A method for repairing paddy field soil

Abstract

The application provides a paddy field soil body repairing method and belongs to the technical field of soil repairing. The application comprises the following steps: ploughing a paddy field block, putting viscous soil, bentonite and organic material, irrigating the paddy field to saturate the soil, rotary ploughing, depositing slurry and drying the paddy field. The method provided by the application can effectively repair the paddy field soil body, quickly reconstruct the damaged plough bottom layer, significantly improve the water retention performance of the paddy field, save water resources and be conducive to the rapid repair of non-grain reclamation farmland. The method provided by the application solves the leakage problem of the repaired paddy field block, improves the water and fertilizer utilization rate, can ensure the normal tillering and earing of rice, can reduce the rice field grass damage and is helpful to promoting the rational use of cultivated land.

Description

Technical Field

[0001] This invention belongs to the field of soil remediation technology, and in particular relates to a method for remediating paddy field soil. Background Technology

[0002] Rice is a staple food crop. With rapid urbanization and the irrational development and utilization of arable land, the conversion of paddy fields to non-agricultural and non-grain uses is widespread, seriously threatening food security. Therefore, the relocation and clearing of non-grain arable land for the cultivation of rice and other food crops is of great significance.

[0003] Existing paddy field soil remediation mainly relies on engineering measures, including topsoil stripping, field seepage prevention, and topsoil backfilling. These methods suffer from drawbacks such as being time-consuming, costly, and wasteful of resources. In particular, the parent material of arable land in river valleys and plains originates from river alluvium, resulting in a shallow topsoil, high sand content, and a texture dominated by sandy loam and sandy soil. The soil structure is loose, with an extremely thin plow pan (generally <5cm), making the paddy field soil structure fragile and easily damaged. After non-grain uses such as seedling planting in paddy fields in river valleys and plains, the deep root systems and transplanting of seedlings with soil attached lead to significant problems such as plow pan damage, severe seepage, poor soil moisture and fertilizer retention, and low rice yields. Currently, there is a lack of soil remediation technologies for paddy fields in river valleys and plains, resulting in many reclaimed paddy fields remaining unused for extended periods.

[0004] Patent CN109588077A discloses a method for constructing paddy fields on sandy topsoil: analyzing the soil structure to determine its topsoil, transition layer, and clay layer; sequentially peeling off the topsoil, transition layer, and clay layer from top to bottom and storing them in a temporary storage area; backfilling the transition layer soil; taking clay layer soil, evenly spreading it on top of the transition layer, and compacting it to form a plow pan; evenly spreading the remaining clay layer soil on the plow pan, and evenly spreading the topsoil layer soil on top of the clay layer soil, then using a rotary tiller to tillage until the clay layer soil and topsoil soil are fully mixed. This invention has good practicality and operability for specific sandy soil structures, but the soil layer in river valley plains is thin, and there is no excess clay layer at the bottom, making it impossible to construct a plow pan and "mix" the topsoil with clay. Therefore, this method is not suitable for river valley plains. Patent CN110268933A discloses a method for converting dry land into paddy fields in mountainous yellow soil areas: determining the scope of the fields to be converted, stripping the topsoil and leveling the base, constructing field ridges, backfilling the topsoil and leveling the field surface; soaking the field to make slurry; transplanting rice seedlings and cultivating the field, and carrying out rice transplanting and daily management of the fields in the traditional way. This invention takes advantage of the high clay content of yellow soil in the region to promote the rapid formation of a high-quality plow pan. However, it is less effective in river valleys and plains where the clay content is low. Moreover, it still requires the use of engineering machinery to strip the topsoil and backfill the topsoil, making the conversion process time-consuming and costly, which is not conducive to its widespread application. Patent CN105766118A discloses a method for reconstructing sandbar soil for rice cultivation: the surface of the sandbar is leveled; the leveled surface is irrigated with muddy water to form a soil layer; the soil layer is dried, covered with loess, and compacted to form an artificial plowshare; the artificial plowshare is leveled using a shovel-and-base method; and loess is then covered on top of the leveled artificial plowshare to form an artificial tillage layer. This invention addresses the transformation of paddy fields under extreme sandification conditions. However, the soil in both the plowshare and tillage layers originates entirely from transported loess, resulting in high costs, long processing times, and resource waste. The soil remediation method disclosed in the above technology is specific to certain soil types and is not applicable to the remediation of non-grain-producing reclaimed farmland in river valleys and plains. Currently, there is no universally applicable soil remediation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for restoring paddy field soil, which can restore non-grain-producing reclaimed farmland in river valley plains and is of great significance for promoting the rational use of farmland.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for remediating paddy field soil includes the following steps: tilling the paddy field, adding clay soil, bentonite and organic materials, irrigating the field until the soil reaches saturation, rotary tilling, settling mud, and drying the field.

[0008] Preferably, the paddy field is a reclaimed paddy field in a river valley plain.

[0009] Preferably, the irrigation paddy field is submerged to a depth of 10-15 cm for 3-6 hours.

[0010] Preferably, after the field is dried, the field is irrigated until the surface is submerged by 10-15 cm. The rate at which the water level drops is observed. If the rate of drop is greater than 2 cm / day, the irrigation and soaking process is repeated until the soil reaches saturation. Then, the field is rotary tilled, the mud is allowed to settle, and the field is dried.

[0011] Preferably, the application of clay soil is determined based on the results of soil background composition analysis. When the content of clay particles <0.002mm in the 0-20cm topsoil layer of the field is <15%, clay soil needs to be applied.

[0012] Preferably, the amount of clay soil used is determined according to the following formula:

[0013]

[0014] In the formula: M is the amount of clay soil used; Ar is the proportion of the field area whose topsoil has been damaged, in %; C 黏粒 Wc represents the content of clay particles <0.002mm in the applied clay soil, in %; Wc represents the moisture content of the applied clay soil, in %.

[0015] Preferably, the clayey soil includes any one or more of yellow clay, bluish-purple clay, and red clay.

[0016] Preferably, the amount of bentonite added is 10-20% of the amount of clay soil used, and the amount of organic material added is 300-500 kg / mu.

[0017] Preferably, it also includes the maturation of the topsoil after the paddy field soil is restored, including the following steps: year-round rotation of rice and green manure, and full return of rice straw and green manure to the field.

[0018] Preferably, after the rice is harvested, 250-500 kg / mu of biochar and 500-1000 kg / mu of organic fertilizer are applied.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention provides a method for restoring paddy field soil, which can effectively repair paddy field soil, quickly reconstruct damaged plow pans, significantly improve the water retention capacity of paddy fields, save water resources, and facilitate the rapid restoration of non-grain farmland. The method of this invention solves the seepage problem in the restored fields, improves water and fertilizer utilization, ensures normal tillering and panicle formation of rice, reduces weed damage in paddy fields, and helps promote the rational use of arable land. Attached Figure Description

[0021] Figure 1 : Schematic diagram of the plow layer construction process in paddy field soil restoration, where 1 is the tillage layer, 2 is the plow layer, 3 is soil sand, 4 is organic-inorganic composite colloid, and 5 is soil clay. Detailed Implementation

[0022] This invention provides a method for soil remediation in paddy fields, comprising the following steps: tilling the paddy field, adding clay soil, bentonite and organic materials, irrigating the field until the soil reaches saturation, rotary tilling, settling mud, and drying the field. Preferably, the paddy field is a reclaimed paddy field in a river valley plain.

[0023] This invention targets non-grain-producing reclaimed farmland in river valleys and plains. Since most of the soil in these fields is only damaged in patches, targeted classification and restoration are needed based on an analysis of the soil properties. This will make full use of the existing topsoil and avoid a large amount of imported soil.

[0024] In this invention, before soil restoration, the soil damage in the area to be restored is investigated on-site, the thickness of the topsoil and the thickness of the plow pan are investigated, and the proportion of the field area with damaged topsoil is estimated.

[0025] This invention collects mixed samples of surface soil and analyzes and determines soil sample indicators, including pH, salt content, organic matter content, and the content of clay (<0.002mm), silt (0.05-0.002mm), and sand (2-0.05mm) in the soil background composition.

[0026] As one feasible method, this invention collects more than one topsoil mixture sample per hectare, with a sampling depth of 0-20 cm, and the soil sampling depth does not exceed the plow pan. As another feasible method, this invention utilizes a stainless steel soil sampler to sample using a grid method. After sampling, the soil from 15-30 sampling points is mixed to form a topsoil mixture sample.

[0027] In this invention, paddy fields that have undergone baseline surveys are plowed. As an feasible method, a moldboard plow is used to plow the fields, and the plowing depth is determined according to the surveyed topsoil depth. The plowing depth is <20cm, so as not to damage the original plow pan, and to plow the entire field without leaving any dead corners.

[0028] In this invention, the amount of clay soil is determined based on the results of soil background composition measurement. When the content of clay particles <0.002mm in the 0-20cm topsoil layer of the field is ≥15%, no clay soil needs to be added; when the content of clay particles <0.002mm in the 0-20cm topsoil layer is <15%, clay soil needs to be added.

[0029] In this invention, the amount of clay soil used is determined according to the following formula:

[0030]

[0031] In the formula: M is the amount of clay soil used; Ar is the proportion of the field area whose topsoil has been damaged, in %; C 黏粒 Wc represents the content of clay particles <0.002mm in the applied clay soil, in %; Wc represents the moisture content of the applied clay soil, in %.

[0032] In this invention, the clay soil is selected from any one or more of yellow clay, bluish-purple clay, and red clay.

[0033] As one feasible approach, the present invention involves filling the pitted areas where the topsoil has been damaged with clay soil, spreading the remaining soil evenly across the entire field, and maintaining a relatively flat surface in the field.

[0034] In this invention, bentonite and organic materials are evenly spread into the field. The amount of bentonite added is 10-20% of the amount used for clay soil, and the amount of organic materials added is 300-500 kg / mu.

[0035] As an implementable method, the bentonite used in this invention has montmorillonite as its main mineral component and belongs to the 2:1 type of expansive clay mineral. It has strong expansion and contraction properties, a large number of charges, and prominent colloidal characteristics, which can accelerate the formation of the plow pan and increase the soil cation exchange capacity.

[0036] As an feasible approach, the organic material used in this invention can be selected from any one or more of humic acid, biochar, and organic fertilizer. The organic matter in the organic material used in this invention can improve the colloidal state of the soil, enhance its adsorption capacity, and after the organic matter is mixed with the soil, the organic and inorganic colloids can be cemented together by various forces to form an organic-inorganic complex in the soil. This results in a higher water-holding capacity of the soil, improved permeability of the topsoil, accelerated clay particle settling, and the formation of a plow pan.

[0037] In this invention, the irrigation and paddy field soaking involves submerging the field surface to a depth of 10-15 cm for 3-6 hours, preferably to a depth of 12-13 cm for 4-5 hours. After the paddy field soaking is completed, the soil reaches a saturated water absorption state, and then the soil layer is rotary tilled to a depth of 10-15 cm. The irrigation, paddy field soaking, and rotary tilling steps in this invention are completed within one day.

[0038] In this invention, the soil after rotary tillage is in a suspended state. At this time, external disturbance should be avoided, allowing the mud slurry to naturally stratify and settle. Because the soil particles in the upper layer are large, the pores between the particles make it possible for small clay particles to settle. Meanwhile, small-diameter soil clay particles and organic-inorganic composite colloids in the mud slurry sink with the water into the lower layer, which is beneficial for forming the plow pan. As one feasible method, the mud slurry settling time is 2-3 days.

[0039] In this invention, after the mud sedimentation step is completed, excess surface water is drained, and the field is dried. This method of drying the field promotes the cementation and solidification of the underlying soil, reducing subsequent seepage. As an feasible approach, the drying time is approximately 7-10 days, preferably 8-9 days.

[0040] The process of constructing the plow layer in the paddy field soil remediation process of this invention is as follows: Figure 1 As shown, after soaking and rotary tillage, the soil is in a suspension state. Small-diameter soil clay particles and organic-inorganic composite colloids settle to the bottom with the water to form the plow pan. Because the soil particles in the upper part of the tillage layer are large, the pores between the soil particles after the water recedes allow the clay particles to settle smoothly.

[0041] In this invention, after the field is dried, water is poured into the field until the surface is submerged by 10-15cm. The rate at which the water level drops is observed. If the rate of drop is greater than 2cm / day, it indicates that the rate of rapid seepage in the paddy field is too high and the water-proofing performance of the plow layer is not up to standard. At this time, it is necessary to repeat the steps of irrigation and soaking the field until the soil reaches a saturated water absorption state, followed by rotary tillage, sedimentation of mud, and drying of the field.

[0042] The present invention found that damage to the plow pan layer of soil leads to the inability of the field to retain water effectively, which seriously affects the rice yield. In the process of converting dry land into paddy fields, the seepage rate of the paddy field is an important indicator for determining whether it can be used as a paddy field.

[0043] This invention also includes the maturation of the topsoil after paddy field soil restoration, including the following steps: year-round rotation of rice and green manure, and full return of rice straw and green manure to the field.

[0044] In this invention, the green manure is selected from milkvetch or alfalfa.

[0045] As a feasible approach, in the first year after farmland restoration, rice is planted via direct seeding, and the rice straw and green manure are crushed and plowed into the soil to achieve full return of the rice straw and green manure to the field. This invention's method of returning all rice straw and green manure to the field can reduce land use intensity and improve soil fertility.

[0046] In this invention, after rice harvest, 250-500 kg / mu of biochar and 500-1000 kg / mu of organic fertilizer are applied. As an feasible method, the ratio of biochar to organic fertilizer in this invention is 1:2. The combined use of biochar and organic fertilizer improves soil fertility and stability, and accelerates the maturation of the topsoil.

[0047] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a method for remediating paddy field soil.

[0050] Location: Xujiang'an Village, Xikou Town, Fenghua District, Ningbo City, Zhejiang Province

[0051] Time: March 2022 - March 2023

[0052] In the non-grain farming remediation area of ​​Xujiang'an Village, Xikou Town, Fenghua, a 5-mu (approximately 0.33 hectares) paddy field damaged by bamboo shoot cultivation was selected for soil restoration. The specific steps included:

[0053] An on-site investigation was conducted to assess the soil damage in the area to be repaired. The topsoil layer was found to be 15 cm thick and the plow pan layer 3 cm thick. The estimated soil damage rate was approximately 40%.

[0054] One topsoil composite sample was collected at a depth of 0-15 cm using a stainless steel soil sampler following a grid method. Soil samples from 15 sampling points were mixed to form a single composite sample. The soil sample parameters were analyzed and determined: pH, salt content, organic matter content, and the content of clay (<0.002 mm), silt (0.05-0.002 mm), and sand (2-0.05 mm) in the soil's background composition. The results of the soil analysis were as follows: pH 6.33, salt content 0.24 g / kg, organic matter content 31.5 g / kg, and the background composition of clay (13%), silt (22%), and sand (65%).

[0055] Preparation of clay soil: Based on the soil baseline survey results of the site to be remediated, clay soil needs to be transported from elsewhere. Yellow clay soil was selected as the transported clay soil, with a clay particle content (<0.002mm) of 54% and a moisture content of 23%. The amount of clay soil to be used was calculated according to the following formula:

[0056]

[0057] Among them, the proportion of the field with damaged topsoil is 40% (Ar), 54% (C) clay content, and 23% (Wc) moisture content. According to the formula, the yield is 7.2 tons / mu. Therefore, 36 tons of yellow mud need to be transported from outside the field for 5 mu of experimental field.

[0058] Bentonite preparation: The amount of bentonite used is 10% of the amount used for clay soil, which is 720 kg / mu. 3.6 tons are needed for a 5-mu experimental field.

[0059] Organic material preparation: Since the soil is acidic, alkaline biochar is selected as the organic material, with an addition amount of 500 kg / mu. 2.5 tons are needed for a 5-mu experimental field.

[0060] Use a plow to till the field to a depth of 15cm, tilling the entire field without leaving any dead corners.

[0061] The transported clay soil was used to fill the pits and depressions in the damaged topsoil, and the remaining soil was spread evenly across the entire field, while keeping the land in the field relatively flat.

[0062] Spread the biochar and bentonite evenly into the tilled field.

[0063] Water is pumped to irrigate the plowed farmland, submerging the surface by 10cm. After 3 hours, the soil reaches saturation and is then rotary tilled to a depth of 15cm, ensuring that all areas of the field are completely tilled. This process is completed within 1 day.

[0064] The rotary tilled mud was allowed to settle naturally in layers for 2 days.

[0065] After the mud sedimentation process is completed, drain the water from the field and let the field dry for 7 days.

[0066] The field was irrigated to a depth of 10 cm, and the water level was observed to drop at a rate of less than 2 cm / day, which meets the requirements for paddy field seepage rate.

[0067] After the paddy field soil was restored, a season of rice was planted by direct seeding. After the rice production season, milkvetch was planted as green manure. The rice straw and milkvetch were crushed and buryed to achieve full return to the field.

[0068] After the rice harvest, biochar and organic fertilizer are evenly spread on the plot, with a ratio of 1:2. The amount of biochar used is 250 kg / mu and the amount of organic fertilizer used is 500 kg / mu.

[0069] Example 2

[0070] This embodiment provides a method for remediating paddy field soil.

[0071] Location: Lou'ai Village, Chunhu Subdistrict, Fenghua District, Ningbo City, Zhejiang Province

[0072] Time period: March 2022 - May 2023

[0073] In the non-grain conversion remediation area of ​​Chunhulou'ai in Fenghua, a 10-mu (approximately 1.65 acres) paddy field damaged by seedling planting was selected for a soil remediation experiment. The specific steps included:

[0074] An on-site investigation was conducted to assess the soil damage in the area to be repaired. The topsoil layer was found to be 18 cm thick and the plow pan layer 5 cm thick. The estimated soil damage rate was approximately 15%.

[0075] One topsoil composite sample was collected at a depth of 0-18 cm using a stainless steel soil sampler following a grid method. Soil samples from 30 sampling points were mixed to form a single composite sample. Soil sample parameters were analyzed and determined: pH, salt content, organic matter content, and the content of clay (<0.002 mm), silt (0.05-0.002 mm), and sand (2-0.05 mm) in the soil's background composition. The results of the soil analysis were as follows: pH 7.51, salt content 0.55 g / kg, organic matter content 22.2 g / kg, and mechanical composition: clay content 9%, silt content 23%, and sand content 68%.

[0076] Clay soil preparation: Based on the soil baseline survey results of the site to be remediated, clay soil needs to be transported from elsewhere. Yellow clay soil was selected as the transported clay soil, with a clay particle content (<0.002mm) of 48% and a moisture content of 25%. The amount of clay soil to be used is calculated according to the following formula:

[0077]

[0078] Among them, the proportion of the field with damaged topsoil is 15% (Ar), 48% (C) clay content, and 25% (Wc) moisture content. According to the formula, it is calculated to be 3.1 tons / mu. Therefore, 31 tons of transported yellow clay need to be added to 10 mu of experimental field.

[0079] Bentonite preparation: The amount of bentonite used is 10% of the amount used for clay soil, which is 310 kg / mu. 3.1 tons are needed for 10 mu of experimental field.

[0080] Organic material preparation: Due to the alkaline nature of the soil, acidic humic acid was selected as the organic material, with an addition rate of 500 kg / mu. 5 tons are needed for a 10-mu experimental field.

[0081] A plow was used to till the field to a depth of 18cm, ensuring that the entire field was tilled without leaving any dead corners.

[0082] The transported clay soil was used to fill the pits and depressions in the damaged topsoil, and the remaining soil was spread evenly across the entire field, while keeping the land in the field relatively flat.

[0083] Spread humic acid and bentonite evenly into the tilled field.

[0084] Water is pumped to irrigate the plowed farmland, submerging the surface by 10cm. After 5 hours, the soil reaches saturation and is then rotary tilled to a depth of 18cm, ensuring that all areas of the field are completely tilled. This process is completed within 1 day.

[0085] The rotary tilled mud was allowed to settle naturally in layers for 2 days.

[0086] After the mud sedimentation process is completed, the surface water is drained and the field is left to dry for 9 days.

[0087] When the field was irrigated to a depth of 10 cm, the water level was observed to drop at a rate of 3.5 cm / day, which failed to meet the requirements for paddy field seepage rate.

[0088] Repeat the above steps of irrigating and soaking the field until the soil reaches saturation, rotary tilling, settling the mud, and drying the field. Add water to the field to a depth of 10 cm. The observed water level drop rate is <2 cm / day, meeting the requirements for paddy field infiltration rate.

[0089] After the paddy field soil was restored, a season of rice was planted using direct seeding. After the rice production season, milkvetch was planted as green manure. The rice straw and milkvetch were crushed and buryed to achieve full return to the field.

[0090] After the rice harvest, biochar and organic fertilizer are evenly spread on the plot, with a ratio of 1:2. The amount of biochar used is 250 kg / mu and the amount of organic fertilizer used is 500 kg / mu.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that no biochar and bentonite treatment were added; otherwise, it is the same as Example 1.

[0093] Comparative Example 2

[0094] The difference from Example 2 is that the steps of soaking the field until the soil reaches saturation, rotary tillage, sedimentation of mud, and drying of the field were not performed. The rest of the treatment was the same as in Example 2.

[0095] Example 3

[0096] This embodiment compares the effects of different paddy field soil remediation methods.

[0097] 1. In the paddy fields modified in Examples 1-2 and Comparative Examples 1-2, as well as the unrestored control (CK1, CK2) paddy fields, rice was planted in accordance with local conventional methods. CK1 was the non-grain conversion area of ​​Xujiang'an Village, Xikou Town, Fenghua County in Example 1, which was damaged by bamboo shoot planting and had not been restored. CK2 was the non-grain conversion area of ​​Lou'ai, Chunhu Town, Fenghua County in Example 2, which was damaged by seedling planting and had not been restored.

[0098] The rice was irrigated once during the early tillering stage, with an average water depth of 10 cm on the field surface. The water depth on the field surface was measured regularly, and the results are shown in Table 1.

[0099] Table 1. Diurnal variation of field surface water depth under different treatments

[0100]

[0101] As shown in Table 1, the paddy fields in the control group, which were not repaired or modified, dried up completely within 2 and 3 days after being filled with water, respectively, indicating severe soil leakage. The paddy fields in Comparative Examples 1-2, which were modified, showed a certain degree of improvement in water retention, with the surface water lasting for 4-5 days. In contrast, after the rapid soil repair of the paddy fields in Examples 1-2, the surface water lasted for 7 days. This indicates that the present invention can quickly reconstruct the damaged plow pan, significantly improve the water retention performance of paddy fields, save water resources, and facilitate the rapid repair of non-grain farmland.

[0102] 2. Soil samples from the topsoil layers of the paddy fields modified in Examples 1-2 and Comparative Examples 1-2, as well as the paddy fields in CK1 and CK2, were collected one year after remediation. The relevant physicochemical properties of the soils were measured in the laboratory. The physicochemical properties of the soils in each treatment are shown in Table 2.

[0103] Table 2 Physicochemical properties of topsoil under different treatments

[0104]

[0105] Table 2 shows that the soil in the control group was weakly acidic and weakly alkaline, respectively. The pH value of the soil in the comparative example did not change significantly, while the soil in the example tended to be neutral, which is more conducive to rice cultivation. The soil fertility (CEC) in the example was significantly higher than that in the comparative and control groups, indicating stronger soil nutrient retention capacity. Compared with the control group, the soil organic matter and total nitrogen in the example increased by 10.4-16.7% and 23.0-34.1%, respectively, and the contents of available nutrients such as alkaline nitrogen, available phosphorus, and available potassium also increased significantly. The soil CEC, organic matter, total nitrogen, alkaline nitrogen, available phosphorus, and available potassium in the comparative example also increased to some extent compared with the control, but the increase was smaller than that in the example. These results indicate that the method of the present invention improved the fertility level of the topsoil, ensured crop nutrient supply, and laid the foundation for high yield and high efficiency in paddy fields.

[0106] 3. In the paddy fields modified in Examples 1-2 and Comparative Examples 1-2, as well as in CK1 and CK2, rice was planted using the local conventional direct seeding method. Except for the increased irrigation frequency in the control groups 1-2 and Comparative Examples 1-2, other field management measures such as fertilization were the same as the local conventional methods. At the rice maturity period, actual yield measurements were performed on the different treatment fields. Three fields were randomly harvested from each treatment, with each field being 1 mu (approximately 0.067 hectares) as three replicates. The rice yields of each treatment are shown in Table 3.

[0107] Table 3 Rice yield under different treatments

[0108]

[0109]

[0110] Soil was treated with alternating wet and dry conditions according to local conventional rice cultivation water management methods. Irrigation timing was determined by investigating soil moisture content in the paddy fields. Due to damage to the plow pan in both the comparative and control groups, the fields could not effectively retain water, necessitating increased irrigation frequency during rice cultivation. Specifically, the average irrigation frequency for Examples 1-2 was 12 times, for Comparative Examples 1-2 it was 22 times, and for Control Groups 1-2 it was 45 times. Compared to Examples 1-2, the irrigation frequency for the comparative and control groups increased by 83.3% and 275%, respectively. This demonstrates that the present invention can repair the plow pan in paddy fields, saving on rice cultivation costs.

[0111] Table 3 shows that the average rice yield of the two examples reached 573.5 kg / mu, which is comparable to the local average yield, but significantly higher than that of the comparative and control groups. Compared with the control group, the rice yields of comparative examples 1 and 2 increased by 34.6% and 37.6%, respectively, while the yields of examples 1 and 2 increased by 58.6% and 63.3%, respectively. The seepage problem in the repaired fields was solved, which not only ensured the normal tillering and panicle formation of rice, but also greatly reduced weed damage in the paddy fields. In addition, because the examples reduced nutrient loss with water and increased the application of fertilizers such as biochar and organic fertilizer, soil nutrients were replenished and activated, resulting in a significant increase in rice yield.

[0112] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for remediating paddy field soil, characterized in that, The process includes the following steps: tilling the paddy field, adding clay soil, bentonite and organic materials, irrigating the field until the soil is saturated with water, rotary tilling, settling the mud, and drying the field. The paddy fields mentioned are reclaimed paddy fields in river valley plains; The irrigation paddy field is submerged to a depth of 10-15 cm for 3-6 hours. The application of clay soil is determined based on the results of soil background composition analysis. When the content of clay particles <0.002mm in the 0-20cm topsoil layer of the field is <15%, clay soil needs to be applied. The amount of clay soil used is determined according to the following formula: In the formula: M is the amount of clay soil used; Ar is the proportion of the field area whose topsoil has been damaged, in %; C 黏粒 Wc represents the content of clay particles <0.002mm in the applied clay soil, in percentage; Wc represents the moisture content of the applied clay soil, in percentage. After the field is dried, the field is flooded until the surface is submerged by 10-15 cm. The rate at which the water level drops is observed. If the rate of drop is greater than 2 cm / day, the irrigation and soaking process is repeated until the soil reaches saturation. Then, the field is rotary tilled, the mud is allowed to settle, and the field is dried again.

2. The method for remediating paddy field soil according to claim 1, characterized in that, The clay soil includes any one or more of yellow clay, bluish-purple clay, and red clay.

3. The method for remediating paddy field soil according to claim 1, characterized in that, The amount of bentonite added is 10-20% of the amount used for clay soil, and the amount of organic material added is 300-500 kg / mu.

4. The method for remediating paddy field soil according to claim 1, characterized in that, It also includes the maturation of the topsoil after the restoration of paddy field soil, including the following steps: year-round rotation of rice and green manure, and full return of rice straw and green manure to the field.

5. The method for remediating paddy field soil according to claim 4, characterized in that, After the rice is harvested, apply 250-500 kg / mu of biochar and 500-1000 kg / mu of organic fertilizer.

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