重庆市武隆区植烟土壤肥力及其影响因子研究

Fertility of Tobacco-Planting Soils in Wulong District,Chongqing and Its Influencing Factors

为明确重庆武隆区植烟土壤肥力状况及其影响因子,分别在巷口、江口、火炉、白马这4个基地单元的23个乡镇共采集414个土样,测定土壤主要养分含量,利用模糊数学综合评价法计算土壤综合肥力指数(IFI),并探讨海拔、植烟年限、轮作、前茬作物、地形等因素对土壤养分含量及IFI的影响。结果表明:武隆烟区土壤pH值、有机质和全氮含量的平均值分别为6.09、27.08 g/kg和1.70 g/kg,均处于中等水平,其中24.88%土壤pH值低于5.5;31.30%土壤有机质含量高于30 g/kg;土壤碱解氮、有效磷和速效钾含量的平均值分别为140.62、307.24和31.76 mg/kg,均处于高水平,其中73.43%土壤碱解氮含量高于120 g/kg,75.37%土壤有效磷含量高于220 mg/kg,47.34%土壤速效钾含量高于350 mg/kg;白马基地单元土壤有机质、全氮、速效钾和有效磷含量最高,但江口基地单元植烟土壤养分适宜度最佳;土壤有机质、全氮、碱解氮和有效磷含量随海拔高度的增加呈上升趋势;土壤速效钾含量随该海拔高度的增加呈先升后降趋势;随植烟年限增加,土壤全氮、碱解氮含量呈逐渐降低趋势,pH值随植烟年限增加逐渐升高后又逐渐降低;轮作通过适度降低土壤有机质和全氮含量而提高土壤IFI;蔬菜作为前茬作物的土壤碱解氮含量最高;平地植烟土壤速效钾含量显著高于坡地。综上所述,实施轮作有利于提高土壤IFI,白马基地单元土壤肥力较高,肥料减量空间较大;江口基地单元土壤IFI最高,是最适宜植烟区。

In order to clarify the fertility status of tobacco-planting soil in Wulong District,Chongqing and its influencing factors,we have measured the main nutrient contents of 414 soil samples collected from 23 townships in four base units,Xiangkou,Jiangkou,Huolu and Baima.The soil integrated fertility index (IFI) was calculated by fuzzy mathematics comprehensive evaluation method.The effects of altitude,tobacco-planting years,crop rotation,previous crop and terrain on soil nutrient content and IFI were also discussed.The results showed as follows:The average values of soil pH,organic matter and total nitrogen in the tobacco-planting area of Wulong were 6.09,27.08 g/kg and 1.70 g/kg,respectively,which were all at medium levels.Morever,24.88% of the soil samples had a pH value < 5.5,and 31.30% of the soil samples had an organic matter content > 30 g/kg.The average values of soil alkali-hydrolyzable nitrogen,available phosphorous and available potassium were 140.62,307.24 and 31.76 mg/kg,respectively,which were all at high levels.Furthermore,alkali-hydrolyzable nitrogen content was > 120 g/kg in 73.43% of the soil samples,available phosphorous content was > 220 mg/kg in 75.37% of the soil samples,and available potassium content was > 350 mg/kg in 47.34% of the soil samples.The contents of soil organic matter,total nitrogen,available potassium and available phosphorous were the highest in Baima base unit,but Jiangkou base unit had the optimum soil nutrient composition.The contents of soil organic matter,total nitrogen,alkali-hydrolyzable nitrogen and available phosphorous presented an upward trend with the increase of altitude.The content of soil available potassium first increased and then decreased with the increase of altitude.The contents of total nitrogen and alkali-hydrolyzable nitrogen in soil presented a gradual decline trend with the increase of planting years,and the pH value gradually increased and then decreased with the increase of planting years.Crop rotation increased IFI by moderately decreasing soil organic matter and total nitrogen contents.Soil alkali-hydrolyzable nitrogen content was the highest with vegetables as a previous crop.The content of available potassium in flat fields was significantly higher than that in sloping fields.Overall,the implementation of rotation is beneficial to improving soil IFI.Soil fertility in Baima base unit is high,indicating potential for the reduction of fertilizers.Jiangkou base unit has the highest soil IFI,therefore it is the most suitable tobacco-planting area.