A composite organic acid amendment for soda alkaline soils and methods of use

Abstract

The present application relates to a kind of soda alkali soil composite organic acid modifier and its use method, the modifier includes 7-10 parts of citric acid, 1-3 parts of malic acid, 10-20 parts of earthworm manure and 70-80 parts of farm manure by weight fraction;When using, first, the citric acid, malic acid, earthworm manure and farm manure are mixed uniformly, it is composite organic acid modifier;Then, composite organic acid modifier is evenly applied on the surface of soda alkali soil, the application amount is 900-1100 Kg / mu;Subsequently, with the irrigation amount of 50-120 square / mu, it is waterlogged irrigation;Finally, for dry field, it is dried, when the field moisture content is suitable for agricultural machinery to work, it can be planted crops, for paddy field, after irrigation, field soaking and drainage, it is rice precision mechanical fixed-hole transplanting.The present application provides a kind of low-cost, simple operation, pollution-free improvement method.

Description

Technical Field

[0001] This invention belongs to the field of saline-alkali land improvement technology, specifically relating to a compound organic acid improver for soda-alkali soil and its application method. Background Technology

[0002] The soil composition of soda-saline-alkali land is mainly composed of sodium carbonate and sodium bicarbonate, with high alkalinity and an average pH value greater than 8.0. The large amount of Na+ adsorbed in the soil undergoes exchange with other salts, causing soil aggregates to disintegrate, clay particles to disperse and block pores, resulting in poor aeration and permeability. The surface becomes muddy when wet and shrinks and hardens when dry, leading to extremely deteriorated soil physical properties. The soil has very poor permeability and arability, making desalination difficult and extremely detrimental to the growth and development of general crops. Soil alkalization has become one of the fundamental factors restricting the sustainable agricultural development of this region.

[0003] There are many methods for improving soda-saline-alkali land, among which the application of chemical or biological amendments is a common and widely used method in actual production. This involves replacing sodium in the soil through the application of amendments. + Soda-based soil conditioners reduce soil alkalinity, aggregate soil particles, and improve soil structure, thereby improving the soil's physical and chemical properties and accelerating salt leaching, thus achieving the goals of reducing salinity and alkalinity. There are numerous varieties of soda-based soil conditioners available both domestically and internationally, with significant differences in their properties, composition, mechanisms of action, and effectiveness on different soil types. Desulfurized gypsum is currently the most widely used chemical soil conditioner for treating soda-based saline-alkali land. Other sulfate-based conditioners, such as ferric sulfate and aluminum sulfate, primarily work by displacing sodium ions adsorbed by soil colloids, allowing these ions to enter the water and be leached out of the saline-alkali soil, mitigating the harmful effects of high sodium ion content on crop growth. However, these conditioners have low solubility, require large application rates, and incur high transportation costs. They are also less effective at treating moderately to severely saline-alkali land, resulting in higher overall costs. The purpose of applying organic fertilizers or crop straw is to improve soil structure and disperse and dilute sodium ions adsorbed by the soil, thereby reducing the harm of sodium ions to crops. Therefore, organic fertilizers do not reduce the salt and alkali content, and the amount used is large, resulting in high transportation and application costs. In addition, compound microbial organic fertilizers have a wide variety of raw materials, complex processes, and a long fertilizer composting cycle. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a composite organic acid modifier for soda-alkali earth and its application method.

[0005] The technical solution of this invention is:

[0006] A compound organic acid amendment for soda-alkali soil, the key point being that the amendment, by weight, comprises 7-10 parts citric acid, 1-3 parts malic acid, 10-20 parts earthworm castings, and 70-80 parts farmyard manure.

[0007] The improver, by weight, comprises 8.5 parts citric acid, 2 parts malic acid, 15 parts earthworm castings, and 75 parts farmyard manure.

[0008] The improver, by weight, comprises 7 parts citric acid, 2 parts malic acid, 17 parts earthworm castings, and 78 parts farmyard manure.

[0009] The improver, by weight, comprises 9 parts citric acid, 2 parts malic acid, 13 parts earthworm castings, and 72 parts farmyard manure.

[0010] The citric acid mentioned is industrial-grade anhydrous citric acid or citric acid monohydrate.

[0011] The malic acid mentioned is DL-malic acid.

[0012] The process for preparing farmyard manure is as follows: collect fresh cow or pig manure and pile it up, cover it with plastic film or soil, and allow it to ferment and mature naturally at room temperature; when the farmyard manure turns dark brown and has no odor, and the temperature drops to room temperature, the fermentation is complete; the fermentation time is 15-30 days, and the fermented and matured cow or pig manure is dried or dried at high temperature to obtain farmyard manure.

[0013] The key point of the above-mentioned method for using the compound organic acid amendment for soda-alkali earth is that the method includes the following steps:

[0014] A. Preparation of improver

[0015] The citric acid, malic acid, earthworm castings and farmyard manure are thoroughly mixed to form a compound organic acid improver.

[0016] B. Spreading

[0017] Apply the compound organic acid modifier evenly to the surface of the soda-alkali soil at a rate of 900-1100 kg / mu.

[0018] C. Flood irrigation

[0019] A single large-scale flood irrigation is carried out with an irrigation volume of 50-120 cubic meters per mu.

[0020] D. Crop cultivation

[0021] For dry fields, once the moisture content in the field is suitable for agricultural machinery to enter the field, the land can be plowed and leveled for planting crops; for paddy fields, after irrigation, soaking and drainage, rice seedlings can be transplanted by precision machinery in fixed holes.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention addresses the problems of poor permeability and high alkalinity in soda saline-alkali soils by using composite low-molecular-weight organic acids and earthworm castings as materials. It is low-cost, simple to process, and pollution-free.

[0024] 2. Neutralizing the alkalinity of soda-alkali soil with compound low-molecular-weight organic acids and amino acids can rapidly reduce soil alkalinity, significantly reduce soil salinity damage, and achieve soil acid-base balance.

[0025] 3. This invention can replace and decompose sodium ions in soda-alkali soil, effectively inhibit the dispersion of sodium ions, improve soil permeability, realize the flocculation and aggregation of soil colloids, and promote the rapid infiltration of water into soda-alkali soil.

[0026] 4. This invention ensures soil pH balance and accelerates water infiltration, while the application of farmyard manure and earthworm castings increases soil nutrients, which can promote plant growth. Attached Figure Description

[0027] Figure 1 It is a map of the original topography of dry land before improvement;

[0028] Figure 2 This is a diagram of a controlled experiment conducted in different plots of dry land;

[0029] Figure 3 yes Figure 2 Comparison chart showing the differences between plots after application of soil amendment;

[0030] Figure 4 It is a map of the original topography of the paddy fields before improvement;

[0031] Figure 5 yes Figure 4 Improved topographic map after applying the method of the present invention; Detailed Implementation

[0032] This invention provides a compound organic acid amendment for soda-alkali soil and its application method. The amendment mainly consists of citric acid, malic acid, earthworm castings, and farmyard manure. After mixing, it is spread on the surface of the soda-alkali soil, followed by flood irrigation to neutralize soil alkalinity and leach salts into the soil. Finally, the soil is allowed to dry until the moisture content is suitable before agricultural machinery can be used for crop planting. The specific components, application method, and actual effects of the amendment are demonstrated through examples and control groups.

[0033] Example 1

[0034] First, the collected fresh cow or pig manure is piled up, covered with plastic film or soil, and allowed to ferment and mature naturally at room temperature. When the manure turns dark brown and has no odor, and the temperature drops to room temperature, fermentation is complete. The fermentation time is between 15 and 30 days. After fermentation and maturation, the cow or pig manure is dried or dried at high temperature to form farm manure fertilizer.

[0035] Then, thoroughly mix 75kg of industrial-grade anhydrous citric acid, 15kg of DL-malic acid, 200kg of earthworm castings and 700kg of farmyard manure, and then evenly spread the compound organic acid improver on the surface of the soda alkaline soil at a rate of 1000kg per acre.

[0036] Then, flood irrigation is carried out, with an irrigation volume of 60 cubic meters per mu, which neutralizes the soil alkalinity and leached salts and allows them to infiltrate for 2-3 days.

[0037] If it is dry land, let it dry for 2-3 days until the moisture content in the field is suitable, and then the farm machinery can be used to plow and level the land for crop planting.

[0038] If it is a paddy field, after irrigation, soaking and drainage, rice seedlings are transplanted by mechanical precision in fixed holes.

[0039] Control group 1

[0040] As a control group for the dryland in Example 1, no soil amendment was applied. Due to the extremely poor permeability of the soda-alkali soil, only about 1 mm of water infiltrated. The migration rate of the wetting front gradually decreased over time, with a migration rate of 0.02-0.76 cm / d. Under the same water conditions, after ten days, the wetting front only migrated to the 14.5-15.0 cm soil layer and could not leach out the 20 cm soil layer. Therefore, severe water accumulation occurred on the soil surface, and the infiltration rate could not be calculated, as shown in Table 1.

[0041] Table 1: Comparison of dryland fields without soil amendment and those treated with the method of this invention

[0042]

[0043] Control group 2

[0044] As a control group distinct from the soil conditioner components in Example 1, desulfurized gypsum was used for soil improvement. Desulfurized gypsum is a commonly used alkaline soil conditioner in production practice, with significant improvement effects. Desulfurized gypsum can significantly improve soil porosity, increase soil permeability, and facilitate downward leaching of salts. The alkalinity, sodium adsorption ratio, and pH of soils with added desulfurized gypsum decreased after irrigation and leaching, and the total salt content decreased. Chi Chunming et al. (2009) found that although the hydraulic conductivity of soda-alkali soils with added desulfurized gypsum increased by 23.05 times compared to soils without desulfurized gypsum, with a hydraulic conductivity rate of 3.14 mm / d, the infiltration rate was still significantly lower than that of the method described in this invention. The comparison results are shown in the table below.

[0045] Table 2: Effects of application of desulfurized gypsum and the modifier of this invention on the infiltration rate of irrigation water in soda-alkali soil

[0046]

[0047]

[0048] According to the research of Zhou Bin et al. (2022; 2023), the wetting front of soil without soil conditioner completely stopped at the 12.7 cm soil layer after 500 min, and no longer moved downward, resulting in water accumulation on the soil surface. In soil with added desulfurized gypsum, the wetting front gradually extended downward with increasing amounts of desulfurized gypsum, and the infiltration rate also continuously increased, reaching a maximum of 0.76 mm / h. The results compared with the present invention are shown in the table below.

[0049] Table 3: Effects of applying desulfurized gypsum and the modifier of this invention on the infiltration rate of irrigation water in soda-alkali soil

[0050]

[0051] After applying desulfurized gypsum, the amount of water infiltrating was far less than that after applying the present invention. This indicates that the modifier of the present invention has a better effect on improving the structure and permeability of soda-alkali soil than desulfurized gypsum.

[0052] Desulfurized gypsum can reduce soil pH and salinity. With increasing application of desulfurized gypsum, the pH value can decrease by 3.9%-9.7% compared to soil without gypsum application. The maximum reduction in the 0-20cm and 20-40cm soil layers is 8.7% and 9.7%, respectively. The total water-soluble salt content in the 0-20cm and 20-40cm soil layers can be reduced by 71% and 66%, respectively, compared to soil without gypsum application (Zhou et al., 2022). Applying 2t of desulfurized gypsum per mu (approximately 0.067 hectares) reduces soil pH from 9.34 to 9.26, and salinity from 9.22g / kg to 3.39g / kg, resulting in a 36.8% reduction (Feng et al., 2015). Applying 1.5t of desulfurized gypsum per mu (approximately 0.067 hectares) reduces soil pH by 0.65, achieving a soil desalination rate of 84.4-95.1% (Du et al., 2018). The results compared with this invention are shown in the table below.

[0053] Table 4: Comparison of pH value and salinity content of soda-alkali soil after application of desulfurized gypsum and the modifier of this invention

[0054]

[0055]

[0056] Based on the comparison of the improvement effects of the amendment of this invention and commonly used desulfurized gypsum, it can be found that the amendment of this invention has better advantages in terms of water infiltration performance, pH value and desalination rate of soda saline-alkali soil; and this invention is an organic and pollution-free material that will not bring additional heavy metals and other pollutants to the soil.

[0057] Figure 1 It is the original landscape of dry land, where nothing grows; Figure 2The work is carried out in separate plots, with the improved agent of this invention applied within the red frame, followed by watering. Figure 3 The vegetation recovered after a period of time following the application of the improver of this invention. The vegetation within the red box recovered well after the improver of this invention was applied, while the vegetation recovered poorly after no improver was applied or other improvers were applied.

[0058] Figure 4 It is the original landform of paddy fields, where crops are in extremely poor condition and large areas cannot grow rice normally. Figure 5 It is an improved paddy field topography, where rice seedlings grow normally after transplanting, and all areas maintain the same consistency.

[0059] The compound organic fertilizer and its application method described in Example 1 have a significant effect on improving soda-alkali soil, mainly in the following aspects:

[0060] 1.1) The polyunsaturated organic acids and amino acids in the compound organic acid amendment can dissolve sodium ions in alkaline soil, while the calcium in earthworm castings can replace sodium ions, resulting in a combined effect of inhibiting sodium ion dispersion. Simultaneously, the humus and organic matter in earthworm castings have a good aggregate structure, improving soil permeability and significantly promoting water infiltration in soda-alkali soil. Table 1-1 shows the water infiltration data of soda-alkali soil after using the amendment and its application method in Example 1 of this invention. Applying the compound organic acid amendment of this invention can achieve an infiltration water volume of 30.5 mm within one day, while the untreated soil, due to its extremely poor permeability, only has about 1 mm of infiltration water, leading to severe surface water accumulation. See Table 1-1 for details.

[0061] Table 1-1: The effect of the amendment in Example 1 of this application on the infiltration of irrigation water into soda-alkali soil

[0062]

[0063] 1.2) This invention utilizes compound organic acids and amino acids to induce an acid-base balance reaction in soda-alkali soil, rapidly reducing soil alkalinity. Tables 1-2 show a comparison of pH and NaHCO3 content in soda-alkali soil after applying the soil conditioner from Example 1 of this invention. After applying this invention, soil samples were taken in 5cm layers at a depth of 20cm. After the soil was air-dried, the soil solution was extracted at a soil-to-water ratio of 1:5, and the soil ion content and pH were measured. HCO3 was determined using a dual-indicator titration method. - The content of Na in soil was determined using atomic absorption spectrophotometry. + Soil pH was measured directly using a pH meter. Results showed that the pH of the top 10cm layer of soda-alkali soil decreased from 9.41 to 8.69. Irrigation of the 20cm soil layer resulted in the leaching of sodium ions, which were removed from the soil, leading to an average decrease of 74.1% in sodium ion content and an average decrease of 50.3% in bicarbonate content.

[0064] Table 1-2: Comparison of pH value and NaHCO3 content of soda-alkali soil after application of the improver of Example 1 of the present invention

[0065]

[0066] 1.3) This invention can significantly reduce soil salinity, thereby reducing the harm of soil salinity to crops. After applying the soil conditioner of this invention, soil samples were taken in stratified layers, with each layer being 5 cm deep and 20 cm deep. After the soil was air-dried, the soil solution was extracted at a soil-to-water ratio of 1:5, and soil ions were measured. HCO3 was determined using a dual-indicator titration method. - Content, determination of Cl by AgNO3 titration method - Determination of SO4 content by EDTA indirect complexometric titration 2- Soil Ca was determined using atomic absorption spectrophotometry. 2+ Mg 2+ K + and Na + The salt content of soil is the sum of all anions and cations. The salt content of the 20cm soil layer was significantly reduced by 66.8% compared with the original soil without the application of the amendment of this invention. Tables 1-3 show the comparison of salt content of soda-alkali soil after application of the amendment of Example 1 of this invention.

[0067] Table 1-3: Comparison of salt content in soda-alkali soil after application of the improver of Example 1 of the present invention

[0068]

[0069] Example 2 is an example of different component ratios from Example 1.

[0070] First, collect fresh cow or pig manure from farms and pile it up, cover it with plastic film or soil, and let it ferment naturally at room temperature. When the manure turns dark brown and has no odor, and the temperature drops to room temperature, fermentation is complete. The fermentation time is about 15 to 30 days. After fermentation, the cow or pig manure is dried or dried at high temperature to form farm manure fertilizer.

[0071] Mix 100kg of industrial-grade anhydrous citric acid, 15kg of DL-malic acid, 200kg of earthworm castings and 800kg of farmyard manure thoroughly, and then spread the compound organic fertilizer evenly on the surface of the soda alkaline soil at a rate of 1200kg per acre.

[0072] Flood irrigation, with an irrigation volume of 100 cubic meters per acre, neutralizes soil alkalinity and leached salts, allowing them to infiltrate for 2-3 days.

[0073] If it is a dry field, the field should be dried and leveled for 2-3 days until the moisture content is suitable, and then the agricultural machinery can be put into the field for planting. If it is a paddy field, after irrigation, soaking and drainage, rice seedlings should be transplanted by precision mechanical planting.

[0074] The compound organic fertilizer and its application method described in Example 2 show a more significant effect on improving soda-alkali soil, mainly in the following aspects:

[0075] 2.1) The water leaching effect was better within 1 day after applying the improver of Example 2 of the present invention, and the infiltration water volume could reach 46.9 mm, as shown in Table 2-1: the promoting effect of applying the improver of Example 2 of the present invention on the infiltration of irrigation water in soda alkaline soil; while the treatment without the improver had extremely poor permeability, with only about 1 mm of infiltration water, and water accumulation on the soil surface.

[0076] Table 2-1: The promoting effect of application of Example 2 of the present invention on the infiltration of irrigation water in soda-alkali soil

[0077]

[0078] 2.2) After applying the improver of Example 2 of the present invention, the pH value of the top 10cm layer of soda-alkali soil decreased from 9.41 to an average of 8.40, a decrease of 10.7%; sodium ions were leached out of the soil layer by irrigation of the 20cm soil layer, with an average decrease of 82.0% in content and an average decrease of 64.1% in bicarbonate content. Table 2-2 shows the comparison of pH value and NaHCO3 content of soda-alkali soil after applying the improver of Example 2 of the present invention.

[0079] Table 2-2: Comparison of pH value and NaHCO3 content of soda-alkali soil after application of materials

[0080]

[0081] 2.3) After applying the soil conditioner of Example 2 of the present invention, the salt content of the 20cm soil layer was significantly reduced by 75.6% compared with the original soil (without soil conditioner), as shown in Table 2-3: Comparison of salt content of soda-alkali soil after applying Example 2 of the present invention.

[0082] Table 2-3: Comparison of salt content in soda-alkali soil after application of the improver of Embodiment 2 of the present invention

[0083]

[0084]

[0085] In summary, based on the specific effects of Examples 1 and 2, the composite organic acid amendment and its application method provided in this invention can significantly improve various indicators of soda-alkali soil. In particular, the improvement of various performance indicators of soda-alkali soil is most prominent after applying and flooding with the amendment of Example 2. Compared with control group 1 without applying any amendment and control group 2 with applying the existing commercially available amendment (desulfurized gypsum), the improvement effects on various indicators such as water infiltration, pH value, NaHCO3 content and salt content are more prominent. This provides a low-cost, pollution-free and simple operation method for the long-term healthy development of saline-alkali areas.

Claims

1. A compound organic acid modifier for soda-alkali earth, characterized in that, The improver, by weight, includes 7-10 parts citric acid, 1-3 parts malic acid, 10-20 parts earthworm castings, and 70-80 parts farmyard manure; The method of use includes the following steps: A. Preparation of improver The citric acid, malic acid, earthworm castings and farmyard manure are thoroughly mixed to form a compound organic acid improver. B. Spreading Apply the compound organic acid modifier evenly to the surface of the soda-alkali soil at a rate of 900-1100 kg / mu. C. Flood irrigation A single large-scale flood irrigation is carried out with an irrigation volume of 50-120 cubic meters per mu; D. Crop cultivation For dry fields, once the moisture content in the field is suitable for agricultural machinery to enter the field, the land can be plowed and leveled for planting crops; for paddy fields, after irrigation, soaking and drainage, rice seedlings can be transplanted by precision machinery in fixed holes.

2. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The improver, by weight, comprises 8.5 parts citric acid, 2 parts malic acid, 15 parts earthworm castings, and 75 parts farmyard manure.

3. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The improver, by weight, comprises 7 parts citric acid, 2 parts malic acid, 17 parts earthworm castings, and 78 parts farmyard manure.

4. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The improver, by weight, comprises 9 parts citric acid, 2 parts malic acid, 13 parts earthworm castings, and 72 parts farmyard manure.

5. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The citric acid mentioned is industrial-grade anhydrous citric acid or citric acid monohydrate.

6. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The malic acid mentioned is DL-malic acid.

7. The composite organic acid modifier for soda-alkali earth according to claim 1, characterized in that, The process for preparing farmyard manure is as follows: collect fresh cow or pig manure and pile it up, cover it with plastic film or soil, and allow it to ferment and mature naturally at room temperature; when the farmyard manure turns dark brown and has no odor, and the temperature drops to room temperature, the fermentation is complete; the fermentation time is 15-30 days, and the fermented and matured cow or pig manure is dried or dried at high temperature to obtain farmyard manure.

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