Method for improving saline-alkali soil by using alkali-reducing fertility-improving stress-resistant saline-alkali soil improver and application of saline-alkali soil improver

Abstract

The invention relates to the field of soil improvement, in particular to a method for improving saline-alkali soil through an alkali-reducing fertility-improving stress-resistant saline-alkali soil improver and application. According to the method, a three-factor four-level orthogonal soil improvement experiment is designed through desulfurization gypsum, wormcast and straw compost, the soil improvement effect is further verified in a crop cultivation mode, the optimal improvement proportion of the composition is calculated and determined through an entropy weight-topsis model, and through the mode of combined application of three substances, the soil improvement effect is improved by improving the most basic soil environment. Therefore, the stress damage of the saline-alkali soil to the plants is effectively reduced, and the purpose of improving the saline-alkali soil is achieved.

Description

Technical Field

[0001] This invention relates to the field of soil improvement, specifically to a method and application of a saline-alkali soil conditioner that reduces alkali content, improves fertility, and enhances stress resistance. Background Technology

[0002] Soil salinization is a serious ecological and environmental problem, not only damaging agricultural productivity and ecosystem diversity and reducing soil fertility, but also adversely affecting plant productivity, growth, and development. With increasing human activities, soil salinization is intensifying. Salt-alkali stress is divided into two types: salinization and alkaliization. Salt stress generally refers to stress caused by the accumulation of neutral salts (NaCl and Na₂SO₄), while alkali stress refers to stress caused by excessive alkaline salts (NaHCO₃ and Na₂CO₃). The coexistence of salt and alkali stress is more severe than either salt stress or alkali stress alone. Salt stress can cause ion toxicity, osmotic stress, oxidative stress, nutrient imbalance, metabolic disorders, and reduce soil fertility and soil water potential. In most cases, the damage caused by alkali stress is more severe than that caused by neutral salt stress. This is because CO₃²⁻... 2- and HCO3 - Hydrolysis increases soil pH. Therefore, salt stress alters the physicochemical properties and structure of the soil, reduces soil aeration and hydraulic conductivity, leads to soluble mineral deficiency, impairs plant root growth and survival, and adversely affects seed germination and photosynthesis. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention aims to provide a method and application of a saline-alkali soil amendment that reduces alkali and improves soil fertility to improve soil stress resistance, thereby solving the problems of soil physicochemical properties and structure altered by saline-alkali stress.

[0004] To solve the above problems, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a method for improving saline-alkali soil with a saline-alkali soil conditioner that reduces alkali and improves soil quality and is resistant to stress, wherein the saline-alkali soil conditioner is applied to the saline-alkali soil; the saline-alkali soil conditioner includes desulfurized gypsum, earthworm castings and straw compost.

[0006] Furthermore, the amount of earthworm castings applied is 5%-20% of the mass of the saline-alkali soil.

[0007] Furthermore, the amount of earthworm castings applied is 20% of the mass of the saline-alkali soil.

[0008] Furthermore, the amount of straw compost applied is 5% of the mass of the saline-alkali soil.

[0009] Furthermore, the application rate of the desulfurized gypsum is 7.5-18.75 t / hm. 2 .

[0010] Furthermore, the application rate of the desulfurized gypsum is 18.75 t / hm. 2 .

[0011] Secondly, the present invention provides the application of the saline-alkali soil conditioner in the preparation of saline-alkali soil conditioner formulations.

[0012] Furthermore, the saline-alkali soil conditioner reduces the pH value, alkalinity, and sodium adsorption ratio of saline-alkali soil.

[0013] Furthermore, the saline-alkali soil conditioner increases the soluble salt content, ammonium nitrogen content, available potassium content, available phosphorus content, nitrate nitrogen content, and available sulfur content of saline-alkali soil.

[0014] Thirdly, the present invention provides an orthogonal design preparation method for a saline-alkali soil conditioner consisting of desulfurized gypsum-earthworm castings-straw compost, comprising the following steps:

[0015] (1) Gradient design: Establish a three-factor, four-level orthogonal experimental system:

[0016] Desulfurization gypsum: 7.5 t / hm 2 11.25 t / hm 2 15t / hm 2 18.75 t / hm 2 Four gradients are applied evenly and mixed into the soil to be improved;

[0017] Earthworm castings were used at four different concentrations: 5%, 10%, 15%, and 20% of the soil quality to be improved.

[0018] Straw composting is set at four gradients: 5%, 10%, 15%, and 20% of the soil quality to be improved.

[0019] (2) By measuring the soil physicochemical indicators such as pH, ESP, SAR, AN, AK, AP, NO3-N, and ES of the soil to be improved, the emergence rate, plant height, plant water content, soluble sugar, single leaf area, Pro, and MDA of silage corn seedlings planted in the soil to be improved were measured. The entropy weight-TOPSIS method was used to comprehensively score all treatment groups.

[0020] (3) The desulfurized gypsum-earthworm castings-straw compost ratio with the highest comprehensive score was selected as the improvement scheme.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention designs a three-factor, four-level orthogonal soil improvement experiment using materials such as desulfurized gypsum, earthworm castings, and straw compost, and further verifies the soil improvement effect through crop cultivation methods. Using the entropy weight-TOPSIS model, the optimal combination A4B4C1 (material ratio of desulfurized gypsum 18.75 t / hm) was determined. 2 The optimal improvement ratio is 20% earthworm castings and 5% straw compost, which ensures that the physical and chemical properties of saline-alkali soil are improved, and the silage corn planted on this basis has achieved good growth and development.

[0023] This invention, based on the improvement of soil physicochemical properties such as pH, alkalinity, and sodium adsorption ratio by desulfurized gypsum, effectively increases the nutrients required by plants in the soil by adding organic matter such as earthworm castings and straw compost, thus laying the foundation for a favorable growth environment for plants. The combined application of these three substances, by improving the most basic soil environment, effectively reduces the stress damage to plants caused by saline-alkali soil, comprehensively and systematically achieving the goal of saline-alkali soil improvement. Attached Figure Description

[0024] Figure 1 This image shows the effect of pH improvement on saline-alkali soil.

[0025] Figure 2 This image shows the effect of improving the alkalinity of saline-alkali soil.

[0026] Figure 3 This diagram illustrates the effect of improving the sodium adsorption ratio in saline-alkali soil.

[0027] Figure 4 This is a diagram illustrating the changes in soluble salts in saline-alkali soil.

[0028] Figure 5 This image shows the effect of improving the ammonium nitrogen content in saline-alkali soil.

[0029] Figure 6 This image shows the effect of improving the available potassium content in saline-alkali soil.

[0030] Figure 7 This image shows the effect of improving the available phosphorus content in saline-alkali soil.

[0031] Figure 8 This image shows the effect of improving nitrate nitrogen content in saline-alkali soil.

[0032] Figure 9 This image shows the effect of improving the effective sulfur content of saline-alkali soil.

[0033] Figure 10 This is a graph showing the germination rate of silage corn.

[0034] Figure 11 This is a diagram showing the plant height of silage corn seedlings.

[0035] Figure 12This is a diagram showing the root growth of silage corn seedlings.

[0036] Figure 13 This is a graph showing the leaf area of ​​a single leaf in a silage corn seedling.

[0037] Figure 14 This is a graph showing the results of moisture content in silage corn seedlings.

[0038] Figure 15 The graph shows the results of proline content in the leaves of silage corn seedlings.

[0039] Figure 16 The graph shows the results of malondialdehyde content in the leaves of silage corn seedlings.

[0040] Figure 17 This image shows the results of superoxide dismutase activity in the leaves of silage corn seedlings.

[0041] Figure 18 The graph shows the results of soluble sugar content in the leaves of silage corn seedlings.

[0042] Figure 19 This is a graph showing the results of intercellular CO2 concentration in the leaves of silage corn seedlings.

[0043] Figure 20 This is a diagram showing the stomatal conductance results of leaves in silage corn seedlings.

[0044] Figure 21 The graph shows the net photosynthetic rate of leaves in silage corn seedlings.

[0045] Figure 22 The graph shows the net photosynthetic rate of leaves in silage corn seedlings. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments.

[0047] It should be noted that these embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Simple improvements to the method under the premise of the present invention are all within the scope of protection claimed by the present invention.

[0048] Example 1

[0049] A soil cultivation experiment was conducted in a greenhouse. The experiment employed single-factor soil improvement methods using different gradients of desulfurized gypsum, earthworm castings, and straw compost. Each treatment was replicated three times, and the experimental period was 30 days. Desulfurized gypsum (A) was added at concentrations of 0, 3.75, 7.5, 11.25, 15, 18.75, 22.5, 26.25, and 30 (t / hm²). 2The application rates of earthworm castings (B) and straw compost (C) were 0%, 5%, 10%, 15%, and 20% respectively, added to 1 kg of saline-alkali soil (see Tables 1 and 2). Each treatment was replicated three times. The saline-alkali soil collected from the field was dried and sieved through a 2 mm sieve before use. The flowerpots used in the experiment were 16×10×14 cm in size, and the actual application rate of desulfurized gypsum was calculated based on the surface area of ​​the flowerpots. 1 kg of soil was added to each pot and mixed thoroughly with the materials. The experimental pots were equipped with drainage holes at the bottom and had trays attached to prevent soil erosion. Regular watering was performed to maintain the soil's physicochemical properties. After 30 days, the effects of different treatments on the soil's physical and chemical properties were measured. Based on the soil culture, silage corn seeds were planted to observe the germination rate. One month after planting, the growth physiological indicators of the corn seedlings were measured.

[0050] Table 1. Experimental Design of Single-Factor Improvement of Desulfurized Gypsum

[0051]

[0052] Table 2 Experimental Design of Single-Factor Improvement of Earthworm Castings and Straw Compost

[0053]

[0054] Effects of applying different materials alone on the physicochemical properties of saline-alkali soil

[0055] Soil pH

[0056] Soil pH is one of the important basic properties for assessing changes in saline-alkali soil characteristics. The original soil pH was 8.96, indicating alkaline soil. The application of desulfurized gypsum significantly reduced soil pH (p<0.01), with the pH reduction rate increasing from 5.50% to 9.70% in treatments A1-A5, and the pH decreasing from 8.96 to 8.09. There was no significant difference in pH between treatments A5-A8 (p>0.05). Earthworm castings significantly reduced soil pH (p<0.05), with the lowest pH value (8.58) observed in treatment B4. Application of straw compost alone also significantly reduced soil pH (p<0.01), with the soil pH dropping to 8.41 in treatment C4.

[0057] Soil alkalinity

[0058] Soil alkalinity (ESP) refers to the ratio of exchangeable sodium ions to cation exchangeable ions in soil colloids, and is an important indicator for evaluating the degree of soil salinization. The original soil alkalinity before improvement was 44.84%. Desulfurized gypsum significantly reduced the alkalinity of saline-alkali soil. Compared with the control (CK), the alkalinity of the A8 treatment group decreased to 20.91%, indicating that the addition of desulfurized gypsum significantly improved soil alkalinity (p<0.01). Application of earthworm castings alone significantly reduced soil alkalinity (p<0.05), with the B4 treatment showing a decrease to 21.71%. Straw compost also significantly reduced alkalinity (p<0.01), with the C3 group showing the largest decrease at 20.63%.

[0059] Soil sodium adsorption ratio

[0060] Sodium adsorption ratio (SAR) is used to quantify the sodium content in soil saturated extracts. + Concentration and Ca 2+ Mg 2+ The ratio of the square roots of the average concentrations of sodium, calcium, and magnesium ions in the soil is not only a reflection of the relative content of sodium, calcium, and magnesium ions in the soil, but also an important indicator for assessing the degree of soil salinization. The original soil SAR was 13.08 mmol / L, and different improvement measures had a significant impact on the soil SAR (p<0.05). Application of desulfurized gypsum alone significantly reduced the soil SAR (p<0.05), but there was no significant difference within the groups. Treatment A7 had the lowest SAR at 4.55 mmol / L, while treatment A2 had the highest at 5.79 mmol / L. The effect of earthworm castings on the soil sodium adsorption ratio decreased with increasing amount (p<0.05), and treatments B1, B2, and B3 all had higher sodium adsorption ratios than the control group. Among them, treatment B4 had the lowest SAR at 12.71 mmol / L, while treatment B1 had the highest sodium adsorption ratio at 18.30 mmol / L. Straw compost significantly affected the sodium adsorption ratio of this saline-alkali soil (p<0.05). The sodium adsorption ratio of group C was higher than that of the control group. With the addition of straw compost, the sodium adsorption ratio showed a decreasing trend. Among them, the lowest sodium adsorption ratio was 14.01 mmol / L in treatment C3 and the highest was 16.86 mmol / L in treatment C1.

[0061] Soil soluble salt content

[0062] Soluble salts in saline-alkali soils are mainly composed of Na+. + K + Ca 2+ Mg 2+ Four cations and HCO 3- CO3 2- SO4 2- Cl -It is composed of four anions. When the sodium ion content in soil colloids accumulates to a certain proportion, the soil becomes alkaline, and its physical properties are damaged. Adding desulfurized gypsum to saline-alkali soil allows the gypsum to neutralize the calcium... 2+ With Na in soil colloids + The addition of desulfurized gypsum significantly increased the soluble salt content of the soil (p<0.01), with A8 having the highest at 7.99 g / kg and A1 the lowest at 5.30 g / kg. Application of vermicompost and straw compost alone significantly reduced the water-soluble salt content of the soil (p<0.05). Within the vermicompost group, the water-soluble salt content showed a gradual upward trend but no significant difference (p>0.05), with B1 having the lowest content at 2.09 g / kg and B4 the highest at 2.33 g / kg. Within the straw compost group, the salt content showed a gradual downward trend, also without significant difference, with C1 having the highest content at 2.30 g / kg and C4 the lowest at 2.14 g / kg.

[0063] Soil ammonium nitrogen content

[0064] The original soil ammonium nitrogen content was low at 2.05 mg / kg. The ammonium nitrogen content in the soil showed a gradually increasing trend in the desulfurized gypsum treatments A1-A6, with a significant difference in AN content when desulfurized gypsum was applied alone (p<0.01). Treatment A1 had the lowest AN content at 0.98 mg / kg, while treatment A6 had the highest at 2.88 mg / kg. The soil ammonium nitrogen content gradually decreased when earthworm castings were applied alone. Treatment B1 had no significant difference in AN content (p>0.05), while treatments B2-B4 significantly affected ammonium nitrogen content (p<0.05), with B1 having the highest content at 1.54 mg / kg and B4 the lowest at 1.14 mg / kg. Straw compost significantly increased the ammonium nitrogen content in saline-alkali soil (p<0.05). There was no significant difference in ammonium nitrogen content among treatments C2, C3, and C4 (p>0.05), with C1 having the lowest content at 3.12 mg / kg and C4 the highest at 5.14 mg / kg.

[0065] Soil available potassium content

[0066] The original soil available potassium content was 67.02 mg / kg. There was no significant difference in available potassium content between the desulfurized gypsum treatment alone and the control group (p>0.05). Earthworm castings and straw compost alone showed a significant positive correlation with available potassium in saline-alkali soils (p<0.05), with both having higher available potassium contents than the control group. Under earthworm castings alone, treatment B1 had the lowest AK content (129.52 mg / kg), while treatment B4 had the highest (311.94 mg / kg). Under straw compost alone, treatment C1 had the lowest content (192.16 mg / kg), while treatment C4 had the highest (414.74 mg / kg).

[0067] Soil available phosphorus content

[0068] The original soil available phosphorus content was 41.50 mg / kg. Desulfurized gypsum had a highly significant negative correlation with soil available phosphorus content (p<0.01). All treatments with desulfurized gypsum alone had higher available phosphorus content than the control group, with A1 having the highest content at 170.99 mg / kg and A8 the lowest at 102.37 mg / kg. Earthworm castings alone significantly affected soil AP content (p<0.01), with all treatments having higher AP content than the control group, but no significant differences between groups (p>0.05). B1 had the highest content at 182.98 mg / kg and B4 the lowest at 175.60 mg / kg. Straw compost alone significantly affected available phosphorus content (p<0.01), with all treatments having higher AP content than the control group, and available phosphorus content showing a decreasing trend with increasing application rate. There were no significant differences among treatments C1, C2, and C3 (p>0.05), with available phosphorus content ranging from 178 to 168 mg / kg. Treatment C4 was significantly different from the other three groups (p<0.05), with an AP content of 143.13 mg / kg.

[0069] Soil nitrate nitrogen content

[0070] The original soil nitrate nitrogen content was 43.08 mg / kg. The effect of applying desulfurized gypsum alone on soil nitrate nitrogen was significantly negatively correlated (p<0.05). The nitrate nitrogen content in all treatment groups with desulfurized gypsum alone was lower than that in the control group, with A1 having the highest content at 37.71 mg / kg and A7 having the lowest at 4.22 mg / kg. The effects of applying earthworm castings and straw compost alone on soil nitrate nitrogen were significantly positively correlated (p<0.05). Earthworm castings alone significantly improved soil nitrate nitrogen content compared to straw compost (p<0.05), with both exceeding the control group's nitrate nitrogen content. In treatment group B, B4 had the highest nitrate nitrogen content at 179.95 mg / kg, and B1 had the lowest at 71.11 mg / kg. In the straw compost treatment group, C4 had the highest content at 145 mg / kg, and C1 had the lowest at 45 mg / kg.

[0071] available sulfur content in soil

[0072] The original soil available sulfur content was 423.64 mg / kg. The effect of desulfurized gypsum on soil available sulfur showed a significant positive correlation (p<0.01). The Es content in all treatment groups with desulfurized gypsum application was higher than that in the control group, and the available sulfur content tended to stabilize from A3 to A8. Treatment A1 had the lowest content at 758.20 mg / kg, and treatment A4 had the highest content at 1268.24 mg / kg. The application of vermicompost and straw compost alone had a significant positive correlation with soil available sulfur content (p<0.05), and the available sulfur content in both groups was higher than that in the control group (CK). The effect of desulfurized gypsum application alone on soil available sulfur content was greater than that of straw compost application alone. In treatment group B, the B1 content was the lowest at 713.76 mg / kg, and the B4 content was the highest at 869.24 mg / kg. In treatment group C, the C1 content was the lowest at 624.27 mg / kg, and the C4 content was the highest at 833.52 mg / kg.

[0073] Corn seedling emergence rate

[0074] The emergence rate of native soil silage corn was 17.78%. Compared with the control group, desulfurized gypsum significantly improved the emergence rate of silage corn (p<0.05). The emergence rates of all desulfurized gypsum treatment groups were higher than those of the control group, with the highest being A2 treatment at 44.44% and the lowest being A1 treatment at 26.67%. Applying earthworm castings alone significantly improved the emergence rate of silage corn compared with the control group (p<0.05), with the highest being B2 treatment at 77.78% and the lowest being B1 treatment at 48.89%. Applying straw compost alone significantly improved the emergence rate of saline-alkali soil silage corn (p<0.01), with no significant difference among the treatment groups (p>0.05). The highest emergence rate was C2 treatment at 77.78% and the lowest was C3 treatment at 64.44%.

[0075] Corn seedling height

[0076] The seedling height of native soil silage corn was 19.67 cm. Application of desulfurized gypsum alone did not significantly affect the seedling height (p>0.05), with treatment A5 showing the highest seedling height at 30.67 cm and treatment A1 showing the lowest at 13 cm. Earthworm castings significantly increased the seedling height of saline-alkali soil silage corn (p<0.05), with treatment B3 showing the highest at 37.50 cm and treatment B1 showing the lowest at 27 cm. Straw compost significantly increased the seedling height of saline-alkali soil silage corn (p<0.05), with no significant difference between treatment groups (p>0.05). Treatment groups C were all higher than the control group, with treatment C3 showing the highest at 35.33 cm and treatment C1 showing the lowest at 30 cm.

[0077] Corn seedlings have long roots

[0078] The root length of native soil silage corn seedlings was 10.33 cm. Desulfurized gypsum treatment had no significant effect on root length (p>0.05), with root lengths ranging from 12 to 14 cm across different desulfurized gypsum treatment groups. Vermicompost significantly improved root length in saline-alkali soil silage corn seedlings (p<0.05), with no significant differences among treatment groups. Treatment B3 had the longest root length at 21.33 cm, while B1 had the shortest at 14.33 cm. Straw compost significantly improved root length in saline-alkali soil silage corn seedlings (p<0.05), with C4 having the longest at 21 cm, while C1 and C3 had the shortest at 19.67 cm.

[0079] single leaf area of ​​corn seedlings

[0080] The leaf area of ​​a single leaf of a native silage corn seedling is 22.92 cm². 2 Compared with the control group, there was no significant difference in leaf area of ​​single leaves in saline-alkali soil silage maize treated with desulfurized gypsum alone (p>0.05). The leaf area of ​​each treatment group with different gradients of desulfurized gypsum ranged from 23.67 to 26.33 cm². 2 Between. The earthworm castings B3 and B4 treatments significantly increased the leaf area of ​​maize silage seedlings in saline-alkali soil (p<0.05), with single leaf areas of 28.25 cm² and 27.74 cm², respectively. 2 There was no significant difference in leaf area of ​​single leaves of corn silage seedlings in saline-alkali soil due to straw composting (p>0.05). The leaf area of ​​each treatment group ranged from 26.32 to 28.51 cm2, which was higher than that of the control group.

[0081] Water content of corn seedlings

[0082] The moisture content of native soil silage corn seedlings was 11.03%. Desulfurized gypsum showed no significant difference in improving the moisture content of silage corn in saline-alkali soil (p>0.05), and the moisture content of each treatment group was not significantly different between 9.67% and 12.60% (p>0.05). Earthworm castings (groups B3 and B4) significantly increased the moisture content of silage corn seedlings (p<0.05), with moisture contents of 18.25% and 17.74%, respectively. Treatments B all had higher moisture contents than the control group. Straw compost showed no significant difference in the moisture content of silage corn seedlings (p>0.05), with treatment C4 having the highest moisture content at 15.17%.

[0083] Effects of applying different materials alone on physiological indicators of maize seedlings

[0084] Proline content in corn leaves

[0085] The proline content in the leaves of native silage maize seedlings was 133.72 Ug / g. Desulfurized gypsum significantly affected the proline content in the seedling leaves (p<0.01). Compared to the control group, the proline content initially increased and then decreased under different gradients of desulfurized gypsum treatments, with the highest proline content (539.85 Ug / g) in treatment A1 and the lowest (45.24 Ug / g) in treatment A7. Earthworm castings significantly reduced the proline content in the leaves (p<0.01), with the lowest proline content (33.68 Ug / g) in treatment B3. Straw compost significantly affected the proline content in the leaves of saline-alkali soil silage maize seedlings (p<0.05), and the proline content was significantly positively correlated with straw compost content. Treatments C1 and C2 had lower proline content than the control group (71.33 Ug / g and 74.94 Ug / g, respectively), while treatments C3 and C4 had higher proline content (160 Ug / g and 524.89 Ug / g, respectively).

[0086] Malondialdehyde content in corn leaves

[0087] The malondialdehyde (MDA) content in the leaves of native silage corn seedlings was 91.81 nmol / g. Compared with the control group, desulfurized gypsum showed a highly significant positive correlation (p<0.01), with all treatment groups showing higher MDA levels than the control group. The influence of A1 was the lowest at 128.22 nmol / g, and A8 had the highest at 204.05 nmol / g. Compared with the control group, earthworm castings showed a significant positive correlation (p<0.05), with all treatment groups showing higher MDA levels than the control group. The lowest MDA content was BI at 124.37 nmol / g, and the highest was B3 at 158.08 nmol / g. Straw compost showed no obvious trend in its effect on leaf MDA, but C1, C2, and C4 significantly affected MDA content compared with the control group (p<0.01).

[0088] Superoxide dismutase activity in maize leaves

[0089] The superoxide dismutase (SOD) activity in the leaves of native silage maize seedlings was 173.76 U / g. Desulfurized gypsum significantly affected SOD activity in the leaves of silage maize seedlings (p<0.05). SOD activity in all treatment groups A was higher than in the control group, with group A4 showing the highest SOD activity at 502.93 U / g and group A8 showing the lowest at 204.34 U / g. Earthworm castings showed a significant positive correlation with leaf SOD activity (p<0.01). SOD activity in groups B1 and B2 was lower than in the control group, while groups B3 and B4 showed higher activities, at 362.46 U / g and 432.08 U / g, respectively. Straw compost reduced leaf SOD activity, with treatments C2 and C4 showing extremely significant effects (p<0.01).

[0090] Soluble sugar content of corn leaves

[0091] The soluble sugar content in the leaves of native silage corn seedlings was 27.12 mg / g. Desulfurized gypsum and vermicompost showed a significant negative correlation with the soluble sugar content in the leaves of silage corn seedlings (p<0.01). In treatment groups A, the soluble sugar content in A1 and A2 was high, at 33.43 mg / g and 32.46 mg / g respectively, while the values ​​in the other treatment groups were lower than the control group. The soluble sugar content in all vermicompost treatment groups was lower than the control group, ranging from 8.89 to 2.85 mg / g. Straw compost showed a significant positive correlation with soluble sugar content (p<0.05), and the soluble sugar content in all groups of group C was lower than the control group, ranging from 10 to 21.95 mg / g.

[0092] Example 2

[0093] This invention designs a three-factor, four-level orthogonal soil improvement experiment by combining desulfurized gypsum, earthworm castings, and straw compost. Based on the soil improvement experiment, silage corn is planted, and the physicochemical properties of the improved soil and the physiological indicators of corn growth are measured. The optimal improvement ratio of the combined application of desulfurized gypsum, earthworm castings, and straw compost is then evaluated using an entropy weight-TOPSIS model. The specific operational steps are as follows:

[0094] 1. Preparation of materials for improvement: Desulfurized gypsum and earthworm castings can be purchased independently, and straw compost is made from fermented corn stalks.

[0095] 2. Test soil: The test soil used in this invention was collected from the area around Dadai Village, Shandai Town, Tumote Left Banner, Hohhot City, Inner Mongolia. Five locations were randomly selected and soil samples of 0-30cm were collected using the plum blossom five-point sampling method. The samples were mixed evenly, dried, and then passed through a 2mm sieve.

[0096] 3. Soil Cultivation: Desulfurized gypsum, earthworm castings, and straw compost are mixed evenly with saline-alkali soil for soil cultivation over a period of 30 days. The soil is then used in a substrate measuring 16×10×14cm with a surface area of ​​177cm². 2 Add 1 kg of the tested saline-alkali soil to the flowerpot. The application rate of desulfurized gypsum (A) is calculated based on the unit area usage as 7.5 t / hm². 2 11.25 t / hm 2 15t / hm 2 15t / hm 2 Earthworm castings (B) and straw compost (C) were added according to the percentages of soil mass, at ratios of 0%, 5%, 10%, 15%, and 20%, respectively. A three-factor, four-level orthogonal co-cultivation scheme was designed. Watering was carried out every five days, with the soil moisture content maintained at 50%. The three-factor, four-level orthogonal co-cultivation scheme is shown in Table 3.

[0097] Table 3. Three-Factor, Four-Level Orthogonal Joint Cultivation Scheme

[0098]

[0099]

[0100] 4. Crop Cultivation

[0101] Based on a 30-day soil improvement cycle, each treatment group was planted with 15 silage corn seeds. The seedling growth cycle was 30 days. The seedlings were irrigated every 4 days, and the soil moisture content was maintained at 50%.

[0102] 5. Overall Evaluation

[0103] The physicochemical properties of soil samples after a 30-day improvement period and the growth physiological indicators of silage maize seedlings planted on the improved soil were measured. The optimal improvement scheme was calculated using an entropy-weighted TOPSI model. Finally, the A4B4C1 combination (material ratio of desulfurized gypsum 18.75 t / hm²) was calculated. 2 The optimal improved formula is 20% earthworm castings and 5% straw compost.

[0104] Soil pH

[0105] See Figure 1 The results showed that the soil pH in the control group was 8.96. The combined application of ABC treatments significantly reduced the pH of saline-alkali soil (p<0.01), and the soil pH gradually decreased with increasing desulfurization gypsum addition. At the same desulfurization gypsum addition level, the pH change decreased with increasing vermicompost addition. Straw compost showed no significant effect on soil pH. Among the ABC groups, treatment A4B4C1 had the lowest pH at 7.57, while treatment A1B1C1 had the highest pH at 8.71.

[0106] Soil alkalinity

[0107] See Figure 2 The results showed that the soil alkalinity (ESP) in the control group was 44.84%. Under the combined application of ABC treatments, the soil alkalinity decreased significantly (p<0.001). All ABC treatments had lower ESP values ​​than the control group, with A4B3C2 showing the lowest ESP value at 11.84%. Desulfurized gypsum had a highly significant effect on ESP, with the ESP value decreasing with its addition. Earthworm castings and straw compost showed significant improvement in soil alkalinity, but no obvious trend was observed.

[0108] Soil sodium adsorption ratio

[0109] See Figure 3The results showed that the soil sodium adsorption ratio (SAR) in the control group was 13.08 mmol / L. The combined application of ABC treatments had a significant effect on soil SAR (p<0.05), with each of the ABC treatments having a lower SAR than the control group. Among them, the A4B4C1 treatment had the lowest SAR at 4.07 mmol / L, while the A2B3C4 treatment had the highest SAR at 9.66 mmol / L. The combined application of desulfurized gypsum, earthworm castings, and straw compost significantly improved the soil sodium adsorption ratio, without a clear trend.

[0110] Soil soluble salt content

[0111] See Figure 4 The results showed that the soluble salt content in the control group soil was 3.85 g / kg, and the combined application of ABC treatments significantly increased the soluble salt content (p<0.01). The salt content in all ABC treatments was higher than that in the control group, with the lowest soluble salt content (9.48 g / kg) in treatment A2B3C4 and the highest (13.17 g / kg) in treatment A1B1C1. The combined application of desulfurized gypsum, vermicompost, and straw compost significantly improved soil salinity, without a clear trend.

[0112] ammonium nitrogen content

[0113] See Figure 5 The results showed that the soil ammonium nitrogen (AN) content in the control group was relatively low at 2.05 mg / kg, while the combined application of ABC significantly increased the soil ammonium nitrogen content (p<0.05). In the combined application of ABC, desulfurized gypsum showed a significant positive correlation with soil ammonium nitrogen content (p<0.05), while earthworm castings and straw compost had no significant effect on ammonium nitrogen content (p>0.05). Among the ABC treatments, A2B2C1 had the lowest content at 25 mg / kg, while A3B2C4 had the highest content at 6.73 mg / kg.

[0114] Quick-acting potassium

[0115] See Figure 6 The results showed that the available potassium (AK) content in the control group was 67.02 mg / kg, and the combined application of ABC significantly increased the available potassium content (p<0.01). The combined application of the three factors A, B, and C showed no significant trend in their effects on available potassium. Under the combined application of ABC, the available potassium content in all treatment groups was higher than that in the control group, with A2B1C2 having the lowest effect (260.94 mg / kg) and A4B2C3 having the highest effect (520.70 mg / kg).

[0116] Quick-acting phosphorus

[0117] See Figure 7The results showed that the available phosphorus (AP) content in the soil of the control group was 41.50 mg / kg, and the combined application of ABC significantly increased the available phosphorus content (p<0.01). Among the ABC combined applications, vermicompost showed a significant positive correlation with the available phosphorus content (p<0.05), while the effects of desulfurized gypsum and straw compost showed no obvious trend. The available phosphorus content in all levels of the ABC combined application treatment was higher than that in the control group, with A4B4C1 having the highest content at 430.44 mg / kg and A2B1C2 having the lowest content at 107.43 mg / kg.

[0118] Nitrate nitrogen

[0119] See Figure 8 The results showed that the soil nitrate nitrogen (NO3-N) content in the control group was 43.08 mg / kg, and the combined application of ABC significantly increased the soil nitrate nitrogen content (p<0.05). Among the three-factor combined application, earthworm castings showed a significant positive correlation with soil nitrate nitrogen content (p<0.05), while the effects of desulfurized gypsum and straw compost showed no obvious trend. The nitrate nitrogen content in all ABC treatments was higher than that in the control group, with A2B4C3 having the highest content at 513.01 mg / kg and A4B1C4 having the lowest content at 88.93 mg / kg.

[0120] Available sulfur

[0121] See Figure 9 The results showed that the available sulfur (Es) content in the soil of the control group was 423.64 mg / kg, and the combined application of ABC significantly increased the available sulfur content in the soil (p<0.05). The effects of desulfurized gypsum, vermicompost, and straw compost on the combined application of the three factors showed no significant trend. The available sulfur content in each of the ABC treatments was higher than that in the control group, but the differences between treatment groups were not significant. The highest content was found in A1B3C3 (1262.58 mg / kg), and the lowest was found in A3B2C4 (967.10 mg / kg).

[0122] This invention, based on experiments to improve saline-alkali soil, involves planting silage corn and verifying the effectiveness of soil improvement by measuring the emergence rate and physiological indicators of the silage corn seedlings. The following are supporting examples of the emergence rate and physiological indicators of silage corn planted on the soil improved by this invention:

[0123] Silage corn emergence rate

[0124] See Figure 10The results showed that the emergence rate of silage maize in the control group was 17.78%. Under the combined application of ABC treatments, A1B3C3, A2B3C4, A3B2C4, A3B4C2, A4B2C3, A4B3C2, and A4B4C1 all significantly improved the emergence rate of silage maize in saline-alkali soil compared to the control group (p<0.05). The emergence rate of the ABC treatments was higher than that of the control group, with A1B3C3, A3B2C4, and A4B4C1 showing the highest emergence rate of 72.22%.

[0125] Corn seedling height

[0126] See Figure 11 It can be seen that the seedling height of silage corn in the control group was 19.67 cm. The combined application of ABC significantly increased the seedling height of silage corn compared with CK (p<0.05), with the seedling height of A2B4C3 silage corn seedlings reaching the highest of 69.90 cm.

[0127] Corn seedlings have long roots

[0128] See Figure 12 As shown in the figure, the root length of the control group silage corn seedlings was 10.33 cm. The combined application of ABC significantly increased the root length of the silage corn seedlings compared with CK (p<0.05), with the A3B1C3 silage corn seedlings having the highest root length of 60.67 cm.

[0129] single leaf area of ​​corn seedlings

[0130] See Figure 13 It can be seen that the leaf area of ​​the control group silage corn seedlings was 22.92 cm². 2 Compared with the control group, the combined application of ABC significantly increased the leaf area of ​​single leaves in silage maize seedlings (p<0.05), with the A2B3C4R silage maize seedlings having the largest single leaf area of ​​94 cm². 2 .

[0131] Water content of corn seedlings

[0132] See Figure 14 It can be seen that the moisture content of silage corn seedlings in the control group was 11.03%. The combined application of ABC significantly increased the moisture content of silage corn seedlings compared with CK (p<0.05), with the highest moisture content of silage corn seedlings in A2B1C2 being 53.33%.

[0133] Leaf proline content

[0134] See Figure 15It was found that the proline (Pro) content in the leaves of silage corn seedlings in the control group was 133.72 Ug / g. The combined application of ABC significantly reduced the proline content in the leaves of silage corn seedlings compared with the control group (p<0.05). Among them, the Pro content in the leaves of silage corn seedlings in the A4B3C2 treatment was the lowest at 25.17 Ug / g, while the Pro content in the A1B3C4 treatment was the highest at 92.52 Ug / g.

[0135] Leaf malondialdehyde content

[0136] See Figure 16 It was found that the malondialdehyde (MDA) content in the leaves of silage corn seedlings in the control group was 91.81 nmol / g. The combined application of ABC significantly reduced the MDA content in the leaves of silage corn seedlings compared with the control group (p<0.05). Among them, the MDA content in the leaves of silage corn seedlings of A2B1C2 was the lowest at 40.30 nmol / g, while the MDA content in the leaves of silage corn seedlings of A4B3C2 was the highest at 94.91 nmol / g.

[0137] Leaf superoxide dismutase activity

[0138] See Figure 17 The results showed that the superoxide dismutase (SOD) activity in the leaves of silage corn seedlings in the control group was 173.76 U / g. Compared with the control group, the combined application of ABC treatments (A2B3C4, A4B2C3, and A4B3C2) significantly affected the SOD activity in the leaves of silage corn seedlings (p<0.05). Among the ABC treatments, A4B4C1 had the lowest SOD activity in the leaves of silage corn seedlings (147.26 U / g), while A2B3C4 had the highest (296.29 U / g). Duncan's pairwise comparison analysis revealed that among the four gradients of desulfurized gypsum, group A1 had the lowest SOD activity and group A4 had the highest SOD activity; among the four gradients of earthworm castings, group B4 had the lowest SOD activity and group B3 had the highest SOD activity; and among the four gradients of straw compost, group C1 had the lowest SOD activity and group C3 had the highest SOD activity.

[0139] Leaf soluble sugar content

[0140] See Figure 18 The results showed that the soluble sugar (SS) content in the leaves of silage corn seedlings in the control group was 27.12 mg / g. Compared with the control group, the combined application of ABC treatment significantly affected the SS content in the leaves of silage corn seedlings in all groups except A1B3C3, A3B3C1, A3B4C2, A4B3C2, and A4B4C1 (p<0.05). Among the ABC treatments, the lowest SS content in the leaves of silage corn seedlings was 10.49 mg / g in A2B4C3, while the highest soluble sugar content was 48.56 mg / g in A3B1C3.

[0141] intercellular CO2 concentration in leaves

[0142] See Figure 19 As shown in the figure, the intercellular CO2 concentration (Ci) in the leaves of silage corn seedlings in the control group was 254.55 ppm. Compared with the control group (CK), only the A1B1C1, A1B4C4, A2B1C2, A2B3C4, A3B2C4, A3B3C1, A4B3C2, and A4B4C1 groups significantly affected the Ci content in the leaves of silage corn seedlings (p<0.05). Among the ABC treatments, the A2B2C1 group had the lowest Ci content in the leaves of silage corn seedlings (217.26 ppm), while the A2B1C4 group had the highest Ci content (387.67 ppm).

[0143] Blade porosity

[0144] See Figure 20 It can be seen that the stomatal conductance (gs) of the leaves of the control group silage corn seedlings is 86.6 mmol / m. 2 Compared with the control (CK), the combined application of ABC treatments significantly affected the gs (gs) of silage maize seedling leaves in all groups except A1B3C3, A3B2C4, and A4B3C2 (p<0.05). Among the ABC treatments, A4B1C4 had the lowest gs of silage maize seedling leaves at 31.93 mmol / m². 2 / s, the highest stomatal conductance of A4B3C2 is 69.12 mmol / m. 2 / s.

[0145] Leaf net photosynthetic rate

[0146] See Figure 21 It can be seen that the net photosynthetic rate of the leaves of the control group silage corn seedlings was 3.65 μmol / m. 2 The combined application of ABC treatments significantly affected the net photosynthetic rate compared to the control group, except for groups A2B1C2, A2B2C1, and A4B2C3 (p<0.05). Among the ABC treatments, group A2B2C1 had the lowest net photosynthetic rate at 3.39 μmol / m². 2 / s, the highest net photosynthetic rate of A1B4C4 is 7.03 μmol / m 2 / s.

[0147] Leaf transpiration rate

[0148] See Figure 22 The transpiration rate (Tr) of the leaves of the control group silage corn seedlings was 1.18 mmol / m². 2 / s, the combined application of ABC treatments significantly affected the transpiration rate in all groups except A1B1C1, A1B3C3, and A4B2C3 compared to the control group (p<0.05). Among the ABC treatments, the A1B3C3 treatment had the highest Tr (transient rate) of 1.75 mmol / m². 2 / s, the lowest Tr treated with A4B2C3 was 0.83 mmol / m2 / s.

[0149] The saline-alkali soil improvement experiment designed in this invention uses the entropy weight-TOPSIS model to calculate and evaluate the optimal improvement scheme. Examples of the comprehensive evaluation results on the improvement of soil physicochemical properties and the growth status of silage corn seedlings after soil improvement are as follows:

[0150] Comprehensive evaluation of the physical and chemical properties of saline-alkali soil by combined application of ABC treatment

[0151] The effects of combined ABC application on improving the physicochemical properties of saline-alkali soil were evaluated using an entropy weight method-TOPSIS model, and the results are shown in Table 2. Among the ABC groups, A4B4C1 showed the best results. TOPSIS evaluation was performed on the data generated by weighting eight indicators (pH, ESP, SAR, AN, AK, AP, NO3-N, and Es) using the entropy weight method, with 16 evaluation objects (sample size equal to the number of evaluation objects). First, the evaluation indicators were determined, ensuring they all exhibited a positive trend. pH, ESP, and SAR were negative indicators, so their data were reversed first; the remaining five indicators were processed for positive trend. The obtained data were normalized to the sum of squares, and the weights were calculated using the entropy weight method before TOPSIS analysis. D+ and D- represent the distance between the evaluation object and the positive and negative ideal solutions, respectively, and C represents the degree of closeness between the evaluation object and the optimal solution; a larger value indicates a closer proximity to the optimal solution.

[0152] Table 4. Evaluation Results of the Combined Application of A, B, and C in Improving the Physicochemical Properties of Saline-Alkali Soil

[0153]

[0154] Comprehensive evaluation of maize seedling growth status by combined application of ABC (A, B, and C)

[0155] The effects of combined ABC treatments on the growth of silage maize in improved saline-alkali soil were evaluated using the entropy weight method-TOPSIS model. The results are shown in Table 3. TOPSIS evaluation was performed on 17 indicators, including pH, ESP, SAR, Pro, MDA, AN, AK, AP, NO3-N, ES, emergence rate, plant height, soluble sugar, single leaf area, and plant water content, using the entropy weight method to weight the data. Sixteen evaluation subjects were evaluated (the sample size was the same as the number of evaluation subjects). First, the evaluation indicators were determined, ensuring they all exhibited a positive trend. Of the 15 indicators, pH, ESP, SAR, Pro, and MDA were negative indicators, so their data were reversed. The remaining 10 indicators were positive indicators, so their data were forward-oriented. The obtained data were normalized to the sum of squares, and the weights were calculated using the entropy weight method before TOPSIS analysis. D+ and D- represent the distance between the evaluation subject and the positive and negative ideal solutions, respectively, and C represents the degree of closeness between the evaluation subject and the optimal solution; a larger C value indicates a closer proximity to the optimal solution. The analysis results show that the A4B4C1 score is the best among the desulfurized gypsum + earthworm castings + straw compost treatments.

[0156] Table 5. Evaluation Results of Growth Status of Silage Maize under the Combined Application of A, B, and C Treatments in Improved Saline-Alkali Soil

[0157]

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described with reference to preferred embodiments, those skilled in the art should understand that various changes in form and detail can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for improving saline-alkali soil by using a saline-alkali soil improver for reducing alkali, fertilizing, and resisting stress, characterized in that, A saline-alkali soil improvement agent is applied to a saline-alkali soil; the saline-alkali soil improvement agent comprises desulfurized gypsum, earthworm manure, and straw compost.

2. The method of claim 1, wherein, The application amount of the earthworm manure is 5%-20% of the mass of the saline-alkali soil.

3. The method of claim 2, wherein, The application amount of the earthworm manure is 20% of the mass of the saline-alkali soil.

4. The method of claim 2, wherein, The application amount of the straw compost is 5% of the mass of the saline-alkali soil.

5. The method of claim 4, wherein, The amount of application of the desulfurized gypsum is 7.5-18.75 t / hm 2 .

6. The method of claim 2, wherein, The amount of application of the desulfurized gypsum is 18.75 t / hm 2 .

7. Use of the saline-alkali soil improvement agent described in claim 1 in the preparation of a saline-alkali soil improvement preparation.

8. Use according to claim 7, characterized in that, The saline-alkali soil improvement agent reduces the pH value, alkalization degree, and sodium adsorption ratio of the saline-alkali soil.

9. Use according to claim 7, characterized in that, The saline-alkali soil improvement agent increases the soluble salt content, ammonium nitrogen content, available potassium content, available phosphorus content, nitrate nitrogen content, and effective sulfur content of the saline-alkali soil.

10. A method for preparing a desulfurized gypsum-worm cast fertilizer-straw composted saline-alkali soil conditioner by orthogonal design, characterized in that, The method comprises the following steps: (1) Gradient design: an orthogonal test system with three factors and four levels is established: Desulphated gypsum: 7.5 t / hm 2 , 11.25 t / hm 2 , 15 t / hm 2 , 18.75 t / hm 2 Four gradients, uniformly applied to the mixture in the soil to be improved; The earthworm manure is set to four gradients of 5%, 10%, 15%, and 20% of the mass of the soil to be improved. The straw compost is set to four gradients of 5%, 10%, 15%, and 20% of the mass of the soil to be improved. (2) The soil physicochemical indexes of the soil to be improved, such as pH, ESP, SAR, AN, AK, AP, NO3-N, and ES, the seedling emergence rate, plant height, and plant water content of the silage corn seedlings planted in the soil to be improved, the soluble sugar, single leaf area, Pro, and MDA indexes of the leaves are determined, and the entropy weight-TOPSIS method is used to comprehensively score all the treatment groups. (3) The desulfurized gypsum-earthworm manure-straw compost ratio with the highest comprehensive score is selected as the improvement scheme.

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