Plant growth and nematode dynamics in response to soil amendments with neem products, urea and compost

Two neem-based granular products, Achook and Suneem G (containing azadirachtin), urea and compost manure were incorporated in field soil at different doses. These treatments decreased the number of plant-parasitic nematodes with increasing doses of products. Combinations of both neem-products with urea were the most effective in suppressing plant-parasitic nematode populations. The neem products and product combinations with urea significantly decreased numbers of free-living nematodes compared with controls; however, populations increased in the compost-treated plots. The growth of pigeonpea (Cajanus cajan L.) was improved in all treatments; in part due to the control of plant-parasitic nematodes and in part due to manurial effects. Urea was phytotoxic at 330 kg N/ha when applied alone, however, it was not phytotoxic at this addition rate when given in combination with the neem-based products. (C) 1998 Elsevier Science Ltd. All rights reserved.