The influence of manual and motor-manual pitting implements, pit size and quality on eucalypt performance, South Africa

Abstract

Pitting is the preparation of a planting position. Various methods of pitting exist and range from manual pitting to fully-mechanised operations. Until recently, most pit preparation in South Africa was carried out manually using hand-held pitting implements (agricultural hoe, mattock, road pick) to create a 25 cm wide pit containing friable soil to a depth of 15–25 cm. However, there are several negative factors associated with manual pit preparation, such as poor ergonomics, intensive labour requirements, and inconsistent pit preparation. This has resulted in an increasing interest in semi- to fully-mechanised operations, where semi-mechanised motor-manual pitting methods are often considered more efficient and cost-effective than traditional manual operations. This study compared the performance of eucalypts planted into pits created by various pitting methods. Two trials were established with eucalypts on contrasting sites, one at Greenhill in the KwaZulu-Natal Midlands and one at Vroegeveld, Mpumalanga. Four manual implements (notch, agricultural hoe, mattock, road pick) and three different motor-manual heads (inverted A,  Archimedes screw and Mondi-designed pitting head) were used to prepare and determine the effect of pit size/quality on tree survival, growth and uniformity. The notch pit implement created the smallest pit (1 L volume), whilst other implements created larger pits (4–6 L volumes). Pitting  method did not have a significant effect on the success of re-establishment and subsequent tree performance on both sites (2.5 years after planting and thereafter). This indicates that for the soils tested, any possible negative tillage effects caused by any of the pitting implements did not affect the species planted. Factors such as operational costs, efficiency and ergonomics must therefore be considered to select relevant pitting methods, together with tree performance.

Keywords: manual pitting, re-establishment practices, semi-mechanised pitting, tree performance