石灰、钙镁磷肥对烤烟生产及土壤酸度调节的影响

广东植烟土壤酸度普查结果表明，沙泥田的pH值在3．45～5．75之间，大于5．5的很少。pH值偏低是制约沙泥田烤烟产量、质量进一步提高的主要障碍因子之一。在沙泥田烟区进行石灰施用量及提高钙镁磷肥施用比例的试验结果表明，随着石灰施用量的增加，气斑病、青枯病有下降的趋势；而赤腥病有上升的趋势，而烤烟的产值、均价、上等烟率等都是在石灰施用量1500kg／hm^2时为最高。提高钙镁磷肥的施用比例，烤烟的产量、产值、均价、上等烟率等也相应提高。施用石灰及钙镁磷肥均有提高土壤pH值的作用。建议在沙泥田烟区每公顷施石灰1500kg，全部以钙镁磷肥作为磷的来源。

Influence of lime and serpentine-fused phosphate on tobacco production and soil acidity regulation

The acidity of tobacco-planting soils were surveyed in guangdong province. The results showed that the value of pH in sandy loam soil ranged from 3.45 to 5.75. The low pH is one of the main obstacles to restrict the increase of tobacco yield and the improvement of tobacco quality. The other experimentation also indicated that the weather-fleck bacterial wilt decreased with the increase in the application rate of lime. As the application amount of lime is 1500 kghm-2, the value of output, average price and rate of first-class tobacco leaves is the highest. The tobacco yield, value of output, average price and rate of first-class tobacco leaves could be also increased by increasing the application ratio of serpentine-fused phosphate. When lime or serpentine-fused phosphate was applied to this soil there was a rise in pH value. It was suggested that the optimum application amount of lime should be 1500 kghm-2 in the sandy loam soil, and the source of phosphorus should be the serpentine-fused phosphate.