Effects of reduced nitrogen application and intercropping on sweet corn AMF colonization, soybean nodulation and nitrogen and phosphorus absorption

In order to explore a sustainable pattern of sweet corn production in South China, a field experiment was carried out in Guangzhou over the period of 4 growing seasons—autumn of 2014, spring and autumn of 2015 and spring of 2016. The study investigated the effects of 2 N fertilizer levels300 kg·hm^-2 (N1, reduced N dose) and 360 kg·hm^-2 (N2, conventional N dose) and 4 planting patternssweet corn/vegetable soybean intercropping with 2:3 (S2B3) and 2:4 (S2B4) line ratios, sole sweet corn (SS) and sole soybean (SB) on yield of sweet corn and soybean, degree of arbuscular mycorrhizal fungi (AMF) colonization of sweet corn and soybean rhizobia. The results showed that the yield of sweet corn under reduced N application and intercropping treatment was significantly higher than that under monoculture. In spring of 2016, nodule number of soybean under S2B3-N1 treatment was significantly higher than that under S2B3-N2 treatment. In the 4 seasons of the experiment, dry weight of soybean nodule was not affected by reduced N application and intercropping. In 2015, N content and biomass of sweet corn were significantly higher than those under monoculture, regardless of the N application level. In 2015, AMF infection rate of sweet corn under reduced N-intercropping treatment was significantly higher than that under conventional N treatment. In autumn of 2015, phosphorus content of sweet corn under reduced N and intercropping treatment was significantly higher than that under monoculture. In conclusion, the reduction of N input and intercropping with soybean significantly improved N and phosphorus contents, rate of AMF infection, biomass and yield of sweet corn. Intercropping with soybean under reduced chemical N input maintained high yield, increased resource utilization efficiency of sweet corn, and thus it was a practicable pattern for sustainable sweet corn production in southern China.