Effect of Nitrogen Fertilizer Combined with Biochar on the Biomass and Photosynthetic Characteristics of Flue-cured Tobacco/Silage Corn Relay Intercropping on Slope Farmland

PurposeTo study the effect of nitrogen fertilizer combined with biochar on biomass and photosynthetic characteristics of flue-cured tobacco/silage corn relay intercropping system.

MethodUsing Yunyan87 flue-cured tobacco variety and Zhongyu335 silage corn variety as test materials, interplanting experiments were conducted in a simulated plot with a slope of 10°. The experiment set up two factors of nitrogen fertilizer level (N) and biochar level (B). The three nitrogen fertilizer application rates (flue-cured tobacco+silage corn) were 0+0 (N₀), 52.5 kg/hm²+100 kg/hm² (N₁) and 105 kg/hm²+200 kg/hm² (N₂); the two biochar application rates are B₀ without biochar addition, and B₁ with 3% biochar (adding 3 kg biochar per 100 kg soil). The content of plastid pigments, photosynthetic parameters and fresh and dry weight of flue-cured tobacco and corn at maturity stage were determined.

ResultsUnder the same nitrogen fertilizer level, the addition of biochar could increase the plastid pigment content of flue-cured tobacco leaves at the mature stage; the combined application of nitrogen fertilizer with biochar had a positive effect on the fresh and dry weight of flue-cured tobacco and silage corn, and could increase the chlorophyll content of silage corn leaves at the jointing stage. It could improve the net photosynthetic rate, stomatal conductance and transpiration rate of flue-cured tobacco at maturity, and it could improve the photosynthetic parameters of silage maize at the jointing stage.

ConclusionBiochar combined with conventional nitrogen application has the best effect on improving the fresh and dry weight of flue-cured tobacco and the photosynthesis intensity of silage corn, and the treatment with biochar combined with conventional nitrogen fertilizer halving is the second. Therefore, the combination of biochar and nitrogen-reducing fertilization can reduce the application of nitrogen fertilizer, but the specific amount of nitrogen fertilizer reduction needs to be determined according to the soil type and the amount of biochar added.