Poultry litter enhances soybean productivity in field infested with soybean cyst nematode

Soil infested with the soybean cyst nematode (SCN), Heterodera glycines, was amended with poultry litter in a three-year study designed to evaluate the effectiveness of the organic amendment for improving soybean productivity and reducing damage by the nematode. Poultry litter was split-applied at V2 and V5 stages of soybean development, at rates of 0, 5 or 10 t ha(-1). The experimental plots were in Wicomico County, MD, and planted to Manokin (resistant) and Essex (susceptible) soybean cultivars. Cyst index was inversely correlated with poultry litter, although the difference between the 5 t ha(-1) and 10 t ha(-1) treatment was not significant. Poultry litter had a greater impact on reducing cyst infestation in Essex. Over the three-year period, cyst index increased incrementally on Manokin but this was significantly lower than on Essex. Nodule number and foliar N content were depressed by application of poultry litter. Shoot and root dry weight were improved by amending soil with 5 t ha(-1) poultry litter, but were reduced by the 10 t ha(-1) rate. Seed yield of both cultivars also tended to be reduced by 10 t ha(-1) poultry litter treatment, but stimulated by the 5 t ha(-1) treatment. The results indicate that 5 t ha -1 poultry litter is an effective means of improving productivity when soybean is grown in SCN-infested soil.