不同前作对烟田土壤养分、酶活性及烤烟生长的影响

为明确不同前茬作物对土壤和烤烟生产的影响，采用田间试验研究了冬闲、绿肥和大蒜3种前茬处理对土壤养分、土壤酶活性、烤烟生长和烟叶质量的影响。结果表明：（1）与冬闲处理相比较，烤烟移栽时，前作种植大蒜与种植绿肥处理的土壤pH分别降低了0.48和0.46个单位；土壤速效钾分别增加了108.80和217.39 mg/kg；采收结束后，前作大蒜和绿肥处理的土壤有效磷、速效钾及可溶性有机碳含量显著升高，且绿肥效果显著大于大蒜；前作大蒜和绿肥处理提高了土壤蔗糖酶、脲酶活性，且绿肥效果大于大蒜处理。（2）前作大蒜处理烤烟生物产量移栽后30 d与冬闲处理相当，移栽后60 d显著高于冬闲处理；前作绿肥处理在移栽后30 d生物产量显著低于冬闲处理，但移栽后60 d显著高于冬闲处理；不同前作处理对烤烟氮素和钾素吸收的影响与对生物产量影响的趋势相一致。（3）前作种植大蒜和绿肥可以提高烟叶产量和产值，且绿肥效果高于大蒜，但需要注意的是种植绿肥导致烟叶氮含量增加，烟叶感官评吸质量明显下降。综上所述，前茬种植大蒜与绿肥均能在一定程度上改善烟田土壤条件、提高烟叶产量，绿肥还田后烤烟要适当减少施肥量。

Effects of Different Preceding Crops on Conditions of Tobacco-planting Soil Nutrients,Enzyme Activities and the Growth of Flue-cured Tobacco

In order to study the effects of different preceding crops on the nutrients of tobacco-planting soil and on growth, yield and quality of flue-cured tobacco, a field experiment was conducted by using winter fallow and garlic and green manure. The results showed that:(1) Compared with the winter fallow treatment, the garlic and green manure treatments significantly decreased soil pH by 0.48 and 0.46 units, while increased soil available potassium by 108.80 and 217.39 mg/kg respectively. Garlic and green manure treatments significantly increased the contents of soil available phosphorus, available potassium and soluble organic carbon, and the effects of green manure were significantly higher than those of garlic. Both garlic and green manure treatments significantly enhanced the activities of soil invertase and urease and the effect of green manure was higher than that of garlic. (2) Compared with the winter fallow treatment, tobacco biomass of the garlic treatment was similar 30 d after transplanting, but significantly higher 60 d after transplanting. Tobacco biomass of the green manure treatment was significantly lower 30 d after transplanting, but became significantly higher than that of the winter fallow treatment 60 d after transplanting. The same trends were found in the effects of different pre-treatments on absorption of nitrogen and potassium in flue-cured tobacco. (3) The garlic and green manure treatments increased the yields and output values of tobacco, but the green manure treatment increased nitrogen content in tobacco leaves, thus significantly decreased the sensory evaluation quality of tobacco leaves. Therefore nitrogen fertilizer should be reduced when planting tobacco in this case. Overall, the preceding crops garlic and green manure could improve the soil conditions of the tobacco field to a certain extent, and increase the yield of tobacco leaves, but the amount of fertilizer should be reduced properly after the green manure was returned to the field.