Evaluering van grondvoorbereidingspraktyke wat in die wingerdbedryf uitgevoer word in terme van geselekteerde grondfisiese eienskappe

[摘要] ENGLISH ABSTRACT: The study was conducted in the Western Cape Province to investigate the effect of soilpreparation on selected soil physical properties. This study was necessitated by the negativeeffects that high soil bulk density has on the growth and production of a vine. Soil preparationin South Africa are applied to remove root limiting layers in the subsoil and to create a largersoil volume for root growth. The question is whether it is always necessary because of thedestruction of macropore structure and also the high costs that is involved. The study includesdifferent soil forms, different depths of tillage, different tillage operations and also the changeof soil physical properties with time. Soil physical properties that was investigated include,bulk density (cloth method), infiltration (mini disk infiltrometer and double ringinfiltrometer), shear strength (pocket vane tester), soil strength (penetrometer) and rootdistribution (profile wall method).The main finding was that the positive effects of soil preparation were still clear after 25years. The bulk density, shear strength, penetration resistance and infiltration with the doublering infiltrometer of the deeper soil preparation practices were considerably lower than thoseof undisturbed soil. Soil preparation shallower than 60 cm recompacted more than the deepertillage treatments. Hydraulic conductivity with the mini disk infiltrometer yielded mixedresults. This was mainly because measurements represented hydraulic conductivity throughthe whole profile and therefore can be influenced by many factors. Root distribution hasincreased 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 soilpreparation methods (delve plough and soilmix) at Kanonkop, although the effect ofsecondary compaction by the soilmix was quite clear. Recompaction over a year was clear inthe 2009 and 2010 tillage treatments at Broodkraal. The methods that were used to determinethe soil physical properties have all yield good results. At all the sites the tillage treatmentsgenerally yielded better results than the undisturbed soils. It was also clear that the longer thetime after tillage the smaller become the difference between the tillage treatments and theundisturbed soils. Recompaction did occur and therefore soil preparation might possibly beapplied again before new vines wants to be planted.

[发布机构] Stellenbosch University