SA Grain October 2017

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October 2017

FOCUS

Irrigation

Special

Produk-inligting

Stabiliseer wielspoor

van spilpunte só

s jy moeg vir ‘n spilpunt wat vasval, strukturele skade aan

jou spilpunt, gewasopbrengsverliese en onnodige waterver-

morsing as gevolg van modderige of swaar geërodeerde

spilpuntwielspore?

Voorkom frustrasie en onnodige besteding en neem beheer van

jou spilpunt se wielspoorstabiliteit deur ‘n gebruikersvriendelike

aanwending van Terraplex 30 een keer per plantseisoen.

Terraplex 30 is bekostigbaar. Vergeet van spesiale bandgroottes

of duur wielspoormodifikasietoerusting. Hierdie produk bied

100% aktiewe bestanddele en is veilig om te gebruik op besproei-

ingsgewasse.

Vervaardiging van die produk voldoen aan standaarde soos

voorgeskryf deur ons ISO 9001, ISO 14001, ISO2 2000 en OHSAS

18001 geakkrediteerde bestuurstelsel.

Terraplex 30 sal stadig oplos deur die water vanaf die spil-

puntsproeierkoppe wat op die sakkies drup. Die oplossing sal dan

direk in die wielspoor drup. Die aktiewe bestanddele kom sodoende

in kontak met die grond in die wielspoor, waar dit met die grond

vermeng soos wat die spilpuntwiele daaroor beweeg. Die resultaat

is ‘n omgewingsvriendelike, gestabiliseerde matriks.

GERRIT FOUCHÉ,

KimLeigh Chemicals SA

Improve irrigation efficiency

System efficiency defines the ratio between

net and gross irrigation requirements (NIR

and GIR). NIR is therefore the volume of wa-

ter that should be available to the crop as a

result of the planned irrigation system and

GIR is the volume of water supplied to the

irrigation system that will be subject to the

envisaged in-field losses.

The approach makes provision for the oc-

currence of non-beneficial spray evapora-

tion and wind drift, in-field conveyance,

filter and other minor losses. The sum of all

these losses makes up the value in the col-

umn ‘Total losses’.

The default system efficiency values in the

last column were obtained by subtracting

the total losses from 100%. With this in

mind, the system must also function opti-

mally and be managed correctly to obtain

these required results.

When an irrigation system is evaluated, the

system efficiency value can be compared

to these default values, and possible sig-

nificant water loss components identified

as areas for improvement. The approach

is therefore more flexible and easier to ap-

ply than the original efficiency framework

where definitions limited the applications.

It should always be kept in mind that a

system’s water application efficiency will

vary from irrigation event to irrigation

event, as the climatic, soil and other influ-

encing conditions are never exactly the

same.

Care should therefore be taken when apply-

ing the SE indicator as a benchmark, as it

does not make provision for irrigation man-

agement practices. This can be determined

as the ratio between the volume of water

lost to non-beneficial spray evaporation and

wind drift, in-field conveyance, filter and

other minor losses and the volume of water

entering the irrigation system for a specific

period of time. The losses can also be ex-

pressed as a depth of water per unit area,

rather than a volume. Improvements can

therefore only be made by improved man-

agement practices and functionality.

In conclusion, it can be said that the water

balance resulting approach of ‘measure, as-

sess, evaluate, improve’, promotes an inves-

tigative water balance approach to improve

irrigation efficiency to assist managers and

designers alike to use this developed infor-

mation and tool that incorporate both detail

investigations with the flexibility to be ap-

plied at any level to improve irrigation sys-

tem performance.

For more information, contact

Felix Reinders at

ReindersF@

arc.agric.za

Reference

Reinders, FB, Van der Stoep, I, Lecler, NL, Greaves,

KR, Vahrmeijer, JT, Benadé, N, Du Plessis, FJ,

Van Heerden, PS, Steyn, JM, Grové, B, Jumman,

A and Ascough, G. 2010.

Standards and guidelines

for improved efficiency of irrigation water use from

dam wall release to root zone application: Main re-

port

. WRC report no. TT 465/10. Volume 1 of 3. Water

Research Commission: Pretoria, South Africa.