The impact of different herbicides and cover crops on soil biological activity in vineyards in the Western Cape, South Africa

Abstract

The bait-lamina method was used to study the effects of different herbicides on biological activity in vineyard soil with and without cover crops in the Western Cape, South Africa. An evaluation of two different bait substances was also made under two different cover crops, an unplanted control and an unplanted, mechanically tilled plot. The highest feeding activity was measured under the cover crops and the lowest in the mechanically tilled soil. After spraying with the herbicide glyphosate on four different cover crops, the feeding activity was determined on treated and untreated plots on three occasions. The results indicated that the feeding activity generally increased following treatment with glyphosate. A comparison of feeding activity after treatment with paraquat, simazine, glyphosate and a glyphosate-terbutylazine mixture on different soil plots without cover crops was also undertaken. It showed that, with the exception of simazine, the herbicide application had a positive influence on feeding activity. It is concluded that the bait-lamina technique, although not representative of all the many complex soil biological processes, can still provide a simple and practical tool to complement studies on the effects of chemicals on functional aspects of soil ecosystems.