A cultivation method for improving intercropping nitrogen fixation efficiency

Abstract

The present application belongs to the field of cultivation, and particularly relates to a cultivation method for improving nitrogen fixation efficiency, which comprises interplanting or intercropping legume plants under plum trees; when the plum tree is a St. Julien plum tree, soybeans are intercropped or interplanted, or arrow pea is intercropped; when the plum tree is a Giant early plum tree, soybeans are intercropped; when the plum tree is a Purple king plum tree, soybeans are intercropped. The present application can improve the nitrogen fixation efficiency by intercropping or interplanting legume plants under plum trees. The St. Julien plum tree interplanted with arrow pea can improve soil nutrients and obtain high-quality plum fruits and soybeans. The St. Julien plum tree interplanted with soybeans and the Giant early plum tree interplanted with soybeans can obtain plum fruits with rich nutrients and good flavor. The Purple king plum tree interplanted with soybeans can obtain selenium-rich plums by adding selenium-rich fertilizer. When the plum tree is intercropped or interplanted with soybeans, the use amount of decomposed organic fertilizer can be reduced by applying a slow-release agent, and the nitrogen fixation efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cultivation, in particular to a cultivation method for improving the nitrogen fixation efficiency of intercropping. BACKGROUND

[0002] Plums belong to the Rosaceae family of dicotyledonous plants. As a major plum-producing province, Sichuan has currently cultivated more than ten varieties including Qingcu plum, Honey Plum, Juzao plum, Crispy plum, and Apple plum. In addition, some newly bred varieties such as Zihuang and Shengxue are also cultivated.

[0003] Compared with high-input agriculture, intercropping improves the stability of the total yield of low-input systems over the years. At the same time, intercropping has great potential, and the complementary effects between crops can achieve long-term improvement of productivity.

[0004] Currently, there are few studies on intercropping of plums and legume plants. For example, the method for intercropping plums and grapes disclosed in CN108370790A, the method for intercropping plum and tea in a tea garden disclosed in CN117378422A, the method for intercropping Huangjinba and plum trees disclosed in CN110622753A, the method for intercropping Honey Plum and Taizishen under the plum trees disclosed in CN106797778A, the method for intercropping plum trees and loquats disclosed in CN105010066A, the method for intercropping plum trees and watermelons disclosed in CN108781977A, and the method for intercropping plums and Sanqi under the plum trees disclosed in CN107258830A.

[0005] The effects of intercropping crops are not only limited to soil nutrients, but also may involve the mutual relationship between crops. The competition, synergy, or symbiotic relationship between different crops may result in different degrees of influence, which may change the quality of plum fruits.

[0006] Therefore, in the present application, different intercropping modes will be explored, including intercropping experiments between different plum varieties and different legume plants, aiming to explore the effects of intercropping legume crops on the quality of plum fruits and the content of soil nutrients, and to obtain a more optimized agricultural production mode.

[0007] Based on this, the present application is proposed. SUMMARY

[0008] The present application aims to provide a cultivation method for improving the nitrogen fixation efficiency of intercropping, to solve the above problems, and the specific technical solution is as follows:

[0009] A cultivation method for improving the nitrogen fixation efficiency of intercropping, which intercrops or interplants legume plants under plum trees;

[0010] When the plum tree is the St. Julien plum tree, the intercropping or the relay cropping soybean is performed;

[0011] or,

[0012] When the plum tree is the St. Julien plum tree, the intercropping or the relay cropping arrow pea is performed;

[0013] or,

[0014] When the plum tree is the Giant early plum tree, the intercropping or the relay cropping soybean is performed;

[0015] or,

[0016] When the plum tree is the Purple King plum tree, the intercropping or the relay cropping soybean is performed.

[0017] Further, when the plum tree is the St. Julien plum tree or the Giant early plum tree, the intercropping method of the plum tree and the soybean comprises the following steps:

[0018] Step 1, selecting the plum tree with a distance between two crown drip lines reaching 80 cm or more in the orchard for intercropping;

[0019] Step 2, when the spring soybean is selected for sowing, the sowing period is in the middle and late March to the early April, and the soil temperature is stable at 12 ℃ or more;

[0020] When the summer soybean is selected for sowing, the sowing period is in the middle of June to the early July;

[0021] Step 3, performing soil fertilization, leaf fertilization and weeding for the intercropped plum tree and the soybean;

[0022] Step 4, performing disease and pest control by using pesticides, fungicides and biological control agents.

[0023] Further, in Step 2, the planting density of the soybean is: the average row spacing is 30-40 cm, the plant spacing is 15-25 cm, and the distance between the soybean sowing strip and the crown drip line of the plum tree is not less than 30 cm.

[0024] Further, in Step 3, from the late September to the late October, 1 ton of decomposed organic fertilizer is used as base fertilizer per mu of orchard, and the base fertilizer is combined with the inter-row and the tree pit to be deep ploughed 15-25 cm; 5-7 days before the soybean is sown, 10-25 kg of nitrogen, phosphorus and potassium balanced compound fertilizer is applied per mu of soybean planting strip, and then the inter-row of the plum tree is ploughed and cultivated 1-2 times with a ploughing depth of 20 cm, and the range of the ploughing and cultivation does not exceed the crown drip line of the fruit tree.

[0025] Further, in Step 3, when the grass weeds are in the 2-4 leaf stage and the broadleaf weeds are in the 3-5 cm height, the whole orchard is weeded by using fluthiacet-methyl water agent, quizalofop-p-ethyl emulsifiable concentrate or fluthiacet-methyl.

[0026] Further, in step 4, the insecticide is acetamiprid or lambda-cyhalothrin, the fungicide is thiophanate-methyl or ipconazole, and the biological control agent is Bacillus subtilis.

[0027] Further, when the plum tree is purple emperor plum, soybeans are interplanted; during interplanting, 1 ton of composted organic fertilizer mixed with selenium-rich fertilizer is used as base fertilizer per mu of orchard in late September to late October, the mixed amount of selenium-rich fertilizer is 5% of the mass of the composted organic fertilizer, and the selenium-rich fertilizer is amino acid chelated selenium fertilizer or humic acid selenium fertilizer.

[0028] Further, in step 3, 750 kg of composted organic fertilizer is used as base fertilizer per mu of orchard in late September to late October, the base fertilizer is combined with deep ploughing 15-25 cm in the row and the tree disc; and, a ditch is also opened at the tree disc and a slow-release agent is applied, and the amount of the slow-release agent is 50 kg per mu;

[0029] 5-7 days before soybean seeding, 10-25 kg of nitrogen, phosphorus and potassium balanced compound fertilizer is applied per mu of soybean planting belt, and then the plum tree row is ploughed and leveled 1-2 times, with a ploughing depth of 20 cm, and the leveling range does not exceed the plum tree crown drip line.

[0030] Further, the preparation method of the slow-release agent is as follows:

[0031] The sludge, iron molybdate and water are mixed and then injected into a sealed electrolytic chamber, high-voltage pulse discharge is performed on the mixture in the electrolytic chamber, the sludge and iron molybdate generate mud under the action of liquid-electric effect, the mud is poured out and filtered, and the filter cake is baked at 180-185 DEG C for 55 min, so that the slow-release agent is obtained.

[0032] Further, the mass ratio of the sludge to the iron molybdate in the electrolytic chamber is 11:5, the initial material liquid ratio in the electrolytic chamber is 1:7, the voltage of the high-voltage pulse discharge is 20 kV, the pulse width is 850 ns, and the discharge is performed 150 times.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1. The St. Catherines plum interplanted with white clover, soybeans, arrow pea, light leaf purple amaranth and red clover can all improve the nitrogen fixation efficiency.

[0035] 2. The St. Catherines plum interplanted with soybeans can harvest soybean by-products with high economic value, and the St. Catherines plum interplanted with arrow pea can improve soil nutrients and obtain high-quality optimized plum fruits and soybeans.

[0036] 3, the technical effects brought by the specific varieties of plum trees intercropped with soybeans are different. The use of the methods of intercropping the plum trees of the varieties of St. Cyprian and Juzao with soybeans can harvest plum fruits rich in nutrients and good in flavor. During the soil and fertilizer management period, the use of the method of intercropping the plum trees of the variety of Zihuang with soybeans can harvest selenium-rich plums, and the selenium content in the selenium-rich plums is 7-11 times that of the other intercropped varieties.

[0037] 4, when plum trees and soybeans are intercropped or interplanted, the slow-release agent prepared by using sludge, iron molybdate and water as raw materials through the liquid-electric effect can slowly release organic iron and molybdate in the soil. During the soil and fertilizer management period, the use of the method of intercropping the plum trees of the variety of Zihuang with soybeans can harvest selenium-rich plums, and the selenium content in the selenium-rich plums is 7-11 times that of the other intercropped varieties. DETAILED DESCRIPTION

[0038] The present application will be further described in detail through specific examples.

[0039] The detailed description of the examples of the present application below is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the examples in the present application, all other examples obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0040] Example 1

[0041] 1, test material

[0042] Plant samples: 20 fruits were randomly picked from each plot in the test field, and the fruits were immediately transported back to the laboratory for measurement of fruit quality indicators after being packaged with foam boxes and ice bags.

[0043] Soil samples: 1 portion of 0-20 cm soil samples was collected from each sampling point, dried in the laboratory, impurities were removed and ground, and then passed through 0.25 mm and 1 mm sieves, respectively, for use.

[0044] 2, test site

[0045] The test base is a 4-year-old St. Cyprian plum tree field intercropped with five kinds of legume plants, namely white clover, soybean, arrow-shaped pea, light purple amaranth and dark red clover.

[0046] 3, test design

[0047] The experiment employed a randomized block design, with a total of 6 treatments: 5 intercropping treatments and 1 control (CK). Treatment 1: Saint-Sherbert plum intercropped with white clover (plum-white clover); Treatment 2: Saint-Sherbert plum intercropped with soybean (plum-soybean); Treatment 3: Saint-Sherbert plum intercropped with arrowhead pea (plum-arrowhead pea); Treatment 4: Saint-Sherbert plum intercropped with glossy purple sweet potato (plum-glossy purple sweet potato); Treatment 5: Saint-Sherbert plum intercropped with crimson clover (plum-crimson clover); The control (CK) consisted of no intercropping (plum only). Each treatment was replicated 3 times, resulting in a total of 18 experimental plots.

[0048] 4. Indicator Measurement

[0049] Soil parameters: Organic matter was measured using the potassium dichromate titration method (external heating method); total nitrogen and available nitrogen were measured using the alkaline diffusion method; total phosphorus was measured using the molybdenum-antimony colorimetric method after digestion with perchloric acid and sulfuric acid; available phosphorus was measured using the molybdenum-antimony colorimetric method after extraction with hydrochloric acid-sulfuric acid; and total potassium and available potassium were measured using the flame photometry method.

[0050] Fruit indicators: The average weight of fresh fruit was measured using a Liping electronic scale with an accuracy of 0.01. Soluble solids content was determined using a handheld digital saccharimeter, and the results are expressed as a percentage (%).

[0051] 5. Results and Analysis

[0052] 5.1 Effects of intercropping leguminous plants on plum fruit quality

[0053] Table 1

[0054]

[0055] Table 1 shows that intercropping with white clover increases plum fruit weight compared to monoculture of plums; however, the soluble solids and ascorbic acid content in the plum fruit are not significantly different from the control (CK); but the total acid content is significantly lower than the CK, decreasing by 0.81 kg. -1 • g. Intercropping plums with soybeans increased fruit weight, with an increase exceeding that of intercropping with white clover, but the difference was not significant. Soluble solids and ascorbic acid in the fruit increased, while total acid decreased, but the differences were not significant. Intercropping plums with arrowhead peas significantly increased fruit weight by 19.5g. Soluble solids and ascorbic acid in the fruit increased, while total acid decreased, but the differences were not significant. Intercropping plums with glossy purple sweet potatoes increased fruit weight by 16.5g, but the increase was weaker than with arrowhead peas. Soluble solids and ascorbic acid in the fruit increased, while total acid decreased, but the differences were not significant. Intercropping plums with crimson clover increased fruit weight by 19g, with a significant difference. Soluble solids and ascorbic acid in the fruit increased, while total acid decreased, but the differences were not significant.

[0056] 5.2, the influence of interplanting crops on soil nutrients

[0057] Table 2 Influence of interplanting different crops on soil total nutrient content

[0058]

[0059] From Table 2, it can be seen that for organic matter, the organic matter content of the five interplanting modes is significantly higher than that of CK, indicating that interplanting plum with different legume crops can improve the content of organic matter in the soil, and the soil organic matter content of the five interplanting modes is in the order of arrow-shaped pea > white clover > light-leafed purple amaranth > soybean > dark red clover; among them, the organic matter content of arrow-shaped pea interplanting is the highest, which is 14.75 kg higher than that of CK -1 ·g. For total nitrogen, the total nitrogen content of the five interplanting modes is significantly higher than that of CK, indicating that interplanting plum with different legume crops can improve the content of total nitrogen in the soil, and the soil total nitrogen content of the five interplanting modes is in the order of soybean > arrow-shaped pea > white clover > dark red clover > light-leafed purple amaranth, among them, the total nitrogen content of soybean is the highest, which is 0.0685 kg higher than that of CK -1 ·g. For total phosphorus, the soil total phosphorus content of the five interplanting modes is higher than that of CK, but there are two interplanting modes without significant difference; among them, there is significant difference between plum and white clover, light-leafed purple amaranth, and dark red clover, and the soil total phosphorus content of plum interplanting with dark red clover is the highest, which is 0.0315% higher. For total potassium, plum interplanting with white clover, arrow-shaped pea, and dark red clover is lower than CK and has no significant difference, plum interplanting with soybean is lower than CK and has significant difference, and plum interplanting with light-leafed purple amaranth is higher than CK and has no significant difference; indicating that interplanting with soybean can significantly reduce the total potassium content of the soil, which can be reduced by 0.15%.

[0060] Table 3 Influence of interplanting different crops on soil available nutrient content

[0061]

[0062] From Table 3, it can be seen that for available phosphorus, the available phosphorus content of the five interplanting modes is higher than that of CK, among which three modes have significant difference, and the available phosphorus content is in the order of dark red clover > arrow-shaped pea > light-leafed purple amaranth, and the available phosphorus content of plum interplanting with dark red clover is increased by 12.55 kg -1 ·g, and the other two groups have no significant difference. For available potassium, only one of the five interplanting modes is lower than CK, which is the plum interplanting with light-leafed purple amaranth mode, but there is no significant difference; the rest are higher than CK, but only two groups have significant difference, among which the plum interplanting with arrow-shaped pea mode has the highest increase of 17 kg -1• g. For hydrolytic nitrogen, all 5 interplanting modes are higher than CK, and all are significant; the interplanting mode of plum and red clover increases the most, reaching 49.5 kg -1 • g.

[0063] From the above study, after interplanting with 5 legume plants, the fruit weight of the St. Celep plum tree is higher than that of the control (CK); in addition, regardless of which legume plant is interplanted, the soluble solids in the fruit are improved compared to single plums, the total acid is overall reduced and the ascorbic acid is increased. It can be seen that interplanting St. Celep plum trees with legume plants can effectively improve the quality of plum fruit. Among them, the plum-arrow pea interplanting mode obtains the highest single fruit weight. In addition, interplanting soybeans not only allows the original plums to be harvested, but also allows soybeans to be harvested, resulting in higher product diversity and economic benefits. Therefore, the five legume plants are suitable for interplanting between plum trees.

[0064] 5 interplanting modes significantly increased the content of soil hydrolytic nitrogen, i.e., improved nitrogen fixation efficiency. Among them, the plum-arrow pea interplanting mode significantly increased the content of soil organic matter, available phosphorus, available potassium, and hydrolytic nitrogen. The increase in these soil available nutrients can promote plant growth, thereby contributing to the production of high-quality fruits.

[0065] In summary, the five legume plants are suitable for interplanting between plum trees, and plum-soybean is an interplanting mode that can harvest soybean byproducts. Plum-arrow pea is an optimized fruit-soybean interplanting mode that can improve soil nutrients and obtain high-quality fruits.

[0066] Example 2

[0067] Interplanting cultivation method

[0068] Step 1, selecting suitable interplanting orchards

[0069] The distance between the drip lines of the tree crowns of two rows of fruit trees reaches more than 80 cm.

[0070] Step 2, soybean sowing

[0071] 2.1, sowing period

[0072] Spring soybeans can be sown appropriately early, in the middle and late of March to the early of April, when the soil temperature is stable at more than 12°C, and sowing is done in time according to soil moisture conditions; summer soybeans can be sown appropriately late, in the middle of June to the early of July, and sowing is done in time after the soil moisture conditions after the rain, after the harvest of early-maturing fruit tree varieties in interplanting.

[0073] 2.2, planting density

[0074] The average row spacing of soybean is about 30-40 cm, and the plant spacing is about 15-25 cm. The specific number of rows to be sown depends on the spacing between fruit trees: the distance between the soybean sowing strip and the drip line of the fruit tree crown is not less than 30 cm.

[0075] Sow 4-5 seeds per hole, cover with 3-5 cm of fine soil after sowing, and manually thin and transplant the soybean before the first compound leaf unfolds. Remove weak, diseased, small, and weed seedlings, and select 2-3 healthy seedlings per hole.

[0076] Step 3, soil and fertilizer management

[0077] From late September to late October, use 1 ton of decomposed organic fertilizer as base fertilizer per mu of orchard, combine base fertilizer with tree pit, and deep plow 15-25 cm; 5-7 days before soybean sowing, apply 10-25 kg of nitrogen, phosphorus, and potassium (15-15-15) balanced compound fertilizer per mu of bean planting strip, then plow and cultivate 1-2 times in the fruit tree row, with a plowing depth of about 20 cm, to mix and evenly distribute the soil and fertilizer, and rake the soil to make it fine and flat, with a range not exceeding the drip line of the fruit tree crown.

[0078] The flowering and grain swelling period of soybean, combined with the seed and fruit development period of deciduous fruit trees, are critical periods that require nutrient supplementation. At this time, two foliar fertilizations can be performed throughout the orchard.

[0079] At the 2-4 leaf stage of grass weeds and 3-5 cm of broadleaf weeds, use soybean-specific herbicides (such as florasulam water, quizalofop-p-ethyl emulsion, or florasulam) for full-orchard weeding.

[0080] Step 4, disease and pest control

[0081] Aphids, Spodoptera litura, peach borer, and other pests are common to both fruit trees and soybeans. Pesticides, fungicides, and biological control agents can be used for disease and pest control. Pesticides include acetamiprid, lambda-cyhalothrin, etc., fungicides include thiophanate-methyl and ipconazole, etc., and biological control agents include Bacillus subtilis. These can be used in both fruit trees and soybeans (specific pesticide use can refer to GB / T 8321 and NY / T 1276).

[0082] At the 3-4 leaf stage, flowering stage, and grain swelling stage of soybean, 3 comprehensive controls can be performed together with fruit trees. At other times, control can be performed according to the respective disease incidence and needs of fruit trees and soybeans.

[0083] Example 3

[0084] 1. The test adopts a randomized block design, and a total of 7 interplanting experimental groups and 7 control groups are set, totaling 14 groups. Among them, test group 1, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 1, single Prunus salicina Lindl. tree. Test group 2, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 2, single Prunus salicina Lindl. tree. Test group 3, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 3, single Prunus salicina Lindl. tree. Test group 4, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 4, single Prunus salicina Lindl. tree. Test group 5, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 5, single Prunus salicina Lindl. tree. Test group 6, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 6, single Prunus salicina Lindl. tree. Test group 7, interplanting of Prunus salicina Lindl. with soybeans (Prunus salicina Lindl.-soybeans); control group 7, single Prunus salicina Lindl. tree. Each treatment is repeated 3 times, totaling 42 test plots.

[0085] 2. During the soil and fertilizer management period, that is, from late September to late October, 1 ton of composted organic fertilizer mixed with selenium-rich fertilizer is used as base fertilizer per mu of orchard, and the amount of selenium-rich fertilizer mixed is 5% of the mass of composted organic fertilizer. The selenium-rich fertilizer is amino acid chelated selenium fertilizer or humic acid selenium fertilizer.

[0086] 3. The content of selenium in plum fruit is determined by hydride generation atomic fluorescence spectrometry.

[0087] 4. The test results are shown in Table 4:

[0088] Table 4

[0089]

[0090] As can be seen from Table 4, interplanting of plum trees with legume plants can improve nitrogen fixation efficiency. However, for different varieties of plum trees, interplanting with different legume plants, even when adding selenium-rich fertilizer during fertilization, the competition and absorption of selenium elements between different varieties of plum trees and different varieties of legume plants are different and have great differences; in addition, the competition and absorption of nutrients in the soil between different varieties of plum trees and different varieties of legume plants are different, resulting in great differences in the nutritional substances and flavor (high content of soluble solids in the fruit is positively correlated with high sugar accumulation) in plum fruit.

[0091] Therefore, considering the nutritional substances and flavor in plum fruit, interplanting of Prunus salicina Lindl. with soybeans and interplanting of Prunus salicina Lindl. with soybeans are preferred. Considering the selenium content in plum fruit, interplanting of Prunus salicina Lindl. with soybeans is preferred.

[0092] Example 4

[0093] In step 3 of Example 2, during the soil and fertilizer management period, a trench is opened at the tree pit and a slow-release agent is applied, and the amount of composted organic fertilizer can be reduced by 1 / 4 (the actual amount of fertilizer applied is 750 kg). The amount of slow-release agent is 50 kg per mu.

[0094] The preparation method of the slow-release agent:

[0095] Method 1, the sludge, iron molybdate and water are mixed and injected into a sealed electrolytic chamber, the mass ratio of the sludge to the iron molybdate is 11:5, the mixture in the electrolytic chamber is subjected to high-voltage pulse discharge, the sludge and the iron molybdate generate mud under the action of the liquid-electric effect, the initial liquid-solid ratio in the electrolytic chamber is 1:7, the voltage of the high-voltage pulse discharge is 20 kV, the pulse width is 850 ns, and the discharge is performed for 150 times; the mud is poured out and filtered, and the filter cake is baked at 180-185℃ for 55 min, so that the slow-release agent is obtained.

[0096] When a pair of electrodes placed in a liquid is subjected to pulse high voltage, the electrode gap is instantaneously broken down, strong electric arc spark discharge is generated, and a series of significant physical, chemical, biological and mechanical effects are generated, which is called liquid-electric phenomenon. The occurrence chamber can be assisted by the existing electrolytic chamber, but the electrolytic reaction does not occur in the electrolytic chamber.

[0097] The sludge in the pond is destroyed by various physical and chemical effects generated by the liquid-electric effect, and the structure of the flocs and other organic matters in the sludge is destroyed. In addition, the iron molybdate can also undergo a series of decomposition reactions, and can also react with the organic matters in the sludge to generate corresponding molybdenum salts and iron salts; finally, the filter cake obtained by filtration contains a large amount of organic molybdenum salts and iron salts, which are mostly slightly soluble, and after subsequent high-temperature baking, they are combined with the loose and porous sludge, and when soaked in water, they can be released for a long time.

[0098] The sludge treated by the liquid-electric effect can be used as a medium for the attachment of rhizobium after being soaked in water.

[0099] The elements necessary for rhizobium mainly include iron, molybdenum, phosphorus, calcium, magnesium and the like, which play a key role in the nitrogen fixation process. Therefore, the addition of the slow-release agent can promote the growth and reproduction of rhizobium, thereby significantly improving the nitrogen fixation efficiency.

[0100] Method 2, the sludge, iron molybdate and water are mixed to prepare a mud slurry, the mass ratio of the sludge to the iron molybdate is 11:5, and the mud slurry is baked at 180-185℃ for 55 min, so that the slow-release agent is obtained.

[0101] Method 3, the sludge, iron molybdate and water are mixed to prepare a mud slurry, the mass ratio of the sludge to the iron molybdate is 11:5, and the mud slurry is dried and then calcined at 750-760℃ for 30 min, and then crushed, so that the slow-release agent is obtained.

[0102] Method 4, the sludge is baked at 180-185℃ for 55 min, so that the slow-release agent is obtained.

[0103] The total nitrogen measurement is the same as that of Example 2.

[0104] 2kg slow-release agent is poured into a flowerpot (the pot bottom has air holes with a diameter of 1cm), and 500mL water is poured into the flowerpot three times a day; the water pouring is continued for 30 days, and the iron element and molybdenum element contents released by the slow-release agent before and after 30 days of water pouring are measured. The sampling method is as follows: 2g slow-release agent is poured into a test tube, 5mL ion-free water is added into the test tube, and the test tube is shaken for 30min; then, the test tube is filtered, and the filtrate is taken to complete the sampling. The iron element content in the sample is measured by using the spectrophotometry (such as the o-phenanthroline colorimetry), and the molybdenum element content is measured by using the thiocyanate photometry.

[0105] The test results are shown in Table 5:

[0106] Table 5

[0107]

[0108] As shown in Table 5, the slow-release agent can release for a long time in the wet soil, and the released organic iron and molybdenum salt are beneficial to the growth and reproduction of rhizobium bacteria in the vicinity, and can significantly improve the nitrogen fixation effect.

[0109] However, the sludge and iron molybdate treated by direct mixing or calcination cannot generate a large amount of organic molybdenum salt and iron salt for plants and rhizobium bacteria to absorb, and cannot help the nitrogen fixation.

[0110] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all the preferred embodiments and all the changes and modifications falling within the scope of the present application.

[0111] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application encompass such modifications and changes as fall within the scope of the appended claims and their equivalents.

Claims

1. A cultivation method for improving the efficiency of nitrogen fixation in intercropping, characterized by: The plum tree is a Prunus salicina tree, and the leguminous plant is a Glycine max, and the method for intercropping the plum tree and the Glycine max comprises the following steps: Step 1, selecting the plum trees with a distance between two tree crown drip lines reaching 80 cm or above in an orchard for intercropping; Step 2, when selecting spring Glycine max for sowing, the sowing period is in the middle and late March to the early April, and the soil temperature is stable at 12 DEG C or above; When selecting summer Glycine max for sowing, the sowing period is in the middle of June to the early July; Step 3, soil fertilization, leaf surface topdressing and weeding are carried out on the intercropped plum trees and Glycine max; Step 4, insecticides, fungicides and biological control agents are used for disease and pest control; In step 3, 750 kg of decomposed organic fertilizer is used as base fertilizer for each mu of orchard in the late September to the late October, and the base fertilizer is combined with inter-row and tree disc deep ploughing of 15-25 cm; and a ditch is opened at the tree disc and a slow-release agent is applied, and the amount of the slow-release agent is 50 kg per mu; 5-7 days before sowing the Glycine max, 10-25 kg of nitrogen, phosphorus and potassium balanced compound fertilizer is applied to each mu of Glycine max planting belt, and then the intercropped plum trees are ploughed and cultivated 1-2 times to a depth of 20 cm, and the range of the ploughing and cultivating does not exceed the tree crown drip line; The preparation method of the slow-release agent is as follows: The sludge, iron molybdate and water are mixed and then injected into a sealed electrolytic chamber, high-voltage pulse discharge is carried out on the mixture in the electrolytic chamber, the sludge and the iron molybdate generate mud under the action of liquid-electric effect, the mud is poured out and filtered, and the filter cake is baked at 180-185 DEG C for 55 min, so that the slow-release agent is obtained; The mass ratio of the sludge to the iron molybdate in the electrolytic chamber is 11:5, the initial material liquid ratio in the electrolytic chamber is 1:7, the voltage of the high-voltage pulse discharge is 20 kV, the pulse width is 850 ns, and the discharge is carried out 150 times.

2. The cultivation method for improving the efficiency of nitrogen fixation in intercropping according to claim 1, characterized in that: In step 2, the planting density of the Glycine max is that the average row spacing is 30-40 cm, the plant spacing is 15-25 cm, and the distance between the Glycine max edge row sowing belt and the tree crown drip line is not less than 30 cm.

3. The cultivation method for improving the efficiency of nitrogen fixation in intercropping according to claim 2, characterized in that: In step 3, when the grass weeds are at the 2-4 leaf stage and the broadleaf weeds are at the 3-5 cm height, the whole orchard is weeded by using fluthiacet-methyl water agent, quizalofop-p-ethyl emulsifiable concentrate or fluthiacet-methyl.

4. The cultivation method for improving the efficiency of nitrogen fixation in intercropping according to claim 2, characterized in that: In step 4, the insecticide is acetamiprid or lambda-cyhalothrin, the fungicide is thiophanate-methyl or ipconazole, and the biological control agent is selected from Bacillus subtilis.

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