PARENT SESSION
6D Exposure assessment for aquatic and terrestrial risk assessment
9:00 AM to 7:00 PM, Monday, 07 May 2001

(M/FF233) The influence of different management practices on soil mesofaunal activity in vineyards.

Albertus, Randal¹, Reinecke, Adriaan¹, Reinecke, Sophié¹, Raath, Pieter², ^{1 2}

ABSTRACT- Organic farming is becoming more and more popular in South Africa. These methods aim to improve the soil's natural soil-microbe-plant-animal biodiversity by excluding the use of synthetic fertilisers and pesticides. Soil mesofauna play an important decompositioning role in the soil and are together with micro-organisms responsible for most of the decomposition of organic matter in the soil. These processes are responsible for the release of nitrogen, phosphorous and potassium and other nutrients to the soil. Chemical biocides used on conventional vineyards can cause dramatic depressions in these organisms' biomass, negatively influencing the decomposition of organic matter and indirectly the release of nutrients to the soil. The aim of this study was to investigate whether herbicides like glyphosate and simazine which are commonly used on conventional vineyards influence the activity of the soil fauna. Organically and conventionally managed blocks of vineyards were compared to each other. Each was divided into twenty four plots. Six different management treatments were used on both the organic and conventional blocks - one treatment per plot and four repetitions of each treatment. Three of the treatments were strictly organic and the other three conventional. The bait-lamina technique was used to assess the feeding activity of the soil fauna. Results show that the activity of the soil fauna was closely related to the amount of moisture in the soil. The application of the herbicides glyphosate and simazine influenced the soil faunal feeding activity. The organic method of farming increases the soil's ability to retain water which create a more favourable and balanced habitat for the soil fauna, thus enhancing the processes by which nutrients and minerals are released to the soil.

Key words: Bait-lamina, Conventional, Organic, mesofauna