Nitrogen fertilizer applying method for multiple cropping of winter green manure and corn in saline-alkali dry land

Abstract

The invention relates to the technical field of agriculture, and particularly discloses a nitrogen fertilizer applying method for multiple cropping of winter green manure and corn in saline-alkali dry land. According to the method, the sowing time and the returning time of the leguminous winter green manure in the saline-alkali dry land, the sowing time and the base fertilizer application time of the corn, the application amount and the topdressing time of the chemical nitrogen fertilizer in the base fertilizer and the topdressing amount of the chemical nitrogen fertilizer are determined; according to the nitrogen fertilizer application method, the application amount of chemical nitrogen fertilizer in corn base fertilizer and topdressing under the condition that leguminous winter green manure is planted in the mild saline-alkali dry land in the winter-spring idle field and full-amount field returning is determined, the phenomenon of excessive application of chemical nitrogen fertilizer in the corn production process is avoided, the fertilizer utilization rate is increased, and the purpose of reducing the application amount of the chemical nitrogen fertilizer is achieved. The environment-friendly nitrogen fertilizer applying method for multiple cropping of the winter green manure and the corn in the saline-alkali dry land has great significance in improving the quality of saline-alkali cultivated land, developing and utilizing coastal saline-alkali cultivated land resources, guaranteeing national grain safety, protecting the ecological environment and promoting transformation and upgrading of animal husbandry.

Description

Technical Field

[0001] The present invention relates to the technical field of agriculture, and particularly relates to a nitrogen fertilizer application method for winter green manure and multiple cropping of corn in saline-alkali dry land. Background Art

[0002] The saline-alkali cultivated land area in Hebei Province reaches 5.7025 million mu, mainly located in the Bohai Rim region, with great development potential. Huanghua City is the main distribution area of saline-alkali cultivated land along the Bohai Sea in Hebei Province. In this area, the groundwater is shallowly buried, the salt source is rich, and the fresh water resources are scarce, so irrigation cannot be carried out. Precipitation is scarce in winter and spring, and salt accumulation on the surface is serious. The rain and heat are in the same period from June to September. Therefore, one-season corn is the main crop planting system in this area. Due to the high salt content, low organic matter and nutrient content, and poor microbial activity in the soil, the corn yield is low and unstable. To increase the yield, there is a common phenomenon of excessive nitrogen application in corn production, resulting in low nitrogen fertilizer utilization rate, waste of fertilizer resources, increase in agricultural production costs, and pollution of the ecological environment. And after the corn is harvested, the surface of the winter and spring fallow fields is bare, which is prone to sand and dust blowing, leading to surface soil loss and serious soil wind erosion, reducing soil quality and damaging the ecological environment. Therefore, providing a nitrogen fertilizer application method for winter green manure and multiple cropping of corn in saline-alkali dry land can not only cover the winter and spring fallow fields, reduce sand and dust blowing, prevent soil wind erosion, but also reduce soil evaporation, prevent soil salinization, reduce the salt content in the plough layer soil. At the same time, after the green manure is returned to the field, nitrogen nutrients can be released through the mineralization process to replace part of the chemical fertilizer nitrogen input for the next crop. It is of great significance for realizing the goals of "replacing chemical fertilizers with organic fertilizers" and "reducing chemical fertilizer application" in China and improving the nitrogen fertilizer utilization rate of corn in saline-alkali dry land. Summary of the Invention

[0003] Aiming at the problem of low nitrogen fertilizer utilization rate of corn in existing coastal saline-alkali dry land, the present invention provides a nitrogen fertilizer application method for winter green manure and multiple cropping of corn in saline-alkali dry land.

[0004] To solve the above technical problems, the technical solution provided by the present invention is:

[0005] The present invention provides a nitrogen fertilizer application method for winter green manure and multiple cropping of corn in saline-alkali dry land, comprising the following steps:

[0006] Step 1: Sowing winter green manure: From late July to early September, after the effective rainfall starts, sow leguminous winter green manure between the rows of corn in saline-alkali land;

[0007] Step 2: Harvesting corn: From late September to mid-to-early October, harvest the corn, and carry out stubble cutting on the corn straw, with the stubble height being 10 cm - 15 cm;

[0008] Step 3: Measure the nitrogen nutrient accumulation of winter green manure: In the first and middle ten days of May of the following year, measure the nitrogen nutrient accumulation AN of leguminous winter green manure, then incorporate the leguminous winter green manure in the flower and pod stage and the corn stubble into the field, and calculate the base fertilizer application rate XN1 and top dressing application rate XN2 of the target nitrogen requirement for the next-season corn according to the nitrogen nutrient release characteristics after the return of leguminous winter green manure to the field, the nutrient utilization efficiency NUE of the nitrogen supplied by leguminous winter green manure in the next-season corn gm and the nitrogen fertilizer application rate XN required for the target yield of corn; where XN1 = XN × 40%, XN2 = XN × 60%;

[0009] Step 4: Apply base fertilizer and sow the next-season corn: From late May to early July, apply base fertilizer, prepare the land, and sow corn in a timely manner after the effective rainfall ends. Among them, the nitrogen fertilizer application rate XN1 in the corn base fertilizer 基 = XN1 - AN × V t1 × NUE gm , V t1 is the nitrogen nutrient release rate t1 days after the return of leguminous winter green manure when applying base fertilizer and sowing corn;

[0010] Step 5: Top-dress nitrogen fertilizer for the next-season corn: Top-dress nitrogen fertilizer during the jointing stage of corn or when there is effective rainfall during the period from the jointing stage to the large trumpet mouth stage of corn. Among them, the nitrogen fertilizer application rate XN2 of the top dressing 追 = XN2 - AN × (V t2 - V t1 ) × NUE gm , V t2 is the nitrogen nutrient release rate t2 days after the return of leguminous winter green manure when top-dressing nitrogen fertilizer for corn.

[0011] Compared with the prior art, the nitrogen fertilizer application method for winter green manure multiple cropping with corn in saline-alkali dryland provided by the present invention uses the winter and spring fallow fields formed after corn harvest to plant leguminous winter green manure, which can not only cover the ground surface, reduce sand and dust blowing, prevent soil wind erosion, but also reduce soil evaporation, prevent soil salt return, and reduce the salt content of the plow layer soil; after the leguminous winter green manure is returned to the field, it can improve the soil organic matter content and improve the physical and chemical properties of the soil through the humification process. At the same time, through the mineralization process, it can release mineral nutrients to replace part of the chemical fertilizer input of the next-season crop, thereby reducing the input of chemical fertilizer nitrogen in corn production, improving the utilization efficiency of nitrogen fertilizer for corn, and reducing the waste of fertilizer resources; leguminous winter green manure can also improve the soil nitrogen fertility through biological nitrogen fixation. At the same time, its straw has a rich nitrogen content and a low C / N ratio, and can quickly release nitrogen nutrients for the next-season corn to use after being returned to the field.

[0012] The present invention determines the sowing time and field returning time of winter green manure of leguminous materials in saline-alkali dryland, the sowing time, the basal fertilizer application time, the application amount of chemical nitrogen fertilizer in the basal fertilizer, and the topdressing time and the topdressing amount of chemical nitrogen fertilizer, clarifies the application amount of chemical nitrogen fertilizer in the basal fertilizer and topdressing of corn under the condition of planting winter green manure of leguminous materials in idle fields in winter and spring in mild saline-alkali dryland and returning all of it to the field, avoids the phenomenon of excessive nitrogen application in the corn production process, improves the fertilizer utilization rate, and thus achieves the nitrogen fertilizer application method with the goal of reducing the application of chemical nitrogen fertilizer; the present invention establishes an environment-friendly nitrogen fertilizer application method for dual-purpose corn for grain and feed in saline-alkali dryland, which is of great significance to improving the quality of saline-alkali cultivated land, developing and utilizing coastal saline-alkali cultivated land resources, ensuring national food security, protecting the ecological environment, and promoting the transformation and upgrading of animal husbandry.

[0013] Preferably, in step 1, the condition for effective rainfall is: the rainfall in a one-time rainfall process is ≥ 30 mm.

[0014] By limiting the conditions of effective rainfall, there can be sufficient moisture in the soil to initiate the germination of leguminous winter green manure seeds. If the rainfall is too little, the soil moisture is insufficient to initiate the germination of leguminous winter green manure seeds, which will lead to the failure of leguminous winter green manure sowing.

[0015] Preferably, in step 1, the leguminous winter green manure is Turkmen hairy-leaved vetch.

[0016] Turkmen hairy-leaved vetch is a high-quality perennial legume winter green manure that is salt-alkali tolerant, drought-tolerant, barren-tolerant, thermophilic and cold-tolerant, has a large biomass, and can perform biological nitrogen fixation. It is suitable for the high-salt, poor-fertility, and arid soil environment of coastal saline-alkali dryland in the Bohai Rim of Hebei Province. Because the groundwater level in coastal saline-alkali dryland is shallow and the groundwater is salty, irrigation is not possible, so the planting of winter green manure in coastal saline-alkali dryland can only be done by dry farming. Late July to August is a period of concentrated rainfall in the Bohai Rim region of Hebei Province. At this time, it is easy to germinate if sown in the rain, but the temperature is high at this time. Other winter green manures are not heat-resistant, while Turkmen hairy-leaved vetch likes warmth and can resist heat. At the same time, the temperature in this area is low in winter and spring, and other winter green manures cannot survive the winter and have a low greening rate, while Turkmen hairy-leaved vetch is resistant to low temperatures and can survive the winter. Corn is a grass crop that requires a large amount of nitrogen. Hairy vetch can fix nitrogen biologically. Its straw has a high nitrogen content and a low C / N ratio. After returning to the field, it can release a large amount of mineral nitrogen, which can supply nitrogen nutrients for the growth of the next crop of corn. The bean-grass rotation has nitrogen advantages and is an environmentally friendly planting model.

[0017] Preferably, in step 1, the sowing conditions are: after the start of effective rainfall, the leguminous winter green manure seeds are evenly sown between the rows of corn in the saline-alkali land, with a sowing amount of 8kg / mu-10kg / mu, and the seeds are pressed down in time after sowing.

[0018] Before sowing, it is necessary to remove the weeds between the rows of corn plants from the field. Because the seeds are generally scattered on the ground by broadcast sowing, if there are weeds on the ground, the winter green manure seeds will fall on the weeds and cannot come into contact with the ground, unable to absorb the water in the soil and cannot germinate, resulting in sowing failure. On the other hand, if the weeds between the rows of corn plants grow vigorously and the winter green manure seedlings are weak and cannot compete with the weeds, it will also lead to the failure of winter green manure sowing. Therefore, it is necessary to clean up the weeds in the field before sowing winter green manure seeds.

[0019] Compared with the drilling sowing method, the germination rate of the broadcast sowing method is low, so the sowing rate of broadcast sowing should be 20%-30% more than that of drilling. At the same time, the high salt content in the saline-alkali soil inhibits seed germination. The results of field trials show that the sowing rate of leguminous winter green manure by broadcast in the light saline-alkali dry land between the rows of corn in the Bohai Rim coastal area of Hebei Province is 8 kg / mu - 10 kg / mu. The sowing rate should be increased accordingly with the increase of the salinity of the cultivated land.

[0020] To increase the contact between the winter green manure seeds and the soil and improve the seed germination rate, it is necessary to roll the soil in time after broadcast sowing.

[0021] Preferably, in step 1, the conditions of the saline-alkali land are: the salt content in the plough layer soil ≤ 4 g / kg.

[0022] Through field trials, it is found that leguminous winter green manure has a low germination rate, less biomass and low nitrogen nutrient accumulation in the soil with a total salt content > 4 g / kg, and loses its significance in replacing the chemical nitrogen fertilizer of the next crop of corn.

[0023] Preferably, in step 2, when harvesting the corn, the leguminous winter green manure needs to meet the condition of vegetative growth for more than 30 days.

[0024] Whether the winter green manure can survive the winter safely and whether it can recover growth after being trampled during the mechanical harvesting process of corn are the key technical links for the successful establishment of the winter green manure multiple cropping corn model. Through field trials, it is verified that when the vegetative growth of leguminous winter green manure is ≥ 30 days at the time of corn harvesting, it can recover growth quickly after being trampled by the machinery of the harvested corn. At the same time, the larger the crop plant, the stronger the cold tolerance. After 30 days of vegetative growth, the leguminous winter green manure has accumulated a certain amount of biomass and has strong cold tolerance, and can survive the winter safely in the saline-alkali dry land in the Bohai Rim coastal area of Hebei Province.

[0025] Preferably, in step 2, when harvesting the corn, the corn straw is cut with a stubble, and the stubble height is 10 cm - 15 cm.

[0026] After winter green manure is intercropped between rows of corn, mowing the corn straw at ground level will take away the above-ground part of the winter green manure, resulting in the failure of winter green manure planting. Through field trials, when the stubble height of corn straw is 10 cm - 15 cm during mowing, it generally does not cause significant damage to the above-ground part of winter green manure. The stubble height of corn straw can be adjusted according to the thickness of the winter green manure coverage layer to minimize the damage to the above-ground part of winter green manure during corn mechanical harvesting. At the same time, when the stubble height of corn straw is 10 cm - 15 cm, the ash content brought into the harvested straw will be reduced, which will improve the quality of straw feed and reduce the incidence of livestock diseases.

[0027] Preferably, in step 3, the nitrogen nutrient accumulation amount AN (kg / mu) of the leguminous winter green manure = DM × NC × 0.001, where DM (kg / mu) is the biomass of the leguminous winter green manure, and NC (g / kg) is the total nitrogen content of the leguminous winter green manure plants.

[0028] More preferably, in step 3, the measurement method of the nitrogen nutrient accumulation amount AN of the leguminous winter green manure includes the following steps:

[0029] The diagonal method is used to measure the biomass of the leguminous winter green manure. A square area is selected, and 1 sampling point is selected at each of the four corners and the intersection point of the diagonals of the square area. A 0.5 m × 0.5 m sampling frame is used to sample at each sampling point, and the measurement is randomly repeated 4 - 5 times per mu of land; the above-ground part of the leguminous winter green manure in the sampling frame and the roots in the 0 cm - 20 cm soil layer are taken away together to measure the biomass of the leguminous winter green manure. After measuring the total fresh weight (m1, g) of the leguminous winter green manure after the roots are cleaned, 500 g of fresh samples are taken and weighed (m2, g) with a balance with a precision of 0.1 g, and then placed in a constant temperature blast drying oven at 60 °C to dry to a constant weight and weigh the dry weight (m3, g). After weighing the dry weight, it is crushed to measure the total nitrogen content (NC, g / kg) of the leguminous winter green manure plants. According to the fresh weight (m2) and dry weight (m3) of the fresh samples of the leguminous winter green manure, the dry-to-fresh ratio r = m3 / m2 is calculated. The remaining leguminous winter green manure after taking 500 g of fresh samples is put back to the corresponding yield measurement sampling points in the test area. Among them, the biomass DM (kg / mu) of the leguminous winter green manure = m1 × r × C × 0.001 × 667 / 0.25, where C is the coverage of leguminous crops on saline-alkali land.

[0030] More preferably, the square area is a square or rectangular area with a side length of 2 m - 5 m.

[0031] More preferably, the square area is at least 1 m away from the edge or the head of the field.

[0032] It should be further noted that if the selected sampling point falls into the salt spot area, the square area should be adjusted to avoid the salt spot.

[0033] Preferably, in step 3, the conditions for stubble ploughing and returning to the field are as follows: crush the above-ground straw of hairy vetch and corn once with a straw crusher, and plough the soil once with a rotary tiller, with the tillage depth of the soil being 15 cm - 20 cm.

[0034] Specifically, the conditions for stubble ploughing and returning to the field are as follows: crush the above-ground straw of leguminous winter green manure and corn in place with a straw crushing machine, with the crushing length ≤ 3 cm. After crushing, plough the soil once with a rotary tiller, with the tillage depth being 15 cm - 20 cm, and fully mix the crushed straw with the plough layer soil.

[0035] Preferably, in step 3, the nitrogen nutrient release characteristics are determined by the nylon bag buried field method in combination with the logarithmic function equation (V t = a + b × lnt, where V t is the nitrogen nutrient release rate of leguminous winter green manure; t is the number of days after returning to the field, that is, the decomposition days of leguminous winter green manure; both a and b are constants) to clarify the nitrogen nutrient release characteristics of leguminous winter green manure in saline-alkali land.

[0036] Specifically, the parameters a and b can be estimated from the experimental data obtained through the decomposition experiment of winter green manure using the nylon bag buried field method. Taking the calculation of Example 1 as an example (see Table 1), a and b are estimated by substituting the nitrogen nutrient release rate of winter green manure after the buried days (t) determined by the buried field method are 10 d (the first sampling and determination) and the nitrogen nutrient release rate of winter green manure after the buried days (t) are 140 d (the last sampling and determination), as follows:

[0037] Step 1: Substitute the nitrogen nutrient release rate of 57.00% after the buried days of 10 d into V t = a + b × lnt, and get 57.00 = a + b × ln10;

[0038] Step 2: Substitute the nitrogen nutrient release rate of 79.21% after the buried days of 140 d into V t = a + b × lnt, and get 79.21 = a + b × ln140;

[0039] Step 3: Combine Equation (1) and Equation (2) to obtain the estimated values of parameters a and b: a = 37.62171, b = 8.415884;

[0040] Step 4: Substitute a and b into the logarithmic function equation V t = a + b × lnt to obtain the green manure nitrogen nutrient release rate equation: V t = 37.62171 + 8.415884 × lnt;

[0041] Table 1 Data table of the decomposition experiment of hairy vetch in Example 1

[0042]

[0043] Note: The nitrogen (N) nutrient content in Vicia villosa Roth var. kuljaica in nylon bags under different burial days = the dry weight of the remaining Vicia villosa Roth var. kuljaica in nylon bags under the corresponding burial days (d) × 0.001 × the total nitrogen (N) content in the residues of Vicia villosa Roth var. kuljaica in nylon bags under the corresponding burial days (g / kg); the nitrogen nutrient release rate of Vicia villosa Roth var. kuljaica (%) = (the nitrogen nutrient content of Vicia villosa Roth var. kuljaica after 0 days of burial - the nitrogen nutrient content of Vicia villosa Roth var. kuljaica after t days of burial) ÷ the nitrogen nutrient content of Vicia villosa Roth var. kuljaica after 0 days of burial × 100%.

[0044] Preferably, in step 3, the nutrient use efficiency NUE of the leguminous winter green manure nitrogen on the next-season maize gm (%) = c / d × 100%, where c is the amount of N absorbed by the above-ground part of maize from the leguminous winter green manure, 15 and d is the amount of N in the leguminous winter green manure 15 .

[0045] It should be further noted that the amount of N c (kg / ha) absorbed by the above-ground part of maize from the leguminous winter green manure = grain biomass × grain nitrogen content × (grain 15 N percentage excess - 0.3663) + straw biomass × straw nitrogen content × (straw 15 N percentage excess - 0.3663) + leaf biomass × leaf nitrogen content × (leaf 15 N percentage excess - 0.3663), and the amount of N d (kg / ha) in the leguminous winter green manure plants 15 = hairy vetch biomass × plant nitrogen content × (plant 15 N percentage excess - 0.3663). 15 .

[0046] More preferably, in step 3, the nitrogen fertilizer application rate XN required for the target yield of maize = (YN - SN) / NUE, where YN is the nitrogen requirement for maize to obtain the target yield, SN is the soil available nitrogen amount obtained from the detection of soil available nitrogen at 0 cm - 20 cm, and NUE is the nitrogen fertilizer utilization rate of maize.

[0047] More preferably, in step 3, it is necessary to clarify in advance the nitrogen fertilizer application rate required for the target yield of maize.

[0048] More preferably, the nitrogen fertilizer application rate XN required for the target yield of maize can be determined according to the soil and plant testing recommendation method in the Technical Regulation for Soil Testing and Formulated Fertilization (NY / T 2911 - 2016).

[0049] Further preferably, the nitrogen use efficiency (NUE) of the corn can be calculated based on field experiments. The specific calculation formula is: NUE = (nitrogen uptake by corn in the fertilized area - nitrogen uptake by corn in the control area) / nitrogen application rate × 100%.

[0050] Currently, the average nitrogen use efficiency of corn in China in the current season is 35%. Therefore, NUE is generally taken as 35%.

[0051] Preferably, in step 4, the condition for effective rainfall is that the soil water content reaches 60%-70% of the field capacity after rainfall.

[0052] Preferably, in step 4, the corn is Jiyuan 128, Denghai 605 or Zhengdan 958.

[0053] Preferably, in step 4, the V t1 = a + b × lnt1.

[0054] Preferably, in step 5, the condition for effective rainfall is that the rainfall amount in a single rainfall process is ≥ 30 mm.

[0055] Preferably, in step 5, the specific operation of topdressing during the jointing stage of corn is as follows: When using a small corn topdressing machine to apply fertilizer in furrows between corn rows, the conditions are that the corn plant height is < 60 cm, the distance from the corn plant is 15 cm - 20 cm, the furrow opening depth is 10 cm - 20 cm, and the soil is covered in time after furrow opening and fertilization.

[0056] Preferably, in step 5, the V t2 = a + b × lnt2.

[0057] The beneficial effects of the present invention are as follows: The method of the present invention is an environmentally friendly fertilization method specifically for reducing nitrogen fertilizer and increasing efficiency in one-season corn in coastal slightly saline-alkali dryland. This method combines the method of replacing part of the chemical nitrogen fertilizer with salt-tolerant leguminous winter green manure, improves the formula fertilization technology and the traditional conventional fertilization method, and establishes a precise fertilization method for nitrogen fertilizer in the mode of leguminous winter green manure multiple cropping corn in coastal slightly saline-alkali dryland. It reduces the nitrogen fertilizer input in corn production in coastal saline-alkali dryland, improves the nitrogen use efficiency, reduces environmental pollution, protects the ecological environment, and at the same time, this fertilization method has strong practicability and fills the domestic gap in this field. Specific embodiments

[0058] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0059] Example 1

[0060] This embodiment provides a nitrogen fertilizer application method for winter green manure and multiple cropping of corn in saline-alkali dry land, which includes the following steps:

[0061] Step 1: Sow winter green manure. On August 14, 2022, when the effective rainfall (the rainfall amount in this one-time rainfall process was 51 mm) started, the seeds of Vicia villosa Roth were evenly sown between the rows of corn in the saline-alkali land, and the seeding rate was 8 kg / mu. Among them, the salt content of the middle tillage layer soil in the saline-alkali land was 2.10 g / kg;

[0062] Step 2: Harvest corn. On October 8, 2022, the corn was harvested using a silage harvester, and the corn stubble height was 10 cm;

[0063] Step 3: Measure the nitrogen nutrient accumulation amount of winter green manure. On May 16, 2023, a rectangular biomass measurement area with a width of 2 m and a length of 4 m was randomly selected in the test area. The biomass DM and nitrogen nutrient accumulation amount AN of Vicia villosa Roth were measured using the diagonal yield measurement method, and the average value was taken after repeating 4 times. At the same time, the coverage C of Vicia villosa Roth in the test area was investigated and calculated. The measurement results of the average biomass DM and average nitrogen nutrient accumulation amount AN of Vicia villosa Roth in 2023 are shown in Table 2. The nitrogen nutrient utilization rate NUE of the nitrogen supplied by Vicia villosa Roth in the next-season corn was calculated using the data results obtained through pot experiments, in-situ undisturbed soil column methods, 15 N isotope tracer technology in 2022. gm The calculation process is shown in Table 3. On May 17, 2023, soil samples of the 0 cm - 20 cm soil layer were collected according to the soil sample collection method in the Technical Specification for Soil Testing and Formula Fertilization (NY / T 2911 - 2016) to measure the soil available nitrogen content, and the available nitrogen amount supplied by the soil tillage layer was calculated. The specific measurement results are shown in Table 4. All Vicia villosa Roth in the test area and the corn root stubble were stubbled, and the leguminous winter green manure and the above-ground straw of the corn were crushed in place using a straw crushing machine, and the crushing length was ≤ 3 cm. After crushing, the soil was rotary tilled once using a rotary tiller, and the rotary tillage depth was 15 cm. During the rotary tillage process, the crushed straw was fully mixed with the tillage layer soil;

[0064] Step 4: Apply basal fertilizer and sow the next-season corn. On July 4, 2023, the rainfall in the test station was 83.3 mm. On July 5, 2023, when the soil moisture content reached 65% of the field water holding capacity, basal fertilizer was applied, the land was prepared, and corn was sown. The corn variety was Denghai 605. At this time, the buried days (t) of Vicia villosa Roth were 49 days. According to the logarithmic function equation model V t = 37.62171 + 8.415884 × lnt (the derivation process is shown in (6) Nitrogen Nutrient Release Characteristics and Calculation Model of Vicia villosa Roth after the text), the nitrogen nutrient release rate was 70.37%; Using the formula XN1 基 = XN1 - AN × V t1 × NUEgm Calculate the required amount of chemical nitrogen fertilizer in the base fertilizer for the target yield of corn. Among them, XN1 is 5.12 kg / mu, AN is 12.32 kg / mu, V t1 is 70.37%, and NUE gm is 46.99% (see the calculation process in (2) below for the nutrient utilization rate NUE of nitrogen from Vicia villosa Roth in the next crop of corn gm ). Then, the chemical nitrogen fertilizer XN1 required in the base fertilizer of corn 基 is: 5.12 kg / mu - 12.32 kg / mu × 70.37% × 46.99% = 1.05 kg / mu;

[0065] Step 5: Top-dress nitrogen fertilizer for the next crop of corn. On August 10, 2023, when the corn was at the jointing stage with a plant height of 50 cm, a small corn top-dressing machine was used to open a ditch for top-dressing nitrogen fertilizer between the corn rows. The depth of the ditch was 15 cm, and the position of the ditch was 20 cm away from one side of the corn plant. After top-dressing with fertilizer, the soil was covered in time. At this time, the buried days (t) of Vicia villosa Roth was 85 days. According to the logarithmic function equation model V t = 37.62171 + 8.415884 × lnt, the nitrogen nutrient release rate was 75.01%; the application rate of chemical nitrogen fertilizer was XN2 追 = XN2 - AN × (V t2 - V t1 ) × NUE gm = 7.68 kg / mu - 12.32 kg / mu × (75.01% - 70.37%) × 46.99% = 7.41 kg / mu.

[0066] Example 2

[0067] This example provides a method for applying nitrogen fertilizer for winter green manure multiple cropping of corn in saline-alkali dry land, including the following steps:

[0068] Step 1: Sow winter green manure. On August 14, 2022, when the effective rainfall (the rainfall in this one-time rainfall process was 51 mm) started, the seeds of Vicia villosa Roth were evenly sown between the rows of corn in the saline-alkali land, and the seeding rate was 9 kg / mu. Among them, the salt content of the middle tillage layer soil in the saline-alkali land was 3.16 g / kg;

[0069] Step 2: Harvest corn. On October 8, 2022, the corn was harvested using a silage harvester, and the stubble height of the corn was 12 cm;

[0070] Step 3: Measure the nitrogen nutrient accumulation of winter green manure. On May 16, 2023, a rectangular biomass measurement area with a width of 2 m and a length of 4 m was randomly selected in the experimental area. The biomass DM and nitrogen nutrient accumulation AN of Vicia villosa Roth were measured by the diagonal yield measurement method, and the average value was taken after 4 repetitions. At the same time, the coverage C of Vicia villosa Roth in the experimental area was investigated and calculated. The measurement results of the average biomass DM and average nitrogen nutrient accumulation AN of Vicia villosa Roth in 2023 are shown in Table 2; the nitrogen use efficiency NUE of the nitrogen supplied by Vicia villosa Roth in the following stubble of maize was calculated by the pot experiment, in-situ undisturbed soil column method, 15 N isotope tracer technique in 2022 gm , and the calculation process is shown in Table 3. On May 17, 2023, soil samples of the 0 cm - 20 cm soil layer were collected according to the soil sample collection method in the Technical Regulations for Formula Fertilization Based on Soil Testing (NY / T 2911 - 2016) to measure the soil available nitrogen content, and the available nitrogen amount supplied by the soil tillage layer was calculated. The specific measurement results are shown in Table 4. All Vicia villosa Roth in the experimental area were stubbled together with the maize root stubbles, and the above-ground straw of leguminous winter green manure and maize was shredded on-site with a straw shredding machine, and the shredding length was ≤ 3 cm. After shredding, the soil was rotary tilled once with a rotary tiller, and the rotary tillage depth was 20 cm. During the rotary tillage process, the shredded straw was fully mixed with the tillage layer soil;

[0071] Step 4: Apply basal fertilizer and sow the following stubble of maize. The rainfall in the experimental station on July 4, 2023 was 83.3 mm. On July 5, 2023, when the soil water content reached 65% of the field water holding capacity, basal fertilizer was applied, the land was prepared, and maize was sown. The maize variety was Denghai 605. At this time, the burial days (t) of Vicia villosa Roth were 49 days. According to the logarithmic function equation model V t = 31.49653 + 8.578821 × lnt (the derivation process is shown in (6) Nitrogen nutrient release characteristics and calculation model of Vicia villosa Roth after the text), the nitrogen nutrient release rate was 64.88%; the formula XN1 基 = XN1 - AN × V t1 × NUE gm was used to calculate the required amount of chemical fertilizer nitrogen in the basal fertilizer for the target yield of maize, where XN1 was 5.32 kg / mu, AN was 10.87 kg / mu, V t1 was 64.88%, and NUE gm was 43.30% (the calculation process is shown in (2) Nitrogen use efficiency NUE of Vicia villosa Roth in the following stubble of maize after the text gm ), then the required chemical nitrogen fertilizer XN1 基 in the maize basal fertilizer was: 5.32 kg / mu - 10.87 kg / mu × 64.88% × 43.30% = 2.27 kg / mu;

[0072] Step 5: Top-dress nitrogen fertilizer for the following-season corn. On August 12, 2023, when the rainfall began (the rainfall during this one-time rainfall process was 69.8 mm, which was effective rainfall), the remaining chemical nitrogen fertilizer was top-dressed. At this time, the buried days (t) of Vicia villosa Roth was 87 days. According to the logarithmic function equation model V t = 31.49653 + 8.578821×lnt, the nitrogen nutrient release rate was 69.81%; the application rate of chemical nitrogen fertilizer for corn was XN2 追 = XN2 - AN×(V t2 - V t1 )×NUE gm = 7.97 kg / mu - 10.87 kg / mu×(69.81% - 64.88%)×43.30% = 7.74 kg / mu.

[0073] Example 3 This example provides a method for applying nitrogen fertilizer to winter green manure and multiple-cropping corn in saline-alkali dry land, including the following steps:

[0074] Step 1: Sow winter green manure. On August 14, 2022, when the effective rainfall (the rainfall during this one-time rainfall process was 51 mm) began, the seeds of Vicia villosa Roth were evenly sown between the rows of corn in the saline-alkali land, and the seeding rate was 10 kg / mu. Among them, the salt content of the medium tillage layer soil in the saline-alkali land was 4.0 g / kg;

[0075] Step 2: Harvest corn. On October 8, 2022, the corn was harvested using a silage harvester, and the corn stubble height was 15 cm;

[0076] Step 3: Measure the nitrogen nutrient accumulation of winter green manure. On May 16, 2023, a rectangular biomass measurement area with a width of 2 m and a length of 4 m was randomly selected in the test area. The diagonal yield measurement method was used to measure the biomass DM and nitrogen nutrient accumulation AN of Vicia villosa Roth, and the average value was taken after repeating 4 times. At the same time, the coverage C of Vicia villosa Roth in the test area was investigated and calculated. The measurement results of the average biomass DM and average nitrogen nutrient accumulation AN of Vicia villosa Roth in 2023 are shown in Table 2; in 2022, through pot experiments, in-situ undisturbed soil column methods, 15 N isotope tracer technology was used to calculate the nutrient utilization rate NUE of the nitrogen supplied by Vicia villosa Roth in the following-season corn gm, the calculation process is shown in Table 3. On May 17, 2023, soil samples of the 0 cm - 20 cm soil layer were collected according to the soil sampling method in the Technical Regulations for Soil Testing and Formulated Fertilization (NY / T 2911 - 2016) to determine the available nitrogen content in the soil, and the amount of available nitrogen supplied by the soil plough layer was calculated. The specific measurement results are shown in Table 4. All the hairy vetch of Turkmenistan in the experimental area, together with the corn stubble, were stubbled. The leguminous winter green manure and the above - ground straw of corn were crushed in place with a straw crushing machine, and the crushing length was ≤ 3 cm. After crushing, the soil was rotary - tilled once with a rotary tiller, and the rotary tillage depth was 20 cm. During the rotary tillage process, the crushed straw was fully mixed with the plough layer soil;

[0077] Step 4: Apply basal fertilizer and sow the next - season corn. The rainfall at the experimental station on July 4, 2023 was 83.3 mm. On July 5, 2023, when the soil moisture content reached 65% of the field capacity, basal fertilizer was applied, the land was prepared, and corn (variety: Denghai 605) was sown. At this time, the burial days (t) of the hairy vetch of Turkmenistan was 49 d. According to the logarithmic function equation model V t = 26.62643 + 9.32151×lnt (the derivation process is shown in (6) Nitrogen Nutrient Release Characteristics and Calculation Model of Hairy Vetch of Turkmenistan after this article), the nitrogen nutrient release rate was 62.90%; Using the formula XN1 基 = XN1 - AN×V t1 ×NUE gm to calculate the required amount of chemical nitrogen fertilizer in the basal fertilizer for the target yield of corn. Among them, XN1 was 4.92 kg / mu, AN was 10.29 kg / mu, V t1 was 62.90%, and NUE gm was 40.94% (the calculation process is shown in (2) Nitrogen Nutrient Utilization Efficiency NUE of Hairy Vetch of Turkmenistan in the Next - Season Corn after this article gm ), then the chemical nitrogen fertilizer XN1 基 required for the corn basal fertilizer was: 4.92 kg / mu - 10.29 kg / mu×62.90%×40.94% = 2.27 kg / mu;

[0078] Step 5: Top - dress nitrogen fertilizer for the next - season corn. On August 12, 2023, when the rainfall began (the rainfall during this one - time rainfall process was 69.8 mm, which was effective rainfall), the remaining chemical nitrogen fertilizer was top - dressed. At this time, the burial days (t) of the hairy vetch of Turkmenistan was 87 d. According to the logarithmic function equation model V t = 26.62643 + 9.32151×lnt, the nitrogen nutrient release rate was 68.26%; The amount of chemical nitrogen fertilizer top - dressed for corn was XN2 追 = XN2 - AN×(V t2 - V t1 )×NUE gm= 7.37 kg / mu - 10.29 kg / mu × (68.26% - 62.90%) × 40.94% = 7.14 kg / mu.

[0079] Table 2-8 shows the calculation process of the nitrogen application rate required for the target yield of maize in the nitrogen fertilizer application method for winter green manure multiple cropping of maize in saline-alkali dryland provided in Examples 1-3 of the present invention. The specific results are shown in Table 2-8:

[0080] (1) Nitrogen nutrient accumulation amount AN of Vicia villosa Roth var. kuljandica

[0081] On May 19, 2023, the biomass DM of Vicia villosa Roth var. kuljandica planted in Examples 1-3 was measured by the diagonal method, and the total nitrogen (N) content (g / kg) of the plants was analyzed. At the same time, the coverage of Vicia villosa Roth var. kuljandica was investigated. The data results of the biomass, coverage, plant nitrogen content and nitrogen accumulation amount of Vicia villosa Roth var. kuljandica are shown in Table 2:

[0082] Table 2

[0083] Project Example 1 Example 2 Example 3 Biomass (kg / mu) 456.33 409.70 402.33 Coverage (%) 99.00 98.00 96.00 Total nitrogen content (g / kg) 27.27 27.08 26.64 Nitrogen nutrient accumulation (kg / mu) 12.32 10.87 10.29

[0084] Note: Nitrogen nutrient accumulation amount = biomass × coverage × 0.01 × total nitrogen content × 0.001

[0085] (2) Nitrogen use efficiency NUE of Vicia villosa Roth var. kuljandica nitrogen in the following crop of maize gm

[0086] In 2022, pot experiments, in-situ undisturbed soil column methods, 15 N isotope tracer techniques were used to obtain the nitrogen use efficiency of Vicia villosa Roth var. kuljandica nitrogen in the following crop of maize in Examples 1-3. The process was as follows: First, Vicia villosa Roth var. kuljandica in the pots was fed with urea-type 15 N with an abundance of 20%. According to the area of the in-situ soil column, the biomass of Vicia villosa Roth var. kuljandica with the same dry weight was calculated and applied to each soil column. One maize plant was planted in each soil column. The maize was harvested on September 30, 2022. After air-drying, it was divided into three parts: straw, leaves, and grains, and weighed separately. After weighing, it was sent to the Institute of Biotechnology and Food Science, Hebei Academy of Agriculture and Forestry Sciences together with the plant samples of Vicia villosa Roth var. kuljandica labeled with 15 N for determination. The measured data are shown in Table 3. Through calculation, the nitrogen use efficiency NUE of Vicia villosa Roth var. kuljandica nitrogen in the following crop of maize in Examples 1-3 was obtained gm They were 46.99%, 43.30% and 40.94% respectively.

[0087] Table 3

[0088]

[0089] Note: Nitrogen use efficiency NUE of Vicia villosa Roth var. kuljandica nitrogen in the following crop of maize gm(%) = ((Dry weight of corn kernels × N% of corn kernels × (atom% of corn kernels 15 N - 0.3663) + Dry weight of corn straw × N% of corn straw × (atom% of corn straw 15 N - 0.3663) + Dry weight of corn leaves × N% of corn leaves × (atom% of corn leaves 15 N - 0.3663)) ÷ (Dry weight of Vicia villosa Roth var. turkestanica × N% of Vicia villosa Roth var. turkestanica × (atom% of Vicia villosa Roth var. turkestanica 15 N - 0.3663)) × 100%

[0090] (3) Available nitrogen supply SN in the soil before turning under Vicia villosa Roth

[0091] Before turning under Vicia villosa Roth (May 17, 2023), according to the technical regulations for soil testing and formulated fertilization (NY / T 2911 - 2016), soil samples of the 0 cm - 20 cm soil layer were taken by soil auger, and the available nitrogen content (mg / kg) in the soil was determined according to the alkali hydrolysis diffusion method. The plowed layer soil of 1 mu of land was calculated according to 15 × 10 4 kg, and the specific test results are shown in Table 4:

[0092] Table 4

[0093]

[0094] Note: Available nitrogen supply SN in the soil (kg / mu) = Available nitrogen content in the 0 cm - 20 cm soil layer (mg / kg) ×

[0095] 15 × 10 4 kg × 10 -6

[0096] (4) Nitrogen (N) requirement YN for corn to achieve the target yield

[0097] Based on the target yield of corn obtained by farmers' customary fertilization in 2022, the nitrogen requirement for the target yield of corn (kg / mu) was calculated using formulated fertilization. The total nitrogen (N) content of corn straw and kernels in 2022 is shown in Table 5. The above-ground straw and kernel biomass of corn under farmers' customary fertilization in 2022 is shown in Table 6, and the nitrogen (N) requirement for corn to achieve the target yield is shown in Table 7.

[0098] Table 5

[0099]

[0100]

[0101] Table 6

[0102] Maize organs Example 1 Example 2 Example 3 Straw (kg / mu) 556.67 524.18 507.73 Grain (kg / mu) 444.84 438.67 405.46 Harvest index 0.44 0.46 0.44

[0103] Note: Harvest index = grain biomass / (grain biomass + straw biomass)

[0104] Table 7

[0105] Example 1 Example 2 Example 3 Nitrogen requirement for maize to reach target yield (kg / mu) 13.00 12.54 11.37

[0106] Note: Nitrogen requirement for maize to achieve target yield = total nitrogen (N) content in maize straw × straw biomass × 0.001 + total nitrogen (N) content in maize grains × grain biomass × 0.001

[0107] (5) Nitrogen fertilizer (N) application rate XN required for maize to achieve target yield

[0108] According to the research by Zhu Zhaoliang, the nitrogen use efficiency of nitrogen fertilizer for maize in China in the current season, NUE, is 35%. The calculation results of the nitrogen fertilizer (N) application rate XN required for maize to achieve target yield are shown in Table 8:

[0109] Table 8

[0110]

[0111] Note: Nitrogen fertilizer application rate required for maize target yield (kg / mu) = (nitrogen requirement YN for maize to achieve target yield - available nitrogen SN in soil before incorporation of hairy vetch nitrogen) ÷ (nitrogen use efficiency of maize nitrogen fertilizer * 0.01)

[0112] The base fertilizer application rate XN1 and topdressing application rate XN2 in the nitrogen fertilizer (N) application rate XN required for maize to achieve target yield are shown in Table 9:

[0113] Table 9

[0114] Example 1 Example 2 Example 3 Base fertilizer (N) application rate (kg / mu) XN1 5.12 5.32 4.90 Topdressing (N) application rate (kg / mu) XN2 7.68 7.97 7.36

[0115] Note: Base fertilizer (N) application rate XN1 = nitrogen requirement XN for maize to achieve target yield × 40%, topdressing (N) application rate XN2 = nitrogen requirement XN for maize to achieve target yield × 60%

[0116] (6) Nitrogen nutrient release characteristics and calculation model of Vicia villosa Roth var. turkestanica

[0117] On May 16, 2022, after sampling the Vicia villosa Roth var. turkestanica plants in the flowering and podding stage, the nitrogen nutrient release characteristics of leguminous winter green manure were determined by the nylon bag buried field method. The nitrogen mineralization characteristics of leguminous winter green manure can be fitted by the logarithmic function equation V t = a + blnt. See Tables 10 - 13 for details. As can be seen from Table 13, the nitrogen nutrient release rate of Vicia villosa Roth var. turkestanica shows the characteristics of being fast in the early stage and slow in the later stage. Through calculation, the nitrogen nutrient release (mineralization) equation of Vicia villosa Roth var. turkestanica in Example 1 is V t = 37.62171 + 8.415884 × lnt, and for Example 2 it is V t= 31.49653 + 8.578821 × lnt, Example 3 is V t = 26.62643 + 9.32151 × lnt.

[0118] Table 10 Dry weight (g) of the residue of Vicia villosa Roth var. kuljaica in nylon bags under different burial days

[0119] Burying days d Example 1 Example 2 Example 3 0 43.86 42.45 39.73 10 22.92 23.28 22.82 20 20.48 19.68 22.10 30 18.29 19.87 19.99 40 17.57 17.21 19.47 50 15.09 17.64 16.19 60 16.72 14.30 16.15 70 16.18 15.14 13.47 80 13.22 14.33 12.22 90 13.61 13.43 12.55 100 12.88 12.77 13.40 110 12.93 13.06 12.94 120 11.66 12.87 13.39 130 12.55 10.76 13.01 140 12.00 12.05 12.09

[0120] Table 11 Total nitrogen (N) content (g / kg) in the residues of Vicia villosa Roth var. kuljaica in nylon bags under different burial days

[0121] Burying days d Example 1 Example 2 Example 3 0 35.00 32.40 31.20 10 28.80 28.80 28.20 20 26.40 27.80 25.60 30 27.00 27.20 24.60 40 25.40 27.40 26.00 50 28.60 28.40 28.70 60 29.60 30.00 29.00 70 29.40 31.00 32.60 80 33.40 35.00 35.00 90 35.00 33.60 34.80 100 24.40 25.40 24.80 110 29.40 25.80 26.00 120 29.40 26.00 29.60 130 30.60 35.80 30.60 140 26.60 29.80 28.00

[0122] Table 12 Nitrogen (N) nutrient content (g) of Vicia villosa Roth var. kuljaica in nylon bags under different burial days

[0123] Burying days d Example 1 Example 2 Example 3 0 1.54 1.38 1.24 10 0.66 0.67 0.64 20 0.54 0.55 0.57 30 0.49 0.54 0.49 40 0.45 0.47 0.51 50 0.43 0.50 0.46 60 0.49 0.43 0.47 70 0.48 0.47 0.44 80 0.44 0.50 0.43 90 0.48 0.45 0.44 100 0.31 0.32 0.33 110 0.38 0.34 0.34 120 0.34 0.33 0.40 130 0.38 0.39 0.40 140 0.32 0.36 0.34

[0124] Note: The nitrogen (N) nutrient content of Vicia villosa Roth var. kuljaica in nylon bags under different burial days = dry weight (g) of the residue of Vicia villosa Roth var. kuljaica in nylon bags at the corresponding burial days (d) × 0.001 × total nitrogen (N) content (g / kg) in the residues of Vicia villosa Roth var. kuljaica in nylon bags at the corresponding burial days (d)

[0125] Table 13 Nitrogen nutrient release rate (%) of Vicia villosa Roth var. kuljaica in nylon bags under different burial days

[0126]

[0127]

[0128] Note: Nitrogen nutrient release rate (%) of Vicia villosa Roth var. kuljaica = (nitrogen nutrient content of Vicia villosa Roth var. kuljaica after 0 d of burial - nitrogen nutrient content of Vicia villosa Roth var. kuljaica after t d of burial) ÷ nitrogen nutrient content of Vicia villosa Roth var. kuljaica after 0 d of burial × 100%

[0129] Control Example 1

[0130] Winter fallow field in saline-alkali dry land - Grain and forage dual-purpose corn planting pattern: Among them, for corn (variety: Denghai 605), the chemical nitrogen fertilizer adopts the farmer's conventional fertilization rate, that is, the total nitrogen (N) application rate is 18 kg / mu. Among them, 40% of the nitrogen fertilizer and all the phosphorus and potassium fertilizers are applied as base fertilizers along with land preparation, and the remaining 60% of the nitrogen fertilizer is topdressed during the jointing stage - large trumpet mouth stage in case of effective rainfall.

[0131] Control Example 2

[0132] Saline-alkali dryland winter fallow field - Grain and forage dual-purpose corn planting mode: For the chemical nitrogen fertilizer (N) of corn (variety: Denghai 605), the application rate is calculated by the soil testing and formulated fertilization technology method. According to the yield of grain and forage dual-purpose corn under the farmer's conventional fertilization in 2022, the total amount of nitrogen fertilizer (N) required for corn is 15.77 kg / mu. The specific calculation process is shown in Tables 14 - 16. Before calculation, the corn yield and nitrogen accumulation amount are measured before corn harvest. The method is as follows: Randomly select 2 rows of corn in the middle of the test area, select a 3-meter length for each row, break off all corn ears, air-dry them and measure the yield, and repeat the sampling and yield measurement 4 times. At the same time, randomly select 3 corn plants with consistent growth near the yield measurement area and cut them at the ground level, air-dry them and measure the corn harvest index, straw nitrogen content, and grain nitrogen content to calculate the nitrogen requirement for the target yield of corn, and repeat the sampling 4 times. 40% of the total amount of nitrogen fertilizer required for corn and all phosphorus and potassium fertilizers are applied as base fertilizers together with land preparation, and the remaining 60% of nitrogen fertilizer is topdressed during the jointing stage - large bellmouth stage in case of effective rainfall.

[0133] (1) Soil nitrogen supply

[0134] Before corn sowing (June 10, 2023), according to the soil testing and formulated fertilization technical regulations (NY / T 2911 - 2016), soil samples of 0 cm - 20 cm soil layer are taken by soil drill, and the soil available nitrogen content is measured according to the alkali hydrolysis diffusion method. The average measurement result is 49.06 mg / kg (see Table 14). Calculated according to 15×10 4 kg for the plow layer soil of 1 mu of land, then the available nitrogen supply in the 0 cm - 20 cm soil layer of 1 mu of land is 49.06 mg / kg×15×104 kg×10 - 6 = 7.36 kg.

[0135] Table 14 Data table of soil available nitrogen content in 0 cm - 20 cm soil layer before corn sowing in 2023 Unit: mg / kg

[0136]

[0137] (2) Nitrogen requirement for the target yield of corn

[0138] According to the target yield of corn obtained by the farmer's conventional fertilization in 2022, the nitrogen requirement for the target yield of corn in formula fertilization calculation is calculated. The total nitrogen (N) content of corn straw and grains in 2022 is shown in Table 15. The above-ground straw and grain biomass of corn under the farmer's conventional fertilization in 2022 is shown in Table 16. Then the nitrogen requirement for the target yield of corn (kg / mu) = 533.79 kg / mu×8.13 g / kg×0.001 + 463.64 kg / mu×18.41 g / kg×0.001 = 12.88 kg / mu;

[0139] (3) The total amount of chemical nitrogen fertilizer (N) required for the target yield of corn calculated according to the soil and plant testing methods in the soil testing and formulated fertilization technology is: (12.88 kg / mu - 7.36 kg / mu) ÷ 35% = 15.77 kg / mu (note that 35% in the formula is the utilization rate of chemical nitrogen fertilizer. According to the research of Zhu Zhaoliang, the current-season utilization rate of nitrogen fertilizer for corn in China is 35%. It can also be calculated through field experiments according to the nitrogen fertilizer utilization rate formula (nitrogen fertilizer utilization rate = ((nitrogen uptake by crops in the fertilized plot - nitrogen uptake by crops in the control plot) / nitrogen application amount) × 100%)). Among them, 40% i.e., 6.31 kg / mu is used as the base fertilizer, and the remaining 60% i.e., 9.46 kg / mu is used as the topdressing.

[0140] Table 15 Data table of total nitrogen (N) content in corn straw and grains in 2022 Unit: g / kg

[0141]

[0142] Table 16 Data table of biomass of corn straw and grains in 2022

[0143] Maize organs Replicate 1 Replicate 2 Replicate 3 Replicate 4 Average Straw (kg / mu) 556.67 524.18 507.73 546.56 533.79 Grain (kg / mu) 405.46 444.84 438.67 465.59 463.64 Harvest index 0.45 0.47 0.48 0.46 0.47

[0144] Note: Harvest index = grain biomass / (grain biomass + straw biomass)

[0145] The present invention determines the sowing time and returning time of leguminous winter green manure in saline-alkali dry land, as well as the sowing time, base fertilizer application time, application amount of chemical nitrogen fertilizer in the base fertilizer, topdressing time and topdressing amount of chemical nitrogen fertilizer of corn, clarifies the application amount of chemical nitrogen fertilizer in the base fertilizer and topdressing of corn under the condition of planting leguminous winter green manure in the winter-spring fallow fields of slightly saline-alkali dry land and returning it to the field in full amount, reduces the input amount of nitrogen fertilizer in corn production, avoids the phenomenon of excessive nitrogen application in the process of corn production, improves the fertilizer utilization rate, and further realizes the nitrogen fertilizer application method for the goal of reducing chemical nitrogen fertilizer application.

[0146] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dry land, characterized in that, It includes the following steps: Step 1: Sow winter green manure: From late July to early September, after the start of effective rainfall, sow leguminous winter green manure between the rows of saline-alkali land corn. Step 2: Harvest corn: From late September to mid to late October, harvest corn, and conduct stubble cutting on the corn straw, with the stubble height being 10 cm - 15 cm. Step 3: Measure the nitrogen nutrient accumulation of winter green manure: In the first and middle ten days of May of the following year, measure the nitrogen nutrient accumulation AN of leguminous winter green manure, then incorporate the leguminous winter green manure in the flower and pod stage and the corn stubble into the field, and calculate the basal application rate XN1 and topdressing application rate XN2 of the nitrogen required for the target yield of the next-season corn based on the nitrogen nutrient release characteristics after the return of leguminous winter green manure to the field, the nutrient utilization efficiency NUE of the nitrogen supplied by the leguminous winter green manure in the next-season corn gm and the nitrogen fertilizer application rate XN required for the target yield of corn. Among them, XN1 = XN × 40%, XN2 = XN × 60%; Step 4: Applying basal fertilizer and sowing the next crop of maize: From late May to early July, after the effective rainfall ends, promptly apply basal fertilizer, prepare the soil, and sow maize. Among them, the application rate of nitrogen fertilizer XN1 in the maize basal fertilizer 基 = XN1 - AN × V t1 × NUE gm , V t1 is the nitrogen nutrient release rate t1 days after the leguminous winter green manure is returned to the field when applying basal fertilizer and sowing maize; Step 5: Top-dress nitrogen fertilizer for the following-season maize: Top-dress nitrogen fertilizer during the jointing stage of maize or when there is effective rainfall from the jointing stage to the large flare opening stage of maize. Among them, the application rate of nitrogen fertilizer XN2 for top-dressing 追 = XN2 - AN × (V t2 - V t1 ) × NUE gm , V t2 is the nitrogen nutrient release rate t2 days after the leguminous winter green manure is incorporated into the soil when top-dressing nitrogen fertilizer for maize.

2. The nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dry land as described in claim 1, wherein In Step 1, the condition of the effective rainfall is: the rainfall amount in a one-time rainfall process ≥ 30 mm.

3. The nitrogen fertilizer application method for winter green manure multiple cropping corn in saline-alkali dryland as described in claim 1, wherein, In Step 1, the leguminous winter green manure is Vicia villosa Roth var. kuljaica.

4. The nitrogen fertilizer application method for winter green manure multiple cropping corn in saline-alkali dryland as described in claim 1, characterized in that, In Step 1, the sowing condition is: after the start of effective rainfall, evenly broadcast the seeds of leguminous winter green manure between the rows of saline-alkali land corn, with the seeding rate being 8 kg / mu - 10 kg / mu, and promptly roll the soil after sowing.

5. The nitrogen fertilizer application method for winter green manure multiple cropping of maize in saline-alkali dry land as described in claim 1, wherein, In Step 1, the condition of the saline-alkali land is: the salt content in the plough layer soil ≤ 4 g / kg.

6. The nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dry land as described in claim 1, wherein In Step 2, when harvesting corn, the leguminous winter green manure needs to meet the condition of vegetative growth for more than 30 days.

7. The nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dry land as described in claim 1, characterized in that, In Step 3, the nitrogen nutrient accumulation amount AN (kg / mu) of the leguminous winter green manure = DM × NC × 0.001, where DM (kg / mu) is the biomass of the leguminous winter green manure and NC (g / kg) is the total nitrogen content of the leguminous winter green manure.

8. The nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dry land as described in claim 1, characterized in that, In Step 3, the condition of stubble removal and returning to the field is: crush the Vicia villosa Roth var. kuljaica and the above-ground corn straw once with a straw crusher, and rotary till the soil once with a rotary tiller, with the rotary tillage depth of the soil being 15 cm - 20 cm.

9. The nitrogen fertilizer application method for winter green manure multiple cropping of corn in saline-alkali dryland as described in claim 1, characterized in that, In Step 4, the condition of the effective rainfall is that the soil moisture content reaches 60% - 70% of the field water holding capacity after rainfall.

10. The nitrogen fertilizer application method for winter green manure multiple cropping corn in saline-alkali dryland as described in claim 1, characterized in that, In Step 4, the corn can be Optional Era 128, Denghai 605 or Zhengdan 958; and / or in Step 5, the condition of the effective rainfall is that the rainfall amount in a one-time rainfall process ≥ 30 mm.

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