Characteristics of soil nitrogen mineralization and effects on nitrogen absorption and accumulation in tobacco plants in Nanxiong tobacco planting areas
In order to study the characteristics of nitrogen supply of three main tobacco planting soil types (muddy sand soil,“cow liver”soil and purple soil) in Nanxiong and the nitrogen absorption by flue-cured tobacco grown in these soils, field experiments were conducted to study the characteristics of soil nitrogen mineralization and the effects on nitrogen absorption and accumulation in tobacco plants. The results showed that: 1) During the period of tobacco growth, the amount of soil nitrogen mineralization increased continuously, the total mineralization levels were 360.27, 327.50 and 277.82 kg·ha-1 in muddy sand soil,“cow liver”soil and purple soil, respectively. The percentage of nitrogen mineralization at tobacco mature stage was above 60%. 2) The nitrogen accumulation in tobacco generally displayed a“slow-fast-slow”curve, nitrogen accumulation peaked in 45-60 days after transplant with the total accumulation reached 5.36, 4.81 and 4.19 gN·plant-1 in the three soil types, respectively. 3) Nitrogen utilization was 34.04%, 33.11% and 30.53% in the three soil types, respectively. Therefore, to improve the utilization efficiency of nitrogen fertilizers and avoid excessive nitrogen supply at late growth stage, advancing nitrogen application time, reducing application rate and increasing application times were recommended in tobacco production.