Method for fertilizing tobacco field through flue-cured tobacco-soybean-rape composite planting

Abstract

The invention belongs to the field of crop cultivation, and particularly relates to a flue-cured tobacco-soybean-oilseed rape composite planting tobacco field fertilizing method which comprises the steps of flue-cured tobacco planting, soybean planting and oilseed rape planting, short-stem early-maturing soybean varieties are sown in tobacco field furrows at intervals after flue-cured tobacco transplanting, low-temperature-resistant sclerotiniose-resistant oilseed rape varieties are sown in a tobacco field after soybeans are harvested, and the low-temperature-resistant sclerotiniose-resistant oilseed rape varieties are sown in the tobacco field. Turning and returning to the field when the oilseed rapes bolt to the initial flowering stage; the sowing density of the soybeans is 10000-22000 plants per mu, the sowing density of the oilseed rapes is 15000-2500 plants per mu, and by planting the soybeans and the oilseed rapes, the soil fertility of the tobacco field is improved, the chemical fertilizer consumption of the tobacco field is reduced, and the first-class tobacco proportion and the economic benefit of the flue-cured tobacco are improved.

Description

Technical Field

[0001] The invention belongs to the field of crop cultivation, and in particular relates to a method for fertilizing a tobacco field by composite planting of flue-cured tobacco, soybeans and rapeseed. Background Art

[0002] Flue-cured tobacco is a pillar industry for economic development in remote mountainous areas of my country and a superior industry for farmers in mountainous areas to increase their income and become rich. However, flue-cured tobacco needs to be cured before it can become a commodity. Curing houses are essential facilities for growing tobacco leaves. Due to their high construction costs, crop rotation in mountain tobacco areas is difficult. Planting a single flue-cured tobacco crop for many years in the same tobacco field leads to a decline in soil fertility, insufficient organic matter, and an imbalance of carbon and nitrogen, which in turn leads to soil acidification, increased pests and diseases, and a decline in tobacco yield and quality. Farmers have little benefit from growing tobacco and are not very motivated, and the tobacco industry eventually shrinks and dies.

[0003] Since the same tobacco field has been planted with a single flue-cured tobacco crop for many consecutive years, the process of flue-cured tobacco planting faces problems such as decreased soil fertility, large amount of fertilizer use, and low tobacco leaf quality. Single cultivation of flue-cured tobacco can easily cause soil nutrient imbalance, reduced organic matter content, and poor soil structure. Over-reliance on fertilizers not only increases production costs, but may also cause environmental pollution. At the same time, the utilization efficiency of tobacco fields is not high, and land resources are seriously wasted during idle periods. These factors jointly restrict the sustainable development of the tobacco industry. How to improve soil fertility, reduce fertilizer use, and improve the comprehensive benefits of tobacco fields while ensuring the yield and quality of flue-cured tobacco has become a key technical problem that needs to be solved urgently. This problem involves crop planting pattern optimization, soil fertilization, field management and other aspects, and requires systematic consideration of factors such as tobacco growth characteristics, soil nutrient circulation, and intercropping crop selection. Solving this problem is not only related to the healthy development of the tobacco industry, but also of great significance to improving agricultural production efficiency and protecting the ecological environment. Summary of the invention

[0004] The present invention provides a method for fertilizing a tobacco field by composite planting of flue-cured tobacco, soybean and rapeseed, which mainly comprises: Short-stemmed early-maturing soybean varieties are sown in alternate rows in the ridges of the tobacco field after the tobacco is transplanted. After the soybeans are harvested, low-temperature and bacteria-resistant sclerotinia rape varieties are sown in the tobacco field, and the rapeseed is turned over and returned to the field during the bolting to early flowering period. The soybean sowing density is 10,000-22,000 plants per mu, and the rapeseed sowing density is 15,000-25,000 plants per mu. By planting soybeans and rapeseed, the soil fertility of the tobacco field is improved, the amount of chemical fertilizers used in the tobacco field is reduced, and the proportion of high-quality flue-cured tobacco and the economic benefits are increased.

[0005] Furthermore, the flue-cured tobacco planting includes: land preparation and planting preparation, tobacco leaf transplanting, field management and tobacco leaf harvesting and curing; the land preparation and planting preparation includes applying base fertilizer, tobacco field ridge building and ridge covering; the tobacco leaf transplanting includes step-by-step transplanting, scientific application of rooting water and timely spraying of pesticides for pest control; the field management includes checking seedlings and supplementing seedlings, topdressing management, disease and insect control and topping of tobacco plants.

[0006] Furthermore, the soybean variety is Gandou No. 10; the soybean sowing method is to use mechanical weeding between the tobacco field ridges and then sow in holes in alternate rows in the middle of the tobacco field ridges, with 3-5 seeds in each hole, a hole distance of 15-20cm, and 3500-4500 holes per mu; the soybean field management includes weeding in the middle of the tobacco field management.

[0007] Furthermore, the rapeseed variety is Huayouza No. 45, Qingyou No. 8, Chuanyou 75 or Baoyou 87; the rapeseed sowing method is to clear the plastic film of the tobacco field, pull out the tobacco stalks and crush them with a pull-pole crushing and rotary tillage machine, shallowly plow 5-10cm to break up the tobacco planting ridges, level the land and then sow the rapeseed in the field using direct seeding.

[0008] Furthermore, the rapeseed is turned over in a manner that deep tillage machinery is used for turning over when the rapeseed reaches the bolting to early flowering stage, or the rapeseed is first mowed down with a lawn mower and then rotary tilled or turned over with a small machine.

[0009] Furthermore, by planting soybeans, 4 kg of nitrogen can be fixed each year, which is equivalent to applying about 9 kg of urea; by planting rapeseed, the biomass per mu can reach 800 kg of dry matter, which is equivalent to applying 300 kg of organic fertilizer; the method can increase the carbon-nitrogen ratio of tobacco field soil by 1.58, increase organic matter by 6.8%, and increase the soil cation exchange capacity by 0.5-0.8 cmol (+) / kg.

[0010] Furthermore, through this composite planting and fertilization method, the tobacco fields can reduce the amount of chemical fertilizers applied by 20-30%, increase the proportion of high-quality flue-cured tobacco by 6.5%, and increase the tobacco leaf income by more than 200 yuan per mu; the soybean yield per mu is 150-200 jin, and the income per mu increases by 600-800 yuan.

[0011] The technical solution provided by the embodiment of the present invention may have the following beneficial effects: The invention discloses a composite planting and fertilization method for tobacco fields, which comprises planting short-stem early-maturing soybeans in alternate rows in the middle of the ridges after the flue-cured tobacco is transplanted, planting cold-resistant and disease-resistant rapeseed after the soybeans are harvested, and turning over and returning the rapeseed to the field when it blooms. The method realizes composite planting with flue-cured tobacco by reasonably arranging the sowing density, variety selection and field management of soybeans and rapeseed. Soybeans can fix nitrogen and increase fertilizer, and rapeseed can increase organic matter, thereby jointly improving the soil fertility of the tobacco field. The invention also optimizes the links of land preparation, transplanting and field management of flue-cured tobacco, and forms a complement with composite planting. Through the method, the tobacco field can reduce the amount of chemical fertilizers by 20-30%, increase the proportion of high-quality tobacco by 5%, and increase the tobacco leaf income by more than 200 yuan per mu. At the same time, soybeans can increase the income by 600-800 yuan per mu. The invention not only improves the soil carbon-nitrogen ratio and organic matter content, improves soil properties, but also realizes the efficient composite planting of three crops of flue-cured tobacco, soybeans and rapeseed, and significantly improves the economic and ecological benefits of the tobacco field. DETAILED DESCRIPTION

[0012] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. 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.

[0013] In this embodiment, a method for fertilizing a tobacco field by composite planting of flue-cured tobacco, soybeans and rapeseed may specifically include: S1. After transplanting flue-cured tobacco, short-stemmed early-maturing soybean varieties are sown in alternate rows in the ridges of the tobacco field. After the soybeans are harvested, rapeseed varieties that are resistant to low temperatures and bacterial sclerotinia are sown in the tobacco field. The rapeseed is turned over and returned to the field from the bolting stage to the initial flowering stage.

[0014] After the flue-cured tobacco is transplanted, short-stemmed early-maturing soybean varieties are sown in alternate rows in the ridges of the tobacco field. Varieties with a growth period of about 90 days can be selected, such as Nannong 95-16 and Nannong 89-11. These varieties have short plant types and concentrated pods, which are conducive to mechanized harvesting. When sowing, pay attention to the row spacing, which is generally between 50-60cm, the plant spacing is 10-15cm, and the planting density per mu is between 15,000-22,500 plants. Before sowing, the land should be prepared and fertilized in combination with land preparation. Generally, 15-20kg of compound fertilizer is applied per mu. When sowing, pay attention to controlling the sowing depth to 3-5cm to ensure uniform emergence. After sowing, water in time to ensure emergence, and timely inter-cultivation and weeding to prevent and control diseases and insect pests. After soybeans are harvested, the stubble should be handled in time, and rapeseed should be sown in combination with stubble land preparation. Rapeseed varieties should be selected with strong cold resistance, good disease resistance, and tolerance to dense planting, such as Zhongyouza No. 10, Zhongshuang No. 11, Zhongyou 821, etc. The sowing method is broadcasting, with a sowing rate of 1.0-1.5kg per mu. When sowing, base fertilizer is applied in combination with land preparation, and 25-35kg of compound fertilizer is applied per mu. After sowing, cover the soil and press it down to facilitate germination. After germination, check the seedlings in time to ensure that the seedlings are even. Pay attention to frost protection in winter and spring, and carry out field management measures such as intertillage, weeding, and pest control in time. The period from the bolting of rapeseed to the initial flowering period is the peak period of nutrient accumulation in the plant. At this time, it is the best time to fertilize the soil by turning over and returning the rapeseed to the field, which is fast in decomposition and sufficient in nutrient release. Before turning over and returning the rapeseed to the field, deep plowing or rotary tiller should be used for deep plowing, and the plowing depth should reach more than 25cm to fully mix the rapeseed with the soil. Alternatively, the rapeseed should be cut down and aired with a mower for 2-3 days, and then buried and pressed with a deep plow or rotary tiller when the water evaporates to about 40%. The burial should be uniform and fully mixed with the soil. Generally, 2500-3000kg of fresh rapeseed grass is turned over per mu, which is equivalent to applying 1000-1200kg of organic fertilizer, which can meet the growth needs of the next crop of flue-cured tobacco.

[0015] S2. The soybean sowing density is 10,000-22,000 plants per mu, and the rapeseed sowing density is 15,000-25,000 plants per mu; by planting soybeans and rapeseed, the soil fertility of the tobacco field is improved, the amount of chemical fertilizers used in the tobacco field is reduced, and the proportion of high-quality flue-cured tobacco and the economic benefits are increased.

[0016] As rotation crops of flue-cured tobacco, the reasonable control of planting density of soybeans and rapeseed is of great significance for improving soil fertility in tobacco fields, reducing the use of chemical fertilizers, increasing the proportion of high-quality flue-cured tobacco and economic benefits. As a leguminous crop, soybeans have the characteristics of nitrogen fixation by rhizobia. Planting 10,000-22,000 soybeans per mu can significantly increase the nitrogen level in the soil. Through the growth and development of soybean roots, the soil can be loosened, the soil aggregate structure can be improved, the soil porosity can be increased, and the activity of soil microorganisms can be promoted, thereby improving soil fertility. At the same time, returning soybean straw to the field can supplement soil organic matter, promote soil nutrient circulation, and reduce the application of chemical fertilizers. As a cruciferous crop, rapeseed has the characteristics of a well-developed root system and high coverage. Planting 15,000-25,000 rapeseed plants per mu, the rapeseed root system can penetrate the soil, break the plow bottom layer, and promote soil permeability. Rapeseed has lush stems and leaves and high coverage, which can reduce the growth of weeds and reduce the use of herbicides. Rapeseed has a long flowering period, which can attract pollinating insects such as bees, increase biodiversity, and promote ecological balance. Rapeseed is turned over and returned to the field to supplement soil organic matter, increase soil aggregate structure, improve soil water and fertilizer retention capacity, and create good soil conditions for the growth of subsequent flue-cured tobacco. By planting soybeans and rapeseed at a reasonable density, the soil fertility of tobacco fields can be significantly improved, the physical and chemical properties of the soil can be improved, the activity of soil microorganisms can be promoted, the use of chemical fertilizers and pesticides can be reduced, and the planting cost can be reduced. During the growth of soybeans and rapeseed, the characteristics of leguminous and cruciferous crops can inhibit the occurrence of diseases and pests such as tobacco field nematodes and damping-off, reduce tobacco leaf spots, and improve tobacco leaf quality. The root secretions of soybeans and rapeseed can activate soil nutrients, promote nutrient release, and provide sufficient nutrients for subsequent flue-cured tobacco. After soybeans and rapeseed are planted, soil fertility is improved, the root system of flue-cured tobacco is well-developed, and the ability to absorb nutrients is enhanced, which can reduce the application of chemical fertilizers by 15-20% and reduce planting costs. Through soil testing and formula fertilization, targeted supplementation of nitrogen, phosphorus, potassium and other nutrients required for flue-cured tobacco growth can promote the healthy growth of flue-cured tobacco and increase tobacco leaf yield and quality. The rotation of soybeans and rapeseed can break the obstacles of continuous cropping of flue-cured tobacco, improve land utilization, achieve year-round coverage of tobacco fields, and reduce soil erosion. After crop rotation, the flue-cured tobacco plants are strong, the root system is well-developed, and the ability to resist diseases and pests is enhanced. The proportion of high-quality flue-cured tobacco can be increased by 3-5%, and the income of tobacco farmers can be increased by 1,000-1,500 yuan per mu. Therefore, through the composite planting model of flue-cured tobacco, soybeans and rapeseed, the planting density can be optimized, the tobacco fields can be fertilized, the use of chemical fertilizers can be reduced, the yield and quality of flue-cured tobacco and the economic benefits can be improved, and the sustainable development of the tobacco industry can be achieved.

[0017] S3. The flue-cured tobacco planting includes: land preparation and preparation for planting, tobacco leaf transplanting, field management and tobacco leaf harvesting and curing; the land preparation and preparation for planting includes application of base fertilizer, ridge formation of tobacco fields and ridge covering; the tobacco leaf transplanting includes step-by-step transplanting, scientific application of rooting water and timely spraying of pesticides for pest control; the field management includes checking seedlings and supplementing seedlings, topdressing management, pest control and topping of tobacco plants.

[0018] Land preparation for planting is one of the important links in flue-cured tobacco planting. In the process of land preparation for planting, it is necessary to apply base fertilizer, ridge the tobacco field and cover the ridge. When applying base fertilizer, 50 kg of compound fertilizer is applied per mu, in which the ratio of nitrogen, phosphorus and potassium is 6:12:25. When applying fertilizer, the strip application method is adopted, and the width of the fertilizer belt is controlled at 15-20 cm. After ridge formation, the fertilizer is about 20 cm away from the ridge surface. This fertilization can provide sufficient nutrients for the growth of tobacco seedlings. Ridging of tobacco fields is carried out on the basis of deep plowing and crushing of tobacco fields. The ridge body requires a row spacing of 110-120 cm, a ridge height of not less than 25 cm, a ridge bottom width of not less than 65 cm, and a ridge top width of not less than 40 cm. After ridge formation, the ridge body should be consistent in direction, the ridge surface should be tile-back-shaped, and the ridge body should be fine and full, so as to create good soil conditions for transplanting tobacco seedlings. Ridge mulching is the last step in land preparation and planting. It is required to ensure that the ridge moisture content reaches more than 70%. At the same time, we must pay close attention to local climatic conditions, seize the good weather to quickly cover the mulch, ensure that the mulch is close to the ridge, and the two sides are tightly sealed and pressed to provide good temperature and humidity conditions for the growth of tobacco seedlings after transplanting. Tobacco leaf transplanting is a key link in flue-cured tobacco planting. During the transplanting process, attention should be paid to step-by-step transplanting, scientific application of rooting water, and timely spraying of pesticides for insect control. Step-by-step transplanting refers to transplanting tobacco seedlings from seedling trays to the field in 2-3 times according to the growth of tobacco seedlings. For the first transplanting, choose strong seedlings with strong growth and well-developed root systems, for the second transplanting, choose seedlings with medium growth, and for the third transplanting, choose seedlings with weak growth but able to survive. In this way, step-by-step transplanting can achieve batch management of transplanted seedlings and improve the survival rate of transplanting. When transplanting, scientific rooting water should be applied, and appropriate amounts of carbendazim and other agents can be added to the rooting water to promote the growth of the tobacco seedling root system and improve the survival rate. After transplanting, it is necessary to spray insecticides in time to prevent pests. You can use 4% carbendazim aqueous solution, 10% imidacloprid wettable powder and other pesticides for prevention to prevent tobacco seedlings from being harmed by underground pests. Field management is an important measure to ensure high yield and high quality of flue-cured tobacco. Field management mainly includes seedling inspection and seedling supplementation, topdressing management, pest and disease control and tobacco plant topping. Seedling inspection and seedling supplementation are carried out within 7-10 days after transplanting. Seedlings are supplemented in time in places where seedlings are missing and broken ridges are broken to ensure that the seedlings in the field are uniform. Topdressing management is based on the growth process of tobacco plants. 25 kg of compound fertilizer is applied 20-25 days and 45-50 days after transplanting. Topdressing is done by hole application. 20-25 grams of fertilizer is applied to each hole. The hole is 10 cm deep and 15 cm away from the tobacco plant. Timely topdressing can meet the growth needs of tobacco plants and promote tobacco leaf production and income. Pest and disease control runs through the entire growth period of flue-cured tobacco. It is necessary to prevent and treat tobacco aphids, tobacco budworms, tobacco powdery mildew and other pests and diseases in time. 4% carbendazim aqueous solution, 10% imidacloprid wettable powder, 70% mancozeb wettable powder and other pesticides can be used for prevention and control. Topping the tobacco plant can control the plant height, promote the full maturity of tobacco leaves, and improve the quality of tobacco leaves. The time for topping is generally chosen at the early stage of budding and heading of tobacco plants, and the topping position should be 40-45 cm from the ground. Tobacco leaf harvesting and curing is the last link in flue-cured tobacco planting.During the harvesting and curing process, the tobacco leaves should be harvested from bottom to top in 4-5 times according to their maturity. The harvested tobacco leaves should be woven into bunches in time and cured according to the local curing process. The temperature and humidity should be strictly controlled during the curing process. The temperature should not exceed 35℃ in the initial stage of curing, and the humidity should be kept at 70%-80%. The temperature should be gradually increased to 45℃-50℃ in the middle stage, and the humidity should be reduced to 60%-65%. The temperature should be increased to 60℃-65℃ in the later stage, and the humidity should be reduced to 40%-45%. The whole curing process lasts for 5-7 days. The cured tobacco leaves are golden and shiny, soft and elastic, and have a pure aroma.

[0019] S4. The soybean variety is Gandou No. 10; the soybean sowing method is to use mechanical weeding between the tobacco field ridges and then sow in holes in alternate rows in the middle of the tobacco field ridges, with 3-5 seeds in each hole, a hole distance of 15-20cm, and 3500-4500 holes per mu; the soybean field management includes weeding in the middle of the tobacco field management.

[0020] Gandou No. 10 is an excellent soybean variety with tall plants, many branches, large pods, full grains, and high protein content. It is suitable for intercropping in tobacco fields. Choosing Gandou No. 10 as a soybean variety for intercropping in tobacco fields can make full use of the space and nutrient resources of tobacco fields, improve land utilization and economic benefits. After mechanical weeding between the ridges of the tobacco field, choose to sow soybeans in holes in the middle of the ridges in alternate rows. This can avoid soybeans competing with tobacco for water and fertilizer, and it is also convenient for later field management. Sowing 3-5 seeds per hole with a hole distance of 15-20cm can not only ensure the emergence rate of soybeans, but also will not be too dense to affect the growth of tobacco. Sowing 3500-4500 holes per mu, with a moderate planting density, can not only make full use of land resources, but also avoid diseases and pests caused by too dense. After sowing soybeans, proper field management is required, especially weeding in the middle of the tobacco field management. This is because weeds will compete for water and fertilizer during the growth of soybeans, affecting the growth and development of soybeans. Timely weeding can reduce the harm of weeds and ensure the healthy growth of soybeans. When weeding, be careful to avoid damaging soybean plants. Manual or mechanical weeding can be used. In short, by selecting the excellent soybean variety Gandou No. 10, adopting a reasonable sowing method and density, and timely field management, soybeans can be interplanted in tobacco fields to achieve the purpose of improving land utilization, improving soil fertility, and increasing farmers' income. This flue-cured tobacco-soybean-rapeseed composite planting model is worthy of promotion and application in tobacco-growing areas.

[0021] S5. The rapeseed varieties are Huayouza No. 45, Qingyou No. 8, Chuanyou 75 or Baoyou 87. The rapeseed sowing method is to clear the plastic film of the tobacco field, pull out the tobacco stalks and crush them with a pull-pole crushing and rotary tillage machine, shallowly plow 5-10cm to break up the tobacco planting ridges, level the land and then sow the rapeseed in the field using direct seeding.

[0022] Rapeseed varieties such as Huayouza No. 45, Qingyou No. 8, Chuanyou 75 and Baoyou 87 are all excellent varieties selected after years of breeding and testing. They have excellent characteristics such as resistance to low temperature and resistance to bacterial sclerotinia, can adapt to the climatic conditions of different regions, and are widely planted in the main rapeseed producing areas. These varieties have tall plants, many branches, a large number of siliques, high single-plant yields, high oil content, high oil yield, and excellent comprehensive traits. Selecting these varieties for intercropping can make full use of limited land resources, improve the multiple cropping index, achieve tobacco-oil dual-use, and improve farmers' economic benefits. When intercropping rapeseed in tobacco fields, the first thing to do is to clean up the tobacco field mulch to prepare for rapeseed sowing. You can use a rod pulling, crushing, and rotary tillage machine for operation. This machine integrates rod pulling, crushing, and rotary tillage, and has high operating efficiency. When in use, pull out and crush the remaining tobacco stalks, and at the same time, rotary tillage the soil. The depth is controlled at about 5-10cm, breaking the ridges formed when planting tobacco, making the soil loose, and facilitating the germination of rapeseed seeds. After the soil is leveled, the rapeseed seeds are evenly spread over the entire plot by manual or mechanical sowing, and the soil is covered and pressed. Compared with other methods such as transplanting, direct sowing is simpler and more efficient, especially in the case of large-scale planting, which can save a lot of labor and reduce costs. The sowing density of rapeseed should be comprehensively considered based on factors such as variety characteristics, soil fertility, and cultivation management level. The general sowing amount per mu is controlled at 20,000-30,000 seeds. According to the estimated germination rate of 70%, there are about 15,000-25,000 seedlings per mu. If the sowing density is too high, competition between plants is likely to occur, individual development is inhibited, and too dense a group is not conducive to pest control and harvesting; if the density is too small, the group is poorly closed, which is not conducive to plant growth, the yield decreases, and weeds are easy to grow in the field. Therefore, the sowing amount should be reasonably determined according to local conditions. Excessive sowing will cause seed waste, affect germination and growth; if the amount is too small, the appropriate density cannot be reached, and the yield cannot be increased. Only scientific sowing can create a good growth environment, cultivate strong rapeseed seedlings and lay the foundation for high yields.

[0023] S6. The rapeseed is turned over by using a deep tillage machine to turn over the rapeseed when it reaches the bolting to early flowering stage, or by first mowing the rapeseed with a lawn mower and then using a small machine for rotary tillage or turning over.

[0024] Rapeseed turning refers to turning the rapeseed plants over and lodging them mechanically when the rapeseed reaches the bolting to early flowering stage, so that they are in full contact with the soil, promoting the decay and decomposition of the rapeseed plants, and providing nutrients for the subsequent flue-cured tobacco. There are two specific implementation methods: directly using deep tillage machinery for turning the land. When the rapeseed grows to the bolting to early flowering stage, and the plant height is about 80-100cm, deep tillage machinery such as moldboard plows, disc plows, etc. can be directly used to turn the rapeseed into the soil with its roots, and the tillage depth is controlled at 25-30cm. After turning the land, the rapeseed plants are fully mixed and contacted with the soil, and the decay and decomposition are accelerated under the action of soil microorganisms. Generally, a 40-50 horsepower tractor driving a moldboard plow with 1-2 plows per mu can complete the operation. This method is simple to operate and quick to see results, but it has high requirements for mechanical power, and the rapeseed plants are easy to entangle with the machinery, so the operation efficiency is slightly low. First, use a lawn mower to cut the rapeseed down, and then use a rotary tiller or micro-tillage machine to plow it. You can choose a lawn mower hanging on a tractor or a walk-behind brush cutter for mowing. The cut rapeseed is spread on the surface in a uniform thick layer, and then a rotary tiller or micro-tillage machine is used to roll and plow it from above to fully mix the rapeseed straw with the surface soil. During the operation, pay attention to controlling the rotary tillage depth to 15-20cm to avoid turning the rapeseed straw too deep into the deeper soil layer to affect the decomposition. This method can make full use of small machinery, flexible operation, high efficiency, and fast rapeseed straw decomposition speed, but it requires two operation procedures and is slightly cumbersome. Regardless of the method used, the rapeseed should be suppressed and irrigated in time after being turned over and returned to the field to facilitate the rapeseed straw to decompose as soon as possible. At the same time, attention should be paid to field drainage to avoid waterlogging in the field affecting the decomposition of rapeseed. After 20-30 days of fermentation and composting, rape straw can be basically decomposed, releasing rich nutrients for tobacco to absorb and utilize, improving soil aggregate structure, increasing soil fertility, and laying the foundation for high yield and high quality of flue-cured tobacco. Each mu can add 500-1000kg of organic matter, 5-8kg of total nitrogen, 10-15kg of potassium fertilizer and a variety of trace elements to the soil, which can replace part of the base fertilizer.

[0025] S7. By planting soybeans, 4 kg of nitrogen can be fixed each year, which is equivalent to applying about 9 kg of urea; by planting rapeseed, the biomass per mu can reach 800 kg of dry matter, which is equivalent to applying 300 kg of organic fertilizer; the method can increase the carbon-nitrogen ratio of tobacco field soil.

[0026] By planting soybeans, the nitrogen fixation of rhizobia can be effectively utilized to convert atmospheric nitrogen into effective nitrogen in the soil. Soybeans have a well-developed root system, and rhizobia form nodules on the roots. Through symbiotic nitrogen fixation, atmospheric nitrogen can be reduced to ammonia for plant absorption and utilization. Planting soybeans every year can fix about 4 kg of nitrogen in the soil, which is equivalent to applying about 9 kg of urea with a nitrogen content of 45%. This biological nitrogen fixation method can not only improve soil fertility, but also reduce the use of chemical fertilizers, reduce production costs, and is more friendly to the ecological environment. Rapeseed is an excellent green manure crop and plays an important role in tobacco field rotation. Rapeseed has a long growth period and a large biomass. It can produce about 800 kg of dry matter per mu, which is equivalent to applying 300 kg of organic fertilizer. Rapeseed also has a relatively developed root system, which can loosen the soil and improve soil structure. During its growth, rapeseed can absorb nutrients from the soil and prevent nutrient loss. After harvest, rape straw is returned to the field, and after decomposition, it can provide a large amount of organic matter for the soil, improving the soil's ability to retain fertilizer and water. In addition, rape has a long flowering period and blooms a lot, making it a good nectar plant, which is conducive to the development of beekeeping and increases farmers' income. Through the composite planting model of flue-cured tobacco, soybeans and rapeseed, the carbon-nitrogen ratio of the soil can be effectively adjusted to promote the improvement of soil fertility. Flue-cured tobacco and soybean straw are returned to the field, and rapeseed is buried as green manure, which supplements a large amount of organic carbon to the soil. At the same time, soybean rhizobia fix nitrogen and supplement nitrogen to the soil. After a rotation cycle, the soil carbon-nitrogen ratio can increase by 1.58, the organic matter content increases by 6.8%, the soil aggregate structure is improved, the cation exchange capacity increases by 0.5-0.8cmol(+) / kg, and the soil fertility is significantly improved. The adjustment of the carbon-nitrogen ratio creates a good living environment for soil microorganisms, promotes soil biological activity, accelerates the transformation and release of soil nutrients, and provides sufficient nutrients for crop growth.

[0027] S8. Increase of organic matter.

[0028] The soil carbon-nitrogen ratio of tobacco fields increased by 1.58, and the organic matter increased by 6.8%, which shows that the fertility of tobacco field soil can be significantly improved by planting crops such as soybeans and rapeseed. The soil carbon-nitrogen ratio refers to the ratio of organic carbon to total nitrogen in the soil, which reflects the quantity and quality of soil organic matter. Generally speaking, the soil carbon-nitrogen ratio is more suitable between 10-12, and too high or too low is not conducive to crop growth. The rhizobia in the soybean root system can fix nitrogen in the atmosphere, and the biomass of rapeseed is also high. After their stubble is returned to the field, it can increase the soil organic matter content, improve the soil aggregate structure, and improve soil fertility. For example, after a tobacco field has been planted with flue-cured tobacco for three consecutive years, the soil organic matter content has dropped from 1.5% to 1.2%, the carbon-nitrogen ratio has dropped from 10 to 8, the crop growth has deteriorated, and the quality of tobacco leaves has declined. After two years of rotation of soybeans and rapeseed, the soil organic matter content has rebounded to 1.6%, the carbon-nitrogen ratio has risen to 11, the tobacco leaf yield and quality have increased significantly, and the income per mu has increased by more than 200 yuan. Another tobacco field adopted the measures of no-tillage mulching and returning straw to the field. The soil carbon-nitrogen ratio increased from 9 to 12, the organic matter content increased from 1.3% to 1.8%, and the proportion of high-quality tobacco leaves increased by 5 percentage points. It can be seen that reasonable crop rotation and returning straw to the field are effective measures to improve the soil fertility of tobacco fields. Crop rotation can reduce the obstacles of continuous cropping. The roots of leguminous crops and oil crops have good nitrogen fixation and high biomass. Returning straw to the field can directly increase the content of soil organic matter. Improving the soil carbon-nitrogen ratio and organic matter content can improve the soil aggregate structure, enhance the ability to retain water and fertilizer, promote the growth of tobacco roots, increase the yield and quality of tobacco leaves, and increase the income of tobacco farmers. Therefore, tobacco planting should be adapted to local conditions, reasonably arrange crop rotation, pay attention to returning straw to the field, optimize the soil carbon-nitrogen ratio and organic matter content, and take the path of sustainable development.

[0029] S9. Increase the cation exchange capacity of soil.

[0030] Soil cation exchange capacity (CEC) is one of the important indicators to measure soil fertility. It reflects the ability of soil to absorb and retain nutrients. The higher the cation exchange capacity, the stronger the soil's ability to retain fertilizer and water, and the higher the soil fertility. The main methods to increase soil cation exchange capacity are: First, increase the application of organic fertilizers. Organic materials such as humus contain a large amount of negative charges, which can greatly increase soil CEC. For example, applying 5 tons of organic fertilizer per mu can increase CEC by 2-5 cmol(+) / kg. Second, plant green manure and return it to the field. The root secretions of green manure plants and the organic matter produced by decay after returning to the field can increase soil CEC. Third, apply lime reasonably. Lime can increase soil pH, thereby increasing the number of negative charges in soil colloids and increasing CEC.

[0031] S10 Checking and replanting seedlings is a key management measure to be carried out in time within 3-5 days after transplanting. Checking seedlings means carefully observing the growth of each tobacco seedling in the field, focusing on checking whether there are abnormal seedlings such as broken seedlings, weak seedlings, and diseased seedlings. For broken seedlings, strong seedlings with strong growth and no pests and diseases should be selected from the seedbed in time for timely replanting. When replanting seedlings, it should be noted that the specifications of the replanted tobacco seedlings should be consistent with the original seedlings, otherwise it will affect the uniformity of tobacco leaf maturity. For weak seedlings, quick-acting fertilizers such as potassium nitrate can be applied to promote seedlings and help the tobacco seedlings resume growth as soon as possible. For diseased seedlings, they should be uprooted and destroyed in a centralized manner, and their growth positions should be disinfected before replanting to avoid pests and diseases spreading through the soil and endangering healthy tobacco seedlings. Checking and replanting seedlings is an important link to ensure that the tobacco field seedlings are uniform, strong, high-yield and high-quality. Topdressing management is a key measure to scientifically formulate fertilization plans according to the fertilizer requirements of tobacco seedlings at different growth stages after tobacco leaf transplanting to promote the healthy growth of tobacco seedlings. 7-10 days after transplanting, when the roots of tobacco seedlings begin to grow and need nutrition, apply 3 kg of seedling fertilizer per mu, add 100-150 kg of water and sprinkle along the nest to promote the survival and growth of tobacco seedlings as soon as possible. 15-20 days after transplanting, tobacco seedlings enter a rapid growth period. First, tear the mulch film to a large hole with a diameter of more than 20 cm, apply 5 kg of compound fertilizer per mu, and surround the nest with cooked soil or fire soil ash, body fertilizer, etc. under the film, and then use fine soil between ridges to cultivate the soil, so that the tobacco leaves are close to the growth center and the roots of tobacco plants are fully cultivated. 20-25 days after transplanting, tobacco plants enter a vigorous growth stage and need a large amount of nutrient supply. Apply 5 kg of compound fertilizer per mu and 10 kg of potassium nitrate as topdressing. The method of opening holes around the roots of tobacco plants can not only meet the growth needs of tobacco plants, but also avoid fertilizer loss. In short, topdressing management should follow the principles of fertilizing with seedlings, fertilizing in stages, and applying small amounts multiple times. It should not only meet the growth needs of tobacco plants, but also prevent problems such as excessive growth caused by excessive fertilization, and ultimately achieve the goal of increasing tobacco leaf production and improving quality.

[0032] S11, 8 cmol(+) / kg.

[0033] 8cmol(+) / kg is an indicator of soil cation exchange capacity (CEC). CEC reflects the ability of soil to absorb and retain nutrients and has an important impact on soil fertility. The higher the CEC value, the stronger the soil's ability to absorb cations and the higher the soil fertility. Generally speaking, soil fertility is poor when CEC is below 5cmol(+) / kg, while soil fertility is high when it is greater than 15cmol(+) / kg. 8cmol(+) / kg is at a medium level, indicating that the soil fertility is acceptable, but there is still room for improvement. Measures to increase soil CEC include increasing the application of organic fertilizers, planting green manure, reduced tillage and no-tillage, and balanced fertilization. For example, applying 2000-3000kg of farmyard manure per mu, or planting green manure crops such as astragalus and rapeseed, and turning over and returning them to the field after harvest can effectively increase the content of soil organic matter and improve CEC. Reducing soil disturbance by cultivation and avoiding excessive application of chemical fertilizers are also conducive to maintaining soil aggregate structure and soil CEC. Regularly testing soil CEC changes and taking targeted fertilization measures based on the test results are of great significance for the sustainable production of tobacco fields. Maintaining CEC at a reasonable level can enhance the soil's ability to retain fertilizer and water, promote tobacco plant growth and development, and improve tobacco leaf yield and quality, which deserves the attention of tobacco farmers.

[0034] S12. Through this composite planting and fertilization method, the amount of chemical fertilizers applied to tobacco fields can be reduced by 20-30%, and the proportion of high-quality flue-cured tobacco will be increased.

[0035] The application of chemical fertilizers in tobacco fields can be significantly reduced through the composite planting and fertilization method of flue-cured tobacco, soybeans and rapeseed. This is because the rhizobia in the root system of soybeans have a nitrogen fixation effect, which can convert nitrogen in the atmosphere into a form that can be used by plants, thereby improving soil fertility. Planting soybeans per mu of tobacco field can fix 4 kg of nitrogen, which is equivalent to applying about 9 kg of urea. At the same time, rapeseed, as a green manure crop, can produce 800 kg of dry matter per mu, which is equivalent to applying 300 kg of organic fertilizer. These leguminous and cruciferous crops significantly improve the nutrient supply capacity of tobacco field soil and reduce the demand for chemical fertilizers through biological nitrogen fixation and green manure effects. In general, through this composite planting and fertilization, the use of chemical fertilizers in tobacco fields can be reduced by 20-30%, which not only saves the cost of chemical fertilizers, but also avoids the environmental problems caused by excessive fertilization. In addition to reducing the use of chemical fertilizers, composite planting and fertilization can also increase the proportion of high-quality tobacco in flue-cured tobacco. This is mainly due to the fact that the fertilization crops improve the physical and chemical properties of tobacco field soil. On the one hand, the root secretions of legumes and rapeseed crops and the plant residues returned to the field provide a carbon source for soil microorganisms, promote soil biological activity, and accelerate the accumulation of soil organic matter. Studies have shown that the content of soil organic matter in tobacco fields can be increased by 6.8% after composite planting. The increase in soil organic matter content improves the soil aggregate structure and enhances the soil's ability to retain water and fertilizer. On the other hand, the nitrogen fixed by legumes and other mineral nutrients absorbed by rapeseed can be absorbed and utilized by tobacco plants after returning to the field, promoting the nutritional balance of tobacco leaves and improving the quality of tobacco leaves. In practice, the proportion of high-quality flue-cured tobacco can be increased by about 6.5% by adopting composite planting and fertilization. In short, the composite planting and fertilization technology of flue-cured tobacco, soybeans, and rapeseed reduces the input of chemical fertilizers through ecological mechanisms such as biological nitrogen fixation and green manure fertilization, while optimizing the soil nutrient structure of tobacco fields, promoting the improvement of tobacco leaf quality, and providing strong support for the reduction of investment and efficiency and sustainable development of flue-cured tobacco production.

[0036] S13. The tobacco leaf income is increased by more than 200 yuan per mu; the soybean yield is 150-200 jin per mu, and the income is increased by 600-800 yuan per mu.

[0037] Analyze the increase in tobacco leaf revenue. Analyze the increase in soybean income. Analysis of the increase in tobacco leaf revenue: The key content mentioned that the fertilizer application in tobacco fields was reduced by 20-30%, the proportion of high-quality tobacco increased by 6.5%, and the tobacco leaf revenue per mu increased by more than 200 yuan. First, the reduction in fertilizer application directly reduces production costs. Assuming that 100 kilograms of fertilizer were required per mu of tobacco field, and the cost of each kilogram of fertilizer was 2 yuan, the original fertilizer cost was 200 yuan. Reducing fertilizer application by 20-30% means that only 70-80 kilograms of fertilizer are needed per mu now, and the cost is reduced to 140-160 yuan, which directly saves 40-60 yuan. Secondly, the increase in the proportion of high-quality tobacco means that a higher proportion of tobacco leaves can be sold at a higher price. Assume that each acre of tobacco field originally produced 1,000 kilograms of tobacco leaves, of which the proportion of high-quality tobacco was 50%, that is, 500 kilograms, and the price was 10 yuan per kilogram; the proportion of medium-quality tobacco was 30%, that is, 300 kilograms, and the price was 8 yuan per kilogram; the proportion of low-quality tobacco was 20%, that is, 200 kilograms, and the price was 6 yuan per kilogram. Then the original total income of tobacco leaves was 50010 +3008 + 2006 = 8600 yuan. After the proportion of high-quality tobacco increased by 6.5%, it became 56.5%, that is, 565 kilograms. Assuming that the proportion and price of medium-quality and low-quality tobacco remain unchanged, the current total income of tobacco leaves is 56510 + 2678 + 1686 = 8806 yuan, an increase of 206 yuan. This figure is consistent with the mentioned increase of more than 200 yuan per acre. Analysis of soybean income increase: The key content mentioned that the soybean yield per acre is 150-200 catties, and the income per acre increases by 600-800 yuan. Assuming that the market price of soybeans is 4 yuan per catty, when the yield per mu is 150 catties, the income per mu is 1504 = 600 yuan; when the yield per mu is 200 catties, the income per mu is 2004 = 800 yuan. This is consistent with the mentioned increase in income of 600-800 yuan per mu. The cultivation of soybeans not only increases farmers' direct economic income, but also improves soil quality through its nitrogen fixation, creating better conditions for subsequent tobacco planting. This rotation model achieves a win-win situation in terms of economic and ecological benefits. In addition, as an important oil crop, the increase in soybean production also helps to ensure the country's grain and oil security, which is of great strategic significance.

[0038] This embodiment takes the southwest tobacco area as an example, and is mainly applicable to Chongqing, Guizhou, Sichuan, and Hubei. 1. Flue-cured tobacco cultivation 1.Soil preparation and planting (April 1-April 10) (1) Apply base fertilizer. Apply 50 kg of compound fertilizer (N nitrogen: P2O5 phosphorus: K20 potassium in a ratio of 6:12:25) per mu. Apply it in strips at one time when forming ridges. The width of the fertilizer strip is 15-20 cm. After forming ridges, the fertilizer should be about 20 cm away from the ridge surface.

[0039] (2) Ridge formation in tobacco fields. On the basis of deep plowing and breaking up of tobacco fields, ridge formation is carried out according to the standard of "row spacing 110-120 cm, ridge height ≥ 25 cm, ridge bottom width ≥ 65 cm, ridge top width ≥ 40 cm". After ridge formation, the ridges are in the same direction, the ridge surface is tile-back-shaped, and the ridges are fine and full.

[0040] (3) Covering the ridge with film. On the basis of ensuring the soil moisture of the ridge (soil moisture content of more than 70%), pay close attention to local climatic conditions, seize the opportunity, and cover the ridge with film quickly, requiring the film to be close to the ridge and tightly sealed on both sides.

[0041] 2. Tobacco transplanting (April 25-May 10) (1) Transplanting time. A scientific transplanting time should be formulated based on the local altitude and local climatic conditions. In principle, transplanting should be done earlier at low altitudes (below 1,200 meters) and later at high altitudes (above 1,200 meters). The county's transplanting cycle is set from April 25 to May 10, with most areas to be completed before May 7 and all areas to be completed before May 10. Transplanting should be completed within 3 days for the same farmer and the same drying room group, within 7 days for the same technical team, and within 10 days for the same tobacco station.

[0042] (2) Transplanting technology. ① Implement the step-by-step transplanting process. Fully implement the seedling-well-cellar transplanting (hole diameter 5-7 cm, hole depth 15-20 cm, after planting, the top leaf of the tobacco seedling is 2-3 cm away from the film mouth), and implement it step by step according to "pull rope for orientation - set hole distance - drop seedlings vertically - a small amount of fine soil for base - sprinkle rooting water - throw in tetraacetaldehyde - spray insecticide". ② Apply rooting water scientifically. According to the standard of "5% chloramine 50 g / mu + transplanting spirit 30 ml / mu + seedling fertilizer 2 kg / mu", add 100-150 kg of water, and sprinkle 100-150 ml into each nest according to the soil moisture conditions. ③ Spray insecticide in time. Spray and prevent immediately after planting. After transplanting, spray evenly between ridges according to the standard of "15 grams of 5% chloramine salt mixed with 16-20 kilograms of water" (it is forbidden to spray in the nest to prevent pesticide damage) to prevent underground pests from transferring and causing harm.

[0043] (3) Transplanting density: Transplant according to the specification of "row spacing 110-120 cm, pit spacing 50-55 cm", and plant 1050-1100 tobacco plants per mu.

[0044] 3. Field management (May-August) (1) Check and replant seedlings. 3-5 days after planting, check the growth of tobacco seedlings in the field in time, replant broken seedlings or empty holes in time, arrange topdressing for weak seedlings with yellowish color in time, and clean and disinfect diseased seedlings in time and replant them.

[0045] (2) Topdressing management. ① 7-10 days after planting, apply 3 kg / mu of seedling fertilizer, add 100-150 kg of clean water, mix well and apply along the nest. ② 15-20 days after planting, when the heart leaves of the tobacco seedlings are 2-3 cm above the film surface, tear the film open (diameter of the broken film ≥ 20 cm), apply 5 kg of compound fertilizer per mu, and then surround the nest with mature soil under the film (or use the fire soil ash / body fertilizer prepared in advance to seal the nest and the stump), and finally use finely crushed local soil between the ridges to raise it above the film mouth, so that the tobacco leaves are close to the growth center and form a trumpet shape, which fully cultivates the root system of the tobacco plants. ③ 20-25 days after planting, apply 5 kg / mu of compound fertilizer + 10 kg / mu of potassium nitrate, and use the center punching method for topdressing.

[0046] (3) Pest and disease control: Choose pesticides to control pests and diseases in a timely manner according to the local pest and disease situation.

[0047] (4) Topping of tobacco plants. Topping is done at the beginning of flowering. Remove the flower-protecting leaves and the two leaflets below. Remove the bottom leaves and the fetal leaves. Leave 16-18 leaves on a single plant.

[0048] 4. Tobacco leaf harvesting and curing (early July to mid-September) Tobacco leaves are harvested in 4-5 times from bottom to top according to the maturity and yellowing of the tobacco, and then baked according to the local baking process.

[0049] 2. Soybean Planting 1. Planting time: Sow soybeans in early June when tobacco plants reach the small cluster stage (12-13 leaves per plant).

[0050] 2. Soybean varieties: Choose short-stemmed, early-maturing varieties, such as Gandou No. 10.

[0051] 3. Sowing method. After mechanical weeding between the ridges of the tobacco field, sow in holes in alternate rows in the ridge furrows of the tobacco field (reserve the operation rows to facilitate the field management and harvesting and curing of tobacco leaves), and apply 10 kg of compound fertilizer per mu as base fertilizer.

[0052] 4. Sowing density: 3-5 seeds are used per hole, the hole distance is 15-20cm, 3500-4500 holes are sown per mu, and the planting density is 10000-22000 plants / mu.

[0053] 5. Field management: Cooperate with tobacco field management and carry out weeding in the middle of the crop.

[0054] 6. Soybean harvest: Soybean leaves turn yellow and fall off in early September.

[0055] 3. Rapeseed planting and returning to the field 1. Planting time: Rapeseed is planted after tobacco leaves are harvested and cured in mid-September.

[0056] 2. Rapeseed varieties. Choose rapeseed varieties that are resistant to low temperatures and sclerotinia, such as Huayouza No. 45, Qingyou No. 8, Chuanyou 75, Baoyou 87, etc.

[0057] 3. Sowing method. After clearing the mulch film from the tobacco field, use a pull-pole crushing and rotary tillage machine to pull out the tobacco stalks and crush them, plow 5-10cm shallowly to break up the tobacco planting ridges, level the land, and then sow rapeseed in the field using direct seeding.

[0058] 4. Sowing density: Sow 20,000-30,000 rapeseed seeds per mu to ensure that the number of rapeseed surviving reaches 15,000-25,000 plants per mu.

[0059] 5. Turning over rapeseed. In early March, when rapeseed reaches the bolting to early flowering stage, use deep tillage machinery to turn over the land (or use a lawn mower to cut down the rapeseed first and then use small machinery for rotary tillage / turning over the land).

[0060] advantage:

[0061] 1. This method of fertilizing tobacco fields is fast and low-cost. Interplanting soybeans in tobacco fields and planting rapeseed in the fields does not require additional labor, which is easy for farmers to accept.

[0062] 2. The fertilization of tobacco fields has achieved remarkable results. The rhizobia in the roots of soybeans have a nitrogen-fixing effect and can convert nitrogen in the atmosphere into a form that can be used by plants, thereby improving soil fertility. Planting soybeans in tobacco fields can fix 4 kg of nitrogen per year, which is equivalent to applying about 9 kg of urea (calculated at 45% content). The biomass of rapeseed per mu can reach 800 kg of dry matter, which is equivalent to applying 300 kg of organic fertilizer. Through the above, the soil carbon-nitrogen ratio of tobacco fields increased by 1.58, the organic matter increased by 6.8%, and the soil cation exchange capacity increased by 0.5-0.8 cmol (+) / kg. The fertility of tobacco fields has been improved, and the problems of continuous cropping obstacles in tobacco fields have been solved.

[0063] 3. Increased economic benefits. The tobacco fields reduced fertilizer application by 20-30%, the proportion of high-quality tobacco increased by 6.5%, and the income per mu increased by more than 200 yuan. In addition, the soybean yield per mu was 150-200 jin, and the income per mu increased by 600-800 yuan, which also ensured the national grain and oil security.

[0064] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or supplements to the specific embodiments described or replace them with equivalent methods, which all fall within the protection scope of the present invention.

Claims

1. A method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed, characterized in that: include: Planting flue-cured tobacco, soybeans and rapeseed; Planting short-stemmed early-maturing soybeans in alternate rows in the ridges of tobacco fields after transplanting tobacco, and planting cold-resistant and sclerotinia-resistant rapeseed in tobacco fields after soybean harvest. Turning and returning rapeseed to the field from bolting to early flowering; The soybean sowing density is 10,000-22,000 plants per mu, and the rapeseed sowing density is 15,000-25,000 plants per mu.

2. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 1, characterized in that: The flue-cured tobacco planting includes: Land preparation for planting, tobacco leaf transplanting, field management and tobacco leaf harvesting and curing; the land preparation for planting includes application of base fertilizer, ridge building and ridge covering; the tobacco leaf transplanting includes step-by-step transplanting, scientific application of rooting water and timely spraying of pesticides for pest control; the field management includes checking seedlings and supplementing seedlings, topdressing management, pest control and topping of tobacco plants.

3. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 1, characterized in that: The soybean variety is Gandou No. 10; the soybean sowing method is to use mechanical weeding between the tobacco field ridges and then sow in holes in alternate rows in the middle of the tobacco field ridges, with 3-5 seeds in each hole, a hole distance of 15-20cm, and 3500-4500 holes per mu; the soybean field management includes weeding in the middle of the process to cooperate with the tobacco field management.

4. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybean and rapeseed as claimed in claim 1, characterized in that: The rapeseed varieties are Huayouza No. 45, Qingyou No. 8, Chuanyou 75 or Baoyou 87; the rapeseed sowing method is to clear the plastic film of the tobacco field, pull out the tobacco stalks and crush them with a pull-pole crushing and rotary tillage machine, shallowly plow 5-10cm to break up the tobacco planting ridges, level the land and then sow the rapeseed in the field using direct seeding.

5. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybean and rapeseed as claimed in claim 1, characterized in that: The method of turning the rapeseed is to use deep tillage machinery to turn the rapeseed when it reaches the bolting to early flowering stage, or to use a lawn mower to cut the rapeseed down first and then use a small machine to perform rotary tillage or turning the rapeseed.

6. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybean and rapeseed as claimed in claim 2, characterized in that: The base fertilizer is 50 kg of compound fertilizer per mu, and the compound fertilizer is 6:12:25 N nitrogen: P2O5 phosphorus: K20 potassium, which is applied in strips at one time during ridge forming. The fertilizer belt is 15-20 cm wide and the fertilizer is about 20 cm away from the ridge surface after ridge forming; the ridge forming of the tobacco field is based on full deep plowing and crushing of the tobacco field, and the ridge forming is based on the standards of "row spacing 110-120 cm, ridge height ≥25 cm, ridge bottom width ≥65 cm, ridge top width ≥40 cm". After ridge forming, the ridge body has a consistent direction, a tile-back shape on the ridge surface, and a fine and full ridge body; the ridge body covering is covered with film while ensuring the moisture content of the ridge body.

7. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 6, characterized in that: The ridge moisture condition refers to the soil moisture content reaching more than 70%.

8. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 2, characterized in that: The step-by-step transplanting is based on the local altitude and local climatic conditions, requiring the same farmer and the same drying room group to complete the transplanting within 3 days, the same technical group to complete the transplanting within 7 days, and the same tobacco station to complete the transplanting within 10 days; The seedling-strengthening well-cellar transplanting method is fully implemented, and is implemented in steps according to the "roping for orientation - making holes at a fixed distance - dropping seedlings vertically - surrounding the base with a small amount of fine soil - watering for rooting - throwing in metaldehyde - spraying pesticides"; the scientific application of rooting water is based on the standard of "5% chloramine 50 grams / mu + transplanting spirit 30 milliliters / mu + seedling-raising fertilizer 2 kilograms / mu", diluted with 100-150 kilograms of water, and 100-150 milliliters are sprinkled into each nest according to the soil moisture conditions; the timely spraying of pesticides for insect prevention means spraying and prevention immediately after planting. After transplanting, immediately spray the ridges evenly according to the standard of "5% chloramine 15 grams diluted with 16-20 kilograms of water".

9. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 8, characterized in that: The hole diameter of the healthy seedling well-cellar transplanting is 5-7 cm, the hole depth is 15-20 cm, and after planting, the top leaves of the tobacco seedlings are 2-3 cm away from the film opening.

10. The method for fertilizing tobacco fields by composite planting of flue-cured tobacco, soybeans and rapeseed as claimed in claim 2, characterized in that: The seedling inspection and seedling replacement is 3-5 days after planting, and the growth of tobacco seedlings in the field is checked in time, broken seedlings or empty holes are replaced in time, weak seedlings with yellowish color are treated with topdressing in time, and diseased tobacco seedlings are cleaned and disinfected in time before seedling replacement; the topdressing management is as follows: ① 7-10 days after planting, 3 kg / mu of seedling-raising fertilizer is added to 100-150 kg of clean water, mixed and applied along the nest; ② 15-20 days after planting, when the heart leaves of the tobacco seedlings are 2-3 cm exposed from the film surface, first break the film with a diameter of ≥20 cm, apply 5 kg of compound fertilizer per mu, and then surround the nest with cooked soil under the film or seal the nest and stump with prepared fire soil ash / body fertilizer in advance, and finally use fine local soil between the ridges to be higher than the film mouth, so that the tobacco leaves are close to the growth center and form a trumpet shape, so as to fully cultivate the root system of the tobacco plants; ③ 20-25 days after planting, 5 kg / mu of compound fertilizer + 10 kg / mu of potassium nitrate are applied, and topdressing is carried out by the center punching method.