Purpose To reveal the long-term effects of different organic fertilizers on nitrogen utilization and active nitrogen supply of tobacco-planting soil under the condition of continuous fertilizer reduction.
Methods Based on the field positioning experiment, five treatments were set: no fertilizer (CK), local conventional recommended fertilizer (100% chemical fertilizer, CF-1), chemical fertilizer reduction of 20% (CF-2), chemical fertilizer reduction of 20% combined with organic fertilizer (OF), and chemical fertilizer reduction of 20% combined with biological organic fertilizer (BOF). The content of active nitrogen pool components, activity of soil nitrogen pool, nitrogen accumulation, apparent nitrogen utilization rate, apparent nitrogen loss and yield quality of flue-cured tobacco in tobacco-planting soil were analyzed and compared. The effects of different organic fertilizers on the active nitrogen pool and nitrogen utilization of flue-cured tobacco in tobacco-planting soil under continuous fertilizer reduction were discussed.
Results Compared with CF-1 treatment, OF and BOF treatments significantly increased the leaf area per plant by 37.09% and 122.73%, respectively; significantly increased the proportion of medium and high-grade tobacco by 25.58% and 54.41%, respectively; significantly increased the stability of tobacco yield by 47.92% and 83.94%, respectively; significantly increased the soil soluble total nitrogen by 52.11% and 104.60%, respectively; significantly increased the soil ammonium nitrogen by 31.93% and 48.26%, respectively; significantly increased the soil nitrate nitrogen by 48.09% and 118.63%. Compared with CF-1 treatment, BOF treatment significantly increased flue-cured tobacco yield by 46.20%, significantly increased yield sustainability by 74.07%, significantly increased soil activity index of nitrogen pool by 105.23%, significantly increased nitrogen uptake of flue-cured tobacco by 57.40%, significantly increased nitrogen apparent utilization rate by 36.18%, and significantly decreased the apparent nitrogen loss by 38.31%. The correlation analysis showed that the soil activity index of nitrogen pool was extremely significantly positively correlated with the nitrogen apparent utilization rate of flue-cured tobacco, and it was significantly negatively correlated with the apparent nitrogen loss rate.
Conclusion Random forest and partial least square path model analysis show that fertilizer reduction combined with bio-organic fertilizer can increase the content of nitrate and soluble total nitrogen in soil active nitrogen pool, improve soil nitrogen pool activity, promote nitrogen uptake, improve nitrogen apparent utilization rate, and improve flue-cured tobacco yield and quality. It is one of the effective ways of efficient and high-quality sustainable production of tobacco leaves and optimal nitrogen management of tobacco fields.
DownLoad: