Soil fertilization method for paddy fields in Northeast China based on organic matter content and bulk density

Abstract

This method for improving soil fertility in Northeast China's paddy fields, based on organic matter content and bulk density, aims to address the problems of poor targeting and ineffective fertilization in existing methods. The method comprises the following steps: Step 1: Determine the fertilization method based on soil organic matter content: For medium to high organic matter content, use straw return combined with chemical fertilizer application; for low organic matter content, use straw return combined with organic fertilizer application; for extremely low organic matter content, use straw return combined with peat application. Step 2: Measure the soil bulk density at a depth of 25cm and determine the appropriate field management method based on this density. This method enables differentiated soil fertilization, achieving rapid and sustained high-efficiency fertilization, resulting in a stable increase in soil fertility. It also reduces fertilizer input, improves nutrient utilization efficiency, and increases rice yield. This method is applied to soil fertilization in Northeast China's paddy fields.

Description

Technical Field

[0001] The invention relates to the technical field of soil fertilization, and in particular to a method for fertilizing paddy soil in Northeast China. Background Art

[0002] Soil fertilization refers to the process of building a good soil body, cultivating a fertile arable layer, and improving soil fertility and productivity through human production activities. The basic principles of soil fertilization are to combine land use with land conservation, and to prevent fertility decline with soil management.

[0003] In Northeast China, fertilizers are mainly used for rice production, and the amount of organic carbon returned is small. There is a problem of focusing on use and neglecting maintenance in rice production. In the past 10 years, the yield of rice per unit area in the north has stagnated. At the same time, the organic matter in paddy soil has increased slowly, and the soil bulk density has increased. It faces the dual challenges of increasing rice production and conserving soil fertility. Returning straw to the field or applying organic fertilizers with chemical fertilizers is the most effective measure to achieve sustained increase in rice production and improve soil fertility. In recent years, a fertilization model of returning rice straw to the field and a fertilization model with the recycling of organic fertilizers as the core have been initially formed in rice production, which has initially achieved the synergy of soil conservation and increased rice production. However, under what conditions to use straw return technology, under what circumstances to apply organic fertilizers, and the amount of organic matter returned are not completely clear. This has become the main limiting factor and bottleneck problem in the scientific fertilization of soil in the Northeast rice area. In addition, the problem of soil compaction in rice fields is quite prominent. There is an urgent need to establish classified management strategies based on soil organic matter content and soil compaction conditions, and to solve the problem of the difficulty in coordinating soil conservation and high rice yields in the Northeast region through the establishment of scientific and reasonable fertilization and farming models. This is of great significance to the green and healthy development of the rice industry.

[0004] At present, the technology for conserving rice field fertility is generally not targeted. Regardless of high-fertility or low-fertility soil, straw will be fully returned to the field or organic fertilizer will be applied, and the recommended amount of organic fertilizer is about 1.5 cubic meters. As a result, the fertility of low-fertility soil increases slowly due to insufficient input of organic materials, resulting in poor fertilization effect, while excessive input of organic fertilizer in high-fertility soil causes crop greed or aggravates crop lodging. In rice fields in Northeast China, straw is generally returned to the field or organic fertilizer is applied and then the soil is plowed after the autumn harvest. Water slurrying is performed when the fields are soaked in spring, but high-intensity water slurrying can easily destroy the soil structure, further aggravate soil compaction, and reduce soil fertility. It can be seen that the existing fertilization measures have not fully taken into account soil fertility and soil conditions, the technology is poorly targeted, and the fertilization effect is difficult to guarantee. In addition, the application of straw and organic fertilizer has changed the fertilization characteristics of the soil. In the past, high rice yields could be achieved as long as attention was paid to the balance between soil fertilizer supply, rice fertilizer requirement and chemical fertilizer application. However, the addition of organic fertilizer or straw has changed the supply pattern of nutrients. At present, there is a lack of corresponding research on the relationship between the fertilizer supply of soil, organic fertilizer or straw and chemical fertilizer and the fertilizer requirement of rice. In particular, the Northeast region has a large north-south span and obvious temperature differences. The release and fixation characteristics of organic nutrients in each region are unclear, which increases the difficulty of regulating the coordinated high yield and high efficiency of rice, which further affects the fertilization effect of rice fields and makes it difficult to coordinate the improvement of soil fertility and rice production capacity. Therefore, the water and fertilizer management of rice fields urgently needs to be upgraded after the addition of organic materials. Summary of the invention

[0005] The invention aims to solve the problems of poor fertilization targeting and poor fertilization effect in the existing paddy field soil fertilization methods, and provides a northeast paddy field soil fertilization method based on organic matter content and bulk density.

[0006] The present invention discloses a method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density, comprising the following steps:

[0007] Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter:

[0008] The organic matter content of paddy soil in Northeast China was tested and divided into three levels. The medium-high content level standard is: the organic matter content in the southern part of Northeast China is >25g / kg, and the central and northern part of Northeast China is >30g / kg; the low content level standard is: the organic matter content in the southern part of Northeast China is 20-25g / kg, and the organic matter content in the central and northern part of Northeast China is 25-30g / kg; the very low content level standard is: the organic matter content in the southern part of Northeast China is <20g / kg, and the organic matter content in the central and northern part of Northeast China is <25g / kg; wherein the southern part of Northeast China refers to the area where Liaoning Province is located, and the central and northern part of Northeast China refers to the areas where Heilongjiang Province and Jilin Province are located;

[0009] Case 1: When the soil organic matter content is medium to high, the fertilization method of returning straw to the field and applying chemical fertilizers is adopted;

[0010] Under the condition of returning straw to the field, nitrogen, phosphorus and potassium were applied to the soil in the first year, with the dosages of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:3:3, all phosphorus fertilizer was used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer was 1:1. Alternating dry and wet irrigation was adopted, and the flooding time did not exceed 3 weeks.

[0011] In the second year, the amount of nitrogen fertilizer should be reduced by 10%-15%, all of which should be reduced in ear fertilizer, and the amount of potassium fertilizer should be reduced by 15%-20%;

[0012] In the third and fourth years, the amount and method of nitrogen fertilizer application are the same as in the second year, the amount of phosphorus fertilizer application is reduced by 10%-15%, and the amount of potassium fertilizer application is reduced by 30%-40%. Other management methods remain unchanged;

[0013] In the fifth year, potassium fertilizer was reduced by 50%, and other management methods remained unchanged;

[0014] Case 2: When the soil organic matter content is low, the method of returning straw to the field and applying organic fertilizer is adopted;

[0015] Under the condition of returning straw to the field, 20-25t / ha of organic fertilizer is applied in the southern part of Northeast China, and 15-20t / ha of organic fertilizer is applied in the central and northern part of Northeast China, so that the organic fertilizer and straw are buried in the soil layer together;

[0016] At the same time, fertilizers are applied to the soil;

[0017] Case 3: When the soil organic matter content is extremely low, the fertilization method of returning straw to the field and applying peat is adopted;

[0018] When returning straw to the field, add 15-25t / ha of peat to the soil, so that the peat and straw are buried in the soil layer together;

[0019] At the same time, fertilizers are applied to the soil;

[0020] Step 2: Measure the soil bulk density at the 25cm soil layer and determine the field management method based on the soil bulk density:

[0021] When soil bulk density is greater than 1.5 g / cm 3 , in autumn, dry land is leveled, the height difference of the field surface is 3-5cm, water is irrigated 7 days before transplanting, and rice seedlings are directly transplanted after 3-5 days of soaking;

[0022] When soil bulk density is less than 1.3 g / cm 3 , stir the slurry with water 1-2 times and level the land, the height difference of the field surface is 3-5cm;

[0023] When the soil bulk density is 1.3-1.5g / cm 3, level the land 7 days before transplanting, press the straw into the field during the leveling process, ensure that the height difference of the field surface is 3-5cm, and keep the field surface with a water layer until transplanting.

[0024] Furthermore, the specific method of returning the straw to the field in step 1 is: when the rice is harvested, the straw is crushed to a length of 9-11 cm and evenly scattered in the field, the rice stubble height is 10-20 cm, and when the soil moisture content reaches 45%-65% of the saturated moisture content, the soil is plowed to 20 cm in the first year, and the plowing depth in the second and third years is 15-18 cm, and the deep and shallow rotation cultivation is cycled every 3 years.

[0025] Further, in step 1, case 1, the nitrogen fertilizer application rate in the north-central part of Northeast China is 100-140 kg / ha, and the nitrogen fertilizer application rate in the southern part of Northeast China is 140-180 kg / ha.

[0026] Furthermore, in case 2 of step one, the organic matter content of the organic fertilizer is >30%.

[0027] Furthermore, the method of applying fertilizer in case 2 of step 1 is:

[0028] In the first year, nitrogen, phosphorus and potassium are applied to the soil at amounts of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The amount of nitrogen fertilizer in the central and northern regions of Northeast China is 100-140kg / ha, and that in the southern region of Northeast China is 140-180kg / ha. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer is 4:4:2, all phosphorus fertilizer is used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer is 1:1. Alternating dry and wet irrigation method is adopted, and the flooding time shall not exceed 3 weeks.

[0029] In the second year, reduce nitrogen fertilizer use by 10%-15% and potassium fertilizer use by 15%-20%.

[0030] In the third year, the amount and proportion of nitrogen fertilizer are the same as in the second year, the amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%. Other management methods remain unchanged.

[0031] In the fourth year, measure the soil organic matter content. If the organic matter content reaches a medium-high level, stop applying organic fertilizer. Otherwise, continue to apply organic fertilizer. The amount and period of phosphorus and potassium fertilizers are the same as in the third year.

[0032] In the fifth year, potash fertilizer was reduced by 50% and other management methods remained unchanged.

[0033] Furthermore, in case 3 of step 1, the decomposition degree of peat is 45%-55%.

[0034] Furthermore, the method of applying fertilizer in case 3 of step 1 is:

[0035] In the first year, nitrogen, phosphorus and potassium are applied to the soil at a rate of 120-200kg / ha, 40-90kg / ha and 40-120kg / ha respectively. The rate of nitrogen fertilizer in the central and northern regions of Northeast China is 120-160kg / ha, and in the southern region it is 160-200kg / ha. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer is 4:4:3, all phosphorus fertilizer is used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer is 1:1. Alternating dry and wet irrigation is adopted, and the flooding time shall not exceed 3 weeks.

[0036] In the second year, the amount of nitrogen fertilizer should be reduced by 10%-15%, all of which should be reduced in ear fertilizer, and the amount of potassium fertilizer should be reduced by 15%-20%;

[0037] In the third year, the amount of nitrogen fertilizer used is the same as in the second year, the amount of phosphorus fertilizer used is reduced by 10%-15%, and the amount of potassium fertilizer used is reduced by 30%-40%. Other management methods remain unchanged;

[0038] In the fourth year, the soil organic matter content is measured. If the organic matter content increases to a medium-high level, no organic fertilizer is applied. Otherwise, organic fertilizer is applied. The amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%. Other management methods remain unchanged.

[0039] In the fifth year, the amount of potash fertilizer used was reduced by 50%, while other management methods remained unchanged.

[0040] Furthermore, in step 2, when the soil bulk density is greater than 1.5 g / cm 3 , use satellite land levelers for dry land leveling.

[0041] Furthermore, in step 2, when the soil bulk density is less than 1.3 g / cm 3 , use a slurry grader to mix the slurry with water.

[0042] Furthermore, in step 2, when the soil bulk density is 1.3-1.5 g / cm 3 , use a stubble grader to level the ground.

[0043] Beneficial effects of the present invention:

[0044] The present invention determines the fertilization method and the corresponding amount of organic matter added according to the abundance and deficiency of soil organic matter in the Northeast rice-growing areas; at the same time, the water preparation intensity is determined according to the compaction condition and bulk density of the cultivated layer soil; finally, the corresponding water and fertilizer management strategy is determined according to different fertilization methods. Through the comprehensive application of the above methods, on the one hand, the pertinence of fertilization is improved, and fertilization according to soil fertility is achieved. On the other hand, the corresponding water and fertilizer management method is matched with the fertilization method to achieve the coordination of soil fertility conservation and high rice yield, and establish a green fertilization technology system for rice fields.

[0045] 1. The method of the present invention can achieve differentiated soil fertilization, and can achieve soil conservation for medium and high fertility soils. After 3-5 years of fertilization, the soil organic matter content can be increased by 1-2g / kg. For low- and medium-fertility paddy fields, rapid and continuous improvement of soil organic matter can be achieved, and the soil organic matter can be increased by more than 3-5g / kg in 5 years, so that the soil fertility is stably improved, and the bulk density of the surface soil can be significantly reduced, and the thickness of the cultivated layer can be increased. This is because the organic matter in the straw is easier to decompose, and the humification coefficient is low. The humification coefficients in the first three years are approximately 0.4, 0.3 and 0.2, respectively, and the straw humification coefficient is maintained at about 0.1 thereafter. Therefore, even if the soil organic matter increases slowly under the condition of continuous straw return to the field; relatively speaking, fully decomposed organic fertilizers, in which the organic matter has passed the stage of rapid decomposition, can continuously increase the soil organic matter content, and one application can increase more than 1g / kg of organic matter, and two applications can quickly increase the soil organic matter. Peat has high organic matter and humic acid content, and organic matter is difficult to decompose. A single application can increase organic matter by more than 3g / kg, and the added organic matter can remain relatively stable for a considerable period of time. Since the application costs of organic fertilizer and peat are both high, only apply appropriate amounts of organic fertilizer or peat on medium and low fertility soils to achieve the effect of rapid, continuous and efficient fertilization.

[0046] 2. The method of the present invention can reduce the input of chemical fertilizers and improve the efficiency of nutrient utilization. Straw and organic fertilizer contain a large amount of nutrients such as nitrogen, phosphorus, and potassium, which can reduce the amount of chemical fertilizers by more than 20%. Long-term application of potassium fertilizers can reduce the amount of fertilizers by about 50%, and the fertilizer-saving effect is obvious. At the same time, the use of less or no slurry agitation tillage can further reduce the soil bulk density, and can increase the soil nitrogen supply capacity by more than 10%, improve the soil fertilizer supply capacity, and help reduce the use of chemical fertilizers.

[0047] 3. The yield-increasing effect of the method of the present invention is remarkable. By improving soil structure and increasing soil productivity through soil conservation, combined with scientific water and fertilizer management measures, rice production can be increased by more than 10%. In addition, the wide application of the method of the present invention can also reduce the environmental problems caused by straw burning, and achieve the goals of fertilizer saving, high yield, high efficiency and ecological safety in rice fields. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0049] Specific implementation method 1: This implementation method is based on the soil fertilization method of paddy fields in Northeast China based on organic matter content and bulk density, including the following steps:

[0050] Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter:

[0051] The organic matter content of paddy soil in Northeast China was tested and divided into three levels. The medium-high content level standard is: the organic matter content in the southern part of Northeast China is >25g / kg, and the central and northern part of Northeast China is >30g / kg; the low content level standard is: the organic matter content in the southern part of Northeast China is 20-25g / kg, and the organic matter content in the central and northern part of Northeast China is 25-30g / kg; the very low content level standard is: the organic matter content in the southern part of Northeast China is <20g / kg, and the organic matter content in the central and northern part of Northeast China is <25g / kg; wherein the southern part of Northeast China refers to the area where Liaoning Province is located, and the central and northern part of Northeast China refers to the areas where Heilongjiang Province and Jilin Province are located;

[0052] Case 1: When the soil organic matter content is medium to high, the fertilization method of returning straw to the field and applying chemical fertilizers is adopted;

[0053] Under the condition of returning straw to the field, nitrogen, phosphorus and potassium were applied to the soil in the first year, with the dosages of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:3:3, all phosphorus fertilizer was used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer was 1:1. Alternating dry and wet irrigation was adopted, and the flooding time did not exceed 3 weeks.

[0054] In the second year, the amount of nitrogen fertilizer should be reduced by 10%-15%, all of which should be reduced in ear fertilizer, and the amount of potassium fertilizer should be reduced by 15%-20%;

[0055] In the third and fourth years, the amount and method of nitrogen fertilizer application are the same as in the second year, the amount of phosphorus fertilizer application is reduced by 10%-15%, and the amount of potassium fertilizer application is reduced by 30%-40%. Other management methods remain unchanged;

[0056] In the fifth year, potassium fertilizer was reduced by 50%, and other management methods remained unchanged;

[0057] Case 2: When the soil organic matter content is at a low level, the fertilization method of returning straw to the field and applying organic fertilizer is adopted;

[0058] Under the condition of returning straw to the field, 20-25t / ha of organic fertilizer is applied in the southern part of Northeast China, and 15-20t / ha of organic fertilizer is applied in the central and northern part of Northeast China, so that the organic fertilizer and straw are buried in the soil layer together;

[0059] At the same time, fertilizers are applied to the soil;

[0060] Case 3: When the soil organic matter content is extremely low, the fertilization method of returning straw to the field and applying peat is adopted;

[0061] When returning straw to the field, add 15-25t / ha of peat to the soil, so that the peat and straw are buried in the soil layer together;

[0062] At the same time, fertilizers are applied to the soil;

[0063] Step 2: Measure the soil bulk density at the 25cm soil layer and determine the field management method based on the soil bulk density:

[0064] When soil bulk density is greater than 1.5 g / cm 3 , in autumn, dry land is leveled, the height difference of the field surface is 3-5cm, water is irrigated 7 days before transplanting, and rice seedlings are directly transplanted after 3-5 days of soaking;

[0065] When soil bulk density is less than 1.3 g / cm 3 , stir the slurry with water 1-2 times and level the land, the height difference of the field surface is 3-5cm;

[0066] When the soil bulk density is 1.3-1.5g / cm 3 , level the land 7 days before transplanting, press the straw into the field during the leveling process, ensure that the height difference of the field surface is 3-5cm, and keep the field surface with a water layer until transplanting.

[0067] The southern part of Northeast China mentioned in the present invention refers to the area where Liaoning Province is located, and the central and northern part of Northeast China refers to the area where Heilongjiang Province and Jilin Province are located;

[0068] This embodiment can achieve differentiated soil fertilization, and can achieve soil conservation for high-fertility soil. After 3-5 years of fertilization, the soil organic matter content can be increased by 1-2g / kg. For low- and medium-fertility paddy fields, rapid and continuous improvement of soil organic matter can be achieved, and the soil organic matter can be increased by more than 3-5g / kg in 3-5 years, so that the soil fertility can be stably improved, and the bulk density of the surface soil can be significantly reduced, and the thickness of the cultivated layer can be increased. This is because the organic matter in the straw is easier to decompose, and the humification coefficient is low. The humification coefficients in the first three years were approximately 0.4, 0.3 and 0.2, respectively, and the straw humification coefficient was maintained at about 0.1 thereafter. Therefore, even if the soil organic matter increases slowly under the condition of continuous straw return to the field; relatively speaking, fully decomposed organic fertilizers, in which the organic matter has passed the stage of rapid decomposition, can continuously increase the soil organic matter content, and one application can increase more than 1g / kg of organic matter, and two applications can quickly increase the soil organic matter. Peat has high organic matter and humic acid content, and organic matter is difficult to decompose. A single application can increase organic matter by more than 3g / kg, and the added organic matter can remain stable for a considerable period of time. Since the application costs of organic fertilizer and peat are both high, only apply appropriate amounts of organic fertilizer or peat on medium and low fertility soils to achieve the effect of rapid, continuous and efficient fertilization.

[0069] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the specific method of returning the straw to the field in step 1 is: when the rice is harvested, the straw is crushed to a length of 9-11 cm and evenly scattered in the field, the rice stubble height is 10-20 cm, and when the soil moisture content reaches 45%-65% of the saturated moisture content, the soil is ploughed to bury at least 85% of the straw in the soil layer, the first year is ploughed to a depth of 20 cm, the second and third years are ploughed to a depth of 15-18 cm, and the deep and shallow rotation is cycled every 3 years. The rest is the same as specific implementation method 1.

[0070] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: in step 1, the nitrogen fertilizer dosage in the north-central region of Northeast China is 100-140 kg / ha, and the nitrogen fertilizer dosage in the southern region of Northeast China is 140-180 kg / ha. Other aspects are the same as specific implementation method 1 or 2.

[0071] Specific implementation method 4: This implementation method is different from any one of specific implementation methods 1 to 3 in that the organic matter content of the organic fertilizer in case 2 of step 1 is greater than 30%. Other aspects are the same as any one of specific implementation methods 1 to 3.

[0072] Specific implementation method 5: This implementation method is different from one of the specific implementation methods 1 to 4 in that: the method of applying fertilizer in situation 2 of step 1 is:

[0073] In the first year, nitrogen, phosphorus and potassium are applied to the soil at a rate of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The rate of nitrogen fertilizer in the central and northern regions of Northeast China is 100-140kg / ha, and that in the southern regions of Northeast China is 140-180kg / ha. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer is 4:4:2, all phosphorus fertilizer is used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer is 1:1. Alternating dry and wet irrigation is adopted, and the flooding time shall not exceed 3 weeks. In the second year, the amount of nitrogen fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 15%-20%; in the third year, the amount of nitrogen fertilizer and the application ratio are the same as in the second year, the amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%, and other management methods remain unchanged; in the fourth year, the soil organic matter content is measured, and if the organic matter content reaches a medium-high content level, no organic fertilizer is applied, otherwise, organic fertilizer continues to be applied, and the amount and application period of phosphorus and potassium fertilizers are the same as in the third year; in the fifth year, potassium fertilizer is reduced by 50%, and other management methods remain unchanged. Others are the same as the specific implementation methods one to four.

[0074] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the decomposition degree of peat in case 3 of step 1 is 45%-55%. The rest is the same as specific implementation examples 1 to 5.

[0075] Specific implementation method 7: This implementation method is different from one of the specific implementation methods 1 to 6 in that: the method of applying fertilizer in situation 3 of step 1 is:

[0076] In the first year, nitrogen, phosphorus and potassium were applied to the soil at a rate of 120-200kg / ha, 40-90kg / ha and 40-120kg / ha respectively. The rate of nitrogen fertilizer in the central and northern regions of Northeast China was 120-160kg / ha, and that in the southern region was 160-200kg / ha. The ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:4:3, all phosphorus fertilizer was used as base fertilizer, and the ratio of base fertilizer to ear fertilizer in potassium fertilizer was 1:1. Alternating dry and wet irrigation was adopted, and the flooding time did not exceed 3 weeks. In the second year, the nitrogen fertilizer rate was reduced by 10 %-15%, all of which are reduced in ear fertilizer, and potassium fertilizer is reduced by 15%-20%; in the third year, the amount of nitrogen fertilizer is the same as the second year, the amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%, and other management methods remain unchanged; in the fourth year, the soil organic matter content is measured, and if the organic matter content increases to a medium-high content level, organic fertilizer is not applied, otherwise organic fertilizer is applied; the amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%, and other management methods remain unchanged; in the fifth year, the amount of potassium fertilizer is reduced by 50%, and other management methods remain unchanged. Others are the same as the specific implementation methods one to six.

[0077] Specific embodiment 8: This embodiment differs from the specific embodiments 1 to 7 in that: in step 2, when the soil bulk density is greater than 1.5 g / cm 3 , use satellite land leveler to carry out dry land leveling. Others are the same as those in the first to seventh embodiments.

[0078] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that: in step 2, when the soil bulk density is less than 1.3 g / cm 3 , a slurry leveler is used for water slurrying. The rest is the same as that of the first to eighth embodiments.

[0079] Specific embodiment 10: This embodiment differs from the specific embodiments 1 to 9 in that: in step 2, when the soil bulk density is 1.3-1.5 g / cm 3 , using a stubble-burying land leveler to level the land. The rest is the same as the specific implementation modes 1 to 9.

[0080] The embodiments of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation schemes and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0081] Embodiment 1:

[0082] The test area of ​​this example is Jiansanjiang Qixing Farm. The average soil organic matter content in the test area is 34.8 g / kg, and the soil bulk density at 25 cm is 1.45 g / cm 3 The experiment started in 2017 and lasted for 5 years. Two treatments were set up in the experimental area, each treatment was repeated 3 times, and the treatment area was at least 667m 2 , ensuring mechanical operation.

[0083] The present embodiment of the method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density comprises the following steps:

[0084] Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter:

[0085] The soil organic matter content in the test area averaged 34.8 g / kg, and the fertilization method adopted was to return straw to the field and apply chemical fertilizers;

[0086] Returning straw to the field: Every autumn when harvesting, the straw is crushed into small pieces of about 10 cm and evenly scattered in the field. The height of the rice stubble is 18 cm. After the rice straw is scattered, when the soil moisture content reaches 60% of the saturated moisture content, more than 85% of the straw is buried in the soil layer through tillage. The first year, the tillage depth is 20 cm, and the second and third years are 15 cm. The deep and shallow rotation is cycled every 3 years;

[0087] In the first year, nitrogen, phosphorus and potassium were applied to the soil at a rate of 111kg / ha, 50kg / ha and 90kg / ha respectively; the mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:3:3, all phosphorus fertilizer was used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer was 1:1; dry-wet alternating irrigation was adopted, and the flooding time was generally not more than 3 weeks;

[0088] In the second year, the amount of nitrogen fertilizer was reduced by 10%, all of which was reduced in ear fertilizer, and the amount of potassium fertilizer was reduced by 15%;

[0089] In the third and fourth years, the amount and method of nitrogen fertilizer application are the same as in the second year, the amount of phosphorus fertilizer application is reduced by 10%, the amount of potassium fertilizer application is reduced by 30%, and other management methods remain unchanged;

[0090] In the fifth year, potassium fertilizer was reduced by 50%, and other management methods remained unchanged. The amounts of nitrogen, phosphorus, and potassium fertilizers were reduced to 100 kg / ha, 45 kg / ha, and 45 kg / ha, respectively.

[0091] Step 2: Determine the field management method based on soil bulk density:

[0092] The soil bulk density at 25 cm in the test area is 1.45 g / cm 3. Use a stubble-burying land leveler to level the field 7 days before transplanting. During the leveling process, press the straw into the field to ensure that the height difference of the field surface is 5 cm, and keep the field surface with a water layer until transplanting.

[0093] The control group was set up without returning straw to the field. In the control treatment, the straw was removed, and the annual nitrogen, phosphorus and potassium contents of chemical fertilizers were 150kg / ha, 50kg / ha and 90kg / ha respectively, with 40% nitrogen fertilizer as base fertilizer, 30% green fertilizer and 30% tillering fertilizer. All phosphorus fertilizers were used as base fertilizers, 50% potassium fertilizers were applied as base fertilizers, and the other 50% were applied during the jointing period. The soil was plowed in autumn, and the fields were soaked for 7 days in late April and early May of the second year, and the slurry was stirred 2-3 times to maintain the water layer until transplanting. The transplanting density was 24 holes / m 2 , 4-6 seedlings per hole.

[0094] After 5 years, the rice yield of the control group was 9.45t / ha, and the soil bulk density at 0-20cm was 1.27g / cm 3 The method of the present invention, after returning the straw to the field and less stirring, the rice yield reached 10.64t / ha, the soil organic matter increased by 2.2g / kg, and the soil bulk density was significantly reduced to 1.15g / cm 3 The experiment confirmed that the method of the present invention has a stable fertilization and yield-increasing effect (as shown in Table 1).

[0095] Embodiment 2:

[0096] The test area of ​​this example is Huachuan County, Jiamusi City. The average soil organic matter content in the test area is 28.6 g / kg, and the soil bulk density at 25 cm is 1.61 g / cm 3 The experiment started in 2017 and lasted for 4 years. Two treatments were set up in the experimental area, each treatment was repeated 3 times, and the treatment area was at least 667m 2 , ensuring mechanical operation.

[0097] The present embodiment of the method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density comprises the following steps:

[0098] Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter:

[0099] The soil organic matter content in the test area averaged 28.6 g / kg, and the fertilization method adopted was returning straw to the field and applying organic fertilizer;

[0100] Returning straw to the field: During the autumn harvest each year, the straw is crushed into small pieces of about 10 cm and evenly scattered in the field. The rice stubble height is 18 cm. After the rice straw is scattered, 15 t / ha of organic fertilizer (organic matter content 32.2%) is applied. When the soil moisture content reaches 60% of the saturated moisture content, the soil is plowed to bury more than 85% of the straw and organic fertilizer in the soil layer. The plowing depth is 20 cm in the first year, and 15 cm in the second and third years. The rotation of deep and shallow tillage is repeated every 3 years.

[0101] In addition, fertilizers are applied to the soil. The specific method is as follows;

[0102] In the first year, nitrogen, phosphorus and potassium were applied to the soil at 120kg / ha, 50kg / ha and 70kg / ha respectively. The ratio of basal fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:4:2, all phosphorus fertilizer was used as basal fertilizer, and the mass ratio of basal fertilizer to ear fertilizer in potassium fertilizer was 1:1. Alternating dry and wet irrigation was adopted, and the flooding time generally did not exceed 3 weeks; in the second year, the amount of nitrogen fertilizer was reduced by 10%, and the amount of potassium fertilizer was reduced by 15%; in the third year, the amount and application ratio of nitrogen fertilizer were the same as in the second year, the amount of phosphorus fertilizer was reduced by 10%, and the amount of potassium fertilizer was reduced by 30%, and other management methods remained unchanged.

[0103] In the fourth year, since the organic matter content had reached more than 30g / kg, the straw was returned to the field and chemical fertilizers were applied together, and the amount and period of phosphorus and potassium fertilizers were the same as in the third year. The amount of nitrogen, phosphorus and potassium fertilizers was reduced to 108kg / ha, 45kg / ha and 60kg / ha respectively.

[0104] Step 2: Determine the field management method based on soil bulk density:

[0105] The soil bulk density at 25 cm in the test area is 1.61 g / cm 3 In autumn, a satellite land leveler is used to dry-level the land, so that the height difference of the field surface is 5 cm. In spring every year, the fields are flooded 7 days before transplanting rice seedlings, and rice seedlings are directly transplanted 5 days after the fields are flooded.

[0106] The control group was set up without returning straw to the field. In the control treatment, the straw was removed, and the annual fertilizer nitrogen, phosphorus, and potassium contents were 142kg / ha, 50kg / ha, and 90kg / ha, respectively. Nitrogen fertilizer accounted for 40% of the base fertilizer, 30% of the green fertilizer, and 30% of the tillering fertilizer. All phosphorus fertilizers were used as base fertilizers, 50% of potassium fertilizers were applied as base fertilizers, and the other 50% were applied during the jointing period. The soil was plowed in autumn, and the fields were soaked for 7 days in late April and early May of the second year. The slurry was stirred 2-3 times to maintain the water layer until transplanting. The transplanting density was 24 holes / m2 2 , 4-6 seedlings per hole.

[0107] Comparative tests show that in conventional fertilization methods, the average fertilizer dosage is 282 kg / ha and the rice yield is 8.44 t / ha; the rice yield treated by the method of the present invention is 9.61 t / ha on average, the soil organic matter increases by 3.5 g / kg, and the soil bulk density decreases by 10% (as shown in Table 1).

[0108] Embodiment 3:

[0109] The test area of ​​this example is Jiansanjiang Hongwei Farm. The average soil organic matter content in the test area is 23.8 g / kg, and the soil bulk density at 25 cm is 1.59 g / cm 3 The experiment started in 2017 and lasted for 3 years. Two treatments were set up in the experimental area, each treatment was repeated 3 times, and the treatment area was at least 667m 2 , ensuring mechanical operation.

[0110] The present embodiment of the method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density comprises the following steps:

[0111] Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter:

[0112] The average soil organic matter content in the test area is 23.8g / kg, and the fertilization method of returning straw to the field and applying peat is adopted:

[0113] Returning straw to the field: When harvesting in autumn every year, the straw is crushed into small pieces of about 10 cm and evenly scattered in the field. The rice stubble height is 10 cm. After the rice straw is scattered, 15 t / ha of peat (50% decomposition degree) is applied. When the soil moisture content reaches 60% of the saturated moisture content, more than 85% of the straw and peat are buried in the soil layer through rotary tillage. The first year is ploughed to a depth of 20 cm, and the second and third years are ploughed to a depth of 15 cm. The deep and shallow rotation is cycled every 3 years.

[0114] In addition, fertilizers are applied to the soil. The specific method is as follows;

[0115] In the first year, nitrogen, phosphorus and potassium were applied to the soil at 130kg / ha, 60kg / ha and 90kg / ha respectively. The mass ratio of basal fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:4:3, all phosphorus fertilizer was used as basal fertilizer, and the mass ratio of basal fertilizer and ear fertilizer in potassium fertilizer was 1:1. Alternating dry and wet irrigation was adopted, and the flooding time generally did not exceed 3 weeks; in the second year, the amount of ear fertilizer in nitrogen fertilizer was reduced by 10%, and the amount of potassium fertilizer was reduced by 15%; in the third year, the amount of nitrogen fertilizer was the same as the second year, the amount of phosphorus fertilizer was reduced by 10%, the amount of potassium fertilizer was reduced by 30%, and other management methods remained unchanged.

[0116] Step 2: Determine the field management method based on soil bulk density:

[0117] The soil bulk density at 25 cm in the test area is 1.59 g / cm 3 In autumn, a satellite land leveler was used to level the land to ensure that the field surface was flat and the height difference did not exceed 5 cm. In the spring of the second year, the fields were flooded 7 days before transplanting, and the rice seedlings were directly transplanted 5 days after the fields were soaked. After 3 years, the organic matter content increased to 31.7g / kg, and the fertilization method of returning straw to the field and applying chemical fertilizers was adopted.

[0118] The control group was set up without returning straw to the field. In the control treatment, the straw was removed, and the annual fertilizer nitrogen, phosphorus, and potassium contents were 160kg / ha, 50kg / ha, and 100kg / ha, respectively. Nitrogen fertilizer accounted for 40% of the base fertilizer, 30% of the green fertilizer, and 30% of the tillering fertilizer. All phosphorus fertilizers were used as base fertilizers, 50% of potassium fertilizers were applied as base fertilizers, and the other 50% were applied during the jointing period. The soil was plowed in autumn, and the fields were soaked in late April and early May of the second year. The slurry was stirred 2-3 times, and the water layer was maintained for 7 days until transplanting. The transplanting density was 24 holes / m2 2 , 4-6 seedlings per hole.

[0119] Comparative tests show that in conventional fertilization methods, the average fertilizer dosage is 313 kg / ha and the rice yield is 7.95 t / ha; the rice yield treated by the method of the present invention is 9.15 t / ha on average, the soil organic matter reaches a high fertility level, and the soil bulk density is reduced by 19%. The results are shown in Table 1.

[0120] Table 1 Effects of different fertilization modes

[0121]

Claims

1. A method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density, characterized in that The method comprises the following steps: Step 1: Determine the method of fertilizing the rice field according to the content of soil organic matter: The organic matter content of paddy soil in Northeast China was tested and divided into three levels. The medium-high content level standard is: organic matter content in southern Northeast China>25g / kg, and in central and northern Northeast China>30g / kg; the low content level standard is: organic matter content in southern Northeast China is 20-25g / kg, and organic matter content in central and northern Northeast China is 25-30g / kg; the very low content level standard is: organic matter content in southern Northeast China is <20g / kg, and organic matter content in central and northern Northeast China is <25g / kg; Case 1: When the soil organic matter content is medium to high, the fertilization method of returning straw to the field and applying chemical fertilizers is adopted; Under the condition of returning straw to the field, nitrogen, phosphorus and potassium were applied to the soil in the first year, with the dosages of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer was 4:3:3, all phosphorus fertilizer was used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer was 1:

1. Alternating dry and wet irrigation was adopted, and the flooding time did not exceed 3 weeks. In the second year, the amount of nitrogen fertilizer should be reduced by 10%-15%, all of which should be reduced in ear fertilizer, and the amount of potassium fertilizer should be reduced by 15%-20%; In the third and fourth years, the amount and method of nitrogen fertilizer application are the same as in the second year, the amount of phosphorus fertilizer application is reduced by 10%-15%, and the amount of potassium fertilizer application is reduced by 30%-40%. Other management methods remain unchanged; In the fifth year, potassium fertilizer was reduced by 50%, and other management methods remained unchanged; Case 2: When the soil organic matter content is low, the method of returning straw to the field and applying organic fertilizer is adopted; Under the condition of returning straw to the field, 20-25t / ha of organic fertilizer is applied in the southern part of Northeast China, and 15-20t / ha of organic fertilizer is applied in the central and northern part of Northeast China, so that the organic fertilizer and straw are buried in the soil layer together; At the same time, fertilizers are applied to the soil; Case 3: When the soil organic matter content is extremely low, the fertilization method of returning straw to the field and applying peat is adopted; When returning straw to the field, add 15-25t / ha of peat to the soil, so that the peat and straw are buried in the soil layer together; At the same time, fertilizers are applied to the soil; Step 2: Measure the soil bulk density at the 25cm soil layer and determine the field management method based on the soil bulk density: When soil bulk density is greater than 1.5 g / cm 3 , in autumn, dry land is leveled, the height difference of the field surface is 3-5cm, water is irrigated 7 days before transplanting, and rice seedlings are directly transplanted after 3-5 days of soaking; When soil bulk density is less than 1.3 g / cm 3 , stir the slurry with water 1-2 times and level the land, the height difference of the field surface is 3-5cm; When the soil bulk density is 1.3-1.5g / cm 3 , level the land 7 days before transplanting, press the straw into the field during the leveling process, ensure that the height difference of the field surface is 3-5cm, and keep the field surface with a water layer until transplanting.

2. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1, characterized in that: The specific method of returning the straw to the field in step 1 is as follows: when the rice is harvested, the straw is crushed to a length of 9-11 cm and evenly scattered in the field, and the rice stubble height is 10-20 cm. When the soil moisture content reaches 45%-65% of the saturated moisture content, the soil is plowed to 20 cm in the first year, and the plowing depth in the second and third years is 15-18 cm. The deep and shallow rotation cultivation is cycled every 3 years.

3. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1 or 2, characterized in that: In step 1, case 1, the nitrogen fertilizer application rate in the central and northern parts of Northeast China is 100-140 kg / ha, and the nitrogen fertilizer application rate in the southern part of Northeast China is 140-180 kg / ha.

4. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 3, characterized in that: In step 1, case 2, the organic matter content of the organic fertilizer is >30%.

5. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 4, characterized in that: The method of applying fertilizer in case 2 of step 1 is: In the first year, nitrogen, phosphorus and potassium are applied to the soil at a rate of 100-180kg / ha, 40-75kg / ha and 40-100kg / ha respectively. The rate of nitrogen fertilizer in the central and northern regions of Northeast China is 100-140kg / ha, and that in the southern regions of Northeast China is 140-180kg / ha. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer is 4:4:2, all phosphorus fertilizer is used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer is 1:

1. Alternating dry and wet irrigation is adopted, and the flooding time shall not exceed 3 weeks. In the second year, reduce nitrogen fertilizer use by 10%-15% and potassium fertilizer use by 15%-20%; In the third year, the amount and proportion of nitrogen fertilizer used are the same as in the second year, the amount of phosphorus fertilizer used is reduced by 10%-15%, and the amount of potassium fertilizer used is reduced by 30%-40%. Other management methods remain unchanged; In the fourth year, measure the soil organic matter content. If the organic matter content reaches the medium-high level, stop applying organic fertilizer. Otherwise, continue to apply organic fertilizer, and the amount and period of phosphorus and potassium fertilizers are the same as in the third year. In the fifth year, potash fertilizer was reduced by 50% and other management methods remained unchanged.

6. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1, characterized in that: The decomposition degree of peat in case 3 of step 1 is 45%-55%.

7. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1 or 6, characterized in that: The method of applying fertilizer in case 3 of step 1 is: In the first year, nitrogen, phosphorus and potassium are applied to the soil at a rate of 120-200kg / ha, 40-90kg / ha and 40-120kg / ha respectively. The rate of nitrogen fertilizer in the central and northern regions of Northeast China is 120-160kg / ha, and in the southern region it is 160-200kg / ha. The mass ratio of base fertilizer, tillering fertilizer and ear fertilizer in nitrogen fertilizer is 4:4:3, all phosphorus fertilizer is used as base fertilizer, and the mass ratio of base fertilizer to ear fertilizer in potassium fertilizer is 1:

1. Alternating dry and wet irrigation is adopted, and the flooding time shall not exceed 3 weeks. In the second year, the amount of nitrogen fertilizer should be reduced by 10%-15%, all of which should be reduced in ear fertilizer, and the amount of potassium fertilizer should be reduced by 15%-20%; In the third year, the amount of nitrogen fertilizer used is the same as in the second year, the amount of phosphorus fertilizer used is reduced by 10%-15%, and the amount of potassium fertilizer used is reduced by 30%-40%. Other management methods remain unchanged; In the fourth year, the soil organic matter content is measured. If the organic matter content increases to a medium-high level, no organic fertilizer is applied. Otherwise, organic fertilizer is applied. The amount of phosphorus fertilizer is reduced by 10%-15%, and the amount of potassium fertilizer is reduced by 30%-40%. Other management methods remain unchanged. In the fifth year, the amount of potash fertilizer used was reduced by 50%, while other management methods remained unchanged.

8. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1, characterized in that: In step 2, when the soil bulk density is greater than 1.5 g / cm 3 , use satellite land levelers for dry land leveling.

9. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1, characterized in that: In step 2, when the soil bulk density is less than 1.3 g / cm 3 , use a slurry grader to mix the slurry with water.

10. The method for improving soil fertility in paddy fields in Northeast China based on organic matter content and bulk density according to claim 1, characterized in that: In step 2, when the soil bulk density is 1.3-1.5g / cm 3 , use a stubble grader to level the ground.

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