CN102986428B - Crop rotation matching and fertilizing method capable of controlling accumulation of rice heavy metal cadmium - Google Patents

Abstract

The invention relates to a stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice, which belongs to the technical field of rice planting. ^It includes the following steps: 1) Select cruciferous or leguminous crops with high sulfur content as the previous crop; 2) Apply sulfur-based fertilizer with a sulfur value of 0.25-5.0kg/666.7m Spray 0.05-1.0% sulfate at least 1-3 times; 3) 5-15 days before rice transplanting, use the previous stubble as green manure, crush it or directly plow it into the ground and mix it with the soil, and flood it to Rice seedlings are transplanted; 4) Repeat steps 1)-3) between years. The previous stubble matching mode used in the present invention comes from the traditional production methods of farmers, and sulfur fertilizer is also a traditional farming measure. The operation process is simple, the price is low, and the use cost is low. This method is generally applicable to all heavy, medium and light cadmium pollution in my country. Paddy fields and land for crop production can significantly reduce the cadmium content in rice.

Description

A stubble collocation and fertilization method to control the accumulation of heavy metal cadmium in rice

technical field

The invention belongs to the technical field of rice planting, and in particular relates to a stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice.

Background technique

Cadmium, as a toxic heavy metal, has become more and more polluting to crops, and the polluted area of farmland is expanding day by day. Cadmium is a kind of toxic heavy metal and environmental pollutant with a long half-life. In addition to causing human and animal In addition to acute and chronic poisoning, it also has a strong carcinogenic effect. In recent years, due to industrial "three wastes", sewage irrigation, and large-scale application of pesticides and fertilizers, the pollution of heavy metals in farmland has intensified, and the safety of heavy metals in rice has become increasingly prominent. According to the results of the 2002 and 2003 rice quality and safety surveys conducted by the Rice and Product Quality Supervision, Inspection and Testing Center of the Ministry of Agriculture, one of the quality and safety problems of rice is that heavy metals such as cadmium and lead exceed the standard, and the exceeding rate exceeds 10%. The cadmium content of rice in the area is as high as 0.4-1.0mg/kg, far exceeding the maximum allowable cadmium content of 0.2mg/kg in grains in my country, which has threatened food safety and human health. Controlling and reducing cadmium pollution in rice needs to be solved urgently. At present, two important ways to control the accumulation of cadmium in rice are to select varieties with low cadmium accumulation and to reduce the level of available cadmium in soil through agronomic measures.

Aiming at the current situation of paddy field soil and rice heavy metal cadmium pollution becoming more and more serious, a large number of researches on rice cadmium accumulation low-accumulation variety selection and agronomic cultivation techniques have been carried out at home and abroad. The extremely significant differences in cadmium accumulation among rice varieties (rice, the same below) are the essence and basis for the selection of rice varieties with low cadmium accumulation. However, the differences in rice cadmium accumulation are not stable and lasting differences. This difference is closely related to the metabolic pathways of rice utilizing mineral elements, and even these metabolic pathways determine this difference. For example, the utilization pathway of iron in rice is in the To a large extent, it determines the accumulation of cadmium in rice. The current screening of rice varieties with low cadmium accumulation does not take the above factors into consideration, so the selected low cadmium accumulation varieties often have obvious regional differences, and even significant differences between years. In the current production, there is no rice variety at home and abroad that can be used for the production of rice with low cadmium accumulation.

The cadmium (available cadmium) in the soil that can be absorbed by plants is an important factor affecting the absorption and accumulation of cadmium in rice. Therefore, there is a theoretical basis for reducing the accumulation of cadmium in rice by reducing the available cadmium content in paddy soil through agronomic measures. Therefore, the current research on reducing the accumulation of cadmium in rice through the regulation of rice field fertilizer and water, the regulation of soil pH, and the regulation of soil redox potential has been widely carried out at home and abroad. Fertilizer and water regulation is to reduce the available cadmium content in paddy fields through reasonable fertilization and water irrigation techniques. Long-term flood irrigation is a relatively effective way. However, long-term flood irrigation consumes a lot of irrigation water, which is of great concern to northern my country where water resources are increasingly serious. It is unrealistic and not conducive to the growth of rice in the region and some arid regions in the south, and its utilization value is very limited. Applying lime to increase soil pH and reduce the available cadmium content in paddy soil is also an effective technical path, but this technology has great disadvantages. When the pH value of the soil increases, the content of available iron, zinc, manganese, copper, nickel and other metal mineral nutrients in the soil drops sharply, which seriously damages the growth of rice and affects the yield of rice. Since soil cadmium is mainly absorbed and utilized by roots through the absorption of iron, manganese, copper, zinc and other mineral nutrients, controlling the content of available iron and other elements in the soil is an important way to control the accumulation of heavy metal cadmium in rice. The Chinese patent with the publication number CN101133710A has disclosed that soil cadmium can enter the plant body through the iron absorption and metabolism pathway of the rice root system, and has invented agronomic measures to control rice cadmium accumulation through soil application of integrated ferrous fertilizer; and the publication number The Chinese patent CN101507400A discloses the process that soil cadmium can be absorbed into the plant body by the rice root system through the manganese absorption pathway and enter the shoot and grain through the manganese transport pathway, and has invented the method of using soil chelated manganese (divalent) and spraying Agronomic measures of manganese application to control cadmium accumulation in rice. However, the use of chelated divalent metals is relatively large, and the price is relatively high, resulting in high costs.

Contents of the invention

Aiming at the problems existing in the prior art, the present invention provides a design based on the fact that the soil available cadmium content (concentration) is the most critical factor for the absorption and accumulation of cadmium in the rice root system, utilizing the chemical characteristics of cadmium and the solubility of different compounds in the solution, etc. A technical scheme for stubble matching and fertilization methods to control the accumulation of heavy metal cadmium in rice.

Cadmium is a transition element, and divalent cadmium ions belong to Lewis Acid (LA), which can form very stable compounds with S ²⁺ (or mercapto-SH) (Lewis base). Cadmium in plants can form stable compounds with various sulfhydryl compounds, such as glutathione, phytochelatin (PCs) and cysteine. This mechanism has been generally confirmed as the key mechanism for plant cadmium detoxification.

Sulfur is an intermediate element required by crops. It can be divided into inorganic sulfur and organic sulfur in soil. Inorganic sulfur usually exists as sulfate (oxidative soil) and sulfide (anaerobic soil); while organic sulfur usually exists Among microorganisms, organic matter and straw residues, the organic sulfur in paddy soil can reach more than 80% of the total soil sulfur. Returning straw to the field is a traditional farming measure in agricultural production; applying organic fertilizer is also a common fertilization technology in agricultural production. Straw returning and organic fertilizer are usually used as agricultural techniques to increase soil organic matter and improve soil structure. In fact, studies have also shown that straw returning and organic manure are also the main sources of organic sulfur in soil. Studies have shown that the application of organic fertilizers can greatly reduce the accumulation of cadmium in rice plants. It is generally believed that the main mechanism may be that the increase of soil organic matter may increase the cation exchange capacity of the soil, thereby absorbing more cadmium ions and reducing the effective amount of cadmium in the soil solution. State cadmium concentration. However, we speculate that the organic sulfur content in organic fertilizers is high, and the application of organic fertilizers increases the organic sulfur in the soil, which can strongly combine with cadmium ions in the soil, resulting in cadmium ions in the soil. From another perspective, it is speculated that the application of organic fertilizers or the use of high-sulfur previous stubble as green manure to increase soil organic sulfur should be more effective in controlling the accumulation of cadmium in later-season crops such as rice. At present, crops with high sulfur content in straw have been clearly identified in production, such as cruciferous plants, such as rape, cabbage, and leguminous plants, such as soybeans, and the sulfur content can be further significantly increased by applying sulfur fertilizer. Based on the fact that mercapto groups as Lewis bases and cadmium as Lewis acids can only form very stable compounds, the application of sulfur fertilizers can significantly increase the sulfur content of crop straws, thereby increasing the characteristics of soil organic sulfur. Through research and practice, a control method has finally been developed. Stubble matching and fertilization methods for accumulation of heavy metal cadmium in rice.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that it comprises the following steps:

1) Select cruciferous or leguminous crops with high sulfur content as the previous stubble;

2) Apply sulfur-based fertilizer of 0.25-5.0kg/666.7 ^m2 in terms of sulfur when planting the previous crop, or spray 0.05-1.0% sulfate at least twice during the growth period;

3) 5 to 15 days before rice transplanting, use the previous stubble as green manure, crush it or directly plow it into the ground and mix it with the soil, and flood it until the rice seedlings are transplanted;

4) Repeat steps 1)-3) between years.

2. A method of stubble collocation and fertilization for controlling the accumulation of heavy metal cadmium in rice as claimed in claim 1, characterized in that in said step 1), the Brassicaceae are rapeseed, cabbage, kale, cabbage, kohlrabi, kale Leaf mustard, multi-lobed mustard, cauliflower or mustard, leguminous crops are soybeans, kidney beans, lentils, alfalfa, milk vetch, field greens or sweet potatoes.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that the sulfur-based fertilizer of 0.5-4.0 kg/666.7 m ² in terms of sulfur is applied when the previous stubble is planted in the step 2); or Spray 0.1-0.75% sulfate in the peak growth period.

The stubble collocation and fertilization method for controlling heavy metal cadmium accumulation in rice is characterized in that 1.0-2.0 kg/666.7 ^m2 of sulfur-based fertilizer is applied when planting the previous stubble in the step 2); or Spray 0.25-0.5% sulfate in the peak growth period.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that the sulfur-based fertilizer in the step 2) is gypsum, ferrous sulfate, ferric sulfate, potassium sulfate, sodium sulfate, calcium sulfate, ammonium sulfate and one or more mixtures of magnesium sulfate; the sulfate is one or more mixtures of ferrous sulfate, ferric sulfate, potassium sulfate, sodium sulfate, ammonium sulfate and magnesium sulfate.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that the sulfur-based fertilizer in the step 2) is directly applied to the soil, and then fully mixed with the soil.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that in the step 2), sulfate is first dissolved in water and then sprayed.

The stubble collocation and fertilization method for controlling the accumulation of heavy metal cadmium in rice is characterized in that the previous stubble straw is used as green manure in the step 3).

The previous stubble matching mode used in the present invention comes from the traditional production methods of farmers, and sulfur fertilizer is also a traditional farming measure. The operation process is simple, the price is low, and the use cost is low. This method is generally applicable to all heavy, medium and light cadmium pollution in my country. Paddy fields and land for crop production can significantly reduce the cadmium content in rice. At the same time, the method can also improve soil organic matter, provide sulfur for rice growth, and improve rice field soil, thereby promoting rice growth and increasing rice yield. Compared with the prior art, the present invention fully complies with the high multiple cropping index of rice fields and the crop rotation system of multiple crops, and the operation process is also completely combined with the traditional farming process of farmers. It is also more environmentally friendly and can be widely accepted by farmers.

Detailed ways

The present invention will be further described below in conjunction with the examples.

Experimental example 1:

1. Experimental Design

1.1 Experimental matching mode: the matching mode was set to rape-rice, milk vetch-rice, and the idle-rice mode was used for comparison.

1.2 Cultivation of previous crop straw with different sulfur content: sow rapeseed and milk vetch seeds, set 0, 0.01, 0.05 g/kg sulfur treatment (gypsum) after sowing, and harvest rapeseed 15 days before rice transplanting (in full bloom period), milk vetch, sampling and determination of plant sulfur content;

1.3 Straw returning treatment: Soil potting with 9kg of dry soil, Cd content (full amount) of 5.70 mg/kg 10L, and upper diameter of 35 cm. Rapeseed rape and milk vetch according to the same dry weight were respectively turned into the soil as green manure (the turned-in amount was 0.39 g/kg) and flooded until the rice was transplanted. Each treatment was repeated 3 times.

1.4 Rice seedling raising and transplanting: the early rice Zhongzao 22 was used as research material. The seeds were soaked in the soaking spirit water solution for 48 hours, and germinated at 30-35°C for 24 hours. Bud Valley was sown on a sand bed washed with dilute sulfuric acid, with seedlings growing to 4 leaves and 1 heart, and seedlings with consistent growth were selected for transplanting and potting experiments. Transplant 4 holes per pot, 3 plants per hole.

2. Measurement items

Sampling, determination and analysis during the harvest period of rice;

The plant samples were divided into two parts, the kernel (polished rice) and the aerial part.

The samples were dried at 80°C for 3 days to constant weight. After crushing the dry sample, weigh 0.5000g and digest it with a mixture of concentrated nitric acid and perchloric acid at a ratio of 1:3. Spectrometer (ICP-AES) was used to determine the cadmium content.

3. Results and Analysis

3.1 Rice yield characteristics under different treatments

Whether it was rapeseed or milk vetch in the previous crop, after all the straw was returned to the field, the total grain number, solid grain number and thousand-grain weight of Zhongzao 22 increased, and the rice yield per pot also increased significantly (Table 1). As a farming technique, paddy fields have a significant effect on increasing the yield of rice in the second season. In the previous crops, with the increase of sulfur treatment, the yield traits of Zhongzao 22 were also better improved after the corresponding previous crop straw was returned to the field. The production of off-season rice is more favorable; however, this effect may also be due to the application of sulfur fertilizer in the previous crop production process, which suggests from another aspect that the soil used in this experiment may be insufficient in available sulfur.

Table 1. Effects of different previous stubble and sulfur fertilizer treatments on the yield of the late-season rice Zhongzao 22

3.2 Cadmium content in rice plants under different treatments

The cadmium content in the above-ground parts of Zhongzao 22 plants and in milled rice decreased significantly after all the straw was returned to the field whether it was rapeseed or milk vetch in the previous crop (Table 2). However, with the increase of the treatment of sulfur fertilizer in the previous cropping, no matter whether rape was used as green manure or milk vetch had a very obvious inhibitory effect on the cadmium content in the shoots and grains of rice plants in the later seasons. Among them, the cadmium content of the rape straw treated with 0.05 g/kg sulfur was only 17.48% of that of the idle stubble after returning to the field, and the cadmium content in the polished rice was only 0.19 mg/kg; milk vetch also showed Similar phenomenon, but the control effect on plant cadmium accumulation is obviously not as good as that of rapeseed. Generally speaking, increasing the sulfur content of straw through the application of sulfur fertilizer in the previous stubble, and returning the straw to the field, has a significant effect on controlling the accumulation of cadmium in rice.

Table 2. Effects of different previous stubble and sulfur fertilizer treatments on cadmium accumulation in the later season rice Zhongzao 22 plants

Test example 2

1. Experimental design:

This experiment was carried out in Huanyi Village, Huanshan Town, Fuyang City, Zhejiang Province in 2011 and 2012. The town relies on waste ore copper smelting as its economic source all the year round. Due to the excessive discharge of wastewater, heavy metal cadmium pollution in the local paddy soil is very serious. The total cadmium content in the soil is 4.13 mg/kg. The cadmium content in DTPA extract is 1.29 mg/kg, which is not suitable for rice production.

The experiment adopts a large-scale comparative test without repetition. The large area is 0.5 mu. The experimental settings are rapeseed, rapeseed + sulfur spraying treatment, rapeseed + sulfur as base fertilizer treatment, winter idle + sulfur as base fertilizer treatment, CK (winter Idle), on April 18, 2011, the flowering rapeseed was plowed into the field as green manure. The rice variety is Zhongzao 22, which was sown on April 5, 2012 and transplanted on April 29. Rapeseed+sulfur spraying treatment: Spray 0.2% ammonium sulfate (calculated as sulfur) three times on March 25, April 5th, and 15th; Add 1.25 kg of calcium sulfate; idle in winter + sulfur as base fertilizer treatment: do not plant the previous crops, but simulate the soil preparation and spread 1.25 kg of calcium sulfate. Others are the same as usual. This experiment was repeated in 2012 (the operation process was the same).

During the harvest period, the actual rice yield and rice cadmium content in the large area were measured. The samples used for the determination of cadmium content in rice were sampled by the five-point sampling method in a large area. Polished rice samples were dried at 80°C for 3 days to constant weight. After crushing the dry sample, weigh 0.5000g and digest it with a mixture of concentrated nitric acid and perchloric acid at a ratio of 1:3. (ICP-AES) determination of cadmium content.

2. Results and analysis:

2.1 Effects of different previous crop combinations and sulfur fertilizer application on rice yield traits

 Compared with winter idling (CK), no matter whether sulfur fertilizer application or the combination of rapeseed and sulfur fertilizer as the first cropping treatment had a significant impact on rice yield and related trait parameters. The treatment of idle winter + sulfur-based fertilizer resulted in a significant increase in the number of effective panicles and the number of solid grains per panicle, but had no effect on the thousand-grain weight, which indicated that applying sulfur-based fertilizer to the soil in winter can promote the production of late-season early rice. Rapeseed as green manure usually also increases the number of effective panicles and the number of solid grains per panicle, thereby promoting the increase of per unit yield. This also shows that rapeseed as green manure can promote the growth of late-season early rice. Applying sulfur-based fertilizers during the planting of green manure rapeseed or spraying sulfur fertilizers during the growth of rapeseed can promote the increase in the number of effective panicles and the number of solid grains per panicle, thereby increasing rice yield. Among the rapeseed treatments, the sulfur fertilizer treatment had no significant effect on rice yield traits and yield. The results showed that the use of rape as green manure or the application of sulfur fertilizer in the previous crop both had obvious promoting effects on the growth and yield of rice. These results were consistent in 2011 and 2012.

Table 3. Effects of different previous crop combinations and sulfur fertilizer application on rice yield traits

2.2 Effects of different previous crop combinations and sulfur fertilizer application on the accumulation of cadmium in Zhongzao 22

When the paddy fields were idle (CK) in winter, the cadmium in mid-early 22 rice was as high as 0.892 mg/kg in 2011, and as high as 0.977 mg/kg in 2012, both of which were much higher than the national standard of 0.2 mg/kg. The application of sulfur-based fertilizers in paddy fields in winter or planting rapeseed (or application of sulfur fertilizers) significantly reduced the level of cadmium in grains. When only sulfur-based fertilizer was applied, the cadmium content in grains in 2011 and 2012 was only about 50% of the control. When only rapeseed was planted as green manure, the cadmium content in grains in 2011 and 2012 was only about 1/3 of that in the control. However, soil application or spraying of sulfur fertilizer during the previous crop of rape planting can significantly reduce the level of cadmium in rice, both of which are lower than 0.2 mg/kg, and soil application of sulfur-based fertilizer is significantly lower than that of spraying sulfur fertilizer. The results showed that rapeseed as green manure or sulfur fertilizer could significantly reduce the cadmium content in rice, and when rapeseed was used as green manure and sulfur fertilizer combined treatment showed an interactive effect, and the inhibitory effect on rice cadmium accumulation was more obvious.

Table 4. Effects of different previous crop combinations and sulfur fertilizer application on the accumulation of cadmium in Zhongzao 22

In Test Example 2, cabbage, kale, cabbage, kohlrabi, mustard greens, cauliflower, mustard greens, soybeans, green beans, lentils, alfalfa, milk vetch, kale or sweet potato were used in the previous stubble; Apply gypsum, ferrous sulfate, ferric sulfate, potassium sulfate, sodium sulfate, calcium sulfate, ammonium sulfate or magnesium sulfate at 0.25, 1, 3 or 5 kg/666.7 ^m2 in terms of sulfur when planting the previous crop; Spray 0.05%, 0.5%, 0.8% of ferrous sulfate, ferric sulfate, potassium sulfate, sodium sulfate, ammonium sulfate or magnesium sulfate 3 times during the growth period, and finally the same technical effect as in Test Example 2 can be achieved.

Claims (6)

1. control crops for rotation collocation and the fertilizing method of heavy metal cadmium accumulation of paddy, it is characterized in that comprising the following steps:

1) Cruciferae selecting sulfur content high is front stubble, and described Cruciferae is rape, wild cabbage, cabbage mustard, tender flower stalk, root-mustard, leafy mustard, many lobed leaf mustard, cauliflower or leaf mustard;

2) apply when front stubble is planted and count 0.5 ~ 4.0kg/666.7 m with sulphur ²sulfenyl fertile, or the fertility Sheng phase spray sulphate 1-3 time of 0.1 ~ 0.75%;

3) before rice transplanting 5 ~ 15 days, using front stubble as green manure, pulverize or directly turn over into mix with soil, and waterflooding is transplanted to rice seedling;

4) step 1)-3 is repeated between year).

2. as claimed in claim 1 a kind of control heavy metal cadmium accumulation of paddy crops for rotation collocation and fertilizing method, it is characterized in that described step 2) in before stubble plantation time apply and count 1.0 ~ 2.0kg/666.7 m with sulphur ²sulfenyl fertile; Or in giving birth to the sulphate that the Sheng phase sprays 0.25 ~ 0.5%.

3. as claimed in claim 1 a kind of control heavy metal cadmium accumulation of paddy crops for rotation collocation and fertilizing method, it is characterized in that described step 2) in sulfenyl fertilizer be more than one mixtures in gypsum, ferrous sulfate, iron sulfate, potassium sulfate, sodium sulphate, calcium sulphate, ammonium sulfate and magnesium sulfate; Sulphate is more than one mixtures in ferrous sulfate, iron sulfate, potassium sulfate, sodium sulphate, ammonium sulfate and magnesium sulfate.

4. as claimed in claim 1 a kind of control heavy metal cadmium accumulation of paddy crops for rotation collocation and fertilizing method, it is characterized in that described step 2) in during sulfenyl fertilizer is directly manured into soil, more fully to mix with soil.

5. as claimed in claim 1 a kind of control heavy metal cadmium accumulation of paddy crops for rotation collocation and fertilizing method, it is characterized in that described step 2) in sulphate be first dissolved in water, then carry out executing spilling with spray pattern.

6. as claimed in claim 1 a kind of control heavy metal cadmium accumulation of paddy crops for rotation collocation and fertilizing method, to it is characterized in that front stubble stalk in described step 3) as green manure.