Fertilizing method for improving nitrogen utilization of ratoon sugarcane

Abstract

The invention discloses a fertilization method for improving nitrogen utilization of perennial root sugarcanes, and relates to the technical field of sugarcane cultivation. The application of the nitrogen fertilizer is controlled, namely, the inorganic nitrogen fertilizer is only added when the base fertilizer is applied every year, and the fertilizer applied in other periods does not contain the inorganic nitrogen fertilizer; the application method of the base fertilizer comprises the following steps: digging fertilization ditches with the depth of 15-20cm between sugarcane rows, firstly applying a layer of adsorbent, then applying an organic fertilizer and an inorganic nitrogen fertilizer, then carrying out primary soil covering and watering, then applying a layer of water-absorbing and water-retaining agent, and carrying out secondary soil covering. Leguminous plants are interplanted between the rows; the adsorbent is dicyandiamide-humic acid-clay composite particles, and the water absorption and water retention agent is a coconut shell-sodium alginate compound. When the fertilization method is used in the karst region, the stability of the sugarcane yield can be kept under the condition that the nitrogen application amount is reduced, and the nitrogen fertilizer utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of sugarcane cultivation, and particularly relates to a fertilization method for improving nitrogen utilization of ratoon sugarcane. Background Art

[0002] Sugarcane is a large biomass crop with a long growth period and requires a large amount of nitrogen supply, which can lead to soil quality degradation (such as high acidity and low nutrition) and reduced nitrogen utilization efficiency (10 - 40%).

[0003] Currently, existing research has shown that reducing the amount of nitrogen fertilizer applied and intercropping with soybeans can reduce nitrogen fertilizer consumption and improve nitrogen fertilizer utilization efficiency. However, this method cannot effectively prevent the leakage and volatilization loss of nitrogen fertilizer. Patent CN 115053778 B - A sugarcane planting method for improving nitrogen utilization of rain-fed sugarcane and reducing nitrogen migration loss discloses reducing nitrogen loss through film covering, but film covering is not environmentally friendly and labor-intensive; Patent CN 111567350B - A planting method for promoting nitrogen fixation in sugarcane discloses that using nitrogen-fixing microorganisms and foliar spraying of nitrogen fixation synergist solution can improve nitrogen utilization efficiency, but microbial treatment is easily affected by the environment and the effect is unstable when used on karst landform soil; Patent CN 102249817B - A preparation for inhibiting soil nitrogen loss discloses that nitrification inhibitor compounds (pyridines, pyrimidines, thioureas, azides, DCD, 3,4-dimethylpyrazole, sulfhydryl compounds) can inhibit the rate of ammonium oxidation reaction, thereby reducing the loss of nitrogen such as N 2 O, N 2 and other nitrogen losses, but the use of nitrification inhibitor compounds also has the problem of being easily leached and lost with rainwater.

[0004] In summary, the purpose of the present invention is to provide a fertilization method for improving nitrogen utilization of ratoon sugarcane. Summary of the Invention

[0005] In view of the above deficiencies, the present invention provides a fertilization method for improving nitrogen utilization of ratoon sugarcane, which solves the problems of easy leakage and volatilization loss of nitrogen fertilizer when planting sugarcane in karst landform soil. The specific technical solution is as follows:

[0006] A fertilization method for improving nitrogen utilization of ratoon sugarcane, wherein the fertilization controls the amount of nitrogen fertilizer, that is, inorganic nitrogen fertilizer is only added during the application of base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer; the application method of the base fertilizer is: open a fertilization ditch with a depth of 15 - 20 cm between sugarcane rows, first apply a layer of adsorbent, then apply organic fertilizer and inorganic nitrogen fertilizer, then cover the soil once, water, then apply a layer of water-absorbing and water-retaining agent, and cover the soil twice; the adsorbent is a dicyandiamide-humic acid-clay composite particle, and the water-absorbing and water-retaining agent is a coconut shell-sodium alginate complex.

[0007] Further, the preparation method of the dicyandiamide-humic acid-clay composite particles is as follows: S1. Dissolve dicyandiamide in hot water to prepare a dicyandiamide solution with a mass concentration of 70-85%; S2. Pyrolyze humic acid at 330-350 °C for 2-3 h, then add it together with clay into a 1-3 mol / L hydrochloric acid solution and soak for 2-3 h, filter, wash until neutral, and dry at 60-70 °C for standby; S3. Add the dried humic acid and clay into the dicyandiamide solution, stir magnetically for 20-24 h, centrifuge and separate, wash with deionized water 1-2 times, and dry to make particles with a particle size of 5-8 mm, thus obtaining the product.

[0008] Further, the preparation method of the coconut shell-sodium alginate composite is as follows: Soak coconut shell fragments to soften them, and then seal and ferment them at 25-35 °C for 30-60 days to obtain mature coconut shells; soak the mature coconut shells in a 5-10% NaOH solution for 12-16 h, wash until neutral to obtain activated coconut shells; add the activated coconut shells into a sodium alginate solution with a mass concentration of 0.5-1% and soak for 10-15 h, and then dry to obtain the product.

[0009] Further, the organic fertilizer is mature farmyard manure, and the total application amount of the mature farmyard manure is 30000-45000 kg / hm 2 / year, the inorganic nitrogen fertilizer is urea, and the total application amount of the urea is 350-400 kg / hm 2 / year.

[0010] Further, the application thickness of the adsorbent is 2-4 cm, the soil layer thickness of the first soil covering is 2-3 cm, and the application thickness of the water absorbent and water retention agent is 3-5 cm.

[0011] Further, the fertilization method for improving the nitrogen utilization of ratoon sugarcane further includes: intercropping leguminous plants between the sugarcane rows, with a fertilization ditch between the leguminous plants and the ratoon sugarcane, and spreading a layer of ammonia capture agent above the soil layer of the second soil covering in the fertilization ditch.

[0012] Further, the leguminous plant is peanut or soybean.

[0013] Further, the preparation method of the ammonia capture agent is as follows: Crush zeolite or biochar, add it into a 1-3 mol / L hydrochloric acid solution, stir at 60-80 °C for 8-10 h, filter, wash until neutral, and dry at 60-70 °C to obtain the product.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] 1. The present invention reduces the leaching loss and volatilization loss of nitrogen fertilizer by applying an adsorbent, organic fertilizer, inorganic nitrogen fertilizer, first soil covering, water-absorbing and water-retaining agent, second soil covering, etc. in sequence during fertilization. By combining intercropping leguminous plants and applying an ammonia capturer, the nitrogen utilization rate is further improved. After using the fertilization method of the present invention in the karst area, the sugarcane yield can be maintained stable under the condition of reducing the nitrogen application rate.

[0016] 2. The adsorbent in the present invention is a dicyandiamide-humic acid-clay composite particle. By modifying and combining humic acid and clay, this adsorbent has a large specific surface area and a large number of micropores, increasing the binding points for ammonia and having a strong adsorption and complexation effect on ammonia. Applying it to the bottom layer of the fertilization trench can prevent nitrogen from being leached away by rainwater. At the same time, the nitrification inhibitor - dicyandiamide is fixed on humic acid and clay, which can also prevent the loss of dicyandiamide and enable it to continuously enhance the efficiency.

[0017] 3. The water-absorbing and water-retaining agent in the present invention is a coconut shell-sodium alginate complex, which has a large number of hydrophilic groups, can quickly absorb water, has a strong water-holding capacity, can quickly absorb and lock water when it rains, plays a buffering role, slows down the downward penetration speed of rainwater, and prevents water from quickly washing away nitrogen fertilizer downward.

[0018] 4. The ammonia capturer in the present invention has a large number of pores and adsorption sites, can adsorb the nitrogen volatilized from the soil, prevent the volatilization loss of nitrogen during drought, and at the same time the applicant also found that applying the ammonia capturer on the soil surface and intercropping leguminous plants at the same time can increase the yield of leguminous plants and improve the added value of the land. Detailed implementation manners

[0019] The following describes the detailed implementation manners of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the detailed implementation manners.

[0020] Example 1

[0021] The fertilization method of this example is as follows: reduce the amount of nitrogen fertilizer, and only add inorganic nitrogen fertilizer when applying base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first break the ridges and loosen the stumps of the ratoon sugarcane and then hill up the soil. When hilling up the soil, cover the loosened sugarcane stumps with soil. After hilling up the soil, open a fertilization trench with a depth of 15 cm near the roots of the ratoon sugarcane to apply the base fertilizer, that is, open a fertilization trench with a depth of 15 cm between the rows of the ratoon sugarcane, first apply a layer of adsorbent with a thickness of 2 cm, and then apply 30000 kg / hm 2 of well-rotted farmyard manure and 350 kg / hm 2Apply urea, then cover the soil once with a soil layer thickness of 2 cm, water, then apply a layer of water-absorbing and water-retaining agent with a thickness of 3 cm, cover the soil again, and finally sprinkle a layer of ammonia capture agent with a thickness of 1 cm above the soil layer; meanwhile, plant peanuts between the sugarcane rows in April, and there is a fertilization trench for the base fertilizer between the peanuts and the ratoon sugarcane. Harvest the peanuts in August, and immediately carry out secondary soil hilling on the sugarcane after harvesting. When carrying out soil hilling, use the soil from the place where peanuts are planted for soil hilling, without damaging the soil at the fertilization trench of the base fertilizer, and only cover a soil layer on it.

[0022] The adsorbent is a dicyandiamide-humic acid-clay composite particle. The preparation method of the dicyandiamide-humic acid-clay composite particle is as follows: S1. Dissolve dicyandiamide in hot water to obtain a dicyandiamide solution with a mass concentration of 70%; S2. After pyrolyzing humic acid at 330 °C for 3 h, add it to 1 mol / L hydrochloric acid solution together with clay and soak for 3 h, filter, wash until neutral, and dry at 60 °C for standby; S3. Add the dried humic acid and clay to the dicyandiamide solution, stir magnetically for 20 h, centrifuge and separate, wash once with deionized water, and dry to make particles with a particle size of 5 mm, then it is obtained.

[0023] The water-absorbing and water-retaining agent is a coconut shell-sodium alginate composite. The preparation method of the coconut shell-sodium alginate composite is as follows: Soak the coconut shell fragments to soften them, then seal and ferment them at 25 °C for 30 days to obtain decomposed coconut shells; soak the decomposed coconut shells in 5% NaOH solution for 12 h, wash until neutral to obtain activated coconut shells; add the activated coconut shells to a sodium alginate solution with a mass concentration of 0.5% and soak for 10 h, then dry to obtain it.

[0024] The preparation method of the ammonia capture agent is as follows: Crush zeolite and add it to 1 mol / L hydrochloric acid solution, stir at 60 °C for 10 h, filter, wash until neutral, and dry at 60 °C to obtain it.

[0025] Example 2

[0026] The fertilization method in this example is: Reduce the amount of nitrogen fertilizer. Only add inorganic nitrogen fertilizer when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in March every year, first break the ridges and loosen the stumps of the ratoon sugarcane and carry out soil hilling. When carrying out soil hilling, cover the soil on the loosened sugarcane stumps. After soil hilling, open a trench to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization trench with a depth of 20 cm in the row of the ratoon sugarcane. First apply a layer of adsorbent with a thickness of 4 cm, and then apply 45000 kg / hm 2 of decomposed farmyard manure and 400 kg / hm 2Apply urea, then cover it with soil once, with the soil layer thickness being 3 cm, water it, then apply a layer of water-absorbing and water-retaining agent with a thickness of 5 cm, cover it with soil for the second time, and finally sprinkle a layer of ammonia capture agent with a thickness of 2 cm above the soil layer; meanwhile, plant soybeans between the sugarcane rows in April, there is a fertilization trench for the base fertilizer between the soybeans and the ratoon sugarcane, and harvest the soybeans in September. Immediately after the harvest, conduct secondary soil hilling on the sugarcane, and use the soil from the place where soybeans are planted for soil hilling during soil hilling, without damaging the soil at the fertilization trench of the base fertilizer, just cover a soil layer on it.

[0027] The adsorbent is a dicyandiamide-humic acid-clay composite particle, and the preparation method of the dicyandiamide-humic acid-clay composite particle is as follows: S1. Dissolve dicyandiamide in hot water to obtain a dicyandiamide solution with a mass concentration of 85%; S2. After pyrolyzing humic acid at 350 °C for 2 h, add it to 3 mol / L hydrochloric acid solution together with clay and soak for 2 h, filter, wash until neutral, and dry at 70 °C for standby; S3. Add the dried humic acid and clay to the dicyandiamide solution and stir magnetically for 24 h, centrifuge and separate, wash twice with deionized water, and dry to make particles with a particle size of 8 mm, thus obtaining.

[0028] The water-absorbing and water-retaining agent is a coconut shell-sodium alginate composite, and the preparation method of the coconut shell-sodium alginate composite is as follows: Soak the coconut shell fragments to soften them, and then seal and ferment them at 35 °C for 30 days to obtain decomposed coconut shells; soak the decomposed coconut shells in 10% NaOH solution for 16 h, wash until neutral to obtain activated coconut shells; add the activated coconut shells to a 1% sodium alginate solution by mass concentration and soak for 10 h, and then dry.

[0029] The preparation method of the ammonia capture agent is as follows: Crush the biochar, add it to 3 mol / L hydrochloric acid solution, stir at 80 °C for 8 h, filter, wash until neutral, and dry at 70 °C.

[0030] Example 3

[0031] The fertilization method of this example is: Reduce the amount of nitrogen fertilizer. Only add inorganic nitrogen fertilizer when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first break the ridges and loosen the stumps of the ratoon sugarcane and conduct soil hilling. When conducting soil hilling, cover the soil on the loosened sugarcane stumps. After soil hilling, open a trench to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization trench with a depth of 18 cm in the row of the ratoon sugarcane. First, apply a layer of adsorbent with a thickness of 3 cm, and then apply 40000 kg / hm 2 of decomposed farmyard manure and 380 kg / hm 2Apply urea, then cover the soil once with a soil layer thickness of 3 cm, water it, then apply a layer of water-absorbing and water-retaining agent with a thickness of 3 cm, cover the soil a second time, and finally sprinkle a layer of ammonia capture agent with a thickness of 2 cm above the soil layer; meanwhile, plant peanuts between the sugarcane rows in April. There is a fertilization trench for the base fertilizer between the peanuts and the ratoon sugarcane. Harvest the peanuts in August. Immediately after harvesting, conduct a second soil hilling for the sugarcane. When hilling the soil, use the soil from the peanut planting area for hilling, without damaging the soil at the fertilization trench of the base fertilizer, and only cover a soil layer on it.

[0032] The adsorbent is a dicyandiamide-humic acid-clay composite particle. The preparation method of the dicyandiamide-humic acid-clay composite particle is as follows: S1. Dissolve dicyandiamide in hot water to obtain a dicyandiamide solution with a mass concentration of 80%; S2. After pyrolyzing humic acid at 340 °C for 2 h, add it to 2 mol / L hydrochloric acid solution together with clay and soak for 3 h, filter, wash until neutral, and dry at 65 °C for standby; S3. Add the dried humic acid and clay to the dicyandiamide solution, stir magnetically for 22 h, centrifuge and separate, wash twice with deionized water, and dry to make particles with a particle size of 6 mm, thus obtaining.

[0033] The water-absorbing and water-retaining agent is a coconut shell-sodium alginate composite. The preparation method of the coconut shell-sodium alginate composite is as follows: Soak the coconut shell fragments to soften them, then seal and ferment at 30 °C for 50 days to obtain decomposed coconut shells; soak the decomposed coconut shells in 8% NaOH solution for 13 h, wash until neutral to obtain activated coconut shells; add the activated coconut shells to a sodium alginate solution with a mass concentration of 0.6% and soak for 12 h, then dry to obtain.

[0034] The preparation method of the ammonia capture agent is as follows: Crush the biochar and add it to 2 mol / L hydrochloric acid solution, stir at 70 °C for 9 h, filter, wash until neutral, and dry at 65 °C to obtain.

[0035] Comparative Example 1: In this comparative example, the adsorbent is not applied first, and organic fertilizer and urea are directly applied. Other steps are the same as in Example 1.

[0036] The fertilization method of this comparative example is: Reduce the amount of nitrogen fertilizer. Only inorganic nitrogen fertilizer is added when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first break the ridges and loosen the stumps of the ratoon sugarcane and hill the soil. When hilling the soil, cover the loosened sugarcane stumps with soil. After hilling the soil, open a trench to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization trench with a depth of 15 cm in the row of the ratoon sugarcane, first apply 30000 kg / hm 2 of decomposed farmyard manure and 350 kg / hm 2Apply urea, then cover the soil once with a soil layer thickness of 2 cm, water it, then apply a layer of water-absorbing and water-retaining agent with a thickness of 3 cm, cover the soil a second time, and finally sprinkle a layer of ammonia capture agent with a thickness of 1 cm above the soil layer; meanwhile, plant peanuts between the sugarcane rows in April. There is a fertilization trench for the base fertilizer between the peanuts and the ratoon sugarcane. Harvest the peanuts in August. Immediately after harvesting, conduct a second soil hilling for the sugarcane. When hilling the soil, use the soil from the peanut planting area for hilling, without damaging the soil at the fertilization trench of the base fertilizer, and only cover a soil layer on it.

[0037] Comparative Example 2: In this comparative example, after applying organic fertilizer and urea, no water-absorbing and water-retaining agent is applied, and other steps are the same as those in Example 1.

[0038] The fertilization method of this comparative example is: reduce the amount of nitrogen fertilizer. Only add inorganic nitrogen fertilizer when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first break the ridges and loosen the stumps of the ratoon sugarcane and hill the soil. When hilling the soil, cover the loosened sugarcane stumps with soil. After hilling the soil, open a trench to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization trench with a depth of 15 cm in the row of the ratoon sugarcane. First, apply a layer of adsorbent with a thickness of 2 cm, and then apply 30000 kg / hm 2 of decomposed farmyard manure and 350 kg / hm 2 of urea, then cover the soil once with a soil layer thickness of 2 cm, water it, and finally sprinkle a layer of ammonia capture agent with a thickness of 1 cm above the soil layer; meanwhile, plant peanuts between the sugarcane rows in April. There is a fertilization trench for the base fertilizer between the peanuts and the ratoon sugarcane. Harvest the peanuts in August. Immediately after harvesting, conduct a second soil hilling for the sugarcane. When hilling the soil, use the soil from the peanut planting area for hilling, without damaging the soil at the fertilization trench of the base fertilizer, and only cover a soil layer on it.

[0039] Comparative Example 3: In this comparative example, peanuts are planted, but no ammonia capture agent is sprinkled, and other steps are the same as those in Example 1.

[0040] The fertilization method of this example is: reduce the amount of nitrogen fertilizer. Only add inorganic nitrogen fertilizer when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first break the ridges and loosen the stumps of the ratoon sugarcane and hill the soil. When hilling the soil, cover the loosened sugarcane stumps with soil. After hilling the soil, open a trench to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization trench with a depth of 15 cm in the row of the ratoon sugarcane. First, apply a layer of adsorbent with a thickness of 2 cm, and then apply 30000 kg / hm 2 of decomposed farmyard manure and 350 kg / hm 2Apply urea, then cover the soil once with a soil layer thickness of 2 cm, water, then apply a layer of water-absorbing and water-retaining agent with a thickness of 3 cm, and cover the soil again, then it's done. At the same time, plant peanuts between the sugarcane rows in April. There is a fertilization ditch for the base fertilizer between the peanuts and the ratoon sugarcane. Harvest the peanuts in August. Immediately after harvesting, conduct secondary soil hilling for the sugarcane. When doing the soil hilling, use the soil from the place where peanuts were planted for soil hilling, without damaging the soil at the fertilization ditch for the base fertilizer, just cover a soil layer on it.

[0041] Comparative Example 4: In this comparative example, an ammonia capture agent was applied, but peanuts were not planted, and other steps were the same as in Example 1.

[0042] The fertilization method of this example is: reduce the amount of nitrogen fertilizer. Only add inorganic nitrogen fertilizer when applying the base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer. Specifically, in February every year, first conduct ridging and loosening of the ratoon sugarcane and soil hilling. When doing the soil hilling, cover the soil on the loosened sugarcane stumps. After soil hilling, open a ditch to apply the base fertilizer near the roots of the ratoon sugarcane, that is, open a fertilization ditch with a depth of 15 cm between the rows of the ratoon sugarcane. First, apply a layer of adsorbent with a thickness of 2 cm, then apply 30000 kg / hm 2 of decomposed farmyard manure and 350 kg / hm 2 of urea, then cover the soil once with a soil layer thickness of 2 cm, water, then apply a layer of water-absorbing and water-retaining agent with a thickness of 3 cm, cover the soil again, and finally apply a layer of ammonia capture agent with a thickness of 1 cm above the soil layer, then it's done. At the same time, conduct secondary soil hilling for the sugarcane in August. When doing the soil hilling, use the soil outside the fertilization ditch for soil hilling, without damaging the soil at the fertilization ditch for the base fertilizer, just cover a soil layer on it.

[0043] Comparative Example 5: This comparative example is the traditional fertilization method. Apply organic fertilizer as the base fertilizer in February, and apply urea respectively at the seedling emergence stage, tillering stage, elongation stage, and late growth stage. The total application amount of the urea is 520 - 600 kg / hm 2 / year, among which, the application amount at the seedling emergence stage is 150 - 200 kg / hm 2 ; the application amount at the tillering stage is 150 - 200 kg / hm 2 ; the application amount at the elongation stage is 225 - 300 kg / hm 2 ; the application amount at the late growth stage is 75 - 100 kg / hm 2 . And interplant peanuts between the sugarcane rows.

[0044] To illustrate the effectiveness of the fertilization method of the present invention, the applicant conducted a comparative experiment in the sugarcane planting area of Yizhou District, Hechi City, Guangxi in 2023. The test area is of karst landform with poor soil. The physical and chemical properties of the soil are as follows: pH 4.0 - 4.5, organic matter content 18.83 g / kg, total nitrogen content 0.11%, total phosphorus content 0.022%, total potassium content 0.36%, which is acidic soil. The planting variety is Guitang 42, with 1-year ratooning. The length of the planted sugarcane row is 10 m, and the row spacing is 1.5 m. The experiments were carried out using the methods of the examples and comparative examples for fertilization and planting leguminous plants. Each of the examples and comparative examples has 5 rows, repeated 3 times. The sugarcane yield and leguminous plant yield were respectively counted, and the nitrogen fertilizer utilization rate of sugarcane was calculated. Nitrogen fertilizer utilization rate (%) = (nitrogen uptake by crops in the fertilized area - nitrogen uptake by crops in the non-fertilized area) / total nitrogen application amount × 100%. The results are shown in Table 1:

[0045] Table 1 Comparison of yield and nitrogen fertilizer utilization rate of each group

[0046]

[0047] The data of Examples 1 to 3 show that the nitrogen fertilizer utilization rate of the fertilization method of the present invention is higher than that of the traditional method (Comparative Example 5), and the sugarcane yield is even higher when the amount of nitrogen fertilizer used is less. At the same time, the data comparison between Example 1 and Comparative Examples 1 - 4 shows that the fertilization method of the present invention, which sequentially applies adsorbent, organic fertilizer, inorganic nitrogen fertilizer, first soil covering, water-retaining agent, second soil covering, and ammonia capture agent in sequence, can improve the nitrogen fertilizer utilization rate, and thus increase the sugarcane yield. The lack of any one of the adsorbent, water-retaining agent, or ammonia capture agent will reduce the nitrogen fertilizer utilization rate and sugarcane yield. In addition, from the peanut yield data of Example 1 and Comparative Example 3, spreading the ammonia capture agent on the soil surface and intercropping leguminous plants at the same time can increase the yield of leguminous plants and improve the added value of the land.

[0048] In summary, the present invention reduces the leaching loss and volatilization loss of nitrogen fertilizer by sequentially applying adsorbent, organic fertilizer, inorganic nitrogen fertilizer, first soil covering, water-retaining agent, second soil covering, etc. during fertilization. By combining intercropping leguminous plants and applying ammonia capture agent, the nitrogen utilization rate is further improved. After using the fertilization method of the present invention in karst areas, the sugarcane yield can be maintained stable with a reduced nitrogen application amount, and the added value of the land can be increased.

[0049] The foregoing description of the specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the present invention, as well as various different selections and modifications. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A fertilization method for improving nitrogen utilization of perennial sugarcane, characterized in that: The fertilization is to control the amount of nitrogen fertilizer, that is, inorganic nitrogen fertilizer is added only when applying base fertilizer every year, and the fertilizers applied in other periods do not contain inorganic nitrogen fertilizer; the method of applying the base fertilizer is: digging a fertilizer ditch with a depth of 15-20cm between the sugarcane rows, first applying a layer of adsorbent, then applying organic fertilizer and inorganic nitrogen fertilizer, then covering with soil once, watering, then applying a layer of water absorbing and retaining agent, and covering with soil twice, and the adsorbent is dicyandiamide-humic acid-clay composite particles, and the water absorbing and retaining agent is a coconut shell-sodium alginate complex.

2. A fertilization method for improving nitrogen utilization of perennial sugarcane according to claim 1, characterized in that: The preparation method of the dicyandiamide-humic acid-clay composite particles is as follows: S1. dissolving dicyandiamide in hot water to obtain a dicyandiamide solution with a mass concentration of 70-85%; S2. pyrolyzing the humic acid at 330-350°C for 2-3h, adding the humic acid together with clay into a 1-3mol / L hydrochloric acid solution and soaking for 2-3h, filtering, washing to neutrality, drying at 60-70°C for standby use; S3. adding the dried humic acid and clay into the dicyandiamide solution, magnetically stirring for 20-24h, centrifuging, washing with deionized water for 1-2 times, drying, and preparing particles with a particle size of 5-8mm.

3. A fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 1, characterized in that: The preparation method of the coconut shell-sodium alginate complex is as follows: soaking and softening coconut shell pieces, and then sealing and fermenting them at 25-35° C. for 30-60 days to obtain decomposed coconut shells; soaking the decomposed coconut shells in a 5-10% NaOH solution for 12-16 hours, washing until neutral, and obtaining activated coconut shells; adding the activated coconut shells into a sodium alginate solution with a mass concentration of 0.5-1%, soaking them for 10-15 hours, and drying them to obtain the complex.

4. A fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 1, characterized in that: The organic fertilizer is decomposed farmyard manure, and the total application amount of the decomposed farmyard manure is 30000-45000kg / hm 2 / year, the inorganic nitrogen fertilizer is urea, and the total application amount of the urea is 350-400kg / hm 2 / Year.

5. The fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 1, characterized in that: The thickness of the adsorbent applied is 2-4 cm, the thickness of the soil layer of the primary covering is 2-3 cm, and the thickness of the water-absorbing and water-retaining agent applied is 3-5 cm.

6. A fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 1, characterized in that: The fertilization method for improving nitrogen utilization of perennial sugarcane also includes: intercropping leguminous plants between sugarcane rows, forming a fertilization ditch between the leguminous plants and the perennial sugarcane, and spreading a layer of ammonia capture agent above the soil layer of the secondary covering of the fertilization ditch.

7. A fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 6, characterized in that: The legume plant is peanut or soybean.

8. A fertilization method for improving nitrogen utilization of ratoon sugarcane according to claim 6, characterized in that: The preparation method of the ammonia capture agent is as follows: zeolite or biochar is crushed and added to a 1-3 mol / L hydrochloric acid solution, stirred at 60-80° C. for 8-10 hours, filtered, washed to neutrality, and dried at 60-70° C. to obtain the ammonia capture agent.

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