The 2012 ASHS Annual Conference

The detrimental impacts of intensive soil tillage on soil quality are well documented. However, research is still lacking on the impact of alternative reduced-tillage systems on specialty crop yields and weed control in the Mid-South, USA. This is especially true in the case of organic specialty crop production systems, where weed control in reduced-tillage settings cannot rely on synthetic herbicides. In order to evaluate these questions, a field study was implemented beginning in October 2010 in Knoxville, TN to evaluate cover crop based reduced-tillage organic and conventional production systems in comparison to conventionally tilled, plasticulture controls. Treatments included: 1) OrgTill- organically-managed plasticulture system with conventional tillage following a wheat (Triticum aestivum cv. Haas Cover)-crimson clover (Trifolium incarnatum cv. Dixie) cover crop; 2) OrgRT- organically-managed reduced-tillage system planted into roll-killed wheat-crimson clover cover crop residue; 3) ConTill- conventionally-managed plasticulture system with conventional tillage following a wheat cover crop; and 4) ConRT- conventionally managed reduced-tillage system planted into herbicide-killed wheat cover crop residue. Plots were sized 2.4 m by 9.1 m and were arranged in a randomized complete-block design with four replicates. In early May 2011, cover crops on were terminated and eggplant (Solanum melongena cv. Traviata) planted. Total yield of marketable eggplant did not differ between treatments (mean 16.4 Mg·ha^-1). Weight of USDA Fancy grade eggplant was highest from the OrgRT treatment (4.8 Mg·ha^-1), although this was statistically (P > 0.05) greater than only the ConTill treatment (2.2. Mg·ha^-1). Weed control was generally good throughout the season, although total weed populations were generally higher in reduced tillage treatments compared to plasticulture treatments. Measures of soil quality indicated that the particulate organic matter-carbon (POM-C) and –nitrogen (POM-N) were highest in the OrgRT treatment, although only significantly so in the case of POM-N. As a measure of the active fraction of soil organic matter, this indicates that the OrgRT system may provide the greatest benefit to maintenance and enhancement of soil quality in vegetable production systems.