Immediate responses of cyst nematode, soil-borne pathogens and soybean yield to one-season crop disturbance after continuous soybean in northeast China

Habitat disturbance affects numerous ecosystem components and processes, but its effect on continuous soybean system is less available. Soybean was seeded following six preceding crops, including grain soybean (Glycine max L. Merill.), wheat (Triticum aestivum L.), sugar beet (Beta vulgaris L.), tobacco (Nicotiana tabacum L.), corn (Zea mays L.) and hemp (Cannabis Satia L.), on a Mollisol farmland that had previously been cropped to continuous soybean for seven years in Northeast China. Soybean after hemp reduced the number of second-stage juveniles of soybean cyst nematode (J2) by 29.8% compared to continuous soybean, while soybean after corn had the lowest J2 number. The number of soilborne pathogens of Fusarium, Rhizoctonia and Pythium after corn and hemp and root rot disease severity index after all crop disturbance, except sugar beet, were significantly lower than continuous soybean. Soybean yield after hemp disturbance was improved by 10.8%, while sugar beet disturbance had the greatest negative impact on soybean yield. No differences were found among crop disturbance for protein and oil content in soybean seed. Crop disturbance changed the habitat already developed in the continuous soybean system. Adoption of hemp disturbance has the potential to be an alternative approach in managing continuous soybean production system in Northeast China. Keywords: Crop disturbance; Ecosystem components; Cyst nematode; Soil-borne diseases; Seed yield; Continuous soybean; Preceding crop.