Water-carbon-nitrogen combined management and yield prediction method for efficient production of rice-wheat rotation
By combining wet and dry irrigation with straw biochar return to the field, the water, carbon, and nitrogen management method has solved the problems of water waste and high greenhouse gas emissions in rice-wheat rotation, improved rice and wheat yields and water and fertilizer use efficiency, and achieved sustainable and efficient agricultural production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JINLING INST OF TECH
- Filing Date
- 2025-12-19
- Publication Date
- 2026-05-29
Smart Images
Figure CN122115140A_ABST
Abstract
Description
Technical Field
[0001] This invention patent belongs to the fields of efficient utilization of agricultural resources and agricultural production, and specifically relates to a method for integrated water, carbon and nitrogen management and yield prediction in efficient rice-wheat rotation production. Background Technology
[0002] Rice-wheat rotation is one of the most important cropping systems in the Yangtze River Basin and southern regions of China. However, its production process also faces environmental challenges such as high water consumption, high greenhouse gas (CH4, N2O) emissions, and low nitrogen fertilizer utilization. Therefore, how to achieve the synergistic effect of multiple objectives—water conservation, carbon sequestration, emission reduction, and efficiency improvement—through integrated management is a current frontier and hot topic in agricultural sustainable development research. Rice and wheat provide staple food for more than 50% of the world's population. China is the world's largest rice producer and consumer, with rice cultivation accounting for 26% of the country's arable land. Rice cultivation involves large amounts of irrigation water and fertilizer application, resulting in significant nitrogen loss through water usage. Integrating water and fertilizer management can reduce water, fertilizer, and energy inputs and costs in rice production, making it more sustainable than traditional methods. The rice-wheat rotation system is widely adopted in Southeast Asia, ensuring food security for approximately 20% of the world's population. High agricultural productivity results in the annual production of large amounts of rice straw; globally and in my country, the area of rice straw returned to the field has reached approximately 54% and 70%, respectively. With increasing years of crop failure, the direct application of large amounts of straw after rice and wheat planting to the fields leads to decreased soil fertility and increased carbon emissions, ultimately resulting in reduced rice and wheat yields and ecological damage. Effective utilization of agricultural straw has become a key aspect of sustainable agricultural development in relevant regions, making the search for a new, efficient method for utilizing straw resources urgent. Straw biochar, as a carbon source, not only significantly increases soil fertility and crop yield but also provides a more effective way to increase carbon sequestration, significantly reducing the net greenhouse effect. In particular, straw biochar application can improve soil fertility and crop yield in rice and wheat fields while reducing carbon emissions by 18.6%. Therefore, straw biochar treatment systems for rice and wheat have significant application value.
[0003] Furthermore, fertilizer and water management practices in rice-wheat rotation systems have a significant impact on crop growth, yield, and soil health. In recent years, integrated fertilizer and water management strategies have received increasing attention, with researchers focusing on their effects on soil properties, crop growth, and environmental sustainability. The impacts of different fertilizer and water management methods on crop growth, yield, and soil water productivity have been extensively studied, providing a theoretical basis for optimizing agricultural production. In rice-wheat rotation systems, nitrogen fertilizer management is a key factor in improving crop yield and resource utilization efficiency. Residual nitrogen helps increase rice and wheat yields, while high levels of current-season nitrogen can reduce yields. Under different nitrogen fertilizer levels, rice grain yield can increase by up to 9%. Therefore, nitrogen is crucial for ensuring crop yield and significantly affects greenhouse gas emissions from paddy fields. Intensive farmland management can improve crop productivity and will inevitably reduce greenhouse gas emissions by changing nitrogen fertilizer application methods. Direct nitrogen (N) fertilizers account for 84% of total global N2O emissions from human activities. However, the impact of nitrogen fertilizer on greenhouse gas emissions in paddy field ecosystems is related to the type, amount, method, and timing of fertilizer application. Therefore, optimizing nitrogen fertilizer application is key to increasing crop yields and reducing greenhouse gas emissions. In terms of water resource management, reducing water deficit is crucial for mitigating groundwater level decline in rice-wheat rotation systems. Traditional continuous flooding irrigation not only wastes water resources and causes the loss of soil nutrients such as nitrogen, phosphorus, and potassium, but also increases methane emissions. Rational fertilization and water management play a vital regulatory role in reducing soil organic matter decomposition, increasing organic matter accumulation, reducing greenhouse gas emissions, and mitigating global warming, ultimately improving crop productivity. Therefore, water and fertilizer management measures can mitigate the negative impacts of straw return to the field, as straw return without proper water and fertilizer management can easily lead to reduced crop yields.
[0004] In summary, carbon, nitrogen, and water are crucial factors for crop growth and yield improvement. The carbon cycle, involving crop respiration and soil respiration, primarily occurs through the root system, and both root respiration and soil microbial respiration are closely related to plant growth. Plants provide products for root respiration through photosynthesis, while roots, through respiration, facilitate nutrient and water absorption. Increased soil nitrogen significantly alters plant productivity and decomposition capacity, impacting the carbon dynamics of the ecosystem. Water and nitrogen management can regulate the root growth environment and photosynthesis after straw biochar is applied to the field. Currently, although many scholars have conducted extensive indoor and field experiments on biochar application, the effects of water and nitrogen management combined with straw biochar application on the growth of rice-wheat systems remain unclear. To address these technical deficiencies, this invention reduces the frequency and amount of fertilization, combines it with straw biochar application, and implements rice-wheat rotation under alternating wet and dry irrigation. Ultimately, this significantly improves soil fertility and increases yield in rice and wheat crops, while also increasing the nutrient content of edible parts. This invention can also increase the soil carbon content of rice-wheat systems and reduce their greenhouse gas emissions, providing an innovative solution to address the dual challenges of food security and climate change. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method for water, carbon and nitrogen integrated management and yield prediction for efficient rice-wheat rotation production, in order to realize the resource utilization of agricultural straw and achieve economic benefits such as increased crop yield.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] This invention discloses a method for integrated water, carbon, and nitrogen management and yield prediction in high-efficiency rice-wheat rotation production, comprising water management, exogenous carbon application, exogenous nitrogen application, integrated water, carbon, and nitrogen management system, and crop yield prediction method. Figure 1 Water management employed alternating low-water-wet irrigation for rice and precise quantitative irrigation for wheat. Exogenous carbon and nitrogen application utilized self-made straw wet biochar and a mixture of readily available and slow-release urea nitrogen in specific proportions. Four combined water, carbon, and nitrogen application schemes were derived through meta-analysis. The crop yield prediction model based on this combined management system was a multivariate linear equation fitting.
[0008] Furthermore, low-water-level alternating wet and dry irrigation methods and precise quantitative irrigation are employed. Specifically, for rice, the water level is maintained at 1-1.5cm during transplanting, 1-2cm during tillering, and 0.5-1cm during jointing and booting stages, respectively. When the planned number of tillers per rice plant reaches 13-14, irrigation is stopped and the field is allowed to dry naturally. After flowering, the surface water naturally dries until the soil surface is moist, and then irrigated again for 2-3 days later, with a depth of 1-2cm. This process is repeated until the rice reaches grain filling and ripening. Irrigation is stopped 15-20 days before harvest, and the soil is allowed to dry naturally. For wheat planting, the soil is first irrigated to saturation water capacity, and then the wheat seeds are directly sown. The surface is covered with 5-8cm of wheat straw, with a thickness not exceeding 0.3cm. After about 2-3 days, the straw is sprayed with water until the surface is moist. Subsequently, the soil moisture is maintained at 60%-70% of saturation water capacity for one month. Then, irrigation is carried out quantitatively according to the water requirements of wheat at different growth stages. Specifically, irrigation is carried out once at a rate of 2.4-2.8 L / m² about 7 days after the wheat begins to tiller. 2 After 10 days, irrigate with 15.6-16.5 L / m² of water. 2 Then, irrigate with 21.0-22.5 L / m² every 7 days. 2 Two irrigations were performed, followed by irrigation every 7 days at a rate of 11.3-12.5 L / m². 2 Two irrigations were carried out in total, followed by irrigation at a rate of 5.8-6.5 L / m² every 7 days. 2 Two times in total. Water was added 14.4-15.5 L / m³ 3 days later. 2 After that, irrigation was stopped, and the wheat was harvested in about 15-20 days.
[0009] Furthermore, the self-made straw wet biochar has a carbon-to-nitrogen ratio (C / N) of 27:1-28:1 (rice straw wet biochar) and 40:1-42:1 (wheat straw wet biochar), and is applied at a rate of 1.10-1.15 kg per square meter of topsoil.
[0010] Furthermore, slow-release urea nitrogen is applied in a specific ratio, with fast-acting urea nitrogen and slow-release urea nitrogen mixed in a 4:6-3:7 ratio for a single application, resulting in a total nitrogen application rate of 60%-80% of the conventional rate. The fast-acting urea nitrogen contains 42%-46% nitrogen. Slow-release urea nitrogen is mainly available in 60-day (45% nitrogen content), 90-day (44% nitrogen content), and 120-day (43% nitrogen content) formulations, with application rates of 30%, 30%, and 10% of the total nitrogen application rate, respectively. Simultaneously, diammonium phosphate fertilizer with an 18% nitrogen content is applied, at an application rate of 11% of the total nitrogen application rate, or 1.20-1.25 g / kg of topsoil. Potassium fertilizer is applied at a rate of 0.93-0.95 g / kg of topsoil.
[0011] Furthermore, a meta-analysis was conducted on four water, carbon, and nitrogen application schemes, combined with existing literature on water, carbon, and nitrogen input regulation in rice and wheat cultivation over the past 15 years. Keywords such as "rice," "wheat," "rice and wheat," "rice," "wheat," "rice and wheat rotation," and "rice-wheatrotation" were searched on major domestic and international literature platforms and related scientific and technological achievement platforms. The resulting water, carbon, and nitrogen application schemes are summarized as follows:
[0012] When the average total irrigation amount is 60%-80% of the average of the past five years in the planting area, the amount of biochar applied to the topsoil is 80%-90% of the amount of exogenous carbon applied, and the amount of nitrogen fertilizer applied is 90%-100% of the conventional amount applied.
[0013] When the average total irrigation amount is 80%-90% of the local average for the past five years, the amount of biochar applied to the topsoil is 80%-90% of the amount of exogenous carbon applied, and the amount of nitrogen fertilizer applied is 80%-90% of the conventional amount applied.
[0014] When the average total irrigation amount is 80%-90% of the local average for the past five years, the amount of biochar applied to the topsoil is 90%-100% of the amount of exogenous carbon applied, and the amount of nitrogen fertilizer applied is 70%-80% of the conventional amount.
[0015] When the average total irrigation amount is 90%-100% of the average of the past five years in the planting area, the amount of biochar applied to the topsoil is 90%-100% of the amount of exogenous carbon applied, and the amount of nitrogen fertilizer applied is 65%-75% of the conventional amount.
[0016] The phosphorus and potassium fertilizers mentioned above are based on the recommendations of the local planting area.
[0017] Furthermore, yield forecasting is based on the above four water, carbon, and nitrogen application schemes to construct prediction models for rice (Yrice) and wheat (Ywheat) yields.
[0018] Rice yield prediction model: Yrice=(31.95×C+20.76×N+1.155×TIA) / w(R) 2 =0.97, p<0.05)
[0019] Wheat yield prediction model: Ywheat=(5.84×C+3.80×N+0.21×TIA) / r(R) 2 =0.85, p<0.05)
[0020] Rice or wheat yield Y is expressed in kg / mu, and total irrigation water TIA is expressed in m³. 3 / mu, the application rate of straw wet biochar C is in kg / m 2Nitrogen fertilizer application rate (N) is expressed in g / 15kg soil (20cm topsoil layer). w represents the impact of the previous crop on the current crop, typically taken as 0.6 or 1.2. The higher the yield of the previous crop, the lower the value of w. R 2 The coefficient of determination is the model value; a higher value indicates a better fit. All coefficients are statistically significant (p < 0.05). It is recommended that for rice production, the values of C should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [390, 950]; for wheat production, the values of C should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [75, 130]. Otherwise, yield prediction accuracy will decrease if these ranges are exceeded.
[0021] Compared with conventional nitrogen application, the above-mentioned method in this invention reduces nitrogen application by 24.0%-25.5% during rice-wheat rotation, increases average rice and wheat yield by approximately 17.5%-24.5%, increases average nitrogen fertilizer partial productivity by approximately 56.0%-66.0%, increases average irrigation production efficiency by 63.6%-74.5%, and saves average water by 24.3%-32.6%.
[0022] This invention is mainly used in rice-wheat rotation system production. By using agricultural waste straw to make wet biochar and combining it with nitrogen reduction and water control irrigation, it can ultimately improve the crop production capacity of the rice-wheat system, increase water and fertilizer use efficiency and yield, thereby reducing regional farmland non-point source pollution. Attached Figure Description
[0023] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.
[0024] Figure 1 This is a flowchart of the present invention. Detailed Implementation
[0025] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, terms such as "upper," "lower," "front," "rear," and "middle" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.
[0026] The present invention can be better understood from the following embodiments.
[0027] This invention provides a method for integrated water, carbon, and nitrogen management and yield prediction in efficient rice-wheat rotation production. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.
[0028] This embodiment was conducted at the Horticulture Station of Jinling Institute of Technology, Mufu Campus, and provides a method for integrated water, carbon, and nitrogen management and yield prediction in high-efficiency rice-wheat rotation. Specific steps include irrigation, nitrogen fertilizer application, and biochar application at different growth stages of rice and wheat cultivation. This invention is derived from the Jiangsu Provincial Natural Science Foundation Youth Fund project, "Research on the Key Mechanism of Exogenous Carbon, Nitrogen, and Water Coupling in Soil Carbon Sequestration of Rice-Wheat Systems (BK20230112)". The specific steps of this embodiment are as follows:
[0029] I. Planting and Fertilizing
[0030] On July 4, 2024, a rice-wheat rotation (indoors) was implemented. Nitrogen application was 2.4g N per 15kg of paddy soil (fast-acting urea N: slow-release urea N = 4:6), representing 80% of the conventional nitrogen application. The fast-acting urea nitrogen contained 46% nitrogen. Slow-release urea nitrogen was applied in 60-day (45% nitrogen), 90-day (44% nitrogen), and 120-day (43% nitrogen) urea solutions, at application rates of 30%, 30%, and 10% of the total nitrogen application, respectively. Simultaneously, diamine (18% N, 46% P₂O₅) with 18% nitrogen content was applied, at an application rate of 11% of the total nitrogen application, or 1.22g / kg of topsoil. Potassium chloride (60% K₂O) was applied at a rate of 0.94g / kg of topsoil. All fertilizers were applied in a single application. This invention involves applying self-made rice and wheat straw wet biochar at a weight ratio of 6.4 g / kg to paddy soil in a single application to the soil during planting. The carbon-to-nitrogen ratio (C / N) of the applied self-made rice and wheat straw wet biochar is 27.8:1 (rice straw wet biochar) and 41.1:1 (wheat straw wet biochar), respectively. Rice was harvested on November 23, 2024, and wheat was planted on the soil after the rice harvest on December 23 of the same year, with fertilization and management consistent with those for rice.
[0031] II. Moisture Management
[0032] Rice cultivation is primarily controlled through a low-water-level, alternating wet and dry irrigation method. Specifically, from transplanting to the greening stage, tillering stage, jointing and booting stage, the water level is maintained at 1-1.5cm, 1-2cm, and 0.5-1cm respectively. When the planned number of tillers per plant reaches 13-14, the field is allowed to dry out naturally without irrigation. After flowering, the surface water naturally dries until the soil surface is moist. After 2-3 days, irrigate again to a depth of 1cm, repeating this process until the rice reaches grain filling and ripening. Irrigation is stopped 15 days before harvest for all treatments, allowing the soil to dry naturally. For wheat planting, irrigation is first applied until the soil reaches saturation water holding capacity, then wheat seeds are directly sown. The surface is covered with wheat straw (5-8cm long), with a thickness not exceeding 0.3cm. After about 2-3 days, the straw is sprayed with water until the surface is moist. Subsequently, the soil moisture is maintained at 60%-70% of saturation water holding capacity for one month. Then, irrigation is carried out quantitatively according to the water requirements of wheat at different growth stages. Specifically, 2.26 L / m² of water is applied once 7 days after the wheat begins to tiller. 2 After 10 days, the water level was 15.57 L / m². 2 Then, irrigate with 21.23 L / m² every 7 days. 2 Two irrigations were carried out, followed by irrigation at a rate of 11.32 L / m² every 7 days. 2 Two irrigations were carried out, followed by irrigation at a rate of 5.66 L / m² every 7 days. 2 Two times in total. Water was added 14.15 L / m³ 3 days later. 2 Irrigation was then stopped, and the wheat was harvested approximately 15-20 days later. The wheat was harvested on May 24, 2025.
[0033] Meanwhile, a control (CK) treatment was set up with no nitrogen fertilizer, no biochar, and conventional irrigation methods for rice and wheat in Nanjing (C0N0W). The main treatment settings are shown in Tables 1 and 2.
[0034] III. Implementation Effect Analysis
[0035] 1. Rice and wheat yield prediction models
[0036] Based on the results of the rice-wheat rotation experiment in Tables 1 and 2 below, the following results were obtained by fitting a multivariate linear equation:
[0037] Yrice=(31.95×C+20.76×N+1.15×TIA) / w(R 2 =0.97)
[0038] Ywheat=(5.84×C+3.80×N+0.21×TIA) / r(R 2 =0.85)
[0039] 2. Model Evaluation
[0040] R 2 = 0.97 indicates that the model fits very well, R =2 =0.85 The model has a certain good fit. All coefficients are statistically significant (p < 0.05). The above yield Y is in kg / mu, and the total irrigation TIA is in m³. 3 / mu, the application rate of straw wet biochar C is in kg / m 2 Nitrogen fertilizer application rate (N) is expressed in kg / kg soil. w represents the impact of the previous crop on the current crop, typically taken as 0.6 or 1.2. The higher the yield of the previous crop, the lower the value of w. R 2 The coefficient of determination (C) represents the model's performance; a higher value indicates a better fit. It is recommended that for rice production, the C value should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [390, 950]; for wheat production, the C value should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [75, 130]. Otherwise, the accuracy of the predicted yield will decrease, and predictions exceeding 30% of the above ranges are not recommended.
[0041] Table 1. Rice planting situation (application of wheat straw wet biochar)
[0042] deal with C N TIA w Y TR1-1 6.4 2.45 853.2 0.6 629.1 TR1-2 6.4 2.45 914.7 0.6 660.6 TR1-3 6.4 2.45 827.7 0.6 645.7 TR2-1 6.4 1.84 593.2 0.6 801.1 TR2-2 6.4 1.84 617.9 0.6 756.8 TR2-3 6.4 1.84 548.6 0.6 720.8 TR3-1 6.4 0 475.1 0.6 310.4 TR3-2 6.4 0 476.8 0.6 329.9 TR3-3 6.4 0 398.7 0.6 345.1 TR4-1 0 2.45 914.7 1.2 411.4 TR4-2 0 2.45 827.7 1.2 456.3 TR4-3 0 2.45 846 1.2 437.3 TR5-1 0 1.84 683.2 1.2 411.2 TR5-2 0 1.84 637.9 1.2 392.7 TR5-3 0 1.84 648.6 1.2 399.6 CK1 0 0 607.2 1.2 300.2 CK2 0 0 866.1 1.2 316.2 CK3 0 0 783.0 1.2 315.4
[0043] Table 2 Wheat Planting Situation (Application of Rice Straw Wet Biochar)
[0044] deal with C N TIA r Y TW1-1 6.4 2.45 111.1 0.6 115.1 TW1-2 6.4 2.45 126.8 0.6 112.8 TW1-3 6.4 2.45 109.8 0.6 108.2 TW2-1 6.4 1.84 89.1 0.6 155.3 TW2-2 6.4 1.84 86.6 0.6 138.2 TW2-3 6.4 1.84 85.7 0.6 124.1 TW3-1 6.4 0 90.4 0.6 95.6 TW3-2 6.4 0 89.9 0.6 98.1 TW3-3 6.4 0 90.4 0.6 94.7 TW4-1 0 2.45 94.7 1.2 98.4 TW4-2 0 2.45 97.7 1.2 91.2 TW4-3 0 2.45 106 1.2 93.3 TW5-1 0 1.84 83.2 1.2 102.6 TW5-2 0 1.84 87.9 1.2 108.7 TW5-3 0 1.84 78.6 1.2 103.9 CK1 0 0 107.2 1.2 88.5 CK2 0 0 96.1 1.2 89.4 CK3 0 0 103.0 1.2 83.7
[0045] The above explanation indicates that in a rice-wheat rotation system, the total irrigation amount can differ significantly when fertilization management is consistent for rice and wheat. This may be due to differences in the original soil properties, resulting in significant yield differences. These differences can be reduced by leveling and tilling the soil to achieve uniformity. However, based on actual production, yield prediction models with good fits are obtained, and the yield prediction models for rice and wheat are almost identical, indicating that the carbon, nitrogen, and water management design in this invention can be well applied in rice-wheat rotation production.
[0046] The above yield Y is in kg / mu, and the total irrigation TIA is in m³. 3 / mu, the application rate of straw wet biochar C is in kg / m 2 Nitrogen fertilizer application rate (N) is expressed in g / 15kg soil (calculated based on a 20cm topsoil layer). w and r represent the impact of the previous crop on the current crop; the higher the yield of the previous crop, the lower the values of w and r. If no nitrogen is applied, higher values must be used. Analysis of rice-wheat rotation crop yields in existing literature over the past 15 years shows that w or r is taken as 1.2 when the yield (Y) of the previous crop is relatively small, and as 0.6 when the yield (Y) of the previous crop is relatively large. R 2 The coefficient of determination is the model's coefficient of determination; a larger value indicates a better fit of the model.
[0047] The above results indicate that, compared with conventional nitrogen application (nitrogen application rate of 24 kg / kg soil (calculated based on a 20 cm tillage layer)) during rice-wheat rotation, applying biochar to reduce nitrogen by 25% can increase the average yield of rice and wheat by approximately 17.7% and 24.2%, respectively; the average nitrogen fertilizer partial productivity (yield to nitrogen application rate) increases by approximately 57.0% and 65.7%, respectively; the average irrigation productivity (yield to total irrigation water ratio) increases by 73.6% and 64.45%, respectively; and the average water savings are 32.2% and 24.8%, respectively.
[0048] 3. Implementation Plan Recommendations
[0049] According to an embodiment of the present invention, and in conjunction with a meta-analysis of existing literature related to rice and wheat cultivation over the past 15 years, all literature was searched using keywords such as "rice," "wheat," "rice and wheat rotation," and at least 150 articles were retrieved from platforms including CNKI, VIP, Wanfang, Web of Science, the Spark Research Assistant of the Documentation and Information Center of the Chinese Academy of Sciences, the X-MOL Academic Platform, and Baidu Scholar. Based on this, the following carbon-nitrogen-water application scheme was created, adjusting the total irrigation amount (TIA, dry-wet alternating irrigation method), biochar application rate (C), and nitrogen fertilizer application rate (N):
[0050] When the average total irrigation amount is 60%-80% of the local average for the past five years, the amount of biochar applied to the topsoil is 80%-90% of the above-mentioned amount, and the amount of nitrogen fertilizer applied is 90%-100% of the conventional amount.
[0051] When the average total irrigation amount is 80%-90% of the local average for the past five years, the amount of biochar applied to the topsoil is 80%-90% of the above-mentioned amount, and the amount of nitrogen fertilizer applied is 80%-90% of the conventional amount.
[0052] When the average total irrigation amount is 80%-90% of the local average for the past five years, the application rate of topsoil biochar is 90%-100% of the above-mentioned application rate, and the application rate of nitrogen fertilizer is 70%-80% of the conventional application rate. Alternatively, when the average total irrigation amount is 90%-100% of the local average for the past five years, the application rate of topsoil biochar is 90%-100% of the above-mentioned application rate, and the application rate of nitrogen fertilizer is 65%-75% of the conventional application rate.
[0053] This invention provides a method for efficient water, carbon, and nitrogen management and yield prediction in rice-wheat rotation. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.
Claims
1. A method for integrated water, carbon, and nitrogen management and yield prediction in high-efficiency rice-wheat rotation production, characterized in that, This includes water management, exogenous carbon application, exogenous nitrogen application, combined water, carbon, and nitrogen management systems, and crop yield prediction methods. Water management employs low-water-level alternating wet and dry irrigation for rice and precision quantitative irrigation for wheat. Exogenous carbon and nitrogen application consisted of self-made straw wet biochar and a mixture of readily available and slow-release urea nitrogen in specific proportions. Four water, carbon, and nitrogen application schemes were derived through meta-analysis. The crop yield prediction model based on this integrated water, carbon, and nitrogen management system was a multivariate linear equation fitting.
2. The low-water-level alternating wet and dry irrigation and precise quantitative irrigation for wheat as described in claim 1, characterized in that, For rice, maintain a water level of 1-1.5cm during the greening stage, 1-2cm during the tillering stage, and 0.5-1cm during the jointing and booting stage. When the planned tillering number reaches 13-14 plants per plant, stop irrigation and allow the field to dry naturally. After flowering, allow the surface water to recede naturally until the soil surface is moist. Irrigate again for 1-2cm after 2-3 days, repeating this process until the rice reaches grain filling and ripening. Stop irrigation 15-20 days before harvest and allow the soil to dry naturally. For wheat planting, irrigate first until the soil reaches saturation water capacity, then directly sow the wheat seeds. Cover the surface with 5-8cm of wheat straw, no more than 0.3cm thick. Spray the straw with water every 2-3 days until the surface is moist. Maintain soil moisture at 60%-70% of saturation water capacity for the following January. Then, irrigation is carried out quantitatively according to the water requirements of wheat at different growth stages. Specifically, irrigation is carried out once at a rate of 2.4-2.8 L / m² about 7 days after the wheat begins to tiller. 2 After 10 days, irrigate with 15.6-16.5 L / m² of water. 2 Then, irrigate with 21.0-22.5 L / m² every 7 days. 2 Two irrigations were performed, followed by irrigation every 7 days at a rate of 11.3-12.5 L / m². 2 Two irrigations were carried out in total, followed by irrigation at a rate of 5.8-6.5 L / m² every 7 days. 2 Two times in total. Water was added 14.4-15.5 L / m³ after 3 days. 2 After that, irrigation was stopped, and the wheat was harvested in about 15-20 days.
3. The self-made straw wet biochar according to claim 1, characterized in that, The carbon-nitrogen ratio (C / N) is 27:1-28:1 (wet biochar of rice straw) and 40:1-42:1 (wet biochar of wheat straw), and it is applied at 1.10-1.15 kg per square meter of topsoil.
4. The method of applying a mixture of fast-acting and slow-release urea nitrogen according to claim 1, characterized in that, Quick-acting urea nitrogen and slow-release urea nitrogen are applied in a single application at a ratio of 4:6 to 3:7, with the total nitrogen application amount being 60%-80% of the conventional nitrogen application amount. The quick-acting urea nitrogen contains 42%-46% nitrogen. Slow-release urea nitrogen mainly includes 60-day (45% nitrogen content), 90-day (44% nitrogen content), and 120-day (43% nitrogen content) urea nitrogen applications, with application amounts of 30%, 30%, and 10% of the total nitrogen application amount, respectively. Simultaneously, diammonium phosphate fertilizer with a nitrogen content of 18% is applied, at an application rate of 11% of the total nitrogen application amount, which is 1.20-1.25 g / kg of topsoil. Potassium fertilizer is applied at a rate of 0.93-0.95 g / kg of topsoil.
5. The four water, carbon, and nitrogen application schemes according to claim 1, characterized in that, A meta-analysis was conducted based on existing literature on water, carbon, and nitrogen input regulation in rice and wheat cultivation over the past 15 years. Keywords such as "rice," "wheat," "rice and wheat rotation," and "rice-wheat rotation" were searched on major domestic and international literature platforms and related scientific and technological achievement platforms. The resulting water, carbon, and nitrogen application schemes are summarized as follows: Optionally, when the average total irrigation amount is 60%-80% of the average of the local planting area over the past five years, the amount of biochar applied to the topsoil is 80%-90% of the amount of exogenous carbon applied as described in claim 3, and the amount of nitrogen fertilizer applied is 90%-100% of the conventional amount applied. Optionally, when the average total irrigation amount is 80%-90% of the average of the local planting area over the past five years, the amount of biochar applied to the topsoil is 80%-90% of the amount of exogenous carbon applied as described in claim 3, and the amount of nitrogen fertilizer applied is 80%-90% of the conventional amount applied. Optionally, when the average total irrigation amount is 80%-90% of the average of the local area over the past five years, the amount of biochar applied to the topsoil is 90%-100% of the amount of exogenous carbon applied as described in claim 3, and the amount of nitrogen fertilizer applied is 70%-80% of the conventional amount. Optionally, when the average total irrigation amount is 90%-100% of the average of the local area over the past five years, the amount of biochar applied to the topsoil is 90%-100% of the amount of exogenous carbon applied as described in claim 3, and the amount of nitrogen fertilizer applied is 65%-75% of the conventional amount. The phosphorus and potassium fertilizers used in the above plan are based on local recommendations.
6. The crop yield prediction method according to claim 1, characterized in that, Based on the four water, carbon, and nitrogen application schemes described in claim 5, predictive models for rice yield (Yrice) and wheat yield (Ywheat) are constructed: Yrice=(31.95×C+20.76×N+1.155×TIA) / w(R 2 =0.97,p<0.05) Ywheat=(5.84×C+3.80×N+0.21×TIA) / r(R 2 =0.85,p<0.05) The above rice or wheat yield Y is in kg / mu, and the total irrigation water TIA is in m³. 3 / mu, the application rate of straw wet biochar C is in kg / m 2 Nitrogen fertilizer application rate (N) is expressed in g / 15kg soil (20cm topsoil layer). w represents the impact of the previous crop on the current crop, typically taken as 0.6 or 1.
2. The higher the yield of the previous crop, the lower the value of w. R 2 The coefficient of determination is the model value; a higher value indicates a better fit. All coefficients are statistically significant (p < 0.05). It is recommended that for rice production, the values of C should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [390, 950]; for wheat production, the values of C should not exceed [0, 6.4], N should not exceed [0, 2.45], and TIA should not exceed [75, 130]. Otherwise, yield prediction accuracy will decrease if these ranges are exceeded.