Soil compaction by tractor tillage in horticultural fields at Molelwane research farm, Mafikeng, North West Province

Abstract

The study was prompted by concerns that soil compaction in horticultural fields at the University research farm was limiting the performance of fruit trees and vegetable crops after fifteen years of conventional tillage with tractors. Soil penetrometer resistance and bulk density were measured in the profiles of three adjacent fields (vegetable, orchard & vineyard). Over the years, tractor traffic was used in the vegetable field and orchard for seedbed preparation and weeding respectively, while the vineyard was not trafficked. Higher soil compaction was evident in the orchard and vegetable fields compared to vineyard. The location of compacted layers within the profiles was related to the nature of tractor traffic. There was subsoil compaction in the orchard and vegetable fields while shallow compaction was observed in the vineyard. Apart from tractor traffic, low organic matter content and the hardsetting behavior of the soil could have exacerbated the compaction. It was recommended that controlled traffic and deep ripping should be adopted, to not only ameliorate the existing compaction, but also sustain the productivity of the soils.