Effect of Different Fertilizer Reduction Modes on Tobacco Nutrient Utilization Efficiency, Yield and Quality

Chenzhou tobacco-growing area is the most typical producing area of char, sweet, alcohol and sweet flavor tobacco leaves in China. The soil quality and fertilizer utilization rate of tilled layer in Chenzhou tobacco-growing area decreased year by year due to the long shallow ploughing and unreasonable fertilization. In order to clarify the suitable tobacco fertilizer reduction technology model in the typical tobacco-rice rotation area of Chenzhou, Hunan Province, a 3-year field positioning experiment was conducted from 2019 to 2021 in the typical tobacco-rice rotation area of Chenzhou, Hunan Province. Five treatments were set up, including no fertilizer (CK), local conventional fertilization (T1), single application of chemical fertilizer without organic fertilizer (T2), chemical fertilizer reduction by 20% and organic fertilizer unchanged (T3), and organic fertilizer replacement of 20% nitrogen fertilizer (T4). The study investigated the effects of different fertilizer reduction measures on the utilization rate of nitrogen, phosphorus and potassium nutrients, tobacco quality and economic traits of tobacco. The results showed that, T3 could significantly improve the physiological utilization rate of nitrogen, phosphorus and potassium fertilizer, the maximum increase rates were 42.75%, 42.14% and 69.38% respectively; the chemical composition content of tobacco leaves in each treatment was not significantly different, and the appearance quality of tobacco leaves was not significantly different; the sensory quality score of T4 was the highest; the tobacco leaf yields and output value of T4 was relatively high, and the proportion of high-grade tobacco leaf in T4 was the highest, which was 11.88%~13.77% higher than that of other fertilization treatments. Under the condition of ensuring the harvest index and production efficiency of nitrogen, phosphorus and potassium, and the chemical composition and appearance of tobacco leaves, the fertilizer reduction also significantly improved the physiological utilization rate of nitrogen, phosphorus and potassium fertilizer in T3 and the economic traits of T4. The cost effect, environmental benefit and the effect on the yield and quality of tobacco leaves of different treatments were comprehensively compared, and T4 was recommended as the technology of reducing fertilizer and increasing efficiency in Chenzhou tobacco-rice rotation area.