稻草还田对土壤氮素矿化及烟叶品质的影响

Effects of rice straw incorporation on soil nitrogen mineralization and quality of flue-cured tobacco leaves

探索调控土壤供氮的措施,是降低上部烟叶烟碱含量,提高我国烟叶整体质量的关键问题。以云南水旱轮作植烟土壤为研究对象,通过大田原位培养试验,研究了稻草覆盖还田和稻草翻埋还田对土壤氮素矿化及烟叶品质的影响。结果表明,稻草还田提高了土壤供氮能力,稻草还田方式不同对土壤氮素矿化的影响有所差异。在烤烟旺长期,稻草覆盖还田明显增加了土壤氮素矿化量;采收期,稻草翻埋还田处理的土壤氮素矿化量增加显著。在烟株整个生育期,稻草覆盖还田和稻草翻埋还田处理的土壤累积矿化量分别达到139 kg/hm2和129 kg/hm2,比对照处理分别增加了20.4%和12.2%。由此说明,稻草覆盖还田对土壤氮素矿化的促进作用更显著。尽管稻草还田促进了土壤氮素矿化,增加了土壤供氮量,但两种稻草还田方式均显著降低了上部烟叶总氮和烟碱浓度,提高了其总糖和还原糖浓度,改善了上部烟叶品质。其中,两种还田方式的影响差异不大,总氮含量和烟碱浓度约降低18%和17%,总糖和还原糖浓度约增加23%和19%。稻草还田对中部烟叶品质的影响不显著。

Questing for the measures of controlling soil nitrogen supply is the key problem of reducing nicotine concentration of upper leaves and improving holistic quality of flue-cured tobacco leaves. In situ incubation experiment was carried out to study the effects of rice straw incorporation on nitrogen mineralization and quality of tobacco leaves on paddy-upland rotation soil. The experiment showed that rice straw incorporation improved the ability of soil nitrogen supply, but the effects were different under different rice straw incorporation manners. Rice straw mulching markedly accelerated soil nitrogen mineralization in vigorous growing period, but plowing rice straw into soft had better promotion effects on nitrogen mineralization during maturation. Under rice straw mulching and plowing conditions, the accumulation quantities of mineralized nitrogen were 139 kg/hm^2 and 112 kg/hm^2 .in the whole growth period, which increased 20. 4 % and 12. 2 % respectively than control. From above, rice straw mulching was more efficient on promoting soil nitrogen mineralization. While rice straw incorporation increased soil nitrogen mineralization, both rice straw mulching and plowing evidently reduced nitrogen and nicotine concentration and markedly increased total sugar and reductive sugar content of upper leaves. There was little difference between effects of two rice straw incorporation manners on quality of upper leaves. The concentration of total nitrogen and nicotine in two treatments reduced about 18% and 17% than control, and content of total sugar and reduetive sugar increased about 23% and 19%. The experiment indicated that rice straw incorporation improved the quality of upper leaves, but had little effect on quality of middle leaves.