Soil Indexes Influencing Tobacco Growing in Central China

Zhang Yanling Chen Liyan Dai Huaxin Wang Jianwei Guo Weimin Wang AiguoZhengzhou Tobacco Research Institute of CNTCzhangyanling@ztri.com.cn

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Contents

• Backgrounds

• Materials and methods

• Results

• Summary

• Further interests

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Backgrounds• Extensive cultivation made soil degradation a common problem• A latest investigation exhibited several soil problems in tobacco

growing in China:

Reducing of biodiversity

Soil acidity esp. in southern areas

Nutrient imbalance e.g. N excess

Soil compactionShallower of the plough layer

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Backgrounds• Efforts in soil improvement has

been focused on chemical properties.

• Few attention has been put on physical and biological properties

• Practices about soil physics and biodiversity showed obvious effects on tobacco growing.

• However, lack of indexes makes it difficult to take exact practices to improve soil fertility and tobacco growing.

Deep ploughing

Green manure

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Backgrounds

• To find soil indexes relevant closely to tobacco growing and leaf quality

• To provide clear measurements for soil improvement

• To establish soil health assessment system for tobacco growing

The poppers of this study were: 2018

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Materials and Methods• Select traditional tobacco

growing area in Henan province, Central China.

• Similar climate conditions with North Carolina

• Tobacco leaf with good quality.

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Materials and Methods• 76 sites were selected and 76 topsoil samples were collected• 27 indexes were analyzed

Physical Biological ChemicalTextureClay contentBulk densityTotal porosityAvailable water capacityWater-stable aggregate(<3mm)Field capacitySurface and subsurface hardness with penetrometer

Organic carbonActive carbonSoil proteinsEnzymetic activity (urease, phosphatase, catalase, sucrase）Amount and diversity of fungi and bacteria

pHAvailable N, P, K, Fe, Mn, Zn, Cu, Soluble Cl

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Materials and Methods• Sampling sites were divided into three grades according to tobacco

yield, soil fertility, probability of high quality leaf, probability of soil-borne disease

Distribution of soil samples with different health grades

County high middle low

Biyang 3 19 3

Jia county 7 17 4

Xiangcheng 4 15 6

Total 14 51 13

• Relationships of soil grades and soil indexes were also studied.

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More than 1/3 samples showed lower water stable aggregate and higher soil hardness.

Results

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Results

Nearly half samples showed higher pH

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Results

Bulk density g.cm-3

Clay content %

Field capacity %

Total porosity %

Waterstan;e

aggregate %

Surface hardness kg.cm-2

Subsurface hardness kg.cm-2

High

Middle

Low

Significant differences

existed in field

capacity and water-

stable aggregate of

samples with different

grades.

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ResultsChemical properties of samples with different soil grades

Properties High Middle LowpH 6.81a 6.77a 7.40aAvailable N（mg·kg-1） 66.05aA 62.49aA 44.91bBAvailable P（mg·kg-1） 14.50a 13.91a 13.39aAvailable K（mg·kg-1） 119.43a 127.59a 121.42aSoluble Cl（mg·kg-1） 12.74a 13.97a 14.07aAvailable Fe（mg·kg-1） 21.37a 24.51a 13.69aAvailable Mn（mg·kg-1） 28.99a 28.03a 20.42aAvailable Zn（mg·kg-1） 0.93a 1.30a 1.09a

The content of available N increased with soil grades.

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Results

Active C, Protein content and Enzymetic activity of soils with different grades

Properties High Middle Low

Org C（g·kg-1） 17.09aA 15.15aA 10.91bB

Active C（mg·kg-1） 443.03aA 383.06bA 257.91cB

Soil Protein（mg·g-1） 2.64aA 2.37aA 1.61bBUrease（NH3，mg·g-1·d-1） 0.21a 0.23a 0.29aPhosphatase（phenol，mg·g-1·d-1） 0.99a 0.97a 0.61aCatalase（glucose，mg·g-1·d-1） 0.77a 0.76a 0.745a

sucrase（0.1 mol·L-1 KMnO4，ml·g-1·h-1） 8.02aA 6.44abAB 4.91bB

With the decrease of soil grades, the contents of org.C, active C and protein as well as the sucrase activity were all decreased gradually.

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ResultsFungi and Bacteria diversity of soil with different grades

Soil

grades

BacteriaQuantity（108 cfu·g-1） Chao index Shannon index

High 8.96a 2739a 6.17a

Middle 7.21a 2536a 6.13a

Low 7.22a 2921a 6.31a

Soil

grades

FungiQuantity（106 cfu·g-1） Chao index Shannon index

High 4.46a 496a 4.30aA

Middle 4.19a 478a 3.88bB

Low 3.98a 467a 4.00abAB

Shannon index of fungi in high grade soils was

significantly higher.

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Summary• The main problems in tobacco growing soils in central China

were higher pH, soil hardness and lower water stable aggregate.

• Indexes relevant closely to tobacco growing were soil org. C, available N, active C, protein, field capacity, total porosity,sucrase activity and water stable aggregate which increased with the increase of soil grades, as well as soil hardness which showed opposite tendency.

• Physical and biological properties should be put much attention on soil improvement in central China.

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Further interestsScoring functions(cumulative normal distribution)

More is better Less is better Optimum curve

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Further interestsSoil diagnose for tobacco growing 20

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Further interests

Establish soil health assessment systems suitable for different tobacco growing regions.

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Thanks for your attention！

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