SA Graan Januarie 2018

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ISSN 1814-1676
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Besoek Graan SA by of skandeer dié
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ALLE regte van reproduksie van alle berigte, foto’s, teke-
ninge, advertensies en alle ander materiaal wat in hierdie
tydskrif gepubliseer word, word hiermee uitdruklik voorbe-
hou ingevolge die bepalings van Artikel 12(7) van die Wet
op Outeursreg Nr. 98 van 1978 en enige wysigings daarvan.
31 “Buite die boks”-boerdery – ‘n menslike hulpbron-
perspektief
32 Grain Academy – 2017-studente gesels saam
34 Kwaliteitsresultate van die 2016/2017-koringoesopname
37 SASRN to address key issues in Sclerotinia research
38 Bewaringsdag fokus op dekgewasse en vee-integrasie
RUBRIEKE/ FEATURES
4 Graan SA Standpunt: Fokus op dít waaraan jy iets kan doen
5 Grain SA Point of View: Focus on those things you can do something about
7 Uit die Woord
7 Op die kantlyn
40 E-posse: Hoe steel mens ‘n lamppaal?
Pannar is reeds vir 60 jaar ‘n integrale deel
van gewasproduksie in Suid-Afrika en
werk saam met produsente om die regte
produkpakket vir ‘n volhoubare boerdery te
identifiseer.
3
Voorblad/ Cover
Januarie 201812
CA proofs to be key in
sustainability of grain systems
Anumber of producers in the Vrede
area areparticipating in aGrainSA
Conservation Agriculture Farmer
Innovation Programme (FIP) re-
search project, which is funded by the
MaizeTrust.Thisarticlewillput thespotlight
on the farm Skulpspruit of Mr Izak Dreyer
whereCAhasbeendone for five years.
Some experimentswithwinter cover crops
were done in strip plots during the winter
of 2015 and the results of the following
maize cropswere shared in theMarch 2017
edition ofSA Graan/Grain. Those results
were so convincingly positive, even for a
year when extremely dry conditions pre-
vailed formost of the summer, that Dreyer
immediately stopped experimenting and
started implementing cover crops on a
muchbigger scale.
Mixed winter cover crop systems were
subsequently planted after his soybean.
Livestock was then used to utilise the
cover crops during the winter months to
produce beef to the netmargin of roughly
R3 000 (2016) toR7500 (2017)perhectare.
This article will report on themost recent
findings since winter cover crops and live-
stockwere integrated into the farming sys-
tem in 2016.
CA and rainfall use
efficiency
Graph 1 shows how various treatments in-
fluenced thewatercontentof soils.Thepre-
summer rainobservationsweremade three
weeksbefore the rainy season commenced.
It can therefore be assumed that the treat-
mentswithno-tillwinter cover cropsalmost
completely dried out the soil prior to the
first rains.
Cover crops treatmentswere almost asdry
as the tillage treatment. The no-till soybean
control treatments were significantly wet-
ter than the cover crop treatments.Soilwa-
ter content during September andmost of
October 2016was lower than the compara-
ble levelsmeasured the previous year be-
causeofbelow-average rainfall.
The control treatments where maize was
grown theprevious yearhadgenerallydrier
soils than the soybean fields.Thiswouldbe
expected since maize grows well into au-
tumn as opposed to soybeans that are har-
vested early (end ofMarch) allowingmore
soilmoisture conservation.
Graph 1 indicates that soilmoisture conser-
vation throughwinter fallow systems (com-
pared to full utilisation with winter cover
crops, i.e. a green fallow system) was not
essential. The first summer rains fell over
a period of three days during the latter half
ofOctober totalling almost 70mm,which is
almost equal to the long-term average for
October. Graph 1 also shows that this first
rain wetted all treatments properly (effec-
tive soildepth is 60 cm).
All differenceswere quickly removed even
before planting started and maize yields
wouldobviouslynotbeaffectedbydifferent
soil water contents. Yields varied around
8 t/ha,whichwere comparable to yields in
the previous year. The only difference this
year was that any soil water differences
causedby cover cropswerewipedouteven
beforeplanting commenced.
It tookuntil the lastweekofJanuary thepre-
vious yearbefore rain showers increased to
levels that were sufficient to eliminate soil
waterdifferences.
Itwas previously shown thatwater infiltra-
tion rate improved on the no-till fields and
it increased evenmorewherewinter cover
crops were planted. Those results and ex-
cellent yields indicated that there were no
soil compaction problems. Nevertheless,
more soil compaction studieswere done to
improve producers’ and scientists’ under-
standingof this topic.
ON FARM LEVEL Conservation agriculture
DRROBERTSTEYNBERG,senior agronomist,VKB and DRHENDRIKSMITH,CA facilitator,GrainSA
1a and 1b:A concentrationof rootswasobserveddirectly
beneath theplant row (1a) and a second concentrationwas
observedmidwaybetween rowswhere awinter cover crop
rowwaspreviously situated (1b).
1a
1b
13
January 2018
In the absence of penetrometers that can
measure compaction in a direct way, root-
ing patterns andbulkdensitieswere conse-
quently investigated.
CA and soil compaction
Photo 1aand Photo 1bshows a soil profile
with rooting characteristics in amaize field
that has been no-tilled for five years. Soy-
beans were grown the previous summer
andawintermixedcovercroppreceded the
maize.
A concentration of roots is seen directly
under the plant row (Photo 1a). This is co-
incidentallywhere the previous year’s soy-
bean row was situated. A second concen-
tration of rootswas observed in themiddle
between rowswhere thewinter cover crop
rowhadpreviouslybeen (Photo 1b).
These observations could suggest that old
root channelswere usedby themaize roots
to reach and fully exploit the effective root-
ing depth. Soil bulk densitymeasurements
confirmed that the soil porosity would
have been supportive for easy root growth.
These measurements in fact, suggested
that soil porosity was improved by the CA
practices followedon this farm.
Bulk densitywas determined at a depth of
30 cm comparingmeasurements of the no-
till soil with a tilled soil of a neighbouring
farm. The clod and waxmethod was used
(Photo 2 on page 14) on clods that were
sampled under the tractor wheel tracks
where compactionwas supposed to be the
greatest.
Bulk densitieswere 1,3 g/cm3and 1,6 g/cm3
for no-till and tilled soils respectively. This
indicates that the no-till soil ismore porous
and less compacted and defies the con-
ventionalwisdom that tillage to a depth of
45 cm isneeded to alleviate the compaction
in this area.
On the contrary, tillage destroys soil struc-
ture and root channels leading to compac-
tion, lower infiltra-tion rates and less soil
water.Micro-organisms that are necessary
for enhancing andpreserving soil structure,
porosity and aeration, are also disrupted,
sustaining the destructive spiral of tillage
practices.
CA and plant density
A plant population trial on the farm indi-
cated that yield potential had increased be-
yond thepointwhere the traditionalnormof
40 000 plants/ha could utilise the season’s
full potential. It should be noted that total
rainfallwas below normal at approximately
580mm.
In this light, the current year’s high yields
were very satisfactory reaching record
yields in some cases. Graph 2shows that
yields of a little less than 8 t/ha were pos-
sible with approximately 40 000 plants/ha.
It can be assumed that the potential was
even higher (9 t/ha) under higher plant
populations.
This farm’s practice is to use 45 000 plants/
ha, which is already higher than the norm
for the area, but probably not high enough
to match the higher potential under CA
systems.
The following factors generally contribute
to an increased yieldpotentialunderCA:
Improved soilphysicalproperties;
more effective utilisation of rainfall and
sun energy;
improved soil cover, higher soilmicro-
bial activity; and
more favourable microclimate above
the soil surface in the field crops.
CA and soil fertility
Results of a fertilisation experiment at
Skulpspruit supported the notion that CA
practices improve soil health and soil fer-
tility to a levelwhere higher yields are ob-
tainedwith lower fertiliser application. This
fertiliser experimentwasplantedwithdiffe-
rent levelsof a 3:2:1(25) fertilisermixture.
Graph 1:Soilwater content fordifferent tillage treatmentsprior to and after the summer rainsbegan
to fall inOctober 2016.
Graph 2:Plantpopulation/yield curve formaize.
Graph 3:Effectof fertilisation levelsonmaize yieldproducedunderCA conditions.
Farmer innovationprogramme
ON FARM LEVEL 12