Effects of continuous cultivated flue-cured tobacco on soil eco-stoichiometric characteristics

To clarify the influence of continuous cultivated flue-cured tobacco on the ecological and chemometric characteristics of soil, a combination study of field investigation and indoor analysis was performed. Soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK) and their stoichiometric characteristics were determined for crop rotation, and continuous cropping for 1, 3 and 5 year periods in the Luzhou tobacco area of Sichuan Province. The results revealed that:Compared with crop rotation, flue-cured tobacco had no significant effect on the soil nutrient content after 1 year of continuous cropping. However, after 3 years of continuous cropping, the SOC decreased but total P and K increased significantly. In the fifth year of continuous cropping, the SOC content decreased significantly by 9.89%, while total N, P, and K increased by 14.37%, 68.84%, and 27.58%, respectively. Soil C/N, C/P, N/P and N/K decreased as the duration of continuous cropping increased. The decrease observed was 4.06%, 9.25%, 6.51% and 2.36%, respectively, on average. The contribution of soil SOC to C/N, C/P, N/P, and N/K was positive, while the contribution of soil TN, TP, and TK to C/N, C/P, and N/P was negative. The correlation between soil nutrient levels and stoichiometry was affected by all the nutrients. Generally, the flue-cured tobacco led to the accumulation of phosphorus and potassium and a decrease in organic carbon in the soil after three years of continuous cropping, which may alter the eco-stoichiometric ratio, thus affecting the balanced supply of soil nutrients