Composite for enabling sandy soil to have water retention and nutrient retention capabilities, water-retaining agent, and its preparation method and use thereof

Abstract

Disclosed is a composite for enabling sandy soil to have water retention and nutrient retention capabilities, a water-retaining agent, a preparation method, and use thereof. The composite includes polyacrylamide, sodium polyacrylate, and xanthan gum. Also disclosed is a water-retaining agent including the composite and a method for utilizing the composite to improve the water retention and/or nutrient retention capabilities of sandy soil. Through the synergistic effect of polyacrylamide, sodium polyacrylate, and xanthan gum, this invention not only alters the looseness of sandy soil, increases the viscosity, and significantly reduces water loss and volatilization, but also improves the retention capacity of fertilizer nutrients to extend the effective duration. The composite is environmentally friendly, cost-effective, and effectively improves the properties of sand, showing the effects of retaining water and nutrients, facilitating plant growth, and offering high application value.

Claims

1. A composite for enabling sandy soil to have water retention and nutrient retention capabilities, comprising polyacrylamide, sodium polyacrylate, and xanthan gum; wherein a mass ratio of polyacrylamide to sodium polyacrylate to xanthan gum is (1-3):(1-3): (5-8).

2. The composite according to claim 1, wherein the mass ratio of polyacrylamide to sodium polyacrylate to xanthan gum is (1-2):(1-3):(6-8).

3. The composite according to claim 1, wherein the composite is prepared by the following: mixing the polyacrylamide, sodium polyacrylate and xanthan gum to obtain the composite for enabling sandy soil to have water retention and nutrient retention capabilities.

4. A water-retaining agent, comprising the following components: (a) the composite for enabling sandy soil to have water retention and nutrient retention capabilities according to claim 1; and (b) a solvent.

5. The water-retaining agent according to claim 4, wherein a mass-volume ratio of the composite to solvent is 1: (30-50) mg/mL.

6. A method for improving the water retention and/or nutrient retention capabilities of sandy soil, comprising infiltrating the water-retaining agent according to claim 4 into the sandy soil planted with plants or crops.

7. The method according to claim 6, wherein a mass of the water-retaining agent in the sandy soil accounts for 0.25%-0.75%.

8. The method according to claim 6, wherein the plants are Elymus plants.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the XPS spectra of a composite prepared by Example 2.

(2) FIG. 2 is an infrared spectrogram of the composite prepared by Example 2.

(3) FIG. 3 shows a thermogravimetric analysis curve of the composite prepared by Example 2.

(4) FIG. 4 shows SEM graphs of the composite prepared by Example 2, sand, and sand sprayed and fixed with a water-retaining agent, wherein FIG. A is the SEM graph of the composite prepared by Example 2; FIG. B is the SEM graph of sand; and FIG. C and FIG. D are the SEM graphs of the sand sprayed and fixed with the water-retaining agent.

(5) FIG. 5 shows the results of the pot experiment of six groups.

DETAILED DESCRIPTION OF THE INVENTION

(6) The present invention will be further illustrated in the following with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

Example 1 a Composite for Enabling Sandy Soil to have Water Retention and Nutrient Retention Capabilities

(7) Polyacrylamide (PAM, purchased from Hushi, Sinopharm Chemical Reagent Co., Ltd., product No. 30503770, batch No. 220140225, molecular weight of 10000000), sodium polyacrylate (ACR, purchased from Hushi, Sinopharm Chemical Reagent Co., Ltd., product No. 30213370, batch No. 20180316) and xanthan gum (Xgum) were mixed evenly according to a mass ratio of 1:1:5, and a composite for enabling sandy soil to have water retention and nutrient retention capabilities was obtained.

Example 2 a Composite for Enabling Sandy Soil to have Water Retention and Nutrient Retention Capabilities

(8) The present example is different from Example 1 in that PAM, ACR, and Xgum were mixed evenly according to a mass ratio of 1:1:8.

Example 3 a Composite for Enabling Sandy Soil to have Water Retention and Nutrient Retention Capabilities

(9) The present example is different from Example 1 in that PAM, ACR, and Xgum were mixed evenly according to a mass ratio of 2:3:7.

Test Example 1 Characterization of the Composite for Enabling Sandy Soil to have Water Retention and Nutrient Retention Capabilities

(10) The composite prepared by Example 2 was subjected to an XPS test. FIG. 1 shows the XPS spectra of the composite prepared by Example 2. It can be seen from FIG. 1 that the composite contains carbon, oxygen, and sodium.

(11) FIG. 2 is an infrared spectrogram of the composite prepared by Example 2. It can be seen from FIG. 2 that a characteristic peak shows at 1730 cm.sup.1 which corresponds to an ester bond form between ACR and Xgum, indicating an esterification reaction between the carboxylic group in ACR and the hydroxyl group in Xgum.

(12) The composite prepared by Example 2 was subjected to a thermogravimetric analysis test. FIG. 3 shows a thermogravimetric analysis curve of the composite prepared by Example 2. It can be seen from FIG. 3 that the mass of the composite drops by less than 10% below 100 C., indicating that the material has a good thermo-stability in the natural environment.

(13) The composite prepared by Example 2 was mixed with water in a mass-volume ratio of 1:40 mg/mL and stirred evenly at room temperature, and then a water-retaining agent was obtained. The water-retaining agent was sprayed evenly over the sandy soil in a dry amount of 0.5 kg/m.sup.2, and the sprayed drops spontaneously infiltrated into a surface layer of the sandy soil by 10 to 30 cm.

(14) The composite prepared by Example 2, sand, and the sand sprayed and fixed with the water-retaining agent were observed via SEM. It can be seen from A to D of FIG. 4 that the composite formed a three-dimensional net structure which was loaded on the sand and enabled the sand to adhere to each other so that the sand was fixed by the composite.

Test Example 2 Effects of the Composite on Water Retention and Nutrient Retention of Sandy Soil

(15) The water-retaining agent, prepared by Test Example 1, was subjected to a pot experiment as follows: the water-retaining agent (WNLCA) was sprayed onto the surface of 200 g sandy soil (cylindrical with a diameter of 4.5 cm and a depth of 7 cm) according to the mass ratios respectively (the mass ratios of WNLCA to sandy soil were 0%, 0.25%, and 0.50%), and 1% KNO.sub.3 was added to the sandy soil as a fertilizer. Then, the obtained sandy soil was seeded with lyme grass seeds, and preserved at 25 C. indoors with 16 hours of lighting (16 h light/8 h dark) for 13 days. Six experimental groups shown in the following were subjected to the above-mentioned pot experiment: Group 1: sand, without WNLCA, without KNO.sub.3; Group 2: sand+0.25% WNLCA, without KNO.sub.3; Group 3: sand+0.50% WNLCA, without KNO.sub.3; Group 4: sand+KNO.sub.3, without WNLCA; Group 5: sand+0.25% WNLCA+KNO.sub.3; Group 6: sand+0.50% WNLCA+KNO.sub.3.

(16) FIG. 5 shows the results of the pot experiment of the six groups. It can be seen from FIG. 5 that compared with other groups, the group added 0.50% WNLCA and the fertilizer significantly increased survival time, indicating that WNLCA enables the sandy soil to have better water retention and nutrient retention capabilities.

Test Example 3 Effects of the Composite on Water Retention and Nutrient Retention of Sandy Soil

(17) The composites of Examples 1 to 3 were subjected to the pot experiment according to the method of Test Example 2, wherein the mass of the water-retaining agent in the sandy soil accounted for 0.50%, and 1% KNO.sub.3 was added to the sandy soil as a fertilizer. Meanwhile, a control group was established wherein the water-retaining agent was replaced by water, and other operations remained the same as the experimental groups.

(18) Compared with the control group, the group using the composite of Example 1 as the water-retaining agent can reduce the moisture loss by 24%, and the survival time of lyme grass was increased by 10% without continuous watering.

(19) Compared with the control group, the group using the composite of Example 2 as the water-retaining agent can reduce the moisture loss by 42%, and the survival time of lyme grass was increased by 20% without continuous watering.

(20) Compared with the control group, the group using the composite of Example 3 as the water-retaining agent can reduce the moisture loss by 31%, and the survival time of lyme grass was increased by 15% without continuous watering.

(21) The aforementioned examples are only illustrative and are used to explain certain features of the method described in the present invention. The attached claims aim to claim the widest possible scope that can be assumed, and the embodiments presented in the present invention are based on the applicant's actual experimental results for verification. Therefore, the applicant intends that the attached claims are not subject to selection limitations of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include sub-ranges within them, and changes within these ranges should be interpreted as being covered by the attached claims where possible.