Method for improving soil chromium pollution by using irrigation and fertilization period and dosage combination

Abstract

The invention discloses a method for optimizing and improving the productivity of chromium-contaminated soil by using irrigation and fertilization period and dosage combination, and the steps are: selecting a crop variety of silage corn, sowing according to the dense planting sowing amount, randomly sowing and synchronously applying compound fertilizer and humic acid fertilizer as base fertilizer, irrigating water during the sowing period; irrigating again during the jointing period or the large trumpet period of the crop, and simultaneously flushing and applying humic acid fertilizer for combined regulation; irrigating again during the heading and filling period of the crop. The method of the present invention applies humic acid fertilizer during the sowing period, jointing period or the large trumpet period, uses river water for irrigation during the sowing period, jointing period or the large trumpet period, and uses well water for irrigation during the heading and filling period to promote a significant increase in corn biomass, reduce the chromium content of the crop, and reduce the residual amount of total chromium and effective chromium in the root layer soil at the same time, and uses well water for irrigation during the heading and filling period to effectively block the transportation of effective chromium in the soil to the crop plant body, thereby achieving the improvement of chromium-contaminated farmland soil productivity and green restoration of soil chromium pollution.

Description

Technical Field

[0001] The invention relates to the technical field of food security and green agricultural efficiency enhancement, and in particular to a method for improving the productivity of chromium-contaminated soil by utilizing irrigation and fertilization periods and dosage combinations. Background Art

[0002] According to the report "The State of Food Security and Nutrition in the World 2022", in 2021, a total of 702 million to 828 million people in the world will face hunger; compared with 2020, the number of people affected by hunger in 2021 increased by 46 million; since 2019, the number of people affected by hunger has increased by 150 million. In 2021, my country's total grain output was 682.85 million tons, an increase of 2.0% over the previous year and 15.82% over 589.57 million tons in 2012, and grain production achieved "18 consecutive bumper harvests". In the medium and long term, my country's grain supply and demand will still be in a tight balance; and due to the dual hard constraints of resources and environment, it is becoming increasingly difficult to increase grain production.

[0003] According to statistics, my country's annual agricultural irrigation water gap is as high as 30 to 40 billion cubic meters, and the amount of water used for agricultural irrigation will maintain zero growth in the next 15 years; in the past 10 years, the average annual drought-affected area in the country is about 400 million mu, and the grain loss due to drought has reached more than 30 billion kilograms; in addition, my country's soil quality is not optimistic. Currently, there are about 150 million mu of contaminated arable land in the country, and the annual amount of grain contaminated by harmful heavy metals such as cadmium, chromium, and lead in the country is as high as 12 billion kilograms.

[0004] Therefore, providing a green, safe, sustainable, and cost-effective method that can be used on chromium-contaminated farmland so as to achieve both increased food production efficiency and local environmental restoration on contaminated farmland is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of this, the present invention provides a method for improving the productivity of chromium-contaminated soil by utilizing irrigation and fertilization periods and dosage combinations, which is suitable for cultivated land with medium to light chromium contamination, can effectively achieve the improvement of the productivity of contaminated cultivated land and agricultural efficiency, take into account the improvement of the environmental quality of the production area, and effectively alleviate the dual constraints of water resource safety and soil environmental safety in the crop production process.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The method for improving soil chromium pollution by using irrigation and fertilization period and dosage combination comprises the following steps:

[0008] (1) The crop variety selected was silage corn, which was sown according to the dense planting sowing rate. The base fertilizer was compound fertilizer and humic acid fertilizer, which were randomly sown and applied synchronously. River water was used for irrigation during the sowing period;

[0009] (2) Irrigate again during the jointing stage or the flaring stage of the crop, and apply humic acid fertilizer at the same time for combined regulation;

[0010] (3) Use well water for irrigation during the heading and grain filling period of crops.

[0011] Water and fertilizer management is an important measure to regulate the transport of soil nutrients to plants. It is also one of the most important methods to improve soil environmental quality. At present, it is widely used in environmental regulation and agricultural production in polluted cultivated land areas. According to the physiological characteristics of plants, the irrigation, fertilization period and dosage are combined and optimized to regulate soil moisture, nutrient bioavailability and the transport of heavy metal chromium to crop plants, while improving the production environment, which meets the needs of green agricultural production and national food security. Differences in irrigation water volume, irrigation period and irrigation water quality can significantly change the migration law of heavy metal Cr in the soil-crop system.

[0012] Furthermore, the dense planting sowing amount in step (1) is 4000 to 4500 plants per mu, and the sowing method is machine sowing.

[0013] The beneficial effect of adopting the above further scheme is that the dense planting sowing amount adopted by the present invention has the functions of increasing the average biomass per mu, increasing the transport of effective chromium from the root layer soil to the plant body, and effectively reducing the residual chromium in the root layer soil, making full use of silage crops to repair soil pollution, and realizing rapid, efficient and green ecological restoration of chromium-contaminated soil.

[0014] Furthermore, the application amount of the compound fertilizer in step (1) is 40-50 kg / mu, and the application amount of the humic acid fertilizer is 40-50 kg / mu; the fertilization method is to apply fertilizer during deep plowing of the soil.

[0015] Furthermore, the compound fertilizer is a 24-12-12 type compound fertilizer, the humic acid content of the humic acid fertilizer is ≥40%, the total nitrogen content is ≥6%, and the pH value is ≤5.

[0016] The beneficial effect of adopting the above further scheme is that the humic acid fertilizer adopted in the present invention has the functions of improving soil buffering performance, soil microbial community diversity, stimulating crop growth and biomass, promoting the increase of metal ion and trace element activity in the soil, and affecting and changing the biological effectiveness of metal ions.

[0017] Furthermore, river water is used for irrigation during the sowing period, crop jointing period and crop flaring period.

[0018] Furthermore, the amount of river water irrigation during the sowing period is 40-60m 3 / mu;

[0019] The amount of river water irrigation during the jointing or flaring period of the crop is 60-80m 3 / mu.

[0020] The beneficial effect of adopting the above further scheme is that the present invention uses river water for irrigation during the sowing period, the crop jointing period and the large bell mouth period, and the river water irrigation volume during the sowing period is 40-60m 3 / mu, during the jointing or flaring period of crops, the river water irrigation volume is 60-80m 3 / mu, making full use of the physiological growth characteristics of crops, and irrigating river water during the rapid stage of vegetative growth has the advantages of reducing the consumption of clean water sources, increasing the utilization and utilization rate of low-quality water sources such as river water, and at the same time improving the recycling rate of water resources.

[0021] Furthermore, the humic acid fertilizer in step (2) is nitrohumic acid fertilizer, and the fertilizer application amount is 30-40 kg / mu;

[0022] The method of flushing humic acid fertilizer is to flush the humic acid fertilizer into the field with river water irrigation.

[0023] The beneficial effect of adopting the above further scheme is that the humic acid fertilizer adopted in the present invention has the functions of improving soil buffering performance, soil microbial community diversity, stimulating crop growth and biomass, promoting the increase of metal ion and trace element activity in the soil, affecting and changing the biological effectiveness of metal ions, and the transport and accumulation of chromium to crop plants, thereby playing the role of repairing contaminated soil.

[0024] Furthermore, in step (3), well water is used for irrigation during the heading and filling period, and the irrigation volume is 50-70 m 3 The beneficial effect of adopting the above further scheme is that the present invention adopts well water irrigation during the heading and filling period, and the irrigation amount is 50-70m 3 / mu, making full use of irrigation water quality characteristics and crop physiological growth characteristics, and using irrigation water quality to regulate root layer soil properties during the crop reproductive growth stage, thereby blocking the accumulation of chromium to crop plants and reproductive organs, reducing the biosafety risk of chromium-contaminated soil and improving the productivity of contaminated soil.

[0025] The beneficial effects of the present invention are:

[0026] The method of the present invention selects silage corn as a crop variety, applies compound fertilizer and humic acid fertilizer at the bottom, and performs water-fertilizer combination regulation in the sowing period by means of irrigation with river water. River water is used to irrigate the crops in the jointing period or the large trumpet period, and humic acid fertilizer is used to flush the crops to perform water-fertilizer combination regulation, so as to promote the increase of biomass of the crops in the vegetative growth stage and the absorption of metal ions in the root layer soil. Meanwhile, well water is used to irrigate the crops in the heading and filling period, so as to significantly block the transportation of toxic and harmful metal ions in the soil to the crop plant body and the accumulation of reproductive organs, reduce the biosafety risk of chromium-contaminated soil, and improve the productivity of contaminated soil. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for improving the productivity of chromium-contaminated soil by utilizing irrigation and fertilization periods and dosage combinations:

[0030] (1) The crop variety selected was silage corn, which was sown by machine at a density of 4,000 plants / mu. Compound fertilizer and humic acid fertilizer were applied to the soil with deep plowing. The application rate of compound fertilizer was 50 kg / mu and the application rate of humic acid fertilizer was 40 kg / mu. During the sowing period, river water was used for irrigation, and the irrigation rate was 60m 3 / mu; among them, the humic acid content in humic acid fertilizer is ≥40%, the organic matter content is ≥60%, the potassium oxide content is ≥10%, the total nitrogen content is ≥6%, and the pH value is ≤6.

[0031] (2) During the jointing or flaring period of crops, the irrigation volume is 80m 3 / mu, and at the same time, nitro humic acid fertilizer was applied, and the humic acid fertilizer was flushed into the field with river irrigation, with a fertilizer application rate of 30kg / mu;

[0032] (3) During the heading and grain filling period of crops, the irrigation volume is 70m 3 / mu.

[0033] Example 2

[0034] A method for improving the productivity of chromium-contaminated soil by utilizing irrigation and fertilization periods and dosage combinations:

[0035] (1) The crop variety selected was silage corn, which was sown by machine at a density of 4500 plants / mu. Compound fertilizer and humic acid fertilizer were applied to the soil with deep plowing. The application rate of compound fertilizer was 40 kg / mu and the application rate of humic acid fertilizer was 50 kg / mu. During the sowing period, river water was used for irrigation at a rate of 40 m 3 / mu; among them, the humic acid content in humic acid fertilizer is ≥40%, the organic matter content is ≥60%, the potassium oxide content is ≥10%, the total nitrogen content is ≥6%, and the pH value is ≤6.

[0036] (2) During the jointing or flaring period of crops, the river water is irrigated again with a volume of 60m 3 / mu, and at the same time, nitro humic acid fertilizer was applied, and the humic acid fertilizer was flushed into the field with river water irrigation, with a fertilizer application rate of 40kg / mu;

[0037] (3) During the heading and grain filling period of crops, the irrigation volume is 50m 3 / mu.

[0038] Example 3

[0039] A method for improving the productivity of chromium-contaminated soil by utilizing irrigation and fertilization periods and dosage combinations:

[0040] (1) The crop variety selected was silage corn, which was sown by machine at a density of 4250 plants / mu. Compound fertilizer and humic acid fertilizer were applied to the soil with deep plowing. The application rate of compound fertilizer was 45 kg / mu and the application rate of humic acid fertilizer was 45 kg / mu. During the sowing period, river water was used for irrigation, and the irrigation rate was 50m 3 / mu; among them, the humic acid content in humic acid fertilizer is ≥40%, the organic matter content is ≥60%, the potassium oxide content is ≥10%, the total nitrogen content is ≥6%, and the pH value is ≤6.

[0041] (2) During the jointing or flaring period of crops, the river water is irrigated again with a volume of 70m 3 / mu, and at the same time, nitro humic acid fertilizer was applied, and the humic acid fertilizer was flushed into the field with river water irrigation, with a fertilizer application rate of 35kg / mu;

[0042] (3) During the heading and grain filling period of crops, the irrigation volume is 60m 3 / mu.

[0043] Test example

[0044] In the specific implementation manner of the present invention, R (River) means that the irrigation water source is river water, and W (Well) means that the irrigation water source is well water; F0 means no fertilizer is applied, F1 means compound fertilizer is applied, and F2 means humic acid fertilizer is applied;

[0045] The CK treatment refers to irrigation with river water during the sowing period, jointing or trumpet period, and heading and filling period, application of compound fertilizer during the sowing period, jointing or trumpet period, and no fertilizer during the heading and filling period, and the same applies to other treatments; for example, the RRWF20 treatment refers to irrigation with river water during the sowing period, jointing or trumpet period, well water during the heading and filling period, application of humic acid fertilizer during the sowing period, jointing or trumpet period, and no fertilizer during the heading and filling period; the WWWF12 treatment refers to irrigation with river water during the sowing period, jointing or trumpet period, and heading and filling period, application of compound fertilizer during the sowing period, jointing or trumpet period, and humic acid fertilizer during the heading and filling period. According to crop physiology, three key growth stages of crops, namely sowing stage, jointing stage or trumpet stage, and heading and filling stage, were selected for optimization of irrigation and fertilization period and dosage combination. A total of 9 treatments were used, namely CK, RRWF20, RRWF10, RRRF20, WWWF12, RRRF10, RRRF22, WWWF21, and RRRF21. The tillage, plant protection and field management measures were completely consistent throughout the crop growth period.

[0046] Test Example 1

[0047] The experiment was conducted in a typical sewage-irrigated farmland in Henan Province from April to July 2013. The test soil type was sandy loam, pH 8.2-8.5, organic matter 0.85-1.02%, available nitrogen 46-65 mg / kg, available phosphorus 15-20 mg / kg, available potassium 35-42 mg / kg, chromium 260-320 mg / kg (the risk screening value of the "Soil Environmental Quality Standard Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018) is 250 mg / kg).

[0048] The silage corn variety was Zhengdan 958, and the silage treatment was carried out in early July. Samples were taken from each treatment to measure the fresh weight of corn, the content of heavy metal chromium in roots, stems and leaves, the content of heavy metal chromium in the 0-40cm root layer soil, the content of effective cadmium, TN and TP. Tables 1 and 2 show the comparative results of corn biomass, Cr content in different organs and soil Cr residue in different treatments after corn was regulated by water and fertilizer combinations at different periods and dosages.

[0049] The test results are as follows:

[0050] Table 1 Effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organs

[0051]

[0052] Table 2 Effects of different irrigation and fertilization periods and dosage combinations on soil physical and chemical properties and Cr content after corn harvest

[0053]

[0054] Tables 1 and 2 show the effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organ parts, soil Cr residue, soil effective Cr content, soil TN and TP content. The results show that compared with CK, the maize biomass in RRWF20, RRRF22 and RRRF21 treatments increased by 14.53%, 25.99% and 21.41% respectively, but the Cr content in the roots, stems and leaves of maize in RRWF20 treatment decreased by 8.71%, 8.25% and 9.97% respectively compared with CK; in addition, the Cr and effective Cr contents in the 0-40cm soil layer of maize in RRWF20 treatment after harvest decreased by 17.54% and 8.66% respectively compared with CK treatment.

[0055] Test Example 2

[0056] The experiment was conducted in a typical sewage-irrigated farmland in Henan Province from April to July 2013. The silage corn variety was Yu Silage 23, and the silage treatment was carried out in early July. Samples were taken from each treatment to measure the fresh weight of corn, the content of heavy metal chromium in roots, stems and leaves, the content of heavy metal chromium in the 0-40 cm root layer soil, the content of effective cadmium, TN and TP. Tables 3 and 4 are the comparative results of corn biomass, Cr content in different organs and soil Cr residue in different treatments after corn was regulated by water and fertilizer combinations at different periods and dosages. The experimental design, sowing, harvesting and other management measures of Yu Silage 23 were the same as those of Zhengdan 958.

[0057] The test results are as follows:

[0058] Table 3 Effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organs

[0059]

[0060] Table 4 Effects of different irrigation and fertilization periods and dosage combinations on soil physical and chemical properties and Cr content after corn harvest

[0061]

[0062] Tables 3 and 4 show the effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organ parts, soil Cr residue, soil effective Cr content, soil TN and TP content. The results show that compared with CK, the maize biomass in RRWF20, RRRF22 and RRRF21 treatments increased by 12.52%, 23.77% and 19.27% ​​respectively, but the Cr content in the roots, stems and leaves of maize in RRWF20 treatment was 6.89%, 8.04% and 7.79% lower than that in CK, respectively; in addition, the Cr and effective Cr contents in the 0-40cm soil layer of maize in RRWF20 treatment after harvest were reduced by 17.39% and 8.49% respectively compared with those in CK treatment.

[0063] Test Example 3

[0064] The experiment was conducted in a typical sewage-irrigated farmland in Henan Province from April to July 2014. The corn variety was Yu Silage 23, and the silage treatment was carried out in early July. Tables 5 and 6 show the results of the comparison of corn biomass, Cr content in different organs and soil Cr residue in different treatments after the corn was regulated by different periods and dosages of water and fertilizer combinations. The design, sowing, harvesting and other management measures of Yu Silage 23 were the same as those in 2013.

[0065] The test results are as follows:

[0066] Table 5 Effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organs

[0067]

[0068] Table 6 Effects of different irrigation and fertilization periods and dosage combinations on soil physical and chemical properties and Cr content after corn harvest

[0069]

[0070] Tables 5 and 6 show the effects of irrigation quality and chemical control technology integration on spring maize biomass and Cr content in different organ parts, soil Cr residue, soil effective Cr content, soil TN and TP content. The results show that compared with CK, the biomass of spring maize in WWT+CR and WWW+CR treatments increased by 18.21% and 8.97%, respectively; but the Cr content in the roots, stems and leaves of spring maize in WWT+CR treatment decreased by 5.97%, 12.24% and 13.09%, respectively; in addition, the Cr and effective Cr contents in the soil after harvest of spring maize in WWT+CR treatment were reduced by 24.26% and 16.11%, respectively, compared with those in CK treatment.

[0071] Tables 5 and 6 show the effects of different irrigation and fertilization periods and dosage combinations on maize biomass and Cr content in different organ parts, soil Cr residue, soil effective Cr content, soil TN and TP content. The results show that compared with CK, the maize biomass in RRWF20, RRRF22 and RRRF21 treatments increased by 18.21%, 30.03% and 25.30% respectively, but the Cr content in the roots, stems and leaves of maize in RRWF20 treatment decreased by 5.97%, 12.24% and 13.09% respectively compared with CK; in addition, the Cr and effective Cr contents in the 0-40cm soil layer of maize in RRWF20 treatment after harvest decreased by 24.26% and 16.11% respectively compared with CK treatment.

[0072] From the test results in Tables 1 to 6, it can be seen that compared with the CK treatment, the corn biomass increased significantly with the optimization treatment of irrigation, fertilization period and dosage combination during the critical period of crops (RRWF20 treatment), and the comprehensive biomass increased by 15.09%; and the average Cr content in the roots, stems and leaves of corn with the optimization treatment of irrigation, fertilization period and dosage combination during the critical period of crops (RRWF20 treatment) decreased by 7.19%, 9.51% and 10.66%, respectively.

[0073] Compared with the RRWF20 treatment, the RRRF22 and RRRF21 treatments, which used the optimized irrigation period, fertilization period and dosage combination during the critical period of the crop, slightly increased the biomass of corn, and the comprehensive biomass increased by 7.41%; however, the average Cr content in the roots, stems and leaves of corn in the RRRF22 and RRRF21 treatments increased by 13.29%, 5.14% and 9.14%, respectively.

[0074] Compared with the CK treatment, the Cr content and effective Cr content in the 0-40cm soil layer were reduced by 19.73% and 11.09% respectively by using the optimized treatment (RRWF20 treatment) of irrigation, fertilization period and dosage combination during the critical period of crops; compared with the RRWF20 treatment, the effective Cr content in the 0-40cm soil layer was increased by 16.20 and 6.27% respectively by using the optimized treatments (RRRF22 and RRRF21) of irrigation, fertilization period and dosage combination during the critical period of crops.

[0075] Therefore, in farmland with moderate to light chromium pollution, optimizing the irrigation and fertilization period and dosage combination during the critical period of crops and combining it with silage crop planting can achieve safe crop production and improved productivity, while also having a more obvious repair effect on the production environment.

[0076] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for improving soil chromium pollution by utilizing irrigation and fertilization periods and dosage combinations, characterized in that: The following steps are involved: (1) Selecting silage corn as a crop variety, sowing according to the dense planting sowing amount, randomly sowing and synchronously applying compound fertilizer and humic acid fertilizer as base fertilizer, and using river water for irrigation during the sowing period; the application amount of the compound fertilizer is 40-50 kg / mu, and the application amount of the humic acid fertilizer is 40-50 kg / mu; the fertilization method is to apply the fertilizer along with deep plowing; the compound fertilizer is a 24-12-12 compound fertilizer, and the humic acid content of the humic acid fertilizer is ≥40%, the total nitrogen content is ≥6%, and the pH value is ≤5; (2) irrigating the crop with river water again during the jointing stage or the flaring stage, and applying humic acid fertilizer at the same time for combined regulation; the humic acid fertilizer is nitrohumic acid fertilizer, and the fertilizer application rate is 30-40 kg / mu; the method of applying humic acid fertilizer is to irrigate the humic acid fertilizer into the field with river water; (3) Use well water for irrigation during the heading and grain filling period of crops.

2. The method for improving soil chromium pollution by utilizing irrigation and fertilization period and dosage combination according to claim 1, characterized in that: The dense planting sowing amount in step (1) is 4000-4500 plants / mu, and the sowing method is machine sowing.

3. The method for improving soil chromium pollution by utilizing irrigation and fertilization period and dosage combination according to claim 1, characterized in that: River water is used for irrigation during the sowing period, crop jointing period and crop trumpeting period.

4. The method for improving soil chromium pollution by utilizing irrigation and fertilization period and dosage combination according to claim 3, characterized in that: The amount of river water irrigation during the sowing period is 40-60m 3 / mu; The amount of river water irrigation during the jointing or flaring period of the crop is 60-80m 3 / mu.

5. The method for improving soil chromium pollution by utilizing irrigation and fertilization period and dosage combination according to claim 1, characterized in that: In step (3), well water is used for irrigation during the heading and filling period, and the irrigation volume is 50-70m 3 / mu.

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