绿肥中养分释放规律及对烟叶品质的影响

NUTRIENT RELEASE FROM GREEN MANURES AND ITS EFFECT ON QUALITY OF TOBACCO LEAVES

在田间条件下利用埋设玻璃滤纸包法研究了绿肥翻压后的分解规律及其翻压绿肥对烟叶品质的影响。结果表明,经过13周的分解,苜蓿中有机C的矿化率高达81%,N素矿化率为54%;黑麦草有机C的矿化率为63%,N素矿化率为22%。这些矿化N中约92%的N(苜蓿)和74%的N(黑麦草)是在翻压后的前6周释放的。在烟株的整个生长期内,由苜蓿释放的N素约为N 43 kg hm-2,为了防止后期N素供应过多而导致上部烟叶烟碱含量过高,苜蓿宜提前翻压并从总N肥施用量中扣除由苜蓿矿化出的N。黑麦草因N素含量低和N素矿化量少,整个生长季中约释放了N 10.5 kg hm-2的N素,所以在黑麦草生长量不大的情况下,可将黑麦草全部翻压并忽略其释放的N素。在没有减少化肥施用量的情况下,翻压苜蓿提高了上部烟叶中烟碱含量,降低了总糖和还原糖含量。而翻压黑麦草对烟叶中烟碱含量有所降低,总糖和还原糖含量适中,因而烟叶的品质得到了改善。

With the buried glass filter paper bag method a field experiment was carried out in a tobacco field to study mineralization of green manure and its effect on tobacco leaf quality. Results show that about 81% of the organic C and 54% of the organic N in alfalfa, 63% of the organic C and 22% of the organic N in rye grass were mineralized throughout the growth period of tobacco. However, more than 92% of the mineralized N in alfalfa and 74% in rye grass were released in the first 6 weeks after they were incorporated into the soil. In the whole growth period of the plant, about N 43 kg hm^- 2 was released from alfalfa. In order to control of over-supply of N nutrient in the late growth period and resultant higher nicotine content in tobacco leaves at upper stalk position, it is recommended that alfalfa should be ploughed into the field earlier and the total N fertilizer application rate should be reduced by deducting the amount of mineralized N released from the alfalfa. Rye grass released only N 10.5 kg hm^- 2 in the same period of time because of its low N content. So rye grass could totally be ploughed and incorporated into the soil unless its biomass production is getting too high. When the application rate of chemical N fertilizer remained unchanged, the alfalfa treatment resulted in slightly higher nicotine content, lower total sugar and lower reducing sugar content in tobacco leaves at the upper stalk position in this experiment, while the rye grass treatment reduced the nicotine content and kept sugar contents in a proper range, thus improving quality of the tobacco leaves.