Relationship Between pH Value and Physical and Chemical Properties of Tobacco-growing Soil

[Objectives]This study was conducted to understand the relationship between soil pH and soil physical and chemical properties during tobacco planting.[Methods]Through a field experiment,the pH value of tobacco-growing soil,the contents of mineral nutrients(ammonium nitrogen,alkali-hydrolyzable nitrogen,available potassium,available phosphorus),soil bulk density and porosity were investigated.[Results]The pH value of the soil after tobacco planting increased,and the contents of ammonium nitrogen,alkali-hydrolyzable nitrogen,and available potassium were closely related to the change of pH value.The bulk density of the tobacco-planting soil decreased and the porosity increased.Planting flue-cured tobacco had certain impacts on soil pH,soil bulk density and other physical and chemical properties.[Conclusions]This study provides a theoretical basis for the investigation of the fertilization laws in the process of tobacco planting and the selection of subsequent crops.

Evaluation of Soil Fertility Suitability of Yiliang Tobacco-growing Areas in Yunnan Province

Abstract[Objective]This study was conducted to evaluate the soil fertility in Yiliantobacco-growing areas of Hunan Province.[Method]The soil nutrient contents iseven tobacco-growing towns of Yiliang County,Yunnan Province were surveyefrom 2010 to 2013 and integrated soil fertility index(SFI value)was calculated tanalyze the soil fertility suitability in theses areas.[Result]The soil p H,contents oorganic matter,hydrolytic N,rapidly available K and available B were all at an appropriate level,while the contents of rapidly available P,available Mg,available Zand water-soluble Cl-were high.Among them,the contents of available P and water-soluble Cl-had great variation.Finally,the soil fertility suitability of Yiliang tobacco-growing areas was graded based on their SFI values.As a result,20%of thestobacco-growing areas were in Grade I,47.7%in Grade II,29.3%in Grade III1.5%in Grade IV and 1.5%in Grade V.The average SFI was 0.61.From 2010 t2013,the p H value and available Mg content reduced year by year,while the contents of organic matter,hydrolytic N,rapidly available P,rapidly available K,available Zn,available B and water-soluble Cl-were increased.

Trace Elements Loss Characteristics in Runoff Discharge from Tobacco-Growing Red Soil in Sichuan Province of China

Trace elements are found in small concentrations in soil, yet plants require them for physiological functions. The runoff process leads to soil fertility loss by shifting soil particles and elements, and deposits them to a different position. However, there is a lack of information about the amount of trace elements that flow in tobacco-growing red soil during the natural rainy seasons due to runoff. In this study, runoff discharge was collected from two different soil mulching conditions (straw and no straw) at 15?, in Miyi county of Sichuan province, to evaluate the characteristics of trace elements in runoff discharge. The runoff discharge was filtered to separate water (runoff) from sediment. The concentrations of the elements were analyzed in samples obtained from 9 erosive rainfall events, with 3 replications for every sample. The considered trace elements were Zinc (Zn), Copper (Cu), and Molybdenum (Mo). In addition, the total amount of each element loss per unit area (total loss) was also calculated statistically. The results revealed different concentrations and total losses for the selected trace elements. The total loss in runoff ranged from 10.82 to 194.05 mg/ha, 0.62 to 18.91 mg/ha, and 0.32 to 2.37 mg/ha for Zn, Cu, and Mo, respectively. The total loss in sediment ranged from 54.65 to 12036.34 mg/ha, 44.74 to 5285.30 mg/ha, and 1.78 to 399.82 mg/ha for Zn, Cu, and Mo, respectively. Rainfall intensity, runoff depth, and sediment yield showed distinct positive correlations with the trace elements losses. The loss reduced with the addition of straw in the experimental area. Since each trace element showed distinct characteristics in the runoff and sediment, it is crucial to assess the loss of trace elements in runoff discharge from different agronomic practices. In turn, various sustainable practices of preventing soil fertility loss will be identified.

Effects of Microbial Fertilizers in Improving Acidic Tobacco-planting Soil and Tobacco Leaf Quality

[Objectives]This study was conducted to improve acidic soil and enhance the quality of tobacco leaves.[Methods]The effects of different microbial fertilizers on improving acidic tobacco-planting soil and tobacco leaf quality were investigated through plot experiments.[Results]The application of microbial fertilizers could improve the pH value of acidic soil,and composite microbial agent A showed the best application effect.The application of bio-organic fertilizer was beneficial to improving the contents of available phosphorus and available boron in acidic soil.The application of composite microbial agent A was beneficial to improving the contents of available phosphorus and available potassium in acidic soil,and could promote the growth of tobacco plants and improve the economic traits of flue-cured tobacco and the coordination of chemical components in tobacco leaves.The application of composite microbial agent B led to a downward trend in the content of available boron in acidic soil.The application of composite microbial agent B could promote the absorption of nutrients by tobacco plants,and improve their disease resistance and the quality of tobacco leaves.Due to the differences in functional microorganisms contained,the application effects of different microbial fertilizers in improving acidic tobacco-planting soil and improving tobacco leaf quality varied.Overall,the application of microbial fertilizers could increase soil pH,activate soil nutrients,promote tobacco growth,enhance disease resistance,increase tobacco output value,and improve tobacco quality.Microbial fertilizers have good application prospects in improving acidic soil and improving tobacco quality.[Conclusions]The application of microbial fertilizers to improve acidic tobacco-planting soil can ensure the normal growth and development of tobacco plants and the improvement of tobacco leaf quality,achieving high-quality and sustainable development of Zhaotong tobacco.

Soil Respiration Characteristics and Its Relationship with Environmental Factors of Different Vegetation Types during Growing Season in Dongting Lake

In order to ascertain the soil carbon flux characteristics of poplar plantations and crop communities in the Dongting Lake area during the growing season and their correlation with hydrothermal conditions,soil respiration rate was monitored at fixed sites and time points with an LI-8100 A automated soil flux system.Meanwhile,the surface temperature and soil temperature and humidity were measured. The soil respiration variation in the two different vegetation types and its correlation with environmental factors were analyzed. The results showed that in the growing season,the diurnal variation curves of soil respiration rate in the two different vegetation types showed a single peak variation,but there was certain difference in the appearance time of the peak. The peak of the crop appeared around11: 00 am,while the peak of soil respiration in the poplar appeared around 13: 00. The soil respiration rate of the poplar was also significantly higher than that of the crop,and the average difference of soil respiration rate between the two was 3. 09 and 3. 55 μmol/( m^2·s) in April and August,respectively. Temperature and soil moisture were the main factors affecting soil respiration of the poplar plantation and crop community. Temperature had a greater effect on the soil respiration of the crop community,and soil humidity had a greater impact on soil respiration in the poplar plantation,showing a correlation coefficient reaching 0. 952.

Effects of Tillage Depth on Nutrients and Microbial Communities in Tobacco-Planting Soil

The implementation of appropriate tillage practices is of great significance for agricultural production. However, the effects of different tillage depths on soil nutrients content and microbial communities in tobacco-planting soils are still lacking systematic research. In this study, three different tillage depths of 15 cm (T1), 20 cm (T2), and 30 cm (T3) were set up for field experiments in Liupanshui, Guizhou Province, to explore the effects of tillage depth on tobacco-planting soil nutrients and bacterial and fungal communities based on 16S rRNA and ITS sequencing and figure out the key factors affecting soil microbial communities. The results showed that T2 and T3 increased the contents of organic matter, total nitrogen, total phosphorus, available phosphorus, and available potassium in tobacco-planting soil, and increased the diversity of bacterial communities compared with T1. There was no significant difference in the structure of bacterial and fungal communities in different tillage depth treatments, but some dominant genera were significantly enriched in T2 and T3. Desulfobacter, Setophoma, Humicola, and Acremonium were significantly enriched in T2. Chthonomonas and Fusarium were significantly enriched in T3. These genera favor the decomposition of organic matter and the cycling of nutrients, and control soil pests and diseases. Redundancy analysis indicated that TP and AK were the key factors influencing the dominant genera of bacteria and fungi. This study provides a scientific basis for the selection of soil tillage depth for tobacco production in this region.

Research on Soil Conservation and Improvement Technology in Zhaoyang District

The environment of tobacco-growing soil directly affects the yield and quality of tobacco leaves.In order to solve problems of tobacco-growing soil degradation,low organic matter content and unbalanced soil nutrient supply and promote sustainable and healthy development of tobacco production,this paper comprehensively discussed conservation and improvement techniques of tobacco-growing soil based on existing problems in Zhaoyang District,aiming to provide reference for tobacco-growing soil conservation.

Recommendations for Sustainable Development of Ankang Tobacco Growing Area

Sustainable development of high quality characteristic tobacco is the only path for future development of China's tobacco industry.In combination with realities of tobacco development in Ankang tobacco growing area,this paper made analysis on factors restricting sustainable development of Ankang tobacco growing area.On the basis of actual situations,it came up with recommendations including establishing scientific basic tobacco field protection system,gradually cultivating professional tobacco farmers and strengthening tobacco technician team construction,improving scientific and technological innovation,implementing standardized technologies,improving tobacco production organization mode,and improving tobacco production security mechanism.

Non-growing season soil CO_2 efflux and its changes in an alpine meadow ecosystem of the Qilian Mountains,Northwest China

Most soil respiration measurements are conducted during the growing season.In tundra and boreal forest ecosystems,cumulative,non-growing season soil CO2 fluxes are reported to be a significant component of these systems＇ annual carbon budgets.However,little information exists on soil CO2 efflux during the non-growing season from alpine ecosystems.Therefore,comparing measurements of soil respiration taken annually versus during the growing season will improve the accuracy of estimating ecosystem carbon budgets,as well as predicting the response of soil CO2 efflux to climate changes.In this study,we measured soil CO2 efflux and its spatial and temporal changes for different altitudes during the non-growing season in an alpine meadow located in the Qilian Mountains,Northwest China.Field experiments on the soil CO2 efflux of alpine meadow from the Qilian Mountains were conducted along an elevation gradient from October 2010 to April 2011.We measured the soil CO2 efflux,and analyzed the effects of soil water content and soil temperature on this measure.The results show that soil CO2 efflux gradually decreased along the elevation gradient during the non-growing season.The daily variation of soil CO2 efflux appeared as a single-peak curve.The soil CO2 efflux was low at night,with the lowest value occurring between 02：00-06：00.Then,values started to rise rapidly between 07：00-08：30,and then descend again between 16：00-18：30.The peak soil CO2 efflux appeared from 11：00 to 16：00.The soil CO2 efflux values gradually decreased from October to February of the next year and started to increase in March.Non-growing season Q10 （the multiplier to the respiration rate for a 10℃ increase in temperature） was increased with raising altitude and average Q10 of the Qilian Mountains was generally higher than the average growing season Q10 of the Heihe River Basin.Seasonally,non-growing season soil CO2 efflux was relatively high in October and early spring and low in the winter.The soil CO2 efflux was positively correlated with soil temperature and soil water content.Our results indicate that in alpine ecosystems,soil CO2 efflux continues throughout the non-growing season,and soil respiration is an important component of annual soil CO2 efflux.

Study on the Sustainable Development of the Tobacco-growing Area in South Anhui

Based on the actual situation of tobacco production in South Anhui tobacco-growing area,the paper analyzes several major constraints,and discusses several aspects such as tobacco production human resources,production of large-scale cultivation,science and technology service providers,the standardized production management and production security system. The countermeasures and suggestions for sustainable development are also put forward to provide a reference for the sustainable development of tobacco-growing area in South Anhui.

Biodiversity Risk and Opportunity Assessment in BAT Cooperative Tobacco-growing Areas

Using the method in Biodiversity Risk and Opportunity Assessment Handbook of British American Tobacco Biodiversity Partnership,we assess biodiversity risks and opportunities in BAT and China's cooperative tobacco-growing areas. The assessment results indicate that there are 8 risks and 1 opportunity. Action and monitoring plans have been made for medium and high risks as well as opportunity,to reduce impact on biodiversity.

Study on Chemical Characteristics of Rainfall in Tobacco-Growing Regions of Chenzhou, Hunan Province

In order to clarify the chemical properties of rainfall in typical tobacco areas in Chenzhou City, Hunan Province, and analyze its potential for soil and flue-cured tobacco planting, rainfall samples in 2020 were collected by rainfall instruments in Fangyuan Town and Aoquan Town of Guiyang County, and the chemical properties that are closely related to the quality of flue-cured tobacco were determined, such as pH, EC, total nitrogen (TN), nitrate nitrogen (), ammonium nitrogen () and ion concentrations (K+, Na+, Ca2+, Mg2+, , Al3+, , Cl−,). The results show that the pH values of rainfall samples at Fangyuan and Aoquan monitoring sites are in the range of 4.92 - 6.17 and 4.93 - 5.69 respectively, with an average of 5.27 and 5.27 respectively. The acid rain characteristic is very obvious, which is mainly dominated by . The variation of rainfall EC has seasonal characteristics. EC is low from January to September, in the range of 6.09 - 56.72 and 11.83 - 30.93 μS/cm respectively, besides, it is high from October to December, in the range of 102.63 - 174.60 and 25.05 - 86.37 μS/cm respectively. The annual deposition of TN was 22.19 and 20.76 kg/hm2/yr respectively, which were higher than that in the western regions with less human disturbance, but lower than or equal to that in the developed agricultural regions in eastern China. The proportion of in the annual deposition of TN was higher than that of at two monitoring sites, with an average of 56.51% and 38.86% respectively. Ammonia volatilization from agricultural activities contributed more to rainfall nitrogen content. The ratios of ammonium nitrogen to nitrate nitrogen deposition at two monitoring points were 1.84, 1.81, 1.86 and 1.34, 1.46, and 1.29 during the whole year, summer and autumn, winter and spring respectively. The ratio is higher in summer and autumn than in winter and spring. The weighted average equivalent concentrations of the main ions at two monitoring sites were 238.88 μeq/L and 211.21 μeq/L respectively, and the orders of the ion concentrations were slightly different. Both the concentrations of and are higher, while Mg2+, and Al3+ are lower. , and are mainly from human activities with a contribution rate between 91.90% and 99.35%. Ca2+ mainly comes from soil and ground dust, besides, Cl− and Mg2+ mainly come from marine sources and K+ mainly comes from terrestrial sources. In general, the acidic rainfall and higher concentration are beneficial to reducing the high pH value of soil in Aoquan tobacco area and improving the quality of flue-cured tobacco. Higher concentrations of and in rainfall are not conducive to the improvement of flue-cured tobacco quality, because of the high content of soil available sulfur in Chenzhou tobacco area and the characteristics of flue-cured tobacco’s preference for ammonium.

Yield and Nicotine Content of Flue-Cured Tobacco as Affected by Soil Nitrogen Mineralization

Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha,Guizhou Province.The yield and market value of FCT at Fenggang were much lower than those at Jinsha.However,the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied,which might be due to a higher N supply capacity at the Fenggang site.At later stages of growth(7-16 weeks after transplanting),the soil net N mineralization at Fenggang(56 kg N ha^(-1))was almost double that at Jinsha(30 kg N ha^(-1)).While soil NH_4-N and NO_3-N were almost exhausted by the plants or leached 5 weeks after transplanting,the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization,which contributed to a high nicotine content in the upper leaves.The order of soil N contribution to N buildup in different leaves was:upper leaves>middle leaves>lower leaves.Thus,soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.

Study on soil water characteristics of tobacco fields based on canonical correlation analysis

In order to identify the principal factors influencing soil water characteristics （SWC） and evaluate SWC effectively, the multivariate-statistical canonical correlation analysis （CCA） method was used to study and analyze the correlation between SWC and soil physical and chemical properties. Twenty-two soil samples were taken from 11 main tobacco-growing areas in Guizhou Province in China and the soil water characteristic curves （SWCC） and basic physical and chemical properties of the soil samples were determined. The results show that： （1） The soil bulk density, soil total porosity and soil capillary porosity have significant effects on SWC of tobacco fiels. Bulk density and total porosity are positively correlated with soil water retention characteristics （SWRC）, and soil capillary porosity is positively correlated with soil water supply characteristics （SWSC）. （2） Soil samples from different soil layers at the same soil sampling point show similarity or consistency in SWC. Inadequate soil water supply capability and imbalance between SWRC and SWSC are problems of tobacco soil. （3） The SWC of loamy clay are generally superior to those of silty clay loam.

Changes in Soil Enzyme Activity and Nutrient Content in Different Years of Continuous Cropping Tobacco Fields

In order to find out changes in the main fertility indicators of continuous cropping tobacco fields in Henan Province with years of continuous cropping,5 typical tobacco fields( Jia County,Shaoling District,Fangcheng County,Xiangcheng County,and Song County) were studied. Indicators in question included activity of main enzymes( sucrase,urease,catalase,and acid phosphatase),p H value,organic matters,total nitrogen,available phosphorus and available potassium. The results indicate that in most tobacco fields,the activity of sucrase and urease increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping; in some fields,it directly declined with increase in years of continuous cropping; the activity of catalase increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping,and it became stable after three years of continuous cropping;generally,the activity of acid phosphatase declined with increase in the years of continuous cropping within 3 years continuous cropping,later,it became stable. Except Fangcheng County,the soil p H value of other districts( counties) generally declined with increase in years of continuous cropping,and it was in the range of 5. 6-6. 8. With the increase in continuous cropping,the soil organic matters( SOM) in tobacco fields of Jia County and Song County declined,changes of SOM in tobacco fields of Fangcheng County and Xiangcheng County were not obvious,and SOM showed the trend of first decline then rise in Shaoling District. In most tobacco fields( Jia County,Xiangcheng County,and Song County),the total nitrogen showed a declining trend; in Shaoling District,it showed a trend of first decline then rise; in Fangcheng County,it showed a rising trend. The available phosphorus firstly slightly declined then rose in tobacco fields of Shaoling District and Song County; it showed a trend of first rise then decline in Jia County; there were no obvious changes in Fangcheng County and Xiangcheng County. Changes in the available potassium were different in tobacco fields. In sum,there are certain rules for changes in soil enzyme activity and nutrient content in tobacco fields in Henan Province,but changes are not completely the same. It is concluded that the site conditions and farming activities exert a certain influence on soil enzyme activity,p H value,organic matters,and nitrogen,phosphorus and potassium content. Therefore,to solve obstacles in continuous cropping of tobacco fields,different regions should take different measures.

Evaluation and Analysis of Nutrients in Tobacco-Planting Soil in Fuzhou City

[Objective] The aim was to explore the nutrient status of tobacco-planting soil, and find out the fertilization strategy for flue-cured tobacco. [Method] The nutrient contents in 142 soil samples from 7 tobacco planting counties in Fu Zhou city were determined and evaluated. [Result] The organic matter content was on the high side, and most soil was acid soil. The soil had abundant total nitrogen, total phosphorus and total potassium, moderate available nitrogen and available phosphorus, low available potassium, high water soluble chlorine, low soil cation exchange capacity and rich effective zinc, but effective boron was famine. [Conclusion] The meta-acid soil should be conducted with pH adjustment, and rational nitrogen, phosphorus and potassium application.

Threshold of Soil pH for Occurrence of Tobacco Bacterial Wilt in Henan Province

[Objective]The paper was to study the relationship between spatial distribution characteristics of soil p H and bacterial wilt in tobacco-growing area in Henan Province.[Method]The 21 tobacco-growing fields infected by bacterial wilt and 91 tobacco-growing fields with no cases were selected from Henan Province,and the pH of fields was determined.[Result]Bacterial wilt mainly occurred in the tobacco-growing fields in Luoshan,Pingqiao,Queshan,Biyang,Suiping,and Xiping,and the soil pH mainly ranged from 5.5 to 6.5(accounted for 84.75%of total surveyed tobacco fields);bacterial wilt had not been found in tobacco-growing fields in Tanghe,Zhengyang,Shangcai,Sheqi,Wuyang and Chenqu,and the soil pH mainly ranged from 6.5 to 7.0(accounted for 81.25%of total surveyed tobacco fields).There were significant differences in soil pH between the fields with and without bacterial wilt,and soil pH 6.5 could be regarded as the threshold for the occurrence of tobacco bacterial wilt in Henan Province.There was extremely significantly positive linear correlation between soil p H and latitude(y=0.7375 x-17.799,R2=0.386,P<0.01).The geographical boundary of soil pH 6.5 was roughly 33°N,and bacterial wilt was less likely to occur in the north tobacco-growing areas of the boundary.[Conclusion]The study will provide a scientific basis for the prevention and control of tobacco bacterial wilt in Henan.

Regression Analysis of Nutrient Elements between Soil and Tobacco Leaves and Their Influences on Aroma Quality of Flue-cured Tobacco

This study aimed to analyze the relationship between nutrient elements K, Ca, Mg, Cu, Mn, Zn and Fe in tobacco-planting soils and tobacco leaves from six main tobacco-producing areas, and to investigate the influences of these elements on chemical composition and aroma components in tobacco leaves. Results showed that there were certain relationship between contents of nutrient elements in tobacco-planting soils and contents of corresponding elements in tobacco leaves; various elements exhibited different influences on the aroma quality of flue-cured tobacco. Based on the actual situation of nutrient contents in soils from different tobaccoproducing areas, contents of various elements in tobacco leaves should be regulated by soil fertilization and foliar spraying, thereby improving the aroma quality of flue-cured tobacco.

Effects of N Application Rates and NO_3-N to NH_4-N Ratios on Yield and Quality of Flue-cured Tobacco Planted in Black Soil

A field experiment about effects of nitrogen application rates and different NO3-N to NH4-N ratios on agronomic, chemical and biological characteristics as well as yield and quality of flue-cured tobacco grown in a black soil was conducted from 2004 to 2005 in Heilongjiang Province. The results showed that the nitrogen application rates at 45 kg·hm^-2 with the ratio of 75% NO3-N to 25% NH4-N resulted in the highest potassium and reducing sugar contents in the flue-cured tobacco leaving with the highest quality grade and value. It is recommended that this ni- trogen application rate and NO3-N to NH4-N ratio should be widely applied on flue-cured tobacco grown in the black soil in Heilongjiang Province.