Analysis on reutilization characters of fertilizer N in tobacco field with 15N tracing technique

Abstract: In order to study how the later-season flue-cured tobaccos absorb and utilize the fertilizer N that remained by the first season, in 2011, an experiment controlled with different irrigation amount (600, 800 and 1 000 mm) and different fertilizer nitrogen amount (15N double labeled NH4NO3, 90 and 120 kg/hm2) was conducted using the lysimeters, and the 15N-N (fertilizer N originated from 2011) amount in the tobacco organs and the soils were observed during the flue-cured tobacco cultivation from 2012 to 2014. Meanwhile, the impact factors of the tobaccos' reutilization rate to the first-season fertilizer N were analyzed. Results showed that: 1) the amount of fertilizer N that originated from the first season in the later-season tobacco leaf, stem and root, was increased as the nitrogen application increased in the first season, but overall decreased as the irrigation amount increased; 2) the total reutilization rate of the 3 later-season tobaccos to the fertilizer N that applied by the first season was 10.79%-14.58%, and 600 mm amount of irrigation combined with 90 kg/hm2 amount of nitrogen application was most advantageous for the later-season tobaccos to absorb the fertilizer N that remained by the first season; 3) the average reutilization rate of the 3-later season tobaccos to the fertilizer N that applied by the first season, was negatively related with the irrigation amount in the first season (P<0.01), and was positively related with the amount of fertilizer N that remained by the first season in 0-20 cm soils (P<0.05). The first-season irrigation affected the reutilization rate of later-season tobaccos to the fertilizer N that applied by the first season through changing the distribution pattern of the fertilizer N, especially through changing the amount of fertilizer N in the 0-20 cm soils. However, the detailed impact mechanism still needed to be further clarified. Above all, the later-season flue-cured tobaccos can absorb many of the fertilizer N that applied by the earlier season, and the reasonable formulation of irrigation and nitrogen application regimes in the earlier season was extremely important for improving the fertilizer N reutilization rate of later-season tobaccos. The research conclusions can provide useful information for the improvement of the soil ecological environment of tobacco-cultivated areas and the sustainable development of the tobacco agriculture.