BT Cotton, Tillage and Cover Crops Identity: Relative Effects on Above and Below Ground Invertebrate Diversity

View the project final report

• 2005 annual report
• 2006 annual report

Commodities

• Agronomic: cotton, rye

Practices

• Crop Production: conservation tillage, cover crops, foliar feeding, no-till, nutrient cycling
• Natural Resources/Environment: biodiversity, soil stabilization
• Pest Management: biological control, competition, weather monitoring
• Soil Management: organic matter, soil analysis

Research focuses on the effects of Bt cotton on non-target invertebrate diversity above and below ground relative to the effects of tillage and crop identity. It is well known that both tillage and crop choice can have a significant influence over arthropod communities within agroecosystems. Research on the effects of Bt cotton on arthropod communities however is much less conclusive. Below ground diversity measurements are being made on nematodes, and microarthropods, while above ground diversity measurements focus on non-target arthropods (pollinators, predators, parasitoids, etc.). The project is being conducted at Horseshoe Bend Agroecosystem in Athens, GA. Bt cotton is currently being grown at the site under both Conventional Till and No Till management regimes. The tillage methods themselves have been practiced at Horseshoe Bend since 1978. Also employed at the site are winter crops of rye and clover. There are thirty-two subplots within the cotton field which host combinations of tilling regiment, winter crop, and cotton type (Bt or non-Bt). This offers an extremely useful combination of agricultural settings within which to study the effects, if any, of Bt cotton on above and below ground biodiversity. Making large-scale changes to agricultural production techniques takes time and often includes complete overhauls of equipment for things such as planting and harvesting. Given this, it is important that while we are examining new production techniques such as genetically modified crops, we analyze their effects relative to other techniques, which may have much greater influences over biodiversity.

This research project will examine the above and below ground effects of Bt cotton on non-target organisms relative to the effects of microclimate and vegetational variation due to tillage and seasonal crop changes. Below ground diversity measurements will be made on nematodes, and microarthropods, while measurements of above ground diversity will focus on non-target arthropod species collected within the cotton field (pollinators, invertebrates, predators, etc.). The inclusion of both above and below ground diversity measurements stems from three sources. First from the recognition of the strong link between above and belowground ecosystem processes (Coleman 2002) second, from the question of whether or not the exclusion of certain target organisms from Bt cotton plots will have an affect on the remaining assemblage of non-target species and third, to examine the additive effects of tillage method and cotton type on species diversity. The project will be conducted at Horseshoe Bend Agricultural Research Facility. Horseshoe Bend is a LTREB (Long Term Research in Environmental Biology) site in Athens, GA. Bt cotton is currently being grown at the site under both conventional tillage (CT) and no-till (NT) management regimes. The tillage methods themselves have been practiced at Horseshoe Bend since 1978 (Hendrix et al. 2001). Also employed at the site are winter crops of rye and clover. There are thirty-two subplots within the cotton field (each approximately 14 x 14m.) which host combinations of tilling regiment, winter cover crop, and cotton type (Bt or non-Bt). This offers an extremely useful combination of agricultural settings within which to study the effects, if any, of Bt cotton on above and belowground biodiversity relative to other community-shaping forces within the agroecosystem.