Farmer’s Weekly – 09 August 2019

F

or years, a number of farmers

in the Olifants River Valley

have been planting cover

crops between vine rows to

suppress weeds and build up

soil health. But warm climatic

conditions, in combination

with low and erratic rainfall,

ranging between 100mm and

150mm a year and decreasing

as low as 47mm two years ago,

have prevented them from

reaping the full benefit of this

practice, and many farmers

have given up the practice.

To salvage the situation, soil

health expert Stoney Steenkamp

collaborated with Piket

Implemente to design and build

an innovative planter that can

plant cover crops on plant ridges.

These cover crops have access

to the dripper lines that irrigate

the vineyards, and are planted

near the roots of the vines, where

they receive the most benefit.

The planter is light, reducing

the problem of soil compaction.

water use and

soil temper ature

Steenkamp’s objective with the

machine is to enable farmers

to use cover crops to suppress

weeds, so they become less

dependent on herbicides for

weed management, and to

ultimately improve the water-use

efficiency of farms in the region.

“The idea is to promote the

use of cover crops. The planter

itself is merely an enabling tool,

which can actually do a lot of

harm when used to establish

the wrong cover crop mixtures

or monocultures,” he says.

When chosen correctly,

however, cover crops can reduce

water use by forming a thick

blanket of mulch that reduces

evaporation and buffers plants

against temperature extremes,

with soil temperatures being a

few degrees cooler than ambient

temperatures in summer, and

slightly warmer in winter.

Besides this, the roots

of the cover crops help to

loosen and improve the soil

structure, as well as health.

“Forthebestresults,Iusually

adviseproducerstoplanta

mixtureofatleastfivedifferent

annualcrops,aseachhasits

ownuniqueattributes,”says

Steenkamp.“Someareknownfor

theirabilitytobuildsoilhumus

levels,othersloosenthesoilwith

theirthicktaproots,andothersfix

nitrogenandwardoffdiseases.”

Dependingonproduction

targets,mixturesincludecanola,

triticale,oats,barley,Brassica,

mustard,radishes,andlegumes.

Theplanterwastestedon

variousfarmsoveranareaof

100hain2018.Theproducers

involvedinthetrialshavebeenso

happywiththeresultsthatthey

haveenlargedtheareawhere

theyplantcovercrops,bringing

thetotalareato800hathisyear.

Steenkampforeseesthatthe

areawillbeincreasedto 2 000ha

in 2019 as more producers

become aware of the planter

and the benefits of cover crops.

His idea of establishing

cover crops on plant ridges

was inspired by the results

obtainedonAbrieJordaan’s

farm,Kareba,nearKoekenaap.

FastFacts

• covercropshaveaccesstodripirrigation
  whenplantedonplantridges.


• theuseofcovercropmixturescreates
  a highdiversityofplantmaterial
  andthickmulch.


• cover crops can enhance water-use
  efficiency on farms and suppress weeds.

ABOVEFROMLEFT:

• Soilhealthexpert
  StoneySteenkamp
  showstheroots
  oftheradishes
  plantedonlyafew
  weekspreviously
  onKleinjan
  Theubes’sfarm.


• Theubesshows
  thecovercrops
  thatwereplanted
  inhisvineyardrow
  inAprilthisyear.


• FarmerAbrie
  Jordaanshows
  whereheandhis
  teamhaveplanted
  thecovercrops
  inthemulchleft
  bytheprevious
  year’scrop.
  ABOVERIGHT:
  ManfredLot
  establishes
  covercropswith
  Steenkamp’s
  planter.
  OPPOsITEPAGE,
  TOP:
  Thecovercrops
  consistofatleast
  fivedifferentplant
  species,suchas
  triticale,radish,
  whitemustard,
  cloverandoats.
  BELOW:
  Vineyardswhereno
  covercropswere
  plantedhavea
  significantlyhigher
  weedpopulation.
  PHOTOS: GlenneiS Kriel

9 august 2019 farmer’sweekly 43