Carmen Ugarte, University of Illinois-Urbana-Champaign, U. of Illinois Urbana-Champaign, 1102 S. Goodwin Avenue, Urbana, IL 61801 and Michelle Wander, University of Illinois, N-225 Turner Hall Mc-047, 1102 S. Goodwin Ave., Urbana, IL 61801.
The organic certification standards require farmers to use practices that enhance soil quality, although some of their effects and relationships are not well known. Our goal was to understand the relationship between organic transition strategies and biological soil attributes, which could potentially help in the development of management aids for organic farmers. We collected soil samples from the Windsor Organic Research Trail, where three strategies of transition toward organic certification are being compared. These included a ley crop (low intensity), row crop (intermediate intensity), and intensive horticultural (high intensity) systems. Within each strategy, three fertility approaches (fresh manure, compost and cover crops) were used. The dynamics of the nematode community structure (MI, EI, SI), microbial activity (FDA), potentially mineralizable N (PMN) and, soil organic matter (SOM and POM) were investigated. Organic management practices were able to build adequate concentrations of soil organic matter (2.5- 4.0 mg POM-C kg-1 soil) and PMN (> 22 mg N kg-1 soil). The ability of these soils to sustain such concentrations of resource availability is supported by an enhanced microbial activity across all systems and in particular in the manure amended plots (423 mg fluorescein kg-1 soil). Furthermore, this high microbial activity seemed to enhance bacterial feeding nematodes. Further in the growing season, we expect to see a more structured nematode community. Preliminary results showed that biological and resource-based indicators were able determine soil fertility status, which was maintained with the use of organic management practices.
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