Thesis (MScAgric)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The study was conducted in the Western Cape Province to investigate the effect of soil
preparation on selected soil physical properties. This study was necessitated by the negative
effects that high soil bulk density has on the growth and production of a vine. Soil preparation
in South Africa are applied to remove root limiting layers in the subsoil and to create a larger
soil volume for root growth. The question is whether it is always necessary because of the
destruction of macropore structure and also the high costs that is involved. The study includes
different soil forms, different depths of tillage, different tillage operations and also the change
of soil physical properties with time. Soil physical properties that was investigated include,
bulk density (cloth method), infiltration (mini disk infiltrometer and double ring
infiltrometer), shear strength (pocket vane tester), soil strength (penetrometer) and root
distribution (profile wall method).
The main finding was that the positive effects of soil preparation were still clear after 25
years. The bulk density, shear strength, penetration resistance and infiltration with the double
ring infiltrometer of the deeper soil preparation practices were considerably lower than those
of undisturbed soil. Soil preparation shallower than 60 cm recompacted more than the deeper
tillage treatments. Hydraulic conductivity with the mini disk infiltrometer yielded mixed
results. This was mainly because measurements represented hydraulic conductivity through
the whole profile and therefore can be influenced by many factors. Root distribution has
increased with depth of tillage and the effect was clear at Nietvoorbij in the deeper (> 60 cm)
soil preparation treatments. There were no significant difference between the two soil
preparation methods (delve plough and soilmix) at Kanonkop, although the effect of
secondary compaction by the soilmix was quite clear. Recompaction over a year was clear in
the 2009 and 2010 tillage treatments at Broodkraal. The methods that were used to determine
the soil physical properties have all yield good results. At all the sites the tillage treatments
generally yielded better results than the undisturbed soils. It was also clear that the longer the
time after tillage the smaller become the difference between the tillage treatments and the
undisturbed soils. Recompaction did occur and therefore soil preparation might possibly be
applied again before new vines wants to be planted. / AFRIKAANSE OPSOMMING: Die studie is in die Wes-Kaap Provinsie gedoen om die effek van grondvoorbereiding op
geselekteerde grondfisiese eienskappe te ondersoek. Hierdie studie is genoodsaak deur die
nadelige gevolge wat hoë gronddigthede op die groei en produksie van ’n wingerdstok het.
Grondvoorbereiding in Suid-Afrika word toegepas om beperkende lae in die ondergrond te
verwyder en sodoende ‘n groter grondvolume vir wortelgroei beskikbaar te stel. Die vraag is
egter of dit altyd noodsaaklik is weens die vernietiging van voorkeur vloeikanale en die hoë
kostes wat daarmee gepaard gaan. Die studie sluit verskillende grondvorms, verskillende
dieptes van bewerking en verskillende tipes bewerking in asook hoe die toestande met
verloop van tyd verander. Grondfisiese eienskappe wat ondersoek is, sluit in: bulkdigtheid
(kluitmetode), infiltrasie (“mini disk” - en dubbelring infiltrometer), skuifsterkte (skroefbladmeter),
grondsterkte (penetrometer) en wortelverspreidings (profielwand metode). Die studie
is uitgevoer by drie verskillende proeflokaliteite, nl. Nietvoorbij, Kanonkop en Broodkraal.
Die vernaamste bevindings was dat die grondvoorbereidingsbehandelings se voordelige effek
oor die langtermyn, na 25 jaar, steeds duidelik waarneembaar was. Die bulkdigtheid,
skuifsterkte, penetrasieweerstand en infiltrasie met dubbelring infiltrometer van die dieper
grondbewerkingspraktyke was aansienlik laer as die kontrole behandelings (onversteurde
grond) gewees. Die grondvoorbereidingsaksies vlakker as 60 cm het tot ʼn mate weer
herverdig. Hidrouliese geleiding met minidisk infiltrometer het baie wisselvallige resultate
opgelewer. Dit is hoofsaaklik omdat die meting die geleiding deur die hele profiel
verteenwoordig en daar baie faktore is wat dit kan beïnvloed. Die wortelverspreiding het met
diepte van grondbewerking toegeneem en die langtermyn voordelige effek was duidelik by
Nietvoorbij in die dieper (> 60 cm) grondvoorbereidingsbehandelings sigbaar. Die twee
grondvoorbereidingspraktyke (dolbewerking en “soilmix”) by Kanonkop het nie betekenisvol
van mekaar verskil nie, alhoewel die effek van sekondêre kompaksie soos veroorsaak deur die
“soilmix” implement, duidelik was. Herverdigting oor die tydperk van ’n jaar was duidelik
tussen die 2009- en 2010 bewerking by Broodkraal. Die metingsmetodes waarmee die
grondfisiese eienskappe ondersoek is, het almal goeie resultate gelewer. By al die
proeflokaliteite het die bewerkingsbehandelings oor die algemeen beter resultate as die
kontrole-behandelings (onversteur) gelewer. Hoe langer die tydperk na grondvoorbereiding
hoe kleiner was die verskil tussen die bewerkingsbehandelings en die kontrole. Herverdigting
het wel voorgekom en daarom sal grondvoorbereiding moontlik weer toegepas moet word
wanneer nuwe aanplantings gemaak word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6672 |
| Date | 03 1900 |
| Creators | Kritzinger, Daniel Jacobus |
| Contributors | Hoffman, J. E., Myburgh, P. H., University of Stellenbosch. Faculty of AgriSciences. Dept. of Soil Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | Afrikaans |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 108 p. : ill. |
| Rights | University of Stellenbosch |
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