A method for stable yield, phosphorus reduction and improvement of phosphorus absorption and utilization efficiency of rice

Abstract

The application discloses a method for stably producing and reducing phosphorus and improving phosphorus absorption and utilization efficiency of rice, and belongs to the technical field of rice planting. The method is to prepare biochar from invasive plant guettarda speciosa, add the guettarda speciosa biochar into rice seedling raising substrate or seedling raising nutrient soil during seedling raising, and transplant the guettarda speciosa biochar into a field together with the rice during transplanting. The porous structure of the guettarda speciosa biochar is used to adsorb phosphorus in the soil to the surrounding of the soil root system. Hybrid rice and conventional rice are mixed and sowed, the difference in root system morphology is used to increase the absorption range of the rice root system, the absorption and utilization efficiency of the rice to phosphorus fertilizer can be effectively improved, the operation is simple, the invasive plant guettarda speciosa is resourcefully utilized, the biochar consumption is greatly reduced compared with the mode of directly adding biochar into the soil, the energy consumption for preparing the biochar is reduced, the phosphorus fertilizer input is reduced while the yield is stabilized, and the risk of environmental hazards caused by chemical fertilizers is reduced.

Description

Technical Field

[0001] This invention belongs to the field of rice cultivation technology, specifically relating to a method for stabilizing yield, reducing phosphorus content, and improving the efficiency of phosphorus absorption and utilization in rice. Background Technology

[0002] Phosphorus is an essential macronutrient for plant growth, and large amounts of phosphate fertilizer are applied during crop production. However, in rice cultivation, due to the poor mobility of phosphorus in the soil, only about 25% of the applied phosphate fertilizer is absorbed and utilized by rice plants. The remaining phosphate fertilizer is fixed in the soil or flows into rivers and lakes with surface runoff, wasting resources and causing water pollution. Therefore, reducing phosphate fertilizer application and increasing rice absorption and utilization of phosphate fertilizer while ensuring stable rice yields is an important method to reduce phosphorus pollution in water bodies.

[0003] Biochar is a widely available soil conditioner that not only increases soil organic matter content, enhances soil microbial abundance, and improves soil quality, but also promotes crop growth. However, due to the large amount of biochar required and its high cost in field production, its application in crop production remains limited. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a method for stabilizing phosphorus production, reducing phosphorus content, and improving the efficiency of phosphorus absorption and utilization in rice.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for stabilizing phosphorus yield, reducing phosphorus content, and improving phosphorus absorption and utilization efficiency in rice includes the following steps:

[0007] (1) Rice variety selection: Select one hybrid rice and one conventional rice variety with similar growth period and grain shape and complementary genetic traits;

[0008] (2) Substrate preparation: When raising seedlings on a mat, the seedling substrate and biochar are mixed evenly in a certain proportion; when raising seedlings in pots, the seedling nutrient soil and biochar are mixed evenly in a certain proportion.

[0009] (3) Seed soaking and seedling raising: After mixing hybrid rice seeds and conventional rice seeds in a certain proportion, soak the seeds with a seed soaking agent to promote germination until the seeds break through the chest and show white. Then, sow the seeds evenly in the seedling tray in a certain quantity.

[0010] (4) Seedling management: After the seedling trays are placed, cover them with non-woven fabric and keep them moist. When the seedlings grow to 1 leaf and 1 heart, uncover the non-woven fabric. 2-3 days before transplanting, spray "transplanting fertilizer" according to the leaf color. Before transplanting, use alternating dry and wet methods to control growth and promote root growth. When machine transplanting blanket seedlings, wait until the seedlings grow to 3 leaves and 1 heart. When machine transplanting pot seedlings, wait until the seedlings grow to 4-5 leaves with tillers.

[0011] (5) Precision machine transplanting: The field is finely tilled, the straw is buried, the field surface is level, and the height difference does not exceed 3 cm. The soil slurry settles for 2-4 days and a shallow water layer of 2-3 cm is maintained. The number of seedlings taken per hole is adjusted to 2-4, and the transplanting density is 30 cm between rows and 15-17 cm between plants. During transplanting, biochar is attached to the rice roots and transplanted to the field along with the rice.

[0012] (6) Fertilizer and water management: During the entire growth period, apply 16 kg of pure nitrogen, 3.2±0.1 kg of P2O5, and 12.8 kg of K2O per mu, in a ratio of 1:0.2±0.01:0.8, of which the phosphorus fertilizer is 50±2% of the conventional application amount; maintain the water layer at 2-3 cm during transplanting; continue the principle of shallow water irrigation during the tillering period, maintaining the water layer at 3-5 cm; start draining the field when the number of tillers per mu is about 20±10,000, and re-irrigate when the soil is firm and has fine cracks, repeating the cycle 4-5 times for 15-20 days, aiming for the soil to be firm and not sinking, not softening after re-irrigation, and the leaves turning yellow; use alternating shallow water and moist irrigation from branch differentiation to heading stage, and keep the soil shallow or moist throughout the heading and flowering stages, and then alternate between dry and wet irrigation until the rice matures;

[0013] (7) Field management: The field cultivation management is based on the hybrid rice variety, and a healthy population of binary varieties with enhanced comprehensive resistance (resistance to diseases and pests, lodging resistance, etc.) is constructed without adding any additional management measures;

[0014] (8) After the rice matures, they are harvested together. Since the selected varieties have similar growth periods and grain shapes, they will not affect the harvest and subsequent processing. This achieves stable rice production while reducing the input of phosphate fertilizer, and at the same time increases the absorption and utilization efficiency of phosphate fertilizer by rice.

[0015] As a preferred option, the high-quality and high-yield hybrid rice main variety selected in step (1) and the high-quality and high-yield conventional rice variety that is matched with it are selected.

[0016] As a preferred option, the hybrid rice varieties selected in step (1) should have a growth period that differs from that of conventional rice varieties by no more than 5 days, a length-to-width ratio that differs by no more than 10%, and complementary resistance.

[0017] Preferably, in step (2), the biochar is Mikania micrantha biochar;

[0018] The preparation method of Mikania micrantha biochar includes the following steps: drying Mikania micrantha to constant weight, pulverizing and sieving, heating in the absence of oxygen to 500-700℃ and holding for 1.5-2 hours (preferably 500℃ for 2 hours) to obtain Mikania micrantha biochar;

[0019] Furthermore, the sieving is performed through a 10-20 mesh sieve; more preferably through a 20 mesh sieve.

[0020] As a preferred option, in step (2), when raising seedlings on mats, the seedling substrate is mixed with biochar, and the proportion of biochar should be 30-45%, with 65-97 kg used per hectare (based on 300 trays of seedlings transplanted per hectare); when raising seedlings in pots, the seedling nutrient soil is mixed with biochar, and the proportion of biochar should be 50-65%, with 80-104 kg used per hectare (based on 400 trays of seedlings transplanted per hectare).

[0021] Furthermore, when raising seedlings in pots, the seedling nutrient soil should be mixed with biochar, and the proportion of biochar should be 60±2%, with 96 kg used per hectare (calculated based on 400 trays of seedlings transplanted per hectare).

[0022] Preferably, the ratio of hybrid rice seeds to conventional rice seeds in step (3) should be 1:2.5 to 3;

[0023] As a preferred option, in step (3), the seeds are quantitatively and evenly sown in the seedling trays using a mechanical assembly line by means of machine transplanting seedlings.

[0024] As a preferred option, in step (4), the "bridal fertilizer" is urea. Specifically, urea is dissolved in water and sprayed into the seedling tray as "bridal fertilizer". Furthermore, 0.8 to 1 liter of urea solution with a concentration of 10 g / L is sprayed per square meter of seedlings as "bridal fertilizer".

[0025] As a preferred option, in step (8), the harvest should be carried out when the variety with a slightly longer growing period matures.

[0026] The present invention has the following advantages and effects compared with the prior art:

[0027] This invention utilizes the invasive plant *Mikania micrantha* to prepare biochar. During seedling cultivation, *Mikania micrantha* biochar is added to the rice seedling substrate or nutrient soil. Upon transplanting, the biochar is transplanted to the field along with the rice. Due to its unique loose and porous structure, *Mikania micrantha* biochar effectively adsorbs phosphates from the soil, placing them around the rice roots for absorption. This enhances phosphate fertilizer absorption and improves soil quality. Compared to directly adding biochar to the soil, this method is time-saving, labor-saving, significantly reduces biochar usage, lowers energy consumption during biochar preparation, and reduces phosphate fertilizer input while maintaining stable yields, thus mitigating the environmental risks associated with chemical fertilizers. Furthermore, hybrid rice has long, deep roots, while conventional rice has short, shallow roots. Planting hybrid and conventional rice varieties together in the same field leverages these root morphological differences to fully utilize the underground soil space, increasing the root-soil contact area, expanding the absorption range of the rice roots, promoting nutrient absorption from the soil, and effectively improving the efficiency of phosphate fertilizer absorption and utilization by the rice. This method can enhance the absorption of phosphorus by rice, reduce the input of chemical fertilizers, and reduce the risk of non-point source pollution. It is easy to operate and effectively utilizes the invasive plant Mikania micrantha. At the same time, adding biochar to the soil can also improve soil quality and enhance soil fertility. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0029] The hybrid rice variety used in this embodiment and comparative example was Taifengyou 1136 (Guangdong Approved Rice 20220113), and the conventional rice variety was Gengyun Hezhan (Guangdong Approved Rice 20220116). All embodiments and comparative examples used the pot seedling raising and transplanting method in 2022, with sowing on June 30, transplanting on July 22, and harvesting on November 6. An additional field was set up where no biochar was added to the nutrient soil and no phosphate fertilizer was applied during seedling raising, and all other cultivation and management measures were consistent with Example 1, used to calculate the agronomical and physiological utilization rates of phosphate fertilizer.

[0030] In the embodiments and comparative examples of this invention, the technical features not disclosed are all set according to conventional planting methods.

[0031] Example 1

[0032] After the collected Mikania micrantha plants were dried to constant weight, they were pulverized and passed through a 20-mesh sieve. They were then placed in a muffle furnace to isolate oxygen and heated to 500℃ for 2 hours to obtain Mikania micrantha biochar. The biochar was mixed evenly with seedling nutrient soil at a ratio of 60%. Hybrid rice seeds and conventional rice seeds were mixed evenly at a ratio of 1:3 and soaked in a seed soaking agent to promote germination until the seed buds showed white tips. The seeds were then quantitatively and evenly sown into seedling trays using a machine-transplanting method on a automated production line.

[0033] After arranging the seedling trays, cover them with non-woven fabric and keep them moist. When the seedlings grow to 1 leaf and 1 heart, remove the non-woven fabric. 2-3 days before transplanting, dissolve urea in water and spray it into the seedling trays as "pre-transplanting fertilizer" according to the leaf color. Before transplanting, use alternating wet and dry conditions to control growth and promote root growth. When machine transplanting blanket seedlings, wait until the seedlings grow to 3 leaves and 1 heart before machine transplanting. When raising seedlings in pots, wait until the seedlings grow to 4-5 leaves with tillers before machine transplanting.

[0034] The field is carefully tilled, the straw is buried, the field surface is leveled, and the height difference does not exceed 3 cm. The soil and mud settle for 2-4 days and a shallow water layer of 2-3 cm is maintained. The number of seedlings is adjusted to 2-4 per hole, and the transplanting density is 30 cm between rows and 15-17 cm between plants. Biochar is transplanted to the field along with the rice.

[0035] Throughout the entire growth period, apply 16 kg of pure nitrogen, 3.2 kg of P2O5, and 12.8 kg of K2O per mu (approximately 0.067 hectares), in a ratio of 1:0.2:0.8, with phosphate fertilizer accounting for 50% of the conventional application rate. Maintain a water level of 2-3 cm during transplanting; continue shallow irrigation during the tillering stage, keeping the water level at 3-5 cm; when the number of tillers per mu reaches approximately 200,000, begin draining the field. Once the soil has settled and developed fine cracks, re-irrigate, repeating this cycle 4-5 times for 15-20 days, ensuring the soil is firm but not sinking, does not soften after re-irrigation, and the leaves turn yellow; from branch differentiation to heading, use alternating shallow and moist irrigation, maintaining shallow or moist soil throughout the heading and flowering stages, and then alternating between dry and wet irrigation until the rice matures.

[0036] Once the rice is mature, it can be harvested directly using a combine harvester. For varieties with a longer growth period, harvesting should be done at maturity.

[0037] Rice yield, total phosphorus accumulation in plants, agronomical utilization rate of phosphate fertilizer, physiological utilization rate of phosphate fertilizer, and available phosphorus content in rhizosphere and non-rhizosphere soil were measured at rice harvest. All measured data are shown in Tables 1 and 2.

[0038] Comparative Example 1

[0039] Except that no biochar was added to the seedling nutrient soil during seedling raising, and the amount of phosphate fertilizer used was the conventional amount, i.e., 6.4 kg of P2O5, the other planting and cultivation methods were the same as in Example 1.

[0040] Rice yield, total phosphorus accumulation in plants, agronomical utilization rate of phosphate fertilizer, physiological utilization rate of phosphate fertilizer, and available phosphorus content in rhizosphere and non-rhizosphere soil were measured at rice harvest. All measured data are shown in Tables 1 and 2.

[0041] Comparative Example 2

[0042] Except for mixing the seedling nutrient soil with biochar at a ratio of 20% during seedling raising, the other planting and cultivation methods were the same as in Example 1. Rice yield, total phosphorus accumulation in plants, agronomical utilization rate of phosphate fertilizer, physiological utilization rate of phosphate fertilizer, and available phosphorus content in rhizosphere and non-rhizosphere soils were measured at rice harvest. All measured data are shown in Tables 1 and 2.

[0043] Comparative Example 3

[0044] Except for mixing the seedling nutrient soil with biochar at a ratio of 40% during seedling raising, the other planting and cultivation methods are the same as in Example 1.

[0045] Rice yield, total phosphorus accumulation in plants, agronomical utilization rate of phosphate fertilizer, physiological utilization rate of phosphate fertilizer, and available phosphorus content in rhizosphere and non-rhizosphere soil were measured at rice harvest. All measured data are shown in Tables 1 and 2.

[0046] Comparative Example 4

[0047] Except for mixing the seedling soil with biochar at a ratio of 80%, the planting and cultivation methods were the same as in Example 1. Rice yield, total phosphorus accumulation in plants, agronomical utilization rate of phosphate fertilizer, physiological utilization rate of phosphate fertilizer, and available phosphorus content in rhizosphere and non-rhizosphere soils were measured at rice harvest. All measured data are shown in Tables 1 and 2.

[0048] Comparative Example 5

[0049] No biochar or phosphate fertilizer was added to the nutrient soil during seedling raising, and the remaining cultivation and management measures were the same as in Example 1.

[0050] Rice yield and total phosphorus accumulation in the plant were measured at harvest time to calculate the agronomical and physiological utilization rates of phosphate fertilizer in Example 1 and other comparative examples. Available phosphorus content in rhizosphere and non-rhizosphere soils was also measured. All measured data are shown in Tables 1 and 2.

[0051] Table 1. Rice yield, total phosphorus accumulation per plant, agronomical utilization rate, and physiological utilization rate of phosphate fertilizer in the examples and comparative examples.

[0052]

[0053] Note: Different lowercase letters in each column indicate significant differences (P<0.05).

[0054] As shown in Table 1, the yield of Example 1 was not significantly different from that of Comparative Example 1. However, the agronomical and physiological utilization rates of phosphate fertilizer were significantly increased by 96.9% and 28.4% respectively compared to Comparative Example 1. This indicates that adding biochar to the nutrient soil during seedling raising and transplanting it to the field at the same time can effectively improve the agronomical and physiological utilization rates of phosphate fertilizer in rice, thereby increasing the yield. Compared to Comparative Examples 2, 3, and 4, the yield of Example 1 was significantly increased by 12.79%, 6.10%, and 4.24% respectively, and the agronomical utilization rate of phosphate fertilizer was significantly increased by 73.12%, 27.29%, and 28.29% respectively. The physiological utilization rate of phosphate fertilizer in Example 1 was significantly increased by 25.03% and 14.37% compared to Comparative Examples 2 and 3 respectively, but not significantly different from Comparative Example 4. This indicates that the phosphate fertilizer utilization rate and yield vary depending on the proportion of biochar in the nutrient soil, but the yield and agronomical utilization rate are highest when the proportion is 60%. The lower yield of Comparative Example 4 compared to Example 1 was due to the excessively high proportion of biochar during seedling raising and the poor water retention of the seedling substrate, resulting in stunted seedlings, yellowing leaves, and a longer recovery time after transplanting, thus reducing the yield.

[0055] Table 2. Available phosphorus content in rhizosphere and non-rhizosphere soils of rice in the examples and comparative examples.

[0056]

[0057] Note: Different lowercase letters in each column indicate significant differences (P<0.05).

[0058] Table 2 shows that the available phosphorus content in the rhizosphere soil increased significantly with increasing biochar addition (Example 1 and Comparative Examples 2, 3, and 4). The available phosphorus content in the rhizosphere soil of Example 1 was not significantly different from that of Comparative Example 1, but significantly increased by 34.76%, 17.21%, and 4.85% compared to Comparative Examples 2, 3, and 4, respectively. The available phosphorus content in the non-rhizosphere soil decreased significantly with increasing biochar addition. The available phosphorus content in the non-rhizosphere soil of Example 1 was significantly reduced by 33.46% compared to Comparative Example 1, but not significantly different from Comparative Example 4. Furthermore, the available phosphorus content in the non-rhizosphere soil of Comparative Example 1 was significantly higher than that of other treatments (Example 1 and Comparative Examples 2, 3, and 4). This indicates that adding biochar to the nutrient soil during seedling raising can effectively reduce the available phosphorus content in the non-rhizosphere soil, reduce phosphorus surplus in the soil, and lower the risk of phosphorus pollution.

[0059] During transplanting, biochar is transferred into the soil along with the rice and adheres to the rice roots. The biochar surrounding the roots, through its unique structure, adsorbs available phosphorus from the non-rhizosphere soil into the rhizosphere soil, increasing the available phosphorus content in the rhizosphere soil for absorption by the rice roots. This improves the utilization rate of phosphorus fertilizer in rice, ensuring high and stable yields while reducing phosphorus fertilizer application by half. It saves time and labor, enhances phosphorus fertilizer absorption, and improves soil quality. Furthermore, hybrid rice has long and deep roots, while conventional rice has short and shallow roots. Planting hybrid and conventional rice varieties together in the same field fully utilizes the underground space of the soil, increasing the contact area between the roots and the soil, and promoting the absorption of nutrients by the rice roots. This method enhances phosphorus absorption by rice while ensuring stable yields, reduces fertilizer input, eliminates phosphorus surplus in the soil, and reduces the risk of non-point source pollution. Simultaneously, the addition of biochar to the soil also improves soil quality and enhances soil fertility.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0061] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for stabilizing phosphorus yield, reducing phosphorus content, and improving phosphorus absorption and utilization efficiency in rice, characterized in that: Comprise the following steps: (1) Rice variety selection: select 1 hybrid rice and 1 conventional rice variety with similar growth period and grain shape and complementary genetic traits; (2) Matrix preparation: mix the seedling matrix and guijave biochar in a certain proportion when using the mat seedling method, and mix the seedling nutrient soil and guijave biochar in a certain proportion when using the pot seedling method; Among them, when using the mat seedling method, the seedling matrix is mixed with guijave biochar, and the proportion of guijave biochar is 30-45%; When using the pot seedling method, the seedling nutrient soil is mixed with guijave biochar, and the proportion of guijave biochar is 50-65%; (3) Seed soaking and seedling raising: mix hybrid rice seeds and conventional rice seeds in a certain proportion, then use seed soaking agent to soak and germinate until the chest is broken and white, and then uniformly sow the seeds in the seedling tray; (4) Seedling field management: after the seedling tray is placed, cover the seedling tray with non-woven fabric and keep it moist for seedling, then uncover the non-woven fabric when the seedlings grow to 1 leaf 1 heart, spray "seedling transplanting fertilizer" 2-3 days before transplanting according to the leaf color, and use dry-wet alternating control to increase roots before transplanting; When using the mat seedling method, the seedlings are machine-planted when they grow to 3 leaves 1 heart, and when using the pot seedling method, the seedlings are machine-planted when they grow to 4-5 leaves with tillers; (5) Precise machine planting: fine tillage in the field, straw burial, flat field, height difference not more than 3 cm, soil mud slurry sinking for 2-4 days and maintaining 2-3 cm shallow water layer; Adjust the seedling quantity to 2-4 seedlings per hole, and machine plant with a row spacing of 30 cm and a plant spacing of 15-17 cm; Guijave biochar adheres to the rice roots and is transplanted to the field with the rice; (6) Fertilizer and water management: apply 16 kg of pure nitrogen, 3.2±0.1 kg of P2O5 and 12.8 kg of K2O per mu during the whole growth period, the ratio is 1:0.2±0.01:0.8, of which the phosphorus fertilizer is 50±2% of the conventional application amount; The water layer is maintained at 2-3 cm during transplanting; Continue to maintain shallow water irrigation during the green regrowth tillering period, and the water layer is maintained at 3-5 cm; When the stem tiller number per mu is 20±1 million, start to drain and rest in the field, and when the soil is compacted and cracked, re-run the water, cycle 4-5 times, the duration is 15-20 days, the soil is compacted and not sink, and the leaf color is yellow after re-watering; Alternate shallow water layer and wet irrigation from branch differentiation to heading stage, maintain soil shallow water or wetness during the whole heading stage and flowering stage, and then alternate dry and wet field until the rice matures; (7) Field management: according to the variety of hybrid rice, construct a healthy population with dual variety enhanced comprehensive resistance without increasing additional management measures; (8) After the rice matures, it is harvested mixedly, because the selected varieties have similar growth period and grain shape, which will not affect the harvesting and subsequent processing process; It realizes stable yield of rice under the condition of reducing phosphorus fertilizer input, and increases the absorption and utilization efficiency of rice to phosphorus fertilizer.

2. The method of claim 1, wherein: In step (1), 1 high-quality and high-yield hybrid rice main variety and 1 high-quality and high-yield conventional rice variety are selected.

3. The method of claim 1, wherein: The growth period of the hybrid rice variety and the conventional rice variety selected in step (1) should be within 5 days, the length-width ratio of the milled rice should be within 10%, and the varieties should be complementary in resistance.

4. The method of claim 1, wherein: The preparation method of the guettarda speciosa biochar comprises the following steps: drying guettarda speciosa to a constant weight, crushing and sieving, heating to 500-700 DEG C in an oxygen-free environment for 1.5-2 hours to obtain guettarda speciosa biochar.

5. The method of claim 1, wherein: When pot seedling is used for seedling raising, the guettarda speciosa biochar is mixed with the seedling raising nutrient soil, and the proportion of the guettarda speciosa biochar should be 60±2%.

6. The method of claim 1, wherein: In step (3), the ratio of hybrid rice seeds to conventional rice seeds should be 1:2.5-3.

7. The method of claim 1, wherein: In step (4), the "seedling transplanting fertilizer" is urea.

8. The method of claim 1, wherein: In step (8), the harvest should be performed when the variety with a slightly longer growth period is mature.

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