Method for improving saline alkali soil by struvite and application

Abstract

The invention relates to a method for improving saline-alkali soil through struvite and application, and belongs to the technical field of saline-alkali soil improvement. The application comprises the steps of improving the physicochemical properties of soil, promoting the growth of pasture, and improving the microbial activity and nutrient circulation. The struvite is used as the modifier, the coupling mode of struvite and pasture planting is achieved, the remediation mode of'cultivating land with pasture 'is achieved, the comprehensive benefits of the method are better than those of a single chemical modifier (such as gypsum), and the method is environmentally friendly and has remarkable progress compared with the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of saline-alkali soil improvement, and particularly relates to a method for improving saline-alkali soil with struvite and application thereof. Background Art

[0002] Saline-alkali land is a type of soil that has been degraded by high concentrations of soluble salts or sodium ions. It is widely distributed in arid, semi-arid and coastal regions around the world, covering a total area of ​​more than 1 billion hectares. The high pH, ​​high electrical conductivity and sodium ion enrichment of saline-alkali soils lead to soil compaction, poor permeability and nutrient imbalance, which directly inhibit plant root development and nutrient absorption, resulting in low crop biomass or even crop failure.

[0003] Currently, saline-alkali soil improvement technologies primarily include physical, chemical, and biological improvements. However, existing technologies primarily focus on food crops, leaving dedicated improvement solutions for pastures in urgent need of development. Traditional amendments also suffer from high costs and long processing times, necessitating the urgent need for improvement. Struvite (MgNH₄PO₄·6H₂O, MAP), a natural mineral fertilizer rich in nitrogen, phosphorus, and magnesium, boasts a porous structure, slow-release nutrients, and the potential for salt regulation, offering a new approach to addressing saline-alkali soil improvement.

[0004] In view of this, the present invention is proposed to explore a new solution for saline-alkali soil. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and application of using struvite as an improver to alleviate saline-alkali stress and promote forage growth.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for improving saline-alkali soil with struvite, characterized by comprising the following steps: Step 1: Select struvite as the amendment, set the application rate gradient and set up a control group; Step 2: Apply the struvite evenly to the soil surface through tillage and irrigation; Step 3: Select forage grass varieties suitable for saline-alkali and low-temperature environments for planting, and carry out forage grass planting and maintenance in potted experiments according to conventional field management models.

[0007] Furthermore, the struvite application rate in step 1 was 0 / hm² (T0), 0.75 / hm² (T1), 1.0 / hm² (T2), and 1.2t / hm² (T3), and the positive control gypsum was 1.5t / hm² (TS).

[0008] Furthermore, the forage grass in step 3 is cold-resistant No. 1 forage grass.

[0009] The present invention also provides an application of a method for improving saline-alkali soil with struvite, comprising: 1. Improve the physical and chemical properties of the soil Mg in struvite 2+ Replacement of Na in soil + , promoting the reduction of salinity; increasing soil permeability through the original structure of struvite, thereby increasing organic matter content, cation exchange capacity (CEC) and changing the structure of water-stable aggregates; 2. Promote microbial abundance variation and nutrient release It improves the activity of sucrase and urease in saline-alkali soil, and increases the microbial diversity index and the abundance of Firmicutes and Proteobacteria, promoting the mineralization of organic matter and nutrient release.

[0010] 3. The addition of struvite had a significant effect on the plant height, root length, fresh weight and dry weight of above- and below-ground plant parts of forage grass. The addition of struvite significantly increased the plant height and root length of forage grass.

[0011] 4. The results show that the addition of struvite to saline-alkali land with an EC value greater than 3,000μs / cm has a significant reduction in pH. Although saline-alkali land with an EC value <3,000μs / cm showed a restoration effect, the effect was not as significant as that with an EC value >3,000μs / cm. The pH showed a downward trend with the increase in the amount of struvite added. The beneficial effects of the present invention are: The present invention uses struvite as an amendment to achieve a coupling model of struvite and forage planting, and realize a "using grass to nourish the land" restoration model. Its comprehensive benefits are better than those of a single chemical amendment (such as gypsum), and it is environmentally friendly, which is a significant improvement compared to the existing technology.

[0012] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. DETAILED DESCRIPTION

[0013] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0014] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0015] The applicant used struvite (MAP) as an amendment and conducted a two-year field trial to systematically study its effects on the physical and chemical properties of soda saline-alkali soil and the growth of alfalfa and alkaligrana. The experimental process is as follows: Trial location

[0016] Experimental site: Greenhouse, West Second Campus, Qiqihar University, Heilongjiang Province Soil sample collection site: Aobaotun saline-alkali land, Gonghe Village, Chaodeng Township, Zhaoyuan County, Heilongjiang Province (45 degrees 63 minutes north latitude, 124 degrees 65 minutes east longitude).

[0017] Test methods

[0018] 1. Soil structure determination Determination of soil macroaggregate composition by mechanical sieving 2. Determination of soil chemical composition (1) Determination of soil total nitrogen content by Kelvin digestion method (2) Determination of soil nitrate nitrogen content by ultraviolet spectrophotometry (3) Determination of total phosphorus content in soil by sulfuric acid-perchloric acid dissolution-molybdenum antimony colorimetric method Determination of soil available potassium content by flame photometer 3. Soil enzyme activity determination (1) Determination of soil urease by indigo blue colorimetric method Determination of soil sucrase content by 3,5-dinitrosalicylic acid colorimetry 4. Determine soil pH and electrical conductivity (EC) Measure the soil pH using a pH meter (soil / water, 1:5).

[0019] Test conclusion

[0020] 1. Adding struvite reduced the pH value and electrical conductivity (EC) of the soil, but increased the total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3 -1 -N), available potassium (AK), total organic carbon (TOC), available phosphorus (AP), available nitrogen (AN) and the activities of sucrase and urease.

[0021] 2. At maturity, AK, TP, AN, NO3 of each treatment -1 The nutrient contents of -N, AP, TOC, etc. were all higher than those in the T0 treatment (P<0.05). All the physical and chemical properties of the soil increased with the increase of struvite content.

[0022] 3. Analysis of soil aggregates showed that after the addition of struvite, the soil aggregate structure changed significantly in the ranges of 0.25 mm, 0.106 mm, 0.053 mm, and 0.012 mm from T0 to T3. The aggregate structure of soil particles with a size of 0.106 mm increased with the increase in the amount of struvite added, with the most obvious change and the best effect in T3.

[0023] 4. TS had the highest EC value among all soil samples, significantly higher than T0 (P < 0.05). These results indicate that struvite addition significantly reduced pH in saline-alkali soils with EC values ​​greater than 3,000 μs / cm. While saline-alkali soils with EC values ​​< 3,000 μs / cm showed a remediation effect, the effect was less pronounced than that with EC values ​​> 3,000 μs / cm. pH decreased with increasing struvite addition.

[0024] In summary, the present invention uses struvite as an amendment to achieve a coupling model of struvite and forage planting, and realizes a "grass-based land restoration" restoration model. Its comprehensive benefits are better than those of a single chemical amendment (such as gypsum), and it is environmentally friendly, which is a significant improvement compared to the existing technology.

[0025] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0026] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for improving saline-alkali soil with struvite, characterized in that: The following steps are involved: Step 1: Select struvite as the amendment, set the application rate gradient and set up a control group; Step 2: Apply the struvite evenly to the soil surface through tillage and irrigation; Step 3: Select forage varieties suitable for saline-alkali and low-temperature environments for planting, and carry out forage planting and maintenance in potted experiments according to conventional field management models.

2. The method for improving saline-alkali soil with struvite according to claim 1, wherein: The struvite application rate gradient in step 1 was 0 / hm² (T0), 0.75 / hm² (T1), 1.0 / hm² (T2), and 1.2t / hm² (T3), and the positive control gypsum was 1.5t / hm² (TS).

3. The method for improving saline-alkali soil with struvite according to claim 1, wherein: The forage variety in step 3 is cold-resistant No. 1 forage grass.

4. An application of the method for improving saline-alkali soil using struvite according to any one of claims 1 to 3, characterized in that: include:

1. Improve the physical and chemical properties of the soil Mg in struvite 2+ Replacement of Na in soil + , promoting the reduction of salinity; increasing soil permeability through the original structure of struvite, thereby increasing organic matter content, cation exchange capacity (CEC) and changing the structure of water-stable aggregates; 2. Promote changes in microbial abundance and nutrient release Improve the activity of sucrase and urease in saline-alkali soil, increase the microbial diversity index and the abundance of Firmicutes and Proteobacteria, and promote the mineralization of organic matter and nutrient release; 3. It affects the plant height, root length, fresh weight and dry weight of above-ground and underground plant parts of forage grass. The addition of struvite increases the plant height and root length of forage grass.