Document: SUS-3-61-8

Comparing microarthropod and soil quality indices in three agricultural watersheds.

ANDREWS, S.S.* ¹, R.HANSEN ², D.L.KARLEN ¹, C.A.CAMBARDELLA ¹ and T.MOORMAN ¹

USDA-ARS National Soil Tilth Laboratory, Ames, IA 50011 USA ¹
University of South Carolina, SC USA ²

Abstract:
Indexing tools may provide agroecosystem managers with the integrated information necessary to evaluate sustainability of management alternatives. We compared several indices of soil microarthropod diversity with a soil quality (SQ) index comprised of chemical, physical and biological parameters. We used these indices to evaluate 3 management systems at a watershed (WS) scale in deep loess soils. In 1996, after a 25+ year history of continuous corn with conventional tillage, WS 1 and 2 were converted to no-till with corn-soybean and corn-soybean-corn-alfalfa-alfalfa-alfalfa rotations, respectively. WS 3 was in continuous corn with ridge tillage throughout this time. In 1998, we sampled corn plots in all 3 watersheds for microarthropod diversity at the suborder level to incorporate both trophic and life history strategy differences. The indicators chosen for the SQ index included total carbon, potentially mineralizable N, % aggregation, pH, microbial biomass C, and glucosidase activity. Only Margalef's and Menhinick's diversity indices showed significant differences between WS's. The conservation tillage practice in WS 3 supported higher soil microarthropod diversity compared with WS 1 and 2 after two years of no-till. No rotation effects were detected. The SQ index resulted in higher scores for WS 1 and 2 than for WS 3 possibly indicating soil conditions that are improving although not yet apparent within the microarthropod community. Further analysis over time is necessary to reconcile differences in index outcomes.

Keywords: microarthropod diversity, soil quality, conservation tillage, integrative indices, watershed evaluation

This abstract is being presented at: 3:30 PM in session:
AGROECOLOGY