CN113366945B - Intercropping method for safely planting corn while repairing farmland with moderate and mild cadmium pollution - Google Patents
Intercropping method for safely planting corn while repairing farmland with moderate and mild cadmium pollution Download PDFInfo
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Abstract
The invention belongs to the technical field of soil heavy metal phytoremediation, and particularly relates to a intercropping method for safely planting corn while repairing a farmland with moderate and mild cadmium pollution. The invention applies the intercropping planting technology of the southeast sedum and the important grain crop corn in China to the field experiment, and achieves the safe planting of the farmland corn with moderate and slight cadmium pollution by broadcasting the root exudates of the barley on the roots of the southeast sedum. The method has the advantages of low investment, low management technical requirement, no damage to the physicochemical property of soil and no secondary pollution, and is a farmland 'production and restoration while production' technology with wide application range, low investment and simple operation.
Description
Technical Field
The invention belongs to the technical field of soil heavy metal phytoremediation, and particularly relates to a intercropping method for safely planting corn while repairing a farmland with moderate and mild cadmium pollution.
Background
The farmland is an important component of human ecological environment, is a material foundation for sustainable development of economy and society, is one of main natural resources on which human beings depend to survive, and is directly related to the life health of people. In the 90 s of the 20 th century, along with the rapid development of industrialization, urbanization and agricultural modernization, toxic heavy metals from various sources enter farmland environments in various forms, modes and ways such as water, gas (dust), slag, fertilizer, medicine and the like, so that large-area farmland is polluted by heavy metals. Cd has strong accumulation and migration capability in farmlands and can influence deep soil. Cd enters human and animal bodies through food chains and accumulates and enriches, and has toxic effects on bones, kidneys, livers, immune systems and reproductive systems of human bodies, even causes diseases such as bone pain, kidney damage, diabetes, emphysema and hypertension, and can seriously cause diseases such as cancers. For example, a painful event caused by heavy metal Cd poisoning in mountain county in japan; the method is also one of countries with more and serious hazard of cadmium pollution incidents, such as the cadmium pollution incident of 7 months in 2009 of Liuyang in China, the double bridge village of the Liuyang in the Qingyang city is introduced into Changshaxiang and chemical plants by quotients, industrial wastes are discharged for a long time, large-area cadmium pollution is formed at the periphery, vegetation is died greatly, and symptoms such as dizziness, chest distress, joint pain and the like are caused by exceeding of cadmium in bodies of partial villagers, so that two villagers die. For farmland soil, the method mainly comprises the steps of industrially discharging Cd-polluted waste into a water area, so that Cd-containing sewage or underground water enters the soil along with runoff, irrigation and other ways, and thus, exceeding standard and even pollution are caused. Crop is planted in farmlands with exceeding Cd, which can cause accumulation of Cd in agricultural products, so that the Cd content of the agricultural products exceeds the national standard and the health of eaters is endangered. In view of the increasing trend of farmland Cd pollution in China and the huge threat of Cd to agriculture and human beings, effective repair and treatment are urgently needed to be carried out according to the current Cd pollution situation and pollution characteristics of farmland. Some methods for facilitating the regulation of the risk of cadmium exceeding farmland or reducing the low cadmium absorption of crops are sequentially researched and applied.
Currently, the restoration methods of Cd polluted farmland include physical restoration methods (soil-dressing method, electric restoration method and electric heating restoration method), chemical restoration methods (soil leaching method and chemical fixing technology) and biological restoration methods (phytoremediation technology, animal restoration method and microorganism restoration method). The physical repair method and the chemical repair method have good repair effect, but have high cost, are easy to cause secondary pollution, and are not suitable for repairing large-area Cd polluted farmlands. In the biological repair method, the plant repair technology mainly comprising super-accumulated plants is widely accepted and used in China and abroad. The phytoremediation technology is a method with unique advantages in technology and economy, and is a very promising remediation technology for solving the problem of heavy metal pollution of soil. At present, three approaches are mainly used for improving the purification efficiency of the phytoremediation technology on polluted soil: firstly, screening ideal Cd highly enriched crops; secondly, reconstructing plants by using a modern molecular engineering technology to improve the enrichment and tolerance capability of the plants to soil heavy metals, and further enhancing the restoration capability of the plants to polluted soil; thirdly, exogenously added growth promoting bacteria or other strengthening measures are used for enhancing the capability of heavy metal extraction of plants. The technology is concerned by domestic and foreign scholars with the advantages of low cost, in situ, small disturbance to soil, no damage to soil structure, no secondary pollution and the like, but the plant restoration technology takes longer time to treat polluted farmlands, has slow effect, also needs to interrupt agricultural production, does not meet the basic national conditions of Chinese land resource shortage, and is not easily accepted by farmers to be applied to practice.
The intercropping is one of the essences of traditional agriculture in China, a proper heavy metal super-enriched plant and crops are selected to form a crop-super-enriched plant intercropping restoration system, and a method which can efficiently restore, shorten the restoration period and safely plant crops is searched, so that the method is a new approach for restoring Cd polluted farmlands. Corn (Zeamays) is one of important grain crops in China, has wide planting range, short growth period and strong adaptability, and sedum alfredii (sedum alfredii) is a super-enriched plant for cadmium in the south of China, has the advantages of strong adaptability, short growth period and the like, and can be used for the safe planting, repairing and treating farmland polluted by medium and light Cd. The technology of adopting intercropping of other crops and the southeast sedum to repair the heavy metal polluted land has a related report, such as Chinese patent application CN101116865A, a method for simultaneously producing and repairing the soil of the vegetable land with medium and slight heavy metal pollution, adopts an intercropping mode to plant the southeast sedum and the elsholtzia haichowensis, takes away a large amount of heavy metal from the soil by the southeast sedum, achieves the purposes of reducing the heavy metal content in vegetables and guaranteeing the safety of agricultural products, has good effects, but experiments find that the direct sleeving of the southeast sedum on corn according to the method has unsatisfactory intercropping effect, the Cd content in corn is still very high, the Cd content can not meet the national standard requirement, and the plant removal rate of Cd is not high, and the repairing capability is very limited. The technology of remedying heavy metal polluted lands by intercropping corn and sedum alfredii is also reported in a related report, and the Chinese patent application CN107790491A, a method for remedying cadmium polluted farmlands by intercropping corn and sedum alfredii, is characterized in that sedum alfredii and corn are planted in an intercropping mode, and the absorption of heavy metal Cd of sedum alfredii is promoted by applying rape root extract (with potassium sorbate and malic acid) to sedum alfredii, so that the test effect is better, but the test is only carried out in a greenhouse, and Cd-containing soil is applied manually, is not directly planted in the polluted farmlands, and is difficult to popularize and plant in a large area.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a intercropping method for safely planting corn while repairing farmlands with moderate and mild cadmium pollution.
A intercropping method for safely planting corn while repairing a farmland with moderate and slight cadmium pollution comprises the following steps:
(1) Planting barley: weeding, applying a base fertilizer, ploughing, preparing land and ridging are sequentially carried out on the farmland with moderate and slight cadmium pollution in 11 months of the first year, and barley seeds are sowed into the soil to be repaired for cultivation management;
further, the total amount of heavy metal cadmium in the medium and light cadmium polluted farmland soil is 0.3-1.0mg/kg;
further, the broadcast amount of the barley seeds is 12-15 kg/mu;
furthermore, the barley seeds are selected from local common barley varieties;
(2) In spring (4 months) of the next year, in the period of vigorous growth of barley, pulling up the whole barley plant, taking care as much as possible to operate without damaging roots, collecting barley root secretions, and carrying out innocent treatment (such as composting or biogas utilization and the like) on the barley plant after the barley root secretions are collected;
further, the extraction step of the barley root secretion in the step (2) is as follows:
(1) taking fresh complete barley plants, cleaning roots, and putting into CaCl 2 Extracting root secretion (preferably barley root is CaCl) 2 Completely immersed in the solution), the overground part maintains a normal growth environment, the root part is in a shading environment, the extraction time is 36-48h, and CaCl can be replaced during the extraction 2 A solution;
further, the extraction time is 48 hours, and CaCl is exchanged once in 24 hours 2 A solution;
further, caCl in the step (1) 2 The concentration of the solution is 0.5mmol/L;
further, caCl is used per gram (g) of barley root in the step (1) 2 The volume of the solution is 10-20mL;
(2) combining CaCl soaked in the barley root twice in the step (1) 2 Filtering the solution, removing impurities until no obvious impurities are found, obtaining barley root secretion, and refrigerating and storing in an environment of 2-6 ℃;
further, in the step (2), after the extraction of the obtained barley root system secretion is completed, removing overground parts of the whole barley plant in the step (1), taking roots, weighing total weight (g) of barley root system, and diluting the barley root system secretion with deionized water until the concentration is 5g/L, wherein the concentration calculation method of the diluted barley root system secretion comprises the following steps: the ratio of the total weight of the barley root system (g) to the volume of the diluted barley root secretion (L);
further, the filtering step in the step (2) is to filter cloth with more than 300 meshes;
(3) In the next 5 months of year, weeding, applying a base fertilizer, ploughing, preparing land and ridging are sequentially carried out in the medium and light cadmium polluted farmland in which the barley is planted, and corn seedlings and southeast sedum seedlings are planted in a intercropping mode (for example, 2 lines of corn and 3 lines of southeast sedum are planted in each ridge);
further, the sedum alfredii seedling is obtained by adopting a cutting method for propagation and seedling raising;
further, the intercropping planting density of the corn and the southeast sedum is as follows: the plant spacing is 20-30 cm, and the row spacing is 30-40 cm;
(4) After the maize seedlings and the sedum alfredii seedlings are transplanted for 10-15 days (preferably 2 weeks), dressing with nitrogen-phosphorus-potassium compound fertilizer and organic fertilizer for promoting the growth of the sedum alfredii and maize, and irrigating the root of the sedum alfredii with barley root secretion 7-10 days after dressing with the fertilizer; after the maize seedlings and the sedum alfredii seedlings are transplanted for 80-100 days (preferably 3 months), dressing again with nitrogen-phosphorus-potassium compound fertilizer and organic fertilizer for promoting the growth of the sedum alfredii and the maize, and irrigating the root of the sedum alfredii with barley root secretion 7-10 days after dressing with the fertilizer;
further, the topdressing amount is the same twice, wherein: the organic fertilizer amount is 200 kg/mu, and the nitrogen-phosphorus-potassium compound fertilizer amount is 100 kg/mu;
further, when the concentration of the barley root secretion is 5g/L, the first irrigation amount is 100-300 mL/plant, and the amount of the first irrigation is higher than that of the second irrigation because the southeast rhodiola rosea is in a vigorous growth stage;
(5) After the corns are ripe, harvesting the corns and the sedum alfredii.
The principle of the invention is as follows:
the barley root secretion can activate heavy metal cadmium in soil, promote the absorption of the sedum alfredii to cadmium, reduce the cadmium content in the soil, reduce the cadmium absorption of corn, and plant corn meeting national food safety standard GB 2762-2017.
Compared with the prior art, the invention has the following advantages:
1. the invention applies the intercropping planting technology of the southeast sedum and the important grain crop corn in China to a field experiment, and solves the problem that the Cd content in the corn is still high after intercropping planting of the southeast sedum and the corn in the natural environment of the field in the prior art by broadcasting the root secretion of the barley at the root of the southeast sedum. By combining different agronomic regulation measures, on one hand, the absorption and extraction of the sedum alfredii to cadmium are utilized to reduce the content of the effective cadmium in farmland soil, and on the other hand, the intercropping effect among plants is utilized to reduce the absorption and accumulation of the cadmium in corn, so that the safe planting of the farmland corn polluted by medium and light cadmium is achieved on the premise of not damaging the ecological environment of the farmland and the existing planting function, and the normal production of grain crops and the income of farmers are not influenced on the premise of guaranteeing the safety of the corn. The method has the advantages of low investment, low management technical requirement, no damage to the physicochemical property of soil and no secondary pollution, and is a farmland 'production and restoration while production' technology with wide application range, low investment and simple operation.
2. The application of the barley root secretion promotes the absorption of the southeast rhodiola to the Cd in the soil, and the removal rate of the Cd in the soil is obviously improved compared with the application of no barley root secretion, so that the economic benefit and the environmental benefit are better.
Detailed Description
According to the regulations of soil environmental quality agricultural land soil pollution risk management and control standard (trial run) (GB 15618-2018), agricultural land pollution risk screening value and control value are regulated, wherein the requirements of the risk screening value and the control value standard of heavy metal cadmium are respectively shown in the following table 1 and table 2, and according to the regulations of pollutant limit in food safety national standard food (GB 2762-2017), the pollutant limit in food is regulated, wherein the heavy metal cadmium content in grains is regulated as shown in the table 3.
TABLE 1 agricultural soil risk screening values
Table 2 agricultural land soil risk control values
TABLE 3 Standard for cadmium Limit in grains
| Food type | Quantity limited (mg/kg) |
| Cereal | 0.1 |
The following examples and comparative examples:
the organic fertilizer (organic matter is more than or equal to 45%, N+P) 2 O 5 +K 2 O is more than or equal to 5%;35 kg/bag), nitrogen-phosphorus-potassium compound fertilizer (N+P) 2 O 5 +K 2 O≥45％；50 kg/bag) of cadmium, lead, arsenic, chromium and mercury all meet the requirements of the standard GB38400-2019, the cultivation management adopts a heavy metal detection method specified in the soil environmental quality standard (GB 15618-2018) to measure the total cadmium content in soil samples according to the conventional management mode, the heavy metal cadmium content in corns is measured according to the method specified in GB5009.15-2014, and the heavy metal cadmium content in sedum alfredii adopts HNO 3 /HClO 4 Wet ashing, atomic absorption spectrophotometry.
The test land is 1.2 mu farmland (dry land) of Yi Jiang He Zhen Yi Zhen He Zhen in Hunan province, and the pH of the soil of the land is: 5.66, the total cadmium content of heavy metals is: 0.681mg/kg exceeds the risk screening value in the soil pollution risk management and control Standard (trial) for agricultural land with soil environmental quality (GB 15618-2018), corn is planted in the farmland, and the phenomenon that the cadmium content of the produced corn exceeds the standard is caused.
Example 1: a intercropping method for safely planting corn while repairing farmland with moderate and mild cadmium pollution comprises the following steps:
(1) Weeding, applying a base fertilizer, turning over, preparing land and ridging the farmland of the selected test land in sequence on 5-15 days of 11 months in 2019, sowing barley seeds (Xiangpi No. 2) into the soil to be repaired, wherein the sowing amount is 12 kg/mu, and carrying out cultivation management;
(2) In the period of vigorous growth (long stem tillering stage) of barley, the whole barley plant is pulled up, the root is not damaged by careful operation as far as possible, the barley root secretion is collected and stored for standby, and the barley plant is used for biogas fermentation after the collection of the barley root secretion is completed;
wherein, the extraction steps of the barley root secretion are as follows:
(1) taking fresh whole barley plants, cleaning roots, and adding 0.5mmol/L CaCl 2 Extracting root secretion from the solution (barley root is CaCl) 2 The solution was completely submerged, using CaCl approximately per gram (g) of barley root 2 The volume of the solution is 15-20 mL), the overground part maintains a normal growth environment, the root part is a shading environment, the solution is kept for 48h, and CaCl is replaced once in 24h 2 A solution;
(2) combining step(1) CaCl of the root of the barley is soaked for two times 2 Filtering the solution by adopting 300-mesh filter cloth to remove impurities and obtain barley root system secretion, removing overground parts of the whole barley plants in the step (1), taking roots, weighing the total weight W (g) of the barley root system, diluting the barley root system secretion by deionized water until the volume is V (L), wherein the concentration of the barley root system secretion after dilution is as follows: wg/VL=5g/L, and putting the mixture into an environment of 2-6 ℃ for cold storage for standby;
(3) Screening corn varieties: by local investigation, locally popular maize varieties are planted (Xiang Oryza 2008);
(4) Weeding, applying a base fertilizer, ploughing, preparing land and ridging are sequentially carried out in the farmland with moderate and slight cadmium pollution, in which barley is planted in the farmland (11 months in 2019 to 4 months in 2020) in 5 months in 2020;
(5) The seedling of the sedum alfredii is obtained by placing the seedling of the sedum alfredii in a greenhouse plug by adopting a cutting method for propagation and seedling raising; sprouting of the rice seedlings: soaking semen Maydis in water for 8 hr, spreading the soaked semen Maydis on wet gauze, covering with rice straw, watering once every 12-16 hr, and controlling temperature at 25-30deg.C for 3-4 days; transplanting the seedling of the Sedum alfredii in 2020 to the farmland soil of the selected test place together with the corn seedling; planting corn seedlings and southeast sedum seedlings in a intercropping mode, planting 2 rows of corn and 3 rows of southeast sedum in each ridge, wherein the intercropping planting density plant spacing of the corn and the southeast sedum is 20-30 cm, the row spacing is 30-40 cm, and 3 ridges are planted (3 times of repetition); after the maize seedlings and the sedum alfredii seedlings are transplanted for 2 weeks, dressing a nitrogen-phosphorus-potassium compound fertilizer and an organic fertilizer for promoting the growth of the sedum alfredii and the maize, wherein the amount of the nitrogen-phosphorus-potassium compound fertilizer is 100 kg/mu, and the amount of the organic fertilizer is 200 kg/mu;
(6) Irrigating the root of the Sedum alfredii with the root secretion of barley (5 g/L) for one week after the fertilizer is applied, wherein the irrigation amount of the root secretion of barley for the first time is 100mL per plant;
(7) After the maize seedlings and the sedum alfredii seedlings are transplanted for 3 months, dressing again a nitrogen-phosphorus-potassium compound fertilizer and an organic fertilizer for promoting the growth of the sedum alfredii and the maize, wherein the amount of the nitrogen-phosphorus-potassium compound fertilizer is 100 kg/mu, the amount of the organic fertilizer is 200 kg/mu, and one week after dressing fertilizer, irrigating the root of the sedum alfredii with barley root secretions (5 g/L), and the irrigation amount of the barley root secretions for the second time is 200mL per plant;
(8) And (3) harvesting the corn and the sedum alfredii when the black layer at the base of the corn grains is formed and the milk line of the corn grains disappears, namely after the corn is ripe, adopting a local conventional planting management mode, and 9 months and 5 days to 15 days in 2020.
Sampling: the method comprises the steps of repeatedly collecting 3 samples of the aerial parts of the southeast rhodiola and corresponding rhizosphere soil samples, corn fruits and corresponding rhizosphere soil samples; the total cadmium content of heavy metals in rhizosphere soil, the cadmium content of heavy metals in the overground part of the sedum alfredii and the cadmium content of heavy metals in corn fruits are measured, and the results are shown in Table 5.
Example 2: a intercropping method for safely planting corns while repairing a farmland with moderate and slight cadmium pollution comprises the same steps as in the embodiment 1, wherein the difference is that the irrigation amount of the barley root secretions in the steps (5) - (6) in the embodiment 2 is different, the barley root secretions are irrigated to the roots of the sedum alfredii by 3 ridges (3 repetitions) in the embodiment 2, the irrigation amount of the barley root secretions is 150mL per plant for the first time, and the irrigation amount of the barley root secretions is 250mL per plant for the second time.
The heavy metal cadmium contents in the rhizosphere soil, the sedum alfredii and the corn harvested in example 2 were respectively measured by the same method as in example 1, and the results are shown in table 5.
Example 3: a intercropping method for safely planting corns while repairing farmlands with moderate and slight cadmium pollution comprises the same steps as in the embodiment 1, wherein the difference is that barley root secretions are broadcast in different amounts in the steps (5) - (6) in the embodiment 3, the barley root secretions are irrigated to the roots of the sedum alfredii by 3 ridges (3 repetitions) in the embodiment 2, the irrigation amount of the barley root secretions is 200mL per plant for the first time, and the irrigation amount of the barley root secretions is 300mL per plant for the second time.
The heavy metal cadmium contents in the rhizosphere soil, the sedum alfredii and the corn harvested in example 3 were respectively measured by the same method as in example 1, and the results are shown in table 5.
The irrigation amounts of the barley root exudates in examples 1 to 3 are shown in Table 4.
Comparative example 1: intercropping method for planting corn in farmland with moderate and mild cadmium pollution
Taking 3 ridges from the test field, intercropping and planting corn and sedum alfredii, wherein the planting method and the cultivation method are the same as those of the embodiment 1, and the difference is that in the comparison example 1, the root secretion of the barley is irrigated to the root of the sedum alfredii in the steps (5) - (6) is changed into distilled water with the same volume as that of the root secretion, and other steps are identical to those of the embodiment 1. The contents of heavy metal cadmium in the rhizosphere soil, the sedum alfredii and the corn harvested in comparative example 1 were measured by the same method as in example 1, and the results are shown in Table 5.
Comparative example 2: method for planting corn in farmland with moderate and mild cadmium pollution
3 ridges are taken from the test field, corn is singly planted, the planting method and the cultivation method are the same as those of the embodiment 1, the difference is that the southeast sedum is not planted in the comparative example 2, the step of irrigating the root secretion of the barley is omitted, and other steps are the same as those of the embodiment 1. The heavy metal cadmium content in the soil harvested in comparative example 2 and the heavy metal cadmium content in corn were measured by the same method as in example 1, and the results are shown in Table 5.
Table 4 amount of root system secretion (unit: mL) in examples
| Number of times | 1 st time | 2 nd time |
| Example 1 barley root secretion dosage | 100 | 200 |
| Example 2 barley root secretion dosage | 150 | 250 |
| Example 3 barley root secretion dosage | 200 | 300 |
TABLE 5 statistical table of cadmium content detection results of rhizosphere soil and crops (unit: mg/kg)
| Test group | Corn kernels | Corn rhizosphere soil | The overground part of the southeast rhodiola | Sedum alfredii rhizosphere soil |
| Example 1 | 0.097 | 0.502 | 2.865 | 0.425 |
| Example 2 | 0.075 | 0.487 | 3.293 | 0.383 |
| Example 3 | 0.088 | 0.491 | 3.176 | 0.417 |
| Comparative example 1 | 0.111 | 0.545 | 2.779 | 0.469 |
| Comparative example 2 | 0.115 | 0.579 | / | / |
Note that: the test results were averaged over 3 replicates.
As can be seen from Table 5, by adopting the method for intercropping the southeast sedum and the corns, the content of heavy metal cadmium in the corn kernels obtained by spraying the barley root secretions on the southeast sedum is lower than that in corn obtained by spraying the barley root secretions on the intercropped southeast sedum but not on the southeast sedum and the corn kernels obtained by singly planting the corn, and the method reaches the regulations of pollutant limit (GB 2762-2017) in food safety national standard food, and the content of heavy metal cadmium in the harvested southeast sedum is higher than that in the intercropped southeast sedum but not on the terrestrial parts of the southeast sedum. The method for intercropping the sedum alfredii and the corn is matched with the planting mode of irrigating the root of the sedum alfredii by the root exudates of the barley, so that the heavy metal cadmium in the soil is enriched into the sedum alfredii, the heavy metal cadmium content in the corn is reduced, the regulations of pollutant limit in food safety national standard food (GB 2762-2017) are met, the preferred application amount of the root exudates of the barley can be obtained from the table 5 to be about the application amount of the embodiment 2, and meanwhile, the average reduction rate of the heavy metal cadmium content in the soil of the embodiment is 11 percent (the average value of the heavy metal cadmium content in the root soil of the corn and the sedum alfredii in all embodiments is obtained after the reduction, and the average value of the heavy metal cadmium content in the rhizosphere soil of the corn is compared with the rhizosphere soil of the comparative example 1). The method can safely plant corn meeting the national standard, has obvious soil restoration effect, and can be used for 'production and restoration at the same time' of farmlands with medium and light cadmium pollution.
Claims (4)
1. The intercropping method for safely planting corn while repairing a farmland with moderate and mild cadmium pollution is characterized by comprising the following steps of:
(1) Planting barley: in 11 months of the first year, weeding, applying a base fertilizer, ploughing, preparing land and ridging are sequentially carried out on a farmland with moderate and mild cadmium pollution, wherein the total amount of heavy metal cadmium in the farmland is 0.3-1.0mg/kg, and barley seeds are sowed into the soil to be repaired for cultivation management;
(2) In spring of the next year, in the period of vigorous growth of barley, the whole barley plant is pulled up, carefully operated without damaging the root, the root is cleaned, and 0.5mmol/L CaCl is added 2 In the solution, 10-20mL CaCl is used per gram of barley root 2 Extracting root secretion with the solution, maintaining the normal growth environment of overground part, shading the root for 36-48 hr, and changing CaCl during extraction 2 Filtering the solution once, removing impurities until no obvious impurities are found, obtaining barley root secretion, diluting the obtained barley root secretion with deionized water to a concentration of 5g/L, and putting the barley root secretion into an environment of 2-6 ℃ for cold storage for later use; after the collection of the barley root secretions is completed, carrying out innocent treatment on barley plants;
(3) In the next 5 months of year, weeding, applying a base fertilizer, turning over, preparing soil and ridging are sequentially carried out in a farmland polluted by medium and light cadmium, corn seedlings and southeast sedum seedlings are planted in a intercropping mode, 2 rows of corn and 3 rows of southeast sedum are planted in each ridge, and the intercropping planting density of the corn and the southeast sedum is: the plant spacing is 20-30 cm, and the row spacing is 30-40 cm;
(4) Dressing nitrogen-phosphorus-potassium compound fertilizer and organic fertilizer for promoting the growth of the sedum alfredii and the corn, wherein the dressing fertilizer is carried out twice, the first time is 10-15 days after transplanting the corn seedlings and the sedum alfredii seedlings, and the second time is 80-100 days after transplanting the corn seedlings and the sedum alfredii seedlings; irrigating the root of the Sedum alfredii with the root secretion of the barley with the concentration of 5 g/L7-10 days after the fertilizer is applied; the irrigation amount of the first barley root secretion is 150mL per plant, and the irrigation amount of the second barley root secretion is 250mL per plant;
(5) Harvesting the corn and the sedum alfredii after the corn is ripe;
the concentration calculation method of the diluted barley root secretion comprises the following steps: and removing overground parts of the barley plants subjected to root exudate extraction, taking roots, wherein the ratio g/L of the total weight of the barley root system to the volume of the diluted barley root exudate is the concentration of the diluted barley root exudate.
2. The intercropping method for safely planting corn while repairing a farmland with moderate and mild cadmium pollution according to claim 1, wherein the two topdressing amounts are the same, wherein: the organic fertilizer amount is 200 kg/mu, and the nitrogen-phosphorus-potassium compound fertilizer amount is 100 kg/mu.
3. The intercropping method for safely planting corn while repairing a farmland with moderate and mild cadmium pollution according to claim 1, wherein the sedum alfredii seedling is obtained by breeding and raising seedlings by adopting a cutting method.
4. The intercropping method for safely planting corn while repairing a farmland with moderate and light cadmium pollution according to claim 1, wherein the spreading amount of barley seeds is 12-15 kg/mu.
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| CN107790491A (en) * | 2017-12-13 | 2018-03-13 | 江西夏氏春秋环境股份有限公司 | It is a kind of to utilize the method for making restoring cadmium polluted farmland between corn and Sedum alfredii Hance |
| CN110052485A (en) * | 2019-04-16 | 2019-07-26 | 浙江大学 | A method of strengthen to extract using rape-Sedum alfredii Hance intercropping and interplanting and repairs cadmium mild or moderate polluted agricultural land |
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| CN107790491A (en) * | 2017-12-13 | 2018-03-13 | 江西夏氏春秋环境股份有限公司 | It is a kind of to utilize the method for making restoring cadmium polluted farmland between corn and Sedum alfredii Hance |
| CN110052485A (en) * | 2019-04-16 | 2019-07-26 | 浙江大学 | A method of strengthen to extract using rape-Sedum alfredii Hance intercropping and interplanting and repairs cadmium mild or moderate polluted agricultural land |
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| 刘君等.根系分泌物.《花生镉吸收积累的品种间差异及影响因素》.北京理工大学出版社,2019,(第一版), * |
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