Long-term effects of residue and water management practices on plant parasitic nematode abundance and soybean root infection

Soil-borne, plant parasitic nematodes are potentially agronomically and economically damaging in the wheat (Triticum aestivum L.)-soybean (Glycine max L.), double-crop production system that is common in the mid-southern United States. Double-crop field studies with at least five years of consistent management are rare, but can provide a valuable setting to assess long-term, and potentially cumulative, management practice effects on nematode abundance and root damage. The objective of this study was to evaluate the effects of a combination of management practices including residue burning (burned and no burn)-irrigation (irrigated and non-irrigated), wheat residue level (high and low), and tillage (conventional tillage and no-tillage) practices on plant parasitic nematode soil abundance and reproduction on soybean 34 and 70 days after planting following 14 complete cropping cycles in a wheat-soybean, double-crop production system on a silt-loam soil in eastern Arkansas. Stunt and total nematode abundances were at least 8.2 and 4.2 times greater (P < 0.05), respectively, under the burn-non-irrigated-no-tillage than under the other three burn-irrigation-tillage treatment combinations 34 and 70 days after planting. Root-associated soybean cyst nematode egg concentrations were 16.2 and 4.5 times greater under the burn-non-irrigated-low-residue than under the no-burn-irrigated-low-residue and burn-non-irrigated-high-residue treatment combinations, respectively, which did not differ, 34 days after planting, but were unaffected by any field treatment 70 days after planting. Producers may consider avoiding the combination of residue burning, no-tillage, and dryland soybean production to help keep the parasitic nematode population low. Results of this long-term field support the notion that properly managed crop rotations contribute enough diversity of inputs and processes to limit the known negative effects of continuous monoculture.