Method for predicting dispersion rate of clay particles in soda saline-alkali soil

Abstract

In order to solve the problem that in the prior art, research on a soda saline-alkali soil clay dispersion rate prediction method is less, the invention particularly discloses a soda saline-alkali soil clay dispersion rate prediction method which comprises the following steps: S1, soil pretreatment; s2, measuring the Na < + > content by using an atomic absorption spectrophotometric method; determining the content of CO2-3 by using a double indicator-neutralization titration method; determining the cation exchange capacity of the soil by adopting a sodium acetate extraction-flame photometry method; determining the exchangeable Na content of the alkaline soil by using an ammonium acetate-ammonium hydroxide-flame spectrophotometric method; s3, calculating the alkalization degree, wherein the formula is as follows: ESP = Na + ex / CEC; and S4, calculating the dispersion rate of the clay particles in the soil, wherein the dispersion rate of the clay particles is equal to 0.143 + 0.015 * the alkalization degree-0.036 * CO3 < 2->-0.006 * Na +. The determination method disclosed by the invention is time-saving and labor-saving, and can be used for simply, quickly, scientifically and accurately obtaining the clay dispersion rate of the soda saline alkali soil.

Description

Technical Field

[0001] The invention relates to the field of soil technology, and in particular to a method for predicting the clay particle dispersion rate of soda saline-alkali land soil. Background Art

[0002] More than 1.1 billion hectares of soil are affected by salinity worldwide (Wicke et al., 2011), accounting for about 10.69% of the earth. Soil salinization can cause about 1.5 million hectares of farmland to stop production each year, and the agricultural productivity loss caused by salinization is 31 million US dollars each year. Clay dispersion is one of the manifestations of soil salinization. Clay dispersion refers to the behavior of clay particles separating from each other in the soil. Dispersion will cause the collapse of soil aggregates. Dispersed clay will block soil pores, causing the decline of soil structure and soil erosion. Soda saline soil has a high clay content and strong dispersibility. It usually has a high concentration of exchangeable Na+. Most of the negative charges on the clay surface are neutralized by Na+, forming a thick positive charge layer, which hinders the occurrence of clay flocculation behavior. The surface expands and becomes muddy when wet, and shrinks and hardens when dry. The soil structure is extremely poor, the permeability is extremely low, and the physical properties are relatively poor.

[0003] At present, there are many ways to characterize the dispersion characteristics of soil clay particles. Indicators such as ionic index, charge sparsity, net dispersion, cation ratio of soil structure stability and cation exchange capacity can be used to study the dispersion of soil clay particles. The characteristics of each indicator are detailed in Table 1-1. However, the determination methods of each indicator are relatively complicated, and it is impossible to quickly and accurately characterize or predict the dispersion status of clay particles in soda saline-alkali soil. Based on this, the present invention aims to quickly obtain the dispersion status of clay particles in soda saline-alkali soil by establishing a linear relationship between basic physical and chemical indicators of soil and clay dispersion rate, improve the efficiency of regional saline-alkali condition judgment, and help improve regional saline-alkali land. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a method for predicting the clay particle dispersion rate of soda saline-alkali land soil.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for predicting the clay particle dispersion rate of soda saline-alkali land soil comprises the following specific steps:

[0007] S1: Soil pretreatment: Before the determination, the soda saline-alkali soil sample for which the clay dispersion rate is to be predicted is air-dried, crushed, and sieved through a 2 mm sieve for later use;

[0008] S2: Soil index determination: According to the soil agrochemical method, the soil-water ratio is 1:5 to extract the extract, and the extract is subjected to CO2-3 and Na + analyze;

[0009] S21: Determination of Na by atomic absorption spectrophotometry + content;

[0010] S22: Determine the CO2-3 content by double indicator-neutralization titration;

[0011] S23: Sodium acetate extraction-flame photometry was used to determine soil cation exchange capacity (CEC);

[0012] S24: Determination of exchangeable Na content (Na+ex) in alkaline soils by ammonium acetate-ammonium hydroxide-flame photometry;

[0013] S3: Alkalinity calculation: Calculate the exchangeable sodium ion percentage (ESP) of the soil based on the exchangeable cation determination results, also known as alkalinity, with the following formula: ESP = Na+ex / CEC;

[0014] S4: Calculation of soil clay dispersion rate: The clay dispersion rate of soda saline-alkali soil can be predicted according to the following multiple regression prediction equation, namely: Clay dispersion rate (CDR) = 0.143 + 0.015 * alkalinity (ESP) - 0.036 * CO3 2- -0.006*Na + .

[0015] As a further technical solution of the present invention, in S3, the units of Na+ex and CEC in the formula are both mmol / kg, and the unit of ESP is %.

[0016] As a further technical solution of the present invention, in S4, the unit of ESP in the formula is %, CO3 2- and Na + The unit is mmol c / L, CDR value is between 0-1.

[0017] The beneficial effects of the present invention are:

[0018] 1. The calculation is simple, only the soil alkalinity (ESP), CO3 2 and Na + By substituting the content into the formula, the clay dispersion rate of the soil can be predicted. The steps are simple, easy to implement, and save time and cost.

[0019] 2. The accuracy is high. The fitting degree of the basic physical and chemical indicators of soda saline-alkali soil and clay dispersion rate (CDR) is 0.932, and reaches an extremely significant level (p<0.001). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flow chart of a method for predicting clay particle dispersion rate in soda saline-alkali land soil proposed by the present invention;

[0021] Figure 2 It is a line graph between a CDR measured graph and a CDR predicted value of a method for predicting clay particle dispersion rate in soda saline-alkali land proposed by the present invention. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0023] Please see attached Figure 1 A method for predicting the clay dispersion rate of soda saline-alkali land soil comprises the following specific steps:

[0024] S1: Soil pretreatment: Before the determination, the soda saline-alkali soil sample for which the clay dispersion rate is to be predicted is air-dried, crushed, and sieved through a 2 mm sieve for later use;

[0025] S2: Soil index determination: According to the soil agrochemical method, the soil-water ratio is 1:5 to extract the extract, and the extract is subjected to CO2-3 and Na + analyze;

[0026] S21: Determination of Na by atomic absorption spectrophotometry + content;

[0027] S22: Determine the CO2-3 content by double indicator-neutralization titration;

[0028] S23: Sodium acetate extraction-flame photometry was used to determine soil cation exchange capacity (CEC);

[0029] S24: Determination of exchangeable Na content (Na+ex) in alkaline soils by ammonium acetate-ammonium hydroxide-flame photometry;

[0030] S3: Alkalinity calculation: Calculate the soil exchangeable sodium ion percentage (Exchangeable Sodium Percentage, ESP), also known as alkalinity, based on the exchangeable cation determination results. The formula is as follows: ESP = Na+ex / CEC;

[0031] S4: Calculation of soil clay dispersion rate: The clay dispersion rate of soda saline-alkali soil can be predicted according to the following multiple regression prediction equation, namely: Clay dispersion rate (CDR) = 0.143 + 0.015 * alkalinity (ESP) - 0.036 * CO3 2--0.006*Na + .

[0032] In a preferred embodiment, in S3, the units of Na+ex and CEC in the formula are both mmol / kg, and the unit of ESP is %.

[0033] In a preferred embodiment, in S4, the unit of ESP in the formula is %, CO3 2- and Na + The unit is mmol c / L, CDR value is between 0-1.

[0034] With clay dispersion rate (CDR) as the dependent variable, the basic soil physical and chemical indicators pH, EC, CO3 2- 、HCO3 - , Cl - 、SO4 2- Mg 2+ , Ca 2+ , K + 、Na + SAR, CROSS, SOM, ESP, CEC, and Na+ex were used as independent variables to construct a multiple linear regression model using stepwise regression analysis. The regression model was statistically significant (p<0.001), and the explanation rate of soil physical and chemical indicators for clay dispersion was 0.932. Alkalinity (ESP), CO3 2- 、Na + It is an important predictor of clay dispersion rate. The following prediction model was obtained by multivariate linear regression analysis of 42 sample data: Clay dispersion rate (CDR) = 0.143 + 0.015 * alkalinity (ESP) - 0.036 * CO3 2- -0.006*Na + .

[0035] Table 1 Multiple linear regression equation (n = 42)

[0036] Table 1Multiple linear regression equation(n=42)

[0037] Dependent Variable equation <![CDATA[R 2 ]]> F p CDR <![CDATA[CDR=0.143+0.015*ESP-0.036*CO3 2 -0.006*Na + ]]> 0.932 189.55 <0.001

[0038] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the calculation is simple, and only needs to measure the soil alkalinity (ESP), CO3 2 and Na +The clay dispersion rate of the soil can be predicted by substituting the content into the formula. The steps are simple, easy to implement, and save time and cost; the accuracy is high, and the fitting degree of the basic physical and chemical indicators of soda saline-alkali soil and the clay dispersion rate (CDR) is 0.932, and it reaches an extremely significant level (p<0.001).

[0039] Table 1-1 Characterization methods of soil clay dispersion characteristics

[0040] Table 1-1Characterization methods of soil clay dispersion

[0041] characteristics

[0042]

[0043]

[0044] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0045] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for predicting the clay particle dispersion rate of soda saline-alkali land soil, characterized in that: The specific steps include: S1: Soil pretreatment: Before the determination, the soda saline-alkali soil sample for which the clay dispersion rate is to be predicted is air-dried, crushed, and sieved through a 2 mm sieve for later use; S2: Soil index determination: According to the soil agrochemical method, the soil-water ratio is 1:5 to extract the extract, and the extract is subjected to CO2-3 and Na + analyze; S21: Determination of Na by atomic absorption spectrophotometry + content; S22: Determine the CO2-3 content by double indicator-neutralization titration; S23: Sodium acetate extraction-flame photometry was used to determine soil cation exchange capacity (CEC); S24: Determination of exchangeable Na content (Na+ex) in alkaline soils by ammonium acetate-ammonium hydroxide-flame photometry; S3: Alkalinity calculation: Calculate the exchangeable sodium ion percentage (ESP) of the soil based on the exchangeable cation determination results, also known as alkalinity, with the following formula: ESP = Na+ex / CEC; S4: Calculation of soil clay dispersion rate: The clay dispersion rate of soda saline-alkali soil can be predicted according to the following multiple regression prediction equation, namely: Clay dispersion rate (CDR) = 0.143 + 0.015 * alkalinity (ESP) - 0.036 * CO3 2- -0.006*Na + .

2. The method for predicting the clay dispersion rate of soda saline-alkali soil according to claim 1, characterized in that: In the formula of S3, the units of Na+ex and CEC are both mmol / kg, and the unit of ESP is %.

3. The method for predicting the clay dispersion rate of soda saline-alkali soil according to claim 1, characterized in that: In the S4, the unit of ESP in the formula is %, CO3 2- and Na + The unit is mmol c / L, CDR value is between 0-1.

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