Nitrogen fertilizer application method for reducing nitrogen deficiency of double cropping rice under full straw returning

Abstract

The invention provides a nitrogen fertilizer application method for reducing nitrogen deficiency of double cropping rice under full straw returning, and belongs to the technical field of biological agriculture. According to the method, the application proportion of the tillering fertilizer is increased under the straw returning condition, the optimal application scheme is obtained, the content of ammoniacal nitrogen and nitrate nitrogen in soil is remarkably increased, the nitrogen contending benefit of soil microorganisms and crops is effectively relieved, and effective tillering formation is promoted. The technical scheme provided by the invention is beneficial to establishment of a rice root system, remarkably promotes absorption and transfer of nitrogen in plants, and improves the number of effective ears of rice, thereby remarkably improving the rice yield.

Description

Technical Field

[0001] The present invention relates to the technical field of bio-agriculture, and particularly relates to a method for applying nitrogen fertilizer to reduce nitrogen deficiency in double-season rice under full straw return to the field. Background Art

[0003] Returning straw rich in various nutrient elements required for crop growth to farmland can not only solve the problem of straw resource treatment, but also improve soil fertility, reduce the use of chemical fertilizers, and increase farmers' income. Double-season rice continuous cropping is an important way of rice production in southern China. The yield of rice straw is large, and the interval between early rice and late rice is short. Therefore, formulating corresponding nitrogen fertilizer management strategies is of great significance for stabilizing the yield of double-season rice and improving the absorption and utilization of nitrogen by rice.

[0004] At present, in order to alleviate the phenomenon of nitrogen competition between microorganisms and crops in the early stage of straw return to the field, in many regions, a certain amount of nitrogen fertilizer is added as base fertilizer on the basis of local recommended fertilization, or the proportion of base fertilizer is increased, or a decay promoter is added. However, the effect of the existing nitrogen fertilizer application scheme for straw return to the field still needs to be improved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for applying nitrogen fertilizer to reduce nitrogen deficiency in double-season rice under full straw return to the field, which can maximize the advantages of straw return to the field.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for applying nitrogen fertilizer to reduce nitrogen deficiency in double-season rice under full straw return to the field, including the following steps:

[0008] Applying early rice nitrogen fertilizer and late rice nitrogen fertilizer during the continuous cropping of double-season rice;

[0009] The early rice nitrogen fertilizer and the late rice nitrogen fertilizer are applied in 3 times, including base fertilizer, tillering fertilizer and panicle fertilizer;

[0010] In the early rice nitrogen fertilizer application scheme, the application ratios of the base fertilizer, the tillering fertilizer and the panicle fertilizer are 5:3.5 - 4.5:0.5 - 1.5;

[0011] In the late rice nitrogen fertilizer application scheme, the application ratios of the base fertilizer, the tillering fertilizer and the panicle fertilizer are 5:2.5 - 3.5:1.5 - 2.5.

[0012] Preferably, in the early rice nitrogen fertilizer application scheme, the application ratios of the base fertilizer, the tillering fertilizer and the panicle fertilizer are 5:4:1.

[0013] Preferably, in the late rice nitrogen fertilizer application scheme, the application ratios of the base fertilizer, the tillering fertilizer and the panicle fertilizer are 5:3:2.

[0014] Preferably, the application rate of nitrogen fertilizer for early rice is 165 N kg / hm 2 .

[0015] Preferably, the application rate of nitrogen fertilizer for late rice is 195 N kg / hm 2 .

[0016] Preferably, the continuous cropping process of double-cropping rice also includes the application of phosphate fertilizer.

[0017] Preferably, the phosphate fertilizer is calcium magnesium phosphate fertilizer.

[0018] Preferably, the application rate of phosphate fertilizer for each crop is 75 P2O5 kg / hm 2 , and it is applied once as base fertilizer.

[0019] Preferably, the continuous cropping process of double-cropping rice also includes the application of potassium fertilizer.

[0020] Preferably, the application rate of potassium fertilizer for each crop is 75 K2O kg / hm 2 , and it is applied in two times as base fertilizer and panicle fertilizer;

[0021] In the potassium fertilizer application plan, the application ratio of base fertilizer to panicle fertilizer is 1:0.8 - 1.2.

[0022] Advantages of the present invention:

[0023] 1) By increasing the application ratio of tiller fertilizer under the condition of straw returning to the field, the present invention obtains the optimal application plan, significantly increases the contents of ammonium nitrogen and nitrate nitrogen in the soil, effectively alleviates the nitrogen competition benefit between soil microorganisms and crops, and promotes the formation of effective tillers.

[0024] 2) The technical solution provided by the present invention is beneficial to the establishment of rice roots, significantly promotes the absorption and transportation of nitrogen by plants, increases the number of effective panicles of rice, and thus significantly increases the rice yield. Description of the Drawings

[0025] Figure 1 It is a graph showing the influence of nitrogen fertilizer operation under straw returning to the field on the yield of double-cropping rice;

[0026] Figure 2 It is a graph showing the influence of nitrogen fertilizer operation under straw returning to the field on the content of alkaline hydrolyzable nitrogen in the soil of double-cropping rice fields during the main growth periods;

[0027] Figure 3 It is a graph showing the influence of nitrogen fertilizer operation under straw returning to the field on the soil biomass carbon of double-cropping rice fields during the main growth periods;

[0028] Figure 4 It is a graph showing the influence of nitrogen fertilizer operation under straw returning to the field on biomass nitrogen;

[0029] Figure 5 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the contents of ammonium nitrogen and nitrate nitrogen in paddy soil;

[0030] Figure 6 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the root activity and morphological characteristics of rice;

[0031] Figure 7 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the dry weight of rice roots;

[0032] Figure 8 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the nitrogen uptake and translocation of rice;

[0033] Figure 9 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the dry matter accumulation and distribution of rice;

[0034] Figure 10 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the microbial biomass carbon and nitrogen;

[0035] Figure 11 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the soluble carbon content;

[0036] Figure 12 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the contents of ammonium nitrogen and nitrate nitrogen in soil;

[0037] Figure 13 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the root characteristics of late rice;

[0038] Figure 14 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the amino acid content of root exudates of late rice at maturity;

[0039] Figure 15 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the organic acid content of root exudates of late rice at maturity;

[0040] Figure 16 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the soil microbial α-diversity in the late rice season;

[0041] Figure 17 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the soil microbial β-diversity in the late rice season;

[0042] Figure 18 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the species and abundance of soil microorganisms in the late rice season;

[0043] Figure 19 The figure shows the results of the effects of nitrogen fertilizer management under straw return on the soil microbial functions in the late rice season;

[0044] Figure 20 RDA analysis diagram of soil bacterial community and soil physical and chemical properties at the late rice maturity stage;

[0045] Figure 21 Effect result diagram of nitrogen fertilizer management under straw return on β diversity of rhizosphere soil microorganisms of late rice;

[0046] Figure 22 Effect result diagram of nitrogen fertilizer management under straw return on the species and abundance of rhizosphere soil microorganisms of late rice;

[0047] Figure 23 Effect result diagram of nitrogen fertilizer management under straw return on the function of rhizosphere soil microorganisms of late rice;

[0048] Figure 24 RDA analysis diagram of rhizosphere soil microbial diversity of late rice and organic acid components in rhizosphere analytes;

[0049] Figure 25 Effect result diagram of nitrogen fertilizer management under straw return on nitrogen absorption and transport characteristics of late rice;

[0050] Figure 26 Effect result diagram of nitrogen fertilizer management under straw return on dry matter accumulation and distribution of late rice. Detailed implementation mode

[0051] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0052] Embodiment

[0053] The experiment was carried out in Zhanggong Town, Jinxian County, Jiangxi Province. Five treatments were set, namely: straw non-return + conventional nitrogen fertilizer management (basal fertilizer: tillering fertilizer: panicle fertilizer ratio is 5:2:3) treatment, and 4 nitrogen fertilizer management treatments under straw return (basal fertilizer: tillering fertilizer: panicle fertilizer ratios are 5:2:3, 5:3:2, 5:4:1, 5:5:0) respectively. Each treatment was replicated 3 times, and the plot area was 6m×8m. The nitrogen fertilizer application rate in the early rice season was 165 kg N / hm 2 , and the nitrogen fertilizer application rate in the late rice was 195 kg N / hm 2 , the fertilization methods of each treatment are shown in Table 1. In the design of this experiment, the nitrogen in the total nitrogen application rate and each nitrogen application ratio only refers to the nitrogen in chemical nitrogen fertilizer, and does not include the nitrogen contained in the returned rice straw. The input levels of phosphorus and potassium fertilizers in each treatment were the same. The phosphorus (P2O5) fertilizer was applied at 75 kg / hm for each crop 2 , and was applied once as basal fertilizer; the potassium (KCl) fertilizer was applied at 75 kg / hm per mu for each crop 2 , and was applied in two times, basal fertilizer (50%) and panicle fertilizer (50%).

[0054] The transplanting density for each treatment was 13.3 cm × 23.3 cm for early rice, with 2 grains of rice seedlings inserted per hill, and 16.7 cm × 25 cm for late rice, with 4 - 6 seedlings (including tillers) per hill for late rice. Both early and late rice were harvested using a combine harvester with a stubble height of 20 cm. During harvesting, the rice straw was mechanically chopped into pieces of 5 - 15 cm. All the straw in the plots without straw returning to the field was removed. The straw of late rice was mulched and returned to the field during the winter fallow period, and the land was rotary tilled in April of the following year. After the early rice was harvested, the field was flooded for 2 - 3 days and then rotary tilled. The early rice was transplanted on April 20th and harvested on July 19th; the late rice was transplanted on July 25th and harvested on October 26th. Management measures such as field water management and the prevention and control of diseases, insects, and weeds were the same as those in general high - yield fields.

[0055] Test results

[0056] Results of early and late rice in 2019

[0057] Effect of nitrogen fertilizer management under straw returning on the yield of double - cropping rice

[0058] Appropriately increasing the proportion of nitrogen fertilizer for basal and tillering fertilizers under straw returning increased the yield of double - cropping rice ( Figure 1 , different letters indicate significant differences between treatments, P < 0.05). In the early rice season, except for S + 5:5:0, all treatments under full - amount straw returning had an increasing effect on yield compared with NS + 5:2:3. The S + 5:4:1 treatment had the best increasing effect on yield, with a yield of 8136.6 kg / ha. The yields of the S + 5:2:3 and S + 5:3:2 treatments were 7647.6 kg / ha and 7999.1 kg / ha respectively, while the S + 5:5:0 treatment caused a significant reduction in yield, with a yield of only 7097.8 kg / ha. There was no significant difference in the yield of late rice under different nitrogen fertilizer managements with straw returning. Among the three treatments of S + 5:2:3, S + 5:3:2, and S + 5:4:1 for late rice under full - amount straw returning, the yields were slightly higher than that of NS + 5:2:3, with yields of 8159.6 kg / ha, 8462.8 kg / ha, and 8314.4 kg / ha respectively, while the S + 5:5:0 treatment was slightly lower than NS + 5:2:3. It can be seen that the effect of straw returning on increasing the yield of double - cropping early rice is better than that of late rice, and the appropriate operation ratios of nitrogen fertilizer for early and late rice seasons under straw returning are S + 5:4:1 and S + 5:3:2 respectively.

[0059] Effect of nitrogen fertilizer management under straw returning on the content of soil available nitrogen

[0060] Straw returning increased the content of soil available nitrogen in double - cropping rice, and different nitrogen fertilizer managements affected the content of soil available nitrogen at different growth stages of double - cropping rice fields ( Figure 2, different letters in the same period indicate significant differences between treatments (P<0.05). In the early rice season, the available nitrogen content in the soil at the tillering stage of the straw returning treatment was significantly higher than that of the non-straw returning NS+5:2:3 treatment, and it increased with the increase of the nitrogen fertilizer ratio at the tillering stage, with the S+5:5:0 treatment being the highest and the S+5:2:3 treatment being the lowest; at the full heading stage and maturity stage, the available nitrogen content in the soil of the straw returning treatment was significantly higher than that of the non-straw returning NS+5:2:3 treatment, but there was no significant difference between the straw returning treatments. Among them, at the maturity stage, S+5:3:2 was the highest, which was 16.4% higher than the NS+5:2:3 treatment. In the late rice season, at the tillering stage, the available nitrogen content of the conventional operation S+5:2:3 treatment after straw returning was lower than that of the non-straw returning NS+5:2:3 treatment, and the available nitrogen content of the other straw returning treatments was higher than that of the non-straw returning treatment and increased with the increase of the nitrogen fertilizer ratio at the tillering stage; at the full heading stage and maturity stage, the available nitrogen content of the straw returning treatment was significantly higher than that of the non-straw returning NS+5:2:3 treatment, with an increase range of 17.2% - 21.2%, but there was no significant difference between the straw returning treatments.

[0061] Effect of Nitrogen Fertilizer Application under Straw Returning on the Contents of Soil Microbial Biomass Carbon and Nitrogen

[0062] From Figure 3 It can be seen that the soil microbial biomass carbon of the straw returning treatment in the double-season paddy field was significantly higher than that of the non-straw returning treatment. With the progress of the growth period, the soil microbial biomass carbon gradually increased, and the effect of nitrogen fertilizer application on the biomass carbon at different growth stages was inconsistent. At the tillering stage of early and late rice, the soil microbial biomass carbon content of the straw returning treatment was increased by 39.4% - 57.9% and 39.4% - 61.9% respectively compared with the non-straw returning treatment, and it increased with the increase of the nitrogen fertilizer ratio of the tillering fertilizer. Among them, the S+5:2:3 treatment was significantly lower than other straw returning treatments; at the full heading stage and maturity stage of early and late rice, the soil microbial biomass carbon of the straw returning treatment was significantly higher than that of the non-straw returning treatment, and the S+5:4:1 treatment was the highest. Among them, at the full heading stage and maturity stage of early rice, it increased by 40.5% and 34.2% respectively, and at the full heading stage and maturity stage of late rice, it increased by 40.5% and 34.2% respectively.

[0063] From Figure 4 It can be seen that straw returning significantly increased the soil microbial biomass nitrogen at each growth stage of early and late rice, and the effect of nitrogen fertilizer application on the biomass nitrogen at different growth stages was inconsistent. At the tillering stage of early and late rice, the soil microbial biomass nitrogen of the straw returning treatment was significantly higher than that of the non-straw returning treatment, and it increased with the increase of the nitrogen fertilizer ratio of the tillering fertilizer. Among them, the S+5:2:3 treatment was significantly lower than other straw returning treatments; there was no significant difference in the microbial biomass nitrogen content between the straw returning treatments at the full heading stage and maturity stage of early and late rice seasons

[0064] Results of the Early Rice Season in 2021 - 2022

[0065] As shown in Table 1 below:

[0066] Table 1 Results of the early rice season in 2021 - 2022

[0067]

[0068] Effect of nitrogen fertilizer management under straw return on rice yield

[0069] After straw return, the number of grains per panicle and seed - setting rate of early rice increased slightly compared with the non - straw - return treatment. However, the number of effective panicles decreased compared with the straw - return treatment, resulting in an insignificant increase in yield. Appropriately increasing the proportion of basal and tillering fertilizers can effectively increase the number of effective panicles of early rice and the number of grains per panicle, thereby increasing the yield. Among them, the treatment with basal fertilizer: tillering fertilizer: panicle fertilizer = 5:4:1 (T4) had the best effect, and its yields in 2021 and 2022 increased by 24.1% and 25.1% compared with the normal fertilizer treatment.

[0070] The yields of late rice under different treatments are shown in Table 2 below:

[0071] Table 2 Differences in the yields of late rice under different treatments

[0072]

[0073] Effect of nitrogen fertilizer management under straw return on the contents of ammonium - nitrogen and nitrate - nitrogen in the soil of early rice fields

[0074] As Figure 5 shown, straw return significantly reduced the contents of ammonium - nitrogen and nitrate - nitrogen in the soil during the tillering stage of rice. In 2022, the contents of ammonium - nitrogen and nitrate - nitrogen in the T2 treatment decreased by 11.2% and 15.6% respectively compared with the T1 treatment. However, straw return significantly increased the contents of ammonium - nitrogen and nitrate - nitrogen in the soil at the heading and maturity stages of rice. In 2022, the contents of ammonium - nitrogen and nitrate - nitrogen in the T2 treatment at the heading stage increased by 9.8% and 21.9% respectively compared with the T1 treatment; their contents at the maturity stage increased by 30.1% and 15.0% respectively compared with the T1 treatment. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw return can significantly increase the N content in the soil during the tillering stage of rice and maintain a relatively high nitrogen content in the soil during the later growth stage of rice. Among them, the T4 treatment had the most significant effect, and the contents of ammonium - nitrogen and nitrate - nitrogen in the soil during the tillering stage of its rice were 14.9% and 17.9% higher than those in the T2 treatment respectively.

[0075] Effect of nitrogen fertilizer management under straw return on the root activity and morphological characteristics of early rice

[0076] As Figure 6As shown, straw returning significantly affects the root architecture of early rice. The root length, root surface area, and root volume generally show an increasing trend compared to the treatment without straw returning (T1). However, during the tillering stage of early rice, appropriately increasing the proportion of basal tiller fertilizer under the condition of straw returning can significantly increase the root length, root surface area, and root volume of early rice at the tillering stage. Among them, the T4 treatment has the most significant effect. Compared with the normal fertilizer management (T2) under the condition of straw returning, the root length, root surface area, and root volume at the tillering stage are increased by 15.4%, 17.3%, and 14.6% respectively. In addition, straw returning reduces the root activity at the tillering stage, and the T2 treatment decreases by 10.9% compared to the T1 treatment. However, the root activity at the heading and maturity stages of the T2 treatment can significantly increase the root activity of rice at the heading and maturity stages compared to the T1 treatment, but has no significant effect on the root activity of rice at the tillering stage. The root activity at the heading and maturity stages of the T2 treatment increases by 9.0% and 22.3% respectively compared to the T1 treatment. Appropriately increasing the proportion of basal tiller fertilizer under the condition of straw returning can significantly increase the root activity of rice at the tillering stage and maintain a relatively high activity at the heading and maturity stages. The root activity at the tillering, heading, and maturity stages of the T4 treatment increases by 40.5%, 10.2%, and 13.2% respectively compared to the T2 treatment.

[0077] Effect of Nitrogen Fertilizer Management under Straw Returning on Dry Weight of Early Rice Roots

[0078] As Figure 7 shown, straw returning reduces the root growth rate during the early growth stage of rice, especially from the seedling stage to the tillering stage, resulting in a 7.1% and 13.9% reduction in the dry weight of rice roots at the tillering stage in 2021 and 2022 respectively compared to T1. Appropriately increasing the proportion of basal tiller fertilizer significantly increases the root growth rate during the early growth stage of rice and increases the root dry weight. Among them, the T4 treatment has the most significant effect, and the dry weight of rice roots at the tillering stage in 2021 and 2022 increases by 15.4% and 19.7% respectively compared to T2.

[0079] Effect of Nitrogen Fertilizer Management under Straw Returning on Nitrogen Absorption and Translocation of Early Rice

[0080] As Figure 8As shown, straw returning reduced the nitrogen uptake during the tillering stage of rice, slightly increased the nitrogen content in plants at the heading stage and maturity stage, and promoted the distribution of nitrogen to the panicles. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw returning could increase the nitrogen uptake rate of plants during the tillering stage and heading stage, thereby increasing the nitrogen content of plants during the tillering stage, heading stage and maturity stage, and further promoting the translocation of nitrogen to the panicles and increasing the nitrogen content in the panicles. Among them, the effect of treatment T4 was the most significant. Taking 2022 as an example, the nitrogen content of plants during the tillering stage, heading stage and maturity stage increased by 5.2%, 10.4% and 11.7% respectively compared with T1, and increased by 10.2%, 8.6% and 6.2% respectively compared with T2. At the maturity stage of rice in 2022, the distribution ratio of nitrogen in the panicles of treatment T4 increased by 13.4% and 9.7% respectively compared with T1 and T2.

[0081] Effect of Nitrogen Fertilizer Management under Straw Returning on Dry Matter Accumulation and Distribution of Early Rice

[0082] As Figure 9 shown, straw returning significantly increased the dry matter accumulation of rice at the heading stage and maturity stage, but the dry matter accumulation during its tillering stage was lower than that of T1. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw returning could significantly increase the dry matter accumulation rate at each growth stage of rice, thereby increasing the dry matter accumulation of rice. Among them, the effect of treatment T4 was the most significant. Taking 2022 as an example, the dry matter accumulation of plants during the tillering stage, heading stage and maturity stage increased by 3.3%, 26.0% and 26.0% respectively compared with T1, and increased by 11.2%, 20.4% and 18.0% respectively compared with T2. In addition, increasing the proportion of basal and tillering fertilizers promoted the translocation of dry matter to the panicles, and the distribution ratio of dry matter in the panicles of treatment T4 increased by 5.5% and 5.2% respectively compared with T2.

[0083] Straw returning affected the effective panicle number of rice, resulting in an insignificant or even slightly reduced yield increase effect. Increasing the application proportion of tillering fertilizer for late rice by 10% could significantly increase the effective tiller number of late rice by 6.5% and increase the yield by 26.6%.

[0084] Effect of Nitrogen Fertilizer Management under Straw Returning on Soil Microbial Biomass Carbon and Nitrogen in the Late Rice Season

[0085] As Figure 10 shown, straw returning could significantly affect the content of microbial biomass carbon and nitrogen in the soil. Increasing the application proportion of nitrogen fertilizer at the tillering stage could significantly increase the content of microbial biomass carbon and nitrogen in the soil. Among them, increasing the application proportion of tillering fertilizer by 10% (T3) had the most significant effect. The microbial biomass carbon content of treatment T3 increased by 16.8% and 23.3% respectively compared with treatment T2 at the tillering stage and heading stage, and its microbial biomass nitrogen content increased by 1.6% and 93.3% respectively compared with treatment T2.

[0086] Effect of Nitrogen Fertilizer Management under Straw Returning on Soil Soluble Carbon Content in the Late Rice Season

[0087] As Figure 11 shown, increasing the proportion of nitrogen fertilizer application at the tillering stage can significantly increase the content of soluble carbon in the soil. Among them, increasing the proportion of tillering fertilizer by 10% (T3) has the most significant effect. The soluble carbon content in the T3 treatment is 14.6% and 9.2% higher than that in the T2 treatment at the tillering stage and maturity stage, respectively.

[0088] Effect of Nitrogen Fertilizer Management under Straw Returning on the Contents of Ammonium Nitrogen and Nitrate Nitrogen in Paddy Soil

[0089] As Figure 12 shown, increasing the proportion of nitrogen fertilizer application at the tillering stage under the condition of straw returning can significantly increase the content of available nitrogen in the soil. Among them, increasing the proportion of tillering fertilizer by 10% (T3) has the best effect. The ammonium nitrogen content in the T3 treatment is 28.2%, 63.9% and 5.0% higher than that in the T2 treatment at the tillering stage, heading stage and maturity stage, respectively, and its nitrate nitrogen content is 10.5%, 30.2% and 25.1% higher than that in the T2 treatment, respectively.

[0090] Effect of Nitrogen Fertilizer Management under Straw Returning on the Root Characteristics of Late Rice

[0091] As Figure 13 shown, under the condition of straw returning, the root length, root surface area, root volume, active absorption area of roots and root dry weight of late rice at the tillering stage generally show a decreasing trend compared with the treatment without straw returning (T1), among which the active absorption area of roots decreases significantly. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw returning can alleviate the influence of straw returning on the roots of late rice at the tillering stage, and the T3 treatment has the best effect. Taking 2021 as an example, the active absorption area of roots and root dry weight of the T3 treatment at the tillering stage are 11.8% and 16.9% higher than those of the T2 treatment, respectively. In addition, the root length, root surface area, root volume and active absorption area of roots of the T3 treatment remain at a relatively high level throughout the growth period.

[0092] Effect of Nitrogen Fertilizer Management under Straw Returning on the Amino Acid Content of Root Exudates of Late Rice at Maturity

[0093] As Figure 14 shown, by detecting and analyzing the types and contents of amino acids in root exudates, a total of 18 kinds of amino acids are detected. The straw returning treatment significantly increases the amino acid content in root exudates at maturity. Among the 18 kinds of amino acids, all except L-histidine are significantly increased compared with the treatment without straw returning. And nitrogen fertilizer management, especially the T3 treatment, can significantly reverse the phenomenon of increased amino acid content in root exudates caused by straw returning.

[0094] Effect of Nitrogen Fertilizer Management under Straw Returning on the Organic Acid Content of Root Exudates of Late Rice at Maturity

[0095] As Figure 15As shown in the figure, the types and contents of organic acids in root exudates were detected and analyzed. A total of 53 organic acids were detected. Straw returning significantly increased the content of organic acids in root exudates at the maturity stage. Among the 53 organic acids, except for salicylic acid, kynurenic acid, and xanthurenic acid, they were significantly increased compared with the treatment without straw returning. However, nitrogen fertilizer management, especially the T3 treatment, could significantly reverse the increase in the content of organic acids in root exudates caused by straw returning.

[0096] Effect of Nitrogen Fertilizer Management under Straw Returning on the Soil Microbial Community Structure in the Late Rice Season

[0097] As Figure 16 shown in the figure, appropriately increasing the proportion of tillering fertilizer under the condition of straw returning could significantly increase the soil microbial ACE index (species richness), chao index (species richness), sobs, and shannon index (community diversity), and decrease the simpson index. That is, appropriately increasing the proportion of tillering fertilizer under the condition of straw returning could significantly increase the microbial species richness and community diversity.

[0098] As Figure 17 shown in the figure, principal component analysis (PCoA) was used to evaluate the effects of straw returning and nitrogen fertilizer management on the bacterial community structure in rice soil. The results showed that both straw returning and increasing the proportion of tillering fertilizer under the regulation of straw returning caused the reorganization of the bacterial community. The PCoA plot of the bacterial community explained 35.68% of the community variation on the first principal component (PC1) and 16.39% of the community variation on the second principal component. Increasing the proportion of tillering fertilizer under the condition of straw returning significantly changed the structure of the bacterial community.

[0099] As Figure 18 shown in the figure, the results of the differential microbial analysis between groups showed that straw returning would reduce the microbial abundances of Anaerolinea, Haliangium, Thiobacillus, and Candidatus Omnitrophus in the soil, but increase the abundances of bacteria such as Longivirga, Aquicella, Roseiarcus, and Sulfurifustis. However, appropriately increasing the proportion of tillering fertilizer after straw returning could significantly increase the abundances of bacteria beneficial to soil health and rice growth, such as Rhodanobacter, Gemmatimonas, and Aquisphaera.

[0100] As Figure 19 shown in the figure, neither straw returning nor nitrogen fertilizer management had a significant effect on the abundances of bacterial communities involved in nitrogen metabolism processes such as nitrification and nitrogen fixation in the soil. However, straw returning significantly reduced the abundances of bacterial communities involved in nitrate reduction, but appropriately increasing the proportion of tillering fertilizer application could alleviate this downward trend.

[0101] As Figure 20As shown in the figure, redundancy analysis (RDA) was performed on the soil bacterial community and soil physical and chemical properties during the late rice maturity stage. The results showed that axis 1 (RDA1) and axis 2 (RDA2) together explained 41.97% of the variation in bacterial community structure. Among them, soil microbial carbon, urease activity, and ammonium nitrogen content had significant effects on the bacterial community (P = 0.001, P = 0.03, P = 0.009). The order of the correlation between soil physical and chemical factors and changes in bacterial community structure was: microbial carbon > ammonium nitrogen > urease > microbial nitrogen > sucrase activity > nitrate nitrogen > nitrate reductase activity > protease activity.

[0102] Effect of Nitrogen Fertilizer Management under Straw Returning on the Structure of Rhizosphere Soil Microbial Community in the Late Rice Season

[0103] As Figure 21 shown, principal component analysis (PCoA) was used to evaluate the effects of straw returning and nitrogen fertilizer management on the structure of the rice rhizosphere bacterial community. The results showed that both straw returning and increasing the proportion of tillering fertilizer under straw returning regulation caused the reorganization of the rhizosphere bacterial community. The PCoA plot of the bacterial community explained 19.98% of the community variation on the first principal component (PC1) and 12.42% of the community variation on the second principal component. Increasing the proportion of tillering fertilizer under straw returning conditions significantly changed the structure of the bacterial community.

[0104] As Figure 22 shown, the results of the differential microbial analysis between groups showed that after straw returning, the microbial abundances of ADurb.Bin063-1 (related to aboveground and underground biodiversity), Mycobacterium, and Alkanibacter in the soil decreased, but the abundances of bacteria such as Candidatus Nitrotoga, Bellilinea, Pelolinea, and Formivibrio increased. Appropriately increasing the proportion of tillering fertilizer after straw returning could significantly increase the abundances of bacteria such as Reyranella, Gemmatimonas, and Methylomonas.

[0105] As Figure 23 shown, the results of the differential analysis of the rhizosphere microbiome between groups showed that appropriately increasing the proportion of nitrogen fertilizer application during the tillering stage under straw returning significantly reduced the abundances of the microbial communities involved in nitrification and nitrate oxidation processes in the rhizosphere soil at maturity. This may help slow down the turnover of the soil nitrogen cycle and is beneficial to improving the stability of soil nitrogen.

[0106] As Figure 24 shown, RDA analysis was performed on the rhizosphere bacterial community and organic acids in rhizosphere exudates during the late rice maturity stage. The results showed that axis 1 (RDA1) and axis 2 (RDA2) together explained 38.06% of the variation in bacterial community structure, indicating that organic acids in rhizosphere exudates had a significant impact on the rhizosphere bacterial community.

[0107] Effect of Nitrogen Fertilizer Management under Straw Returning on Nitrogen Uptake and Transport Characteristics of Late Rice

[0108] As Figure 25 shown, straw returning had no significant effect on the total nitrogen uptake of late rice, but it increased the distribution ratio of nitrogen in the stems and leaves. The distribution ratio of nitrogen in the stems and leaves of late rice in treatment T2 at the mature stage in 2021 was 7.9% higher than that in treatment T1. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw returning could promote the distribution of nitrogen to the panicles, reduce its distribution ratio in the stems and leaves, and increase its distribution ratio in the panicles. The distribution ratio of nitrogen in the panicles in treatment T3 in 2021 and 2022 was 6.6% and 5.4% higher than that in treatment T2, respectively.

[0109] Effect of Nitrogen Fertilizer Management under Straw Returning on Dry Matter Accumulation and Distribution of Late Rice

[0110] As Figure 26 shown, straw returning significantly increased the dry matter accumulation of late rice at the mature stage, but increased the distribution ratio of dry matter to the roots. Taking 2022 as an example, the distribution ratio of dry matter in the roots in treatment T2 was 26.8% higher than that in treatment T1. Appropriately increasing the proportion of basal and tillering fertilizers under the condition of straw returning could significantly increase the dry matter accumulation of late rice at the mature stage and reduce the distribution ratio of dry matter in the roots, promoting the distribution of dry matter to the panicles. Taking 2022 as an example, the distribution ratio of dry matter in the roots in treatment T3 was 10.2% lower than that in treatment T2, and its distribution ratio of dry matter in the panicles was 7.0% higher than that in treatment T2.

[0111] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for applying nitrogen fertilizer to reduce nitrogen deficiency in double-season rice under full straw return to the field, characterized in that, It includes the following steps: Applying early rice nitrogen fertilizer and late rice nitrogen fertilizer during the continuous cropping of double-season rice; The early rice nitrogen fertilizer and the late rice nitrogen fertilizer are applied in 3 times, including basal fertilizer, tillering fertilizer and panicle fertilizer; In the application plan of the early rice nitrogen fertilizer, the application ratios of the basal fertilizer, tillering fertilizer and panicle fertilizer are 5: 3.5-4.5: 0.5-1.5; In the application plan of the late rice nitrogen fertilizer, the application ratios of the basal fertilizer, tillering fertilizer and panicle fertilizer are 5: 2.5～3.5:1.5～2.5。 2. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under full straw return to field according to claim 1, characterized in that In the application plan of the early rice nitrogen fertilizer, the application ratios of the basal fertilizer, tillering fertilizer and panicle fertilizer are 5: 4:

1.

3. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under full straw return to the field according to claim 1, characterized in that, In the application plan of the late rice nitrogen fertilizer, the application ratios of the basal fertilizer, tillering fertilizer and panicle fertilizer are 5: 3:

2.

4. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under full straw return to the field according to any one of claims 1 to 3, characterized in that, The application rate of nitrogen fertilizer for the early rice is 165 N kg / hm 2 .

5. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under full straw return to the field according to any one of claims 1 to 3, characterized in that, The application rate of nitrogen fertilizer for the late rice is 195 N kg / hm 2 .

6. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under full straw return to the field according to claim 1, characterized in that Applying phosphate fertilizer is also included during the continuous cropping of double-season rice.

7. The nitrogen fertilizer application method for reducing nitrogen deficiency in double - cropping rice under full - amount straw return to the field according to claim 6, characterized in that, The phosphate fertilizer is calcium magnesium phosphate fertilizer.

8. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under the condition of full straw return to the field according to claim 6, characterized in that The application rate of the phosphate fertilizer is 75 P2O5 kg / hm per crop season 2 , and it is applied once as a basal fertilizer.

9. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under the condition of full straw return to the field according to claim 1, characterized in that, Applying potassium fertilizer is also included during the continuous cropping of double-season rice.

10. The nitrogen fertilizer application method for reducing nitrogen deficiency in double-season rice under the condition of full straw return to the field according to claim 9, characterized in that, The application rate of the potassium fertilizer for each crop season is 75 K2O kg / hm 2 , and it is applied twice as basal fertilizer and panicle fertilizer; In the application plan of the potassium fertilizer, the application ratios of the basal fertilizer and panicle fertilizer are 1: 0.8-1.2.

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