Effects of continuous cropping on soil nutrients and ecological stoichiometric characteristics at rhizosphere and non-rhizosphere of flue-cured tobacco
The influence of rhizospheric and non-rhizosphere is soil nutrients and their ecological stoichiometric characteristics in tobacco with different continuous cropping years in Majiang county(study region),Guizhou Province,were discussed.A combination study of field investigation with indoor analysis was performed.The soils with different continuous cropping years(0,1,2,3,5 and 9a)and non-tobacco planting areas(control areas)in the study region were analyzed,and soil pH,soil organic matter(SOM),total nitrogen(TN),total phosphorus(TP),total potassium(TK)and their ecological stoichiometric characteristics were studied.The results revealed that:With the increase of continuous cropping years,SOM and TN content in tobacco fields increased,while TP,TK and pH showed a trend of volatility increase,decrease and decrease,respectively.In the same planting year,the nutrient contents in rhizosphere soil were generally higher than that of in non-rhizosphere soil,which in turn were generally higher than that of in the control areas.The soil nutrient contents in the control areas showed an increasing trend.Compared with C0(normal cropping),the nutrients appeared an increasing trend with the increase of continuous cropping years,except for TK.There was no significant difference in C/N between rhizospheric soil and non-rhizospheric soil with the increase of continuous cropping years,while other ecological stoichiometry ratios exhibited a trend of fluctuating increase.SOC and TN were extremely significantly or significantly correlated with ecological stoichiometry of rhizospheric and non-rhizospheric soils.SOC,TN(except for P/K)and TP had similar effects on soil ecological stoichiometry in the control areas.With the increase of continuous cropping years,the proportion of soil nutrients were unbalanced,and soil acidity increased.Potassium may be the limiting nutrient for continuous cropping of flue-cured tobacco in the study region,and attention should be paid to the application of nitrogen.The ecological stoichiometric ratios of soil nutrients were mainly controlled by soil TN,TP,TK and SOC,and were closely related to their changing range.
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