| Tobacco is one of the most important industries of our country’s Gross National Product (GNP) and it is also the first tax payer for industry and commerce business among all sectors of the nation, which make a positive contribution to the rapid development of national economy. Organic matter is an important component of soil solid phase; it played a important role in the global carbon cycle, soil formation, soil fertility, crop yield and quality and was regarded as one of the most important indicators for the evaluation of soil fertility and soil quality, although it only account for a small proportion of soil. Due to the special need of nitrogen in tobacco’s growth, both soil organic matter content and composition have great influences for tobacco quality, which cannot be too high or too low. Meanwhile, different groups of soil organic matter have different roles and contributions in the aspects of transformation kinetic, carbon storage capacity, soil nutrient supply and soil structure maintain. The application of organic fertilizer is one of the most effective approaches to regulate and control the quantity and composition of soil organic matters; different types of organic fertilizer have different impacts for its quantity and composition, and have different effects for the yield and quality of tobacco. However, there was few studies focused on the relationship between the responsing of the application of soil organic matters for soil conditions and the yield and the quality of tobacco planting at present. Therefore, this paper through the field test in Wushan and Fengdu (Chongqing), as two typical tobacco areas, was to study the response of tobacco planting-soil organic matters for the application of additional organic matters; the relationships between soil organic matter changes and tobacco production factors. And try to provide some supporting for soil quality management and high quality cultivation of tobacco from theoretical and technical aspects. The main results are as follows:(1) The application of organic fertilizer changed the content, composition and distribution of tobacco soil organic matter. The four kinds of organic fertilizer (tobacco special organic fertilizer, straw compost, biomass carbon, humic acid fertilizer) at their routine fertilization, can improve the total soil organic matter in tobacco soil, but the effect levels and the effects on soil organic matter fractions were different. In 2013 the Fengdu area, constant straw compost (DF1) of organic fertilizer treatment have the largest increase for organic matter, active organic matter. High-active organic matter was increased significantly in humic acid fertilizer (FZS1) treatment. In 2014 the Wushan area is different, the FZS1 treatment of organic matter and active organic matter content was the highest, biomass carbon (BC1) in the treatment of active organic matter increased obviously, which higher than that of CK (more than 56.34%). DF1 enhanced the high-active and soil organic matter contents.The application of organic fertilizer could improve both soil light (LFOM) and heavy organic matter fractions. DF1 treatment showed a most obvious enhancement for LFOM, which not only rise the contant of LFOM in soil but also improve the proportion of LFOM in total soil organic matters. In a certain range, soil organic matter and active organic matter will increased with the increasing of organic fertilizer loading, while the increase will becomes slow.Different particle size aggregates with low organic matter content will be affected intensely for soil organic fertilizer. When the content of organic matter content was relative highe in soil, the affect intense of organic fertilizer application will decrease for aggregates. Different organic matter contents of different particle size aggregates have significant responses for different types and amount of organic fertilizer. In the DF treatment, the effects are better than other treatments. Moreover, there was a significant positive correlation between aggregates organic matter contents and the dosage of organic fertilizers, but the rising rate becomes slow when (2) he application of organic fertilizer can improve tobacco yield, output value, the proportion of superior tobacco.2014 Tobacco yield, output value, top-grade tobacco proportion in Wushan area 2014 were significantly higher than that in Fengdu area 2013. Tobacco production output and the quality ratio compared with the control treatment have different degrees of improvement by conducting organic fertilizer process. The effect of BC treatment and DF treatment was better than other treatments. Compared with control treatment (CK), the yield and output value of two test area which compost two times than normal treatment (DF2) were increased 475.90kg/hm2 and 11654.77 yuan/hm2, respectively. The proportion of the top-grade and the second-grade tobacco were largest in BC2 treatment, which increased 2.30%-8.18% and 0.22%-5.55%, respectively. The enhancing effect followed with the adding amount of organic fertilizer in certain degree, however, the growth scope becomes slow.(3)Organic fertilizer has obvious influence on the chemical quality indicators of tobacco and different organic fertilizers have different effects. The application of organic fertilizer can increase the content of nicotine, total nitrogen, total potassium, and total chlorine effectively; among all normal treatments, DF treatment has the highest nicotine content in tobacco leaves. The total nitrogen content of tobacco leaf in Wushan is slightly higher than that in Fengdu area, and the content of total nitrogen in two areas were in a suitable range; DF1 treatment has the highest total nitrogen, total potassium, and total chlorine which closer to the optimum content. The total sugar and reducing sugar content of tobacco leaves in Fengdu area and Wushan area lie in a suitable range, and the total sugar and reducing sugar content of tobacco leaves in every organic fertilizer treatments were higher than that in CK. In 2013 Fengdu area, the highest total sugar and reducing sugar treatment was DF1 treatment. While, the highest total sugar treatment in Wushan area in 2014 was OMF1. The main chemical components in tobacco leaves increased with increasing apply of organic fertilizer with constant in was the, each organic fertilizer constant in total sugar content of OMF1, content of increased with the increase of organic fertilizer, but the increase rate of decline, making it more close to the optimum content of Flue-cured tobacco.(4) The tobacco chemical quality and soil organic matter and available nutrient status was correlated significantly. The tobacco chemical quality was affected by changing the composition and nutrient status of tobacco though the application of organic fertilizer Two years’monitoring data showed that the use of organic fertilizer could significantly improve soil pH value, nitrogen content, available phosphorus and potassium. And there were differences between the different types and amount of organic fertilizer treatments; DF and BC treatments have significant effects on acidic soil pH value and soil nutrient. Besides FZS treatment, the soil available nitrogen, phosphorus, potassium and pH value in every treatment increased with the increasing apply of organic fertilizer. But the increasing rate becomes slower at last. Correlation analysis showed that soil organic matter, the active components were not significantly correlated with soil pH, but significantly correlated with soil available nutrients. Active organic matter was significant or highly significant positive correlated with alkali hydrolyzable nitrogen and available potassium; high-active organic matter was positive correlated with alkali hydrolyzable nitrogen and available potassium. Therefore, soil active organic matter can be regarded as a index to evaluate soil fertility. Main chemical components of tobacco leaves and soil organic matter and active fractions is closely related with the activity of soil organic matter and organic components in tobacco and nicotine, nitrogen, potassium, chlorine, total sugar and reducing sugar were significant or highly significant positive correlation.(5) Significant correlation was shown between the conditions of soil organic matter and the accumulation of heavy metals in tobacco. Organic fertilizer affects heavy metals in tobacco by adjusting soil organic matter content and this effect was different with different types of organic fertilizer and heavy metals. The four kinds of organic fertilizer we chosen in this study all inhibited mercury (Hg) accumulation in tobacco, the content of Hg in tobacco leaves of each treatment were significantly lower than those of CK. BC1 only decreased by 11.11% as the minimum treatment. However, the application of organic fertilizer promotes the accumulation of arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb) in tobacco especially in leaves. Comparing with CK, the leaf-content of As, Cd and Cr were largest in DF1 treatment, which increased 27.58%,15.62% and 40.54%, respectively. The largest content of Pb was appeared in BC1 treatment, which increased 16.66% compared with CK. Correlation analysis indicated that the content of heavy metals in tobacco leaves have close relation with soil organic matter and its active fractions. The soil organic matter and its active fractions present positive relationship with As, Cd, Cr, Pb and negative relationship with Hg content in tobacco leaves. The result implicated that soil organic matter and its active fractions can improve the availability of soil heavy metals in certain degree. Therefore, we should pay close attention to the risks of heavy metals in the application of organic fertilizer. |
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