不同种植制度和施肥措施对烟田土壤养分及微生物的影响

Effects of Different Planting Systems and Fertilization Models on Soil Nutrition and Soil Microflora of Tobacco Field

分析了烤烟连作与轮作对土壤养分含量和微生物区系的影响以及底肥中硝态氮（NO3^--N）、铵态氮（NH4^＋-N）不同配施比例对烤烟生育期土壤NO3^--N的影响。结果表明，烟田连作3年、6年与轮作相比，土壤有机质均下降，速效氮、磷和钾含量增加，pH值上升；连作6年与3年相比，土壤pH值、速效磷和速效钾又有所升高．碱解氮持平，有机质降低4．3％。土壤细菌和放线菌数量随连作年限增加而呈减少趋势，真菌以连作3年最低；连作使细菌和真菌有益菌群数量降低，而腐霉等有害菌群数量增加。烤烟生育前期，随着底肥中NO3^--N施用比例增加，耕层土壤NO3^--N含量增加，而生育中后期没有显著差异；随着烤烟生育期推进，土壤NO3^--N主要累积在40～60cm土层。从烤烟整个生育期土壤NO3^--N变化和累积看，底肥氮以NO3^--N占30％～50％的配比，对烟株吸收NO3^--N较为有利.

The effects of continuous cropping and rotation system on soil nutrient and soil microflora of tobacco field were studied, and the changes of nitrate nitrogen at different growth stages of flue-cured tobacco with different ratios of nitrate nitrogen and ammonium nitrogen as base-fertilizer were analyzed. The result showed that, comparing to rotation pattern, the 3-year and 6-year continuous cropping tobacco led to the decrease of soil organic matter, the increase of soil available nitrogen, phosphorus and potassium, and the rise of pH. Compared to 3-year continuous cropping, the soil of 6-year continuous cropping increased more in pH, available phosphorus and potassium, had the similar level of available N, and decreased in organic matter by 4.3%. The number of bacteria and actinomyces in soil presented a desending trend with the increase of continuous cropping years.The number of fungi was the lowest in 3-year continuous cropping. The number of effective mi- croorganisnrs such as bacteria and fungi reduced gradually along with the extension of continuous cropping years, while the number of harmful microorganisms such as pythium increased.The content of nitrate nitrogen in tilth layer increased with an increase of proportion of nitrate nitrogen in base fertilizer during early growth stage. The nitrate nitrogen mainly accumulated in 40 - 60 cm depth of soil as the development of tobacco. Based on the changes of nitrate nitrogen in soil during whole stage of growth,the optimum ratio of nitrate nitrogen in base fertilizer was 30% -50%.