烤烟连作对土壤生态化学计量特征的影响

为阐明烤烟连作对土壤生态化学计量学特征的影响，采用野外调查与室内分析相结合的方法，对四川泸州烟区正茬和连作1、3、5年土壤的有机碳（SOC）、全氮（TN）、全磷（TP）和全钾（TK）含量及其化学计量特征进行了研究。结果表明：与正茬相比，烤烟连作1年对土壤养分含量无显著影响；连作至第3年时，SOC含量明显下降，而TP和TK含量显著上升；连作至第5年时，SOC含量显著下降了9.89%，TN、TP和TK则分别增加了14.37%、68.84%和27.58%。土壤C/N、C/P、N/P和N/K随连作年限的增加而降低，年均下降4.06%、9.25%、6.51%和2.36%。土壤SOC对C/N、C/P、N/P、N/K贡献为正，而TN、TP、TK对C/N、C/P、N/P贡献为负，土壤养分及其化学计量比的相关性受到各养分的共同影响。总体来看，烤烟在连作3年时即可引起土壤磷钾累积及有机碳降低，使其生态化学计量比发生变化，从而可能影响土壤养分间的平衡供应。

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.