE TYDSKRIF VIR DIE SUID-AFRIKAANSE BESPROEIINGSBEDRYF
Volume 11 • Issue 6 • SABI | AUGUST/SEPTEMBER 2019
ISSN 2071-1883
Viking FarmingGrows greens in abundance
Greenhouses and Nethouses
Hydroponics
Bloubessie sukses/Blueberry success
Kenyan farmers’ revived irrigation
Rugged mobile communications
SALI Awards of Excellence 2019
Do something positive for water
Become an individual or company member
Advertise in SABI Magazine or subscribe
Boost your irrigation knowledge by attending an agricultural or landscape course
SOUTH AFRICAN IRRIGATION INSTITUTESUID AFRIKAANSE BESPROEIINGSINSTITUUT
+ 2 7 2 1 8 5 0 8 2 2 0 – i n f o @ s a b i . c o . z a – w w w . s a b i . c o . z a
MAGAZINE TYDSKRIF
LEARN TO GROW
IrrigationWise Academy
SANCIDSouth African National Committee on Irrigation and Drainage
Greenhouses, hydroponics & Vegetables
Eastern Cape, Viking Farming’s great greens 4
Sensors from lighting company 7
Shielding the world from hunger – net houses 8
Booysen Tunnel Farming, tomatoes in Stellies, Western Cape 13
Blueberries/Bloubessies
Bloubessie sukses verhaal 10
Good work
KSB’s boost for community clinic and water supply 14
Mandela Day river clean-up 15
Africa
Kenya’s Thika District big irrigation revival 17
Technology
Multicloud ventures 18
CAT’s amazing rugged mobile phones 19
Fresh Products
NetBeat, groot innovasie 26
JoJo filters 36
Smallholder Farmers
Jobs Fund boost for Limpopo smallholder farmers 34
Strategic Water Partners Network (SWPN)
WAS system implemented on 21 irrigation schemes 28
How To….Read a PVC Pipe Flowchart 32
Landscape
Golf clubs, Turf Managers and Water Wise water meter project 40
Green Scribbles
St Mary’s Therapeutic Garden 41
SALI Awards of Excellence 44
Tips and Tricks
IrriMaker and Bill of Material 43
Regulars
From the editor 2
President’s message 3
Company members 23-25
Dam levels 39
SABI Approved Designers 22
Subscribe Now 47
Training update 47
Advertisers’ contents 48
Contacts and Diary 48
contents
Pg4
Pg8
Pg10
Pg17
Pg28
Pg32
CONTENTS
Carol Posthumus
Editor
Riana Lombard
Advertising Sales
René van der Merwe
Subscriptions and circulation
Annemarie van der Westhuizen
Training Officer
Liam Hamer-Nel
[email protected] | alliancephoto.com
Graphic Design
Contributors:
Corné Arlow, Sanette Carrick, John
Kamau,Mike de Villiers, Lee-Anne Smith,
Printing
Colourtone Aries, Cape Town, RSA
Tel: +27 21 981 8873
Distribution & Media Support www.mediasupport.co.za
Cover Photograph
Viking Farming, Valhalla, Eastern Cape,
South Africa.
Photo courtesy Mike Pedersen-Horn
Published by SABI
(South African Irrigation Institute /
Suid Afrikaanse Besproeiingsinstituut)
T: +27 21 850 8220 | E: [email protected]
Web: www.sabi.co.za
Address: PO Box 834, Strand, 7139,
Western Cape, South Africa
SABI magazine / tydskrif is a bi-monthly publication.
© Copyright: South African Irrigation Institute/Suid-Afrikaanse Besproeiingsinstituut (SABI). Requests to reproduce material herein should be addressed to [email protected].
All rights reserved. Disclaimer: The views expressed herein by authors or advertisers are not necessarily subscribed to or endorsed by SABI or the editor.
SABI | AUGUST/SEPTEMBER 2019 1
Do something positive for water
Become an individual or company member
Advertise in SABI Magazine or subscribe
Boost your irrigation knowledge by attending an agricultural or landscape course
SOUTH AFRICAN IRRIGATION INSTITUTESUID AFRIKAANSE BESPROEIINGSINSTITUUT
+ 2 7 2 1 8 5 0 8 2 2 0 – i n f o @ s a b i . c o . z a – w w w . s a b i . c o . z a
MAGAZINE TYDSKRIF
LEARN TO GROW
IrrigationWise Academy
SANCIDSouth African National Committee on Irrigation and Drainage
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Greenhouses and hydroponics
Growing good greens and moreViking Farming’s bounteous vegetables
by Carol Posthumus
Whether or not you are one of the vast tribe of Kale connoisseurs, you will agree with the pundits that the burgeoning demand for green vegetables will
just continue to rise worldwide.
Future projections – ongoing growth in populations and urban-isation, huge nutritional and food
security needs and the pervasive food trend of veganism – continu-ally point to the importance of
vegetable farming in agriculture.Growing an excellent vegetable farming operation, like Viking Farming on Valhalla in Kwelera, Eastern Cape, takes a good amount of time and an ongoing investment and dedication to acquiring in-depth knowledge of soils, water and technologies
on-farm. Along, of course, with much talent, labour and TLC.
Mike Pedersen-Horn’s vegetable enterprise, Viking Farming on Valhalla Farm in Kwelera (Eastern Cape) kicked off in 2001 cultivating 2 ha, open-field, of cabbage and spinach.
SABI | AUGUST/SEPTEMBER 201910
Bloubessies/Blueberries
Bloubessie sukses verhaal deur Sanette Carrick
VRAAG:
Japie, ek sien ‘n sekere deel plante word direk in die grond geplant en die ander dele in sakke in ‘n medium. Hoekom so en wat is die voor en nadele van grond teenoor sakke?
JAPIE:
Plante het ‘n groter wortel volume in die grond as in sakke en die besproeiings risiko , sou die plant nie vir n dag besproei kon word nie, is kleiner as by sakke. Ons het aanvanklik met twee inlyn druppers, in twee rye weerskante van die plante begin met die oog daarop om ook doeltreffende kunsmis toediening te kry. Die probleem was egter dat die water net sekere areas van die plant se wortelstelsel veral in die nie-rëen tye, bereik het. Tydens die rëen seisoen het die wortels wyd versprei en wanneer daar besproei word met beperkte aantal drupper-lyne, kry net ‘n kleiner area van die wortels water, wat tot gevolg gehad het dat van die wortels afsterf en die plant benadeel was. Gronde verskil ook van plek tot plek wat besproeiings skedulering en waterverspreiding affekteer. In ander fases van ontwikkeling is daar ook van sakke gebruik gemaak, omrede
die medium wat gebruik is, baie meer homogeniteit as die grond bied en makliker imple-menteer in grond wat baie klip het of swak dreineer. Uiteraard word die bestuur van effektiewe toediening van besproeiing-swater makliker. Drupperlyn is moeilik verskuifbaar onder die onkruid-mat wat oor die walle getrek word wanneer daar in die grond geplant word. Sou die druppers verstop, is dit nie so eenvoudig om net die druppers te vervang nie.
‘n Bloubessie kenner het voorg-estel dat daar na ander metodes van water toediening gekyk moet word. So het die gebruik van die knopie (“button”) drupper met spinnekop uitlaat sy ontstaan by bloubessie besproeiing begin. Die button drupper druk in op die lateraal, waarop n spruitstuk (“manifold”) met 4 uitlate geheg is. Aan elke uitlaat word ‘n dun pypie toegeken en aan die einde van die pyp word n druppen (“peg”) waarlangs die water dan afloop of drup. Die druppenne is maklik beheerbaar en kan geskuif word vir die verkryging van optimale benatting. Wanneer die plantjie klein is kan die “peg” direk langs hom inge-druk word om seker te maak die wortels kry genoegsame water. Soos die plantjie in ouderdom
toeneem word die pegs wyer geskuif om seker te maak dat die wortel area vergroot en die plant optimale besproeiings water kry. Verstopping kan ook maklik raakgesien word by die metode van besproeiing. Dit is ook maklik om die “pegs” te vervang sou dit nodig raak, asook vinniger sigbaar ten opsigte van verstoppings, sou dit voorkom.
VRAAG:
Watter tipe besproeiing is volgens jou opinie die mees koste effektiewe metode?
JAPIE:
Dis ‘n moeilike vraag, die knopie drupper met vier uitlate is effe duurder as die inlyn drupper, maar die voordele wat die konsep bied is op die lange duur meer effektief. Inlyn drupper se watervloei sluit nie onmiddellik af nadat die krane toegedraai is nie,met die gevolg dat die sub-hooflyne van die blok leeg-loop en wanneer die krane weer oopgedraai word, neem dit tyd, om om blokke te vul en weer op druk te kom. Die “button” drupper sluit onmiddellik af met die toemaak van die kraan en die vloei en druk is heelwat vinniger daar wanneer die kraan weer oopgedraai word. Dit lei tot meer
Ek het met Japie Krynauw van Agrilogic ontmoet tydens my besoek in die Noordweste en het n paar vrae aan hom gestel.
Japie is ‘n Landbou Ingenieur wat besproeiingstelsels beplan en ontwerp. Hy assisteer ook sy kliënte met besproeiings beplanning, uitlegte, skedulering asook die inwerkingstelling daarvan. Sy ondervinding strek oor baie gewasse waaronder bloubessies, perskes, pekanneute, verskeie groente soorte en meer.
MISSION OF THE SWPNTo close the projected 17% water gap by 2030, with the
goal of improving water security in South Africa.
In the June/July issue of the SABI magazine issue we reported that the Strategic Water Partners Network (SWPN), a partnership between the private sector and Department of Water and Sanitation (DWS) established in 2011, identified the Water Administration System (WAS) as an instrument to reduce water losses on irrigation schemes in South Africa. Now read on to find out more about how WAS works.
As irrigation consumes 61% of national water resources, the potential for the WAS to reduce water losses on irrigation schemes is significant and can contribute to the objective of closing the water supply-demand gap in South Arica. The supply-demand gap, or deficit, is projected to reach 17%, or 2,7 billion m3 per annum, by 2030.
The SWPN, with additional funding inputs from the 2030 Water Resources Group (2030WRG),
Coca Cola, the Landbank and GIZ, partnered with NB Systems to roll out the implementation of the Water Release Module of the WAS at 21 large irrigation schemes. The roll-out took place in three phases between 2016 and 2018. The result is projected water savings of 268 million m3 per annum (at full quota).
The WAS is suitable for use on irrigation schemes where the allo-cation of water is distributed via canals and has also been adapted
for use on schemes where the allo-cation is abstracted from rivers.
Water release management on irrigation schemes
On the canal-based irrigation schemes water is released from the main dam into a network of canals and farmers draw their water allocation by setting a sluice gate at a specified opening for a given duration. This diverts a pre-determined volume from the canal into the farmers storage dam. As the sluices are open only for a limited time, the timing of flow released into canals is critical to ensure that farmers obtain the water they need and to ensure farmers know when they will be receiving their allo-cation. Irrigation schemes deter-mine how much water to release at any time based on “water orders” from farmers.
These orders are collected on a regular (usually weekly) basis and consolidated to determine the release schedules and the distribu-tion for each of the main canals. Water orders are captured onto a spreadsheet for the whole scheme and the water bailiffs then calculate the losses (seepage and evaporation) that will take place over the length of the canal as well as the lag time for water to reach the abstraction points, at the given flow rate. These calcu-lations inform the water release volumes and times for the water to travel from the schemes’ storage dams. If the release of water is not managed properly (i.e. the operator opens the sluices too
early or closes them too late, incorrect billing of orders, etc.) then significant volumes of water can be lost due to these opera-tional inefficiencies. There may only be a few persons familiar with the scheme and who know how the spreadsheets relate to one another and how the calcula-tions are performed.
WAS as the solution
A solution to improve the accu-racy of releases in these irrigation schemes is to install the WAS with robust logging equipment.
The WAS is a locally developed, IT-based tool to manage water distribution on irrigation schemes, with a specific objective of mini-mizing water losses in canal-based irrigation schemes. The WAS development was initially funded by the Water Research Commission (WRC), and has since evolved to support addi-tional functions.
The WAS has developed into a tool applicable for Water User Associations (WUAs), Catchment Management Agencies (CMAs) and water management officers to manage not only their water usage and distribution, but also to manage water accounts and prepare reports required by the regulator. The WAS is also used for monitoring of and measure-ment of releases, which supports increased efficiency of releases.
Water Administration System Implemented on 21 large irrigation schemes in South Africa
Strategic Water Partners Network (SWPN)
SABI | AUGUST/SEPTEMBER 201928
Water quality How to ...
read a PVC pipe flowchart
How to ...
- by Mike de Villiers
Irrigation is all about supplying water to the planted crop or flowerbed at the required rate, the required frequency and at the optimum time of day. Needless to say, this has become a highly sophisticated process which involves the design of a distribution system made up of pipes, valves and emitters. Designers need to know the operational and flow characteristics of each of these items in order ensure the correct selection to meet the requirements of the design. This editorial will focus on the flow characteristics of PVC pipes and how to read a basic flow calculator.
INTRODUCTIONPlastic pipes have evolved from their beginnings in the RSA during the 1960’s, to become the optimum choice of Irrigation designers for water supply applications. PVC pipe systems have grown in size from 16mm to diameters in excess of 500 mm. The design and production of dedicated distribution systems, to meet the specific needs of the many crops that are Irrigated, have also made great strides over the past 50 years. One of the most notable developments is the concept of drip irrigation, which is the optimum choice for the efficient distribution of irrigation water, especially in the current environment of climate change. All of these pipe systems have one thing in common that is vital to the Irrigation designer. That is the need to know how much water each of these systems delivers, under given design parameters.
The flow of water in a pipe is affected by a number of factors that need to be taken into account before the question of what the pipe will deliver can be answered. Fortunately, the industry has developed flow charts and “apps” to simplify the process for the designer. This editorial will focus on the procedure to read a basic flow chart for PVC pipes, given that manual flow charts serve merely to assist with the basic selection of pipe sizes and are not accurate enough for detailed design purposes.
DESIGN CONCEPTS
Velocity:
In order to understand the concept of flow velocity, trainers use the following analogy. They pose the question to their students, “How long does it take to drive from say Bellville to Paarl, a distance of some 45 kilometers.” Some will say 25 minutes and others as much as 45 minutes. Given that the distance remains constant, the difference in the responses is the speed (velocity) at which one is travelling. One must therefore qualify the answer to the flow ques-tion by stating at which velocity, in metres per second, the delivery volume has been based on for a given pipe diameter and pressure class. This is usually 1.5 metres per second, which in terms of our analogy, is the “speed limit” for the flow of water in pipes for most design appli-cations. Higher flow velocities, above say 2 metres per second, may increase the potential risk of pipe failure and need to be specifically catered for in the design of the system.
Friction/headloss:
Much like the friction between a car’s tyres and the road, there is friction between the water molecules flowing in the pipe and the internal wall of the pipe. This friction, also known as flow
SABI | AUGUST/SEPTEMBER 201932