| By field experiment, the rule of barley mineralization and effects of barley incorporation quantity on tobacco field nutrition, soil enzyme activities, soil rhizospheric microbial biomass , nutritional element of tobacco plant and tobacco quality were studied systematically from 2001 to 2003. The results were showed as follow:Firstly: The change trend of organic C and N was similar. It can be divided into three phases including fast decomposition, gradual decomposition and slow decomposition. The increase of barley incorporation enhanced the amount of available nutrient (N, P , K and organic matter).The rule were showed : T4>T3>T2>T1>CK.Secondly: There were the similar trend about the threesoil enzyme including invertase, polyphenol oxidase and peroxidase. The enzyme activities of the three types reached top value on the 75th day after the transplant. They were decreased after it. The increase of barley incorporation also enhanced the soil enzyme activities. In the all stages, the sequence of the three enzyme in every treatment were showed as T4>T3>T2>T1>CK all along. At the same time , the increase of barley incorporation also improved the amount of the four rhizospheric microbial biomass including(fungi, bacteria, actinomyces and silicate bacteria). Their sequence was similar to that of the four types of enzyme activities. The amount of rhizospheric bacteria and silicate bacteria reached the maximum on the 60th day after transplant, but the amount of rhizospheric actinomyces and rhizospheric fungi was minimum.Thirdly: The increase of barley incorporation enhanced the NR activity of the tobacco leaf in the prophase, moreover, It reduced the NR activities of the tobacco leaf in the anaphase. The enzyme of SOD was being decreased in the whole grow period. At the same time, the increase of barley incorporation improved the enzyme of SOD in every treatment. The enzyme activities was the maximum in the 60th day52after the transplant. The sequence of the SOD activities were showed in different growth phase and treatment as T4>T3>T2>T1>CK. On the contrary, the increase of barley incorporation reduced the content of MDA in the middle phase and anaphase.Fourthly: The increase of barley incorporation enhanced the N content in the root and stem, especially in th anaphase. The N content in the root was being decrease in the whole phase. The leaf N content reach the maximum, At the time, the sequence was showed as T4>T2>T4>T1>CK. at the other stages, the sequence of the leaf N content was T4>T3>T2>T1>CK. the sequence of N content in every organ was leaf N content >root N content >stem N content in the same stage and different treatment. Concerning the phosphorus , the increase of barley incorporation enhanced the P content in the root and stem, moreover, it reduced the P content in the leaves. At the same time , the increase of barley incorporation improved the K content in the roots and leaves. The sequence of K content in all organ was T4>T3>T2>T1>CK, the sugar content and total N were improved. As for nicotine, it was reduced in the whole stage.Finally: The content of chemical composition were enhanced including soluble sugar, reducing sugar, total N and K ion. The correlation coefficient between the following chemical composition and the barley incorporation quantity were positive correlation. The content of soluble total sugar and K ion are significant positive correlation with the barley incorporation quantity. The content of starch, total N and reducing were very significant positive correlation. The correlation coefficient was negative correlation with the barley incorporation quantity, but the correlation coefficient was not significant. By F test to each treatment, total N, starch and K ion were significant different. Soluble total sugar and reducing sugar were very significant different. Nicotine was not significant different. The quality of treatment T3 was the best among them by the analysis of the ratio of various chemical composition.
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