A method for improving a severe coastal saline-alkali soil

Abstract

A method for improving heavy coastal saline-alkali soil, comprising the following steps: S1, in the first year autumn, after deep ploughing and burying straw in the heavy saline-alkali soil, hole sowing crops is covered with mulch film; S2, in the next year autumn, after straw returning and ploughing in the moderate saline-alkali soil, strip sowing crops is covered with liquid mulch film; S3, in the next year autumn, after straw returning and ploughing in the light saline-alkali soil, strip sowing crops is covered with livestock and poultry manure; S4, in the next year autumn, normally sowing crops. The above sowing method realizes not only the improvement of the saline-alkali soil and the gradual change of the saline-alkali soil from heavy to moderate, to light, to normal, but also the gradual change of the yield of crop planting from low to high through four progressive steps.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of saline-alkali soil improvement, in particular to a method for improving heavy coastal saline-alkali soil. BACKGROUND

[0002] Dongying City in Shandong Province is located in the core of the Yellow River Delta, belongs to the coastal saline-alkali type area, the groundwater depth is shallow, the mineralization degree is high, the soil salt content is heavy, mainly chloride, and is greatly affected by the sea tide, which is one of the most difficult delta saline-alkali lands in China and even in the world.

[0003] The existing improvement methods are roughly divided into two kinds:

[0004] One is to use a large amount of water to wash the saline-alkali soil, and to plant crops with high salt tolerance, such as salt-tolerant soybeans, corn, wheat, etc., after the soil salt content is less than 0.3%. For example, the patent No. CN202210125069.1, named a method for improving coastal saline-alkali soil, introduces such an improvement method, but this method uses a large amount of water and a long washing time, which will inevitably cause soil fertility loss. Although the improved salt removal groove and salt removal pipe structure can minimize soil fertility loss, soil fertility loss problem still cannot be ignored over time.

[0005] The other is to give up planting crops and plant salt-tolerant plants such as salt-tolerant grass, poplar, alkali bush, tamarisk, etc. But this causes soil idling and cannot be effectively utilized. SUMMARY

[0006] To solve the technical problems in the background art, the present application provides a method for improving heavy coastal saline-alkali soil, which adopts a gradual improvement method and a complete set of technical solutions for improving saline-alkali soil for many years, so that the saline-alkali soil can be suitable for crop growth for a long time.

[0007] The technical solution of the present application is as follows:

[0008] A method for improving heavy coastal saline-alkali soil, comprising the following steps:

[0009] S1, in the first year of autumn, after deep ploughing and burying straw in the heavy saline-alkali soil, covering the film hole sowing crops;

[0010] S11, the plant straw is crushed and laid on the surface of the saline-alkali soil, the use amount per mu is between 5-10 tons, and the height of the plant straw after laying is not less than 20cm;

[0011] S12, deep ploughing and turning over the soil, the turning depth is between 1-1.2m, the plant straw is turned to the bottom to form a partition layer;

[0012] The deep plowing of the soil in the coastal saline-alkali soil breaks all the non-water permeable layers within 1-1.2 m.

[0013] S13, burying a salt discharge pipe under the lower part of the partition layer, and connecting the end of the salt discharge pipe to a water collecting pool;

[0014] Specifically, the salt discharge pipe is installed on the upper surface of the adjacent non-water permeable layer below the partition layer, so as to facilitate the discharge of salt and prevent the salt from being blocked by the non-water permeable layer below.

[0015] S14, leveling the ground and irrigating and leaching the soil until the salt content of the soil is detected to be lower than 0.7%;

[0016] S14, covering the surface of the saline-alkali soil with ordinary mulch film;

[0017] S15, hole sowing crops;

[0018] S16, planting new crops after harvesting in spring;

[0019] The first year of planting crops is mainly used for soil improvement, and the heavy saline-alkali soil is improved to moderate saline-alkali soil, without regard to crop yield. Therefore, the first year of planting mainly highlights the following points:

[0020] 1. By leaching the soil, the salt content of the soil is only reduced to less than 0.7%, which saves a lot of water resources and also does not cause a large loss of soil nutrients.

[0021] 2. The depth of plowing is about 1 m. The characteristic of the coastal saline-alkali soil is that there are one or more non-water permeable layers with different depths vertically distributed. The non-water permeable layer is a clay layer with different thicknesses. Deep plowing of about 1 m can destroy all the non-water permeable layers within 1 m underground, which is beneficial to the downward infiltration of water and can form a 8-15 cm thick partition layer at a depth of 1 m underground, effectively blocking the salt below the partition layer from rising to the upper part of the partition layer.

[0022] 3. Covering the surface of the saline-alkali soil with ordinary mulch film and hole sowing crops. The hole sowing method causes little damage to the mulch film, and through the wide coverage of the mulch film, water evaporation can be effectively inhibited. As long as the water evaporation is less, the amount of salt rising will be very small.

[0023] The dry and rainy seasons in spring and autumn are the times when water evaporation is the most in the saline-alkali soil. Rainwater and irrigation water infiltrate, taking the salt within 1 m of the soil downward to the salt discharge pipe below the partition layer. The salt below the partition layer cannot pass through the partition layer to reach the upper part of the partition layer, and the mulch film on the surface of the soil will greatly prevent the water in the soil above the partition layer from evaporating upward, so that the salt existing within 1 m above the partition layer will only decrease, not increase.

[0024] After the first year of planting, the soil salt content can generally be reduced from less than 0.7% to less than 0.4%, and the saline-alkali land can be changed from severe saline-alkali land to moderate saline-alkali land.

[0025] In addition, step S17 is further included, that is, detecting the soil salt content after harvesting the crops in autumn, if less than or equal to 0.4%, step S2 is executed, and if greater than 0.4%, planting is suspended, and the reason is analyzed.

[0026] S2, in the next autumn, after the straw returning and plowing of the moderate saline-alkali land, the crops are sowed and covered with liquid mulch film;

[0027] S21, the crop straw in the saline-alkali land is returned to the field and plowed to a depth of 28-35 cm;

[0028] S22, the crops are sowed;

[0029] S23, the liquid mulch film is covered on the surface of the saline-alkali land soil;

[0030] S24, after harvesting in spring, new crops are planted, and after harvesting the crops in autumn, the soil salt content is detected, if greater than 0.2%, step S2 is repeated, and if less than or equal to 0.2%, step S3 is executed;

[0031] After the first stage of soil improvement, this stage is a critical stage, and the main purpose is to start to increase the yield, which can be executed for about one to three years, first, the straw returning is used to increase the soil organic matter, and the plowing depth is reduced to about 30 cm, then the crops are sowed to increase the yield, and the liquid mulch film can reduce the cost compared with the ordinary mulch film. Thus, the severe saline-alkali land is improved at the lowest cost, and the crop yield is gradually increased, which is an important invention point of the present application, that is, the crops are planted on the saline-alkali land in a gradual way, instead of pursuing one-time improvement as in many prior arts, and a large amount of improvement components are added to the soil, for example, CN201911248303.4, a composite improvement method for saline-alkali land.

[0032] In addition, in step S23, the liquid mulch film is timely supplemented when strong wind weather is encountered before the crops emerge. Although the liquid mulch film has low cost, it is not as firm as the ordinary mulch film, and is easily damaged by strong wind, therefore, it needs to be timely supplemented to inhibit the evaporation of water in the soil.

[0033] After 1-3 years of planting, the moderate saline-alkali land will gradually become light saline-alkali land, and the crop yield is gradually increased. The next stage of crop planting method can be performed.

[0034] S3, in the next autumn, after the straw returning and plowing of the light saline-alkali land, the crops are sowed and covered with livestock and poultry manure;

[0035] S31, deep plowing the crop straw in the saline-alkali soil to 18-25 cm;

[0036] S32, sowing the crop;

[0037] S33, covering the soil surface of the saline-alkali soil with livestock and poultry manure;

[0038] S34, planting new crops after harvesting in spring;

[0039] In this stage, the deep plowing depth is further reduced to about 20 cm, which ensures the normal growth of crop roots, and the organic fertilizer is used. As another application point of the present application, the purpose of using the organic fertilizer in this stage is not to increase the soil organic matter by applying it to the soil as in the prior art, but to replace the liquid mulch in the previous stage to inhibit water evaporation in the soil and prevent salt from rising.

[0040] As a preferred solution, in step S33, the proportion of livestock and poultry manure covering the soil surface is greater than 90%. That is, it is uniformly covered on the soil surface, not inside. In this way, the cost of spraying liquid mulch is also saved. In this way, after one year of planting, the salt content of the soil in the light saline-alkali soil is further reduced, and in the autumn of the next year, the crop straw can be turned into the soil together with the livestock and poultry manure to increase the soil organic matter.

[0041] S4, normally sowing crops in the autumn of the next year;

[0042] S41, deep plowing to turn the crop straw in the saline-alkali soil into the soil together with the livestock and poultry manure;

[0043] S42, sowing the crop.

[0044] Through the above four stages, the saline-alkali soil gradually changes from severe to moderate, to light, to normal, with a time span of at least four years, and the yield of crop planting gradually increases from low to high. It is a way to improve severe saline-alkali soil at low cost. It is in sharp contrast to the way of pursuing rapid improvement of severe saline-alkali soil in the prior art to achieve high yield quickly.

[0045] As a preferred embodiment, in step S12, the plowing depth is 1 m. In step S21, the plowing depth is 30 cm. In step S31, the plowing depth is 20 cm.

[0046] Through the above design, the severe coastal saline-alkali soil improvement method is a method for improving severe saline-alkali soil and sowing crops at low cost. It is divided into four progressive stages in total, realizes the gradual change of the saline-alkali soil from severe to moderate, to light, to normal, with a time span of at least four years, and also realizes the gradual change of the yield of crop planting from low to high.

[0047] In the first three stages, according to the different salt content of saline-alkali soil, ordinary mulch, liquid mulch and livestock manure are respectively laid on the soil surface, all of which are used to inhibit water evaporation and prevent salt from rising, and the three coverings cannot be replaced and must be used in the saline-alkali soil with corresponding salt content to play the effect. It is the overall technical solution for gradually improving the severe saline-alkali soil, and cannot be split and combined. DETAILED DESCRIPTION

[0048] This embodiment takes the coastal saline-alkali soil as the improvement object, and is located in the Yellow River Delta region of Dongying City, Shandong Province.

[0049] A method for improving severe coastal saline-alkali soil, comprising the following steps:

[0050] S1, in the first year of autumn, after deep ploughing and burying straw in the severe saline-alkali soil, the crops are hole-seeded by covering the mulch, and the crops can be wheat, corn, soybean, etc.;

[0051] S11, the plant straw is crushed and laid on the soil surface of the saline-alkali soil, and the use amount per mu is between 10 tons, and the height of the laid plant straw is not less than 20 cm;

[0052] S12, the soil is deep ploughed and turned over, and the turning depth is 1 m, the plant straw is turned to the bottom to form a blocking layer;

[0053] The coastal saline-alkali soil has multiple non-water permeable layers in longitudinal distribution, and the deep ploughing and turning break all the non-water permeable layers within 1 m, so that the water can smoothly take away the salt when flowing downward.

[0054] S13, a salt discharge pipe is buried under the blocking layer, and the end of the salt discharge pipe is connected to a water collecting pool;

[0055] Specifically, the salt discharge pipe is installed on the upper surface of the adjacent non-water permeable layer below the blocking layer, so as to facilitate the removal of salt and prevent being blocked by the lower non-water permeable layer.

[0056] S14, the ground is leveled, and the soil is irrigated and leached until the soil salt content is detected to be less than 0.7%;

[0057] S14, the ordinary mulch is covered on the soil surface of the saline-alkali soil;

[0058] S15, hole-seeding crops, such as wheat;

[0059] S16, after harvesting in spring, new crops, such as corn, are planted;

[0060] S17, the soil salt content after harvesting the crops in autumn is detected, if it is less than or equal to 0.4%, step S2 is executed, and if it is greater than 0.4%, the planting is suspended and the reason is analyzed.

[0061] The first year of planting crops is mainly for soil improvement, changing severe saline-alkali land into moderate saline-alkali land, and not caring about crop yield. Therefore, the first year of planting mainly highlights the following points:

[0062] 1. By leaching the soil, the soil salt content is only reduced to less than 0.7%, saving a large amount of water resources, and also not causing a large amount of soil nutrients to be lost.

[0063] 2. The depth of turning over the soil is about 1m. The characteristic of coastal saline-alkali land is that there is one or more layers of non-permeable water layer with different depths vertically distributed. The non-permeable water layer is a clay layer with different thicknesses. Deep plowing about 1m can destroy all non-permeable water layers within 1m underground, which is beneficial to water infiltration. After the plant straw is buried underground, a 8-15cm thick barrier layer can be formed at a depth of 1m underground, effectively blocking the salt below the barrier layer from rising to the above of the barrier layer.

[0064] 3. Covering the saline-alkali land soil surface with ordinary mulch film and hole planting crops. The hole planting method of crops causes less damage to the film. Through the wide coverage of the film, water evaporation can be effectively inhibited. As long as the water evaporation is less, the amount of salt rising will be less.

[0065] The dry and rainy spring and autumn seasons are the times when water evaporation from saline-alkali land is the most. Rainwater and irrigation water infiltrate, taking the salt within 1m of the soil down to the salt discharge pipe below the barrier layer. The salt below the barrier layer cannot pass through the barrier layer to reach the above of the barrier layer, and the soil surface film will greatly prevent the water in the soil above the barrier layer from evaporating upward, so that the salt existing within 1m above the barrier layer will only continue to decrease, not increase.

[0066] After one year of planting, the soil salt content can generally be reduced from less than 0.7% to less than 0.4%, changing the saline-alkali land from severe saline-alkali land to moderate saline-alkali land.

[0067] If the soil salt content after harvesting crops in the first year is greater than 0.4%, planting needs to be suspended, the reasons need to be analyzed, and whether there are improper operations in the process of turning over the soil, burying the pipe, and planting needs to be found out and corrected in time.

[0068] S2, in the autumn of the next year, after the straw is returned to the field and plowed in the moderate saline-alkali land, the crops are sown and covered with liquid mulch film;

[0069] S21, the crop straw in the saline-alkali land is returned to the field and deep plowed 30cm;

[0070] S22, the crops are sown, for example, wheat;

[0071] S23, the saline-alkali land soil surface is covered with liquid mulch film. When strong winds are encountered before the crops emerge, liquid mulch film needs to be supplemented in time;

[0072] S24, after harvesting in spring, plant new crops, such as corn, etc. After harvesting in autumn, detect the salt content of the soil, if greater than 0.2%, repeat step S2, if less than or equal to 0.2%, perform step S3;

[0073] After the first stage of soil improvement, this stage is a critical period, the main purpose is to start to increase yield, which can be performed for one to three years, first straw returning to increase soil organic matter, deep plowing depth is reduced to about 30 cm, then strip planting crops to increase yield, liquid mulch can reduce the cost compared with ordinary mulch. Thus, with the lowest cost to improve severe saline-alkali soil and gradually increase crop yield, which is also an important point of the present application - using a gradual way to plant crops on saline-alkali soil, rather than like many prior art, pursuing one-time improvement, adding a large amount of improvement components in the soil, such as CN201911248303.4 a composite improvement method for saline-alkali soil.

[0074] In addition, although the cost of liquid mulch is low, it is not as firm as ordinary mulch, and it is easy to be damaged by strong winds, so if it is windy, it needs to be supplemented in time to inhibit water evaporation in the soil and prevent salt return.

[0075] After 1-3 years of planting, moderate saline-alkali soil will gradually become light saline-alkali soil, and crop yield will gradually increase. The next stage of crop planting method can be performed.

[0076] S3, in the next autumn, after the straw returning and plowing of the light saline-alkali soil, strip planting crops and covering livestock and poultry manure;

[0077] S31, returning crop straw in saline-alkali soil and deep plowing 20 cm;

[0078] S32, strip planting crops, such as wheat;

[0079] S33, covering livestock and poultry manure on the surface of the saline-alkali soil, and the proportion of livestock and poultry manure covering the soil surface should be greater than 90%;

[0080] S34, after harvesting in spring, plant new crops, such as corn;

[0081] In this stage, the deep plowing depth is further reduced to about 20 cm, which ensures the normal growth of crop roots, and organic fertilizer is started to be used. As another point of the present application, the purpose of using organic fertilizer in this stage is not to apply in the soil to increase soil organic matter as in the prior art, but to replace the liquid mulch of the previous stage to inhibit water evaporation in the soil and prevent salt rise.

[0082] Moreover, the proportion of livestock and poultry manure covering the soil surface is greater than 90%, and the amount used per mu is between 1-6 tons, depending on the input. That is, evenly cover the soil surface, not inside. In this way, the cost of spraying liquid mulch is also saved. In this way, after a year of planting, the soil salt content of the light saline-alkali soil is further reduced, and in the fall of the next year, crop straw can be turned into the soil along with livestock and poultry manure to increase soil organic matter.

[0083] After the third stage of improvement, the soil salt content will generally be reduced to less than 0.1%, and the fourth stage of normal planting of crops such as wheat and corn can be carried out.

[0084] S4, normal sowing of crops in the fall of the next year;

[0085] S41, deep plowing, turning crop straw in the saline-alkali soil into the soil along with livestock and poultry manure;

[0086] S42, strip sowing of crops.

[0087] Through the above four stages of gradual progress, the saline-alkali soil gradually changes from severe to moderate, to light, to normal, with a time span of at least four years, and the crop yield gradually changes from low to high. It is a way to improve severe saline-alkali soil in a low-cost and benign way. It is in sharp contrast to the existing technology of pursuing rapid improvement of severe saline-alkali soil in order to achieve high yield quickly.

[0088] The applicant takes wheat planting as an example, and after more than four years of actual improvement of a piece of severe saline-alkali soil, the wheat yield changes as follows:

[0089] In the first year, wheat was planted in severe saline-alkali soil, with an average yield of 200-300 kg per mu;

[0090] In the second year, wheat was planted in moderate saline-alkali soil, with an average yield of 300-500 kg per mu;

[0091] In the third year, wheat was planted in light saline-alkali soil, with an average yield of 500-700 kg per mu;

[0092] In the fourth year, normal soil planting, wheat yield per mu increased to about 800 kg.

[0093] The effect of saline-alkali soil improvement is very significant.

Claims

1. A method for improving a severe coastal saline soil, characterized by, It comprises the following steps: S1, in the first year autumn, after deep ploughing and burying straw in severe saline-alkali soil, hole sowing crops is carried out; S11, plant straw is crushed and laid on the surface of saline-alkali soil, and the use amount per mu is 5-10 tons; S12, deep ploughing is carried out on the soil, the depth is between 1-1.2m, the plant straw is turned to the bottom to form a blocking layer, the saline-alkali soil is longitudinally distributed with multiple non-water permeable layers, and the deep ploughing breaks all the non-water permeable layers within 1-1.2m; S13, a salt discharge pipe is buried under the blocking layer, and the tail end of the salt discharge pipe is connected to a water collecting pool; S14, the ground is leveled, and the soil is irrigated and leached until the soil salt content is less than 0.7%; S14, ordinary mulching film is covered on the surface of the saline-alkali soil; S15, hole sowing crops is carried out; S16, after harvesting in spring, new crops are planted; S17, the soil salt content after harvesting crops in autumn is detected, if it is less than or equal to 0.4%, step S2 is executed, and if it is greater than 0.4%, planting is suspended; S2, in the next autumn, after straw returning and ploughing in moderate saline-alkali soil, crops are sowed and covered with liquid mulching film; S21, crop straw in saline-alkali soil is returned and deep ploughed to 28-35cm; S22, crops are sowed in strips; S23, liquid mulching film is covered on the surface of the saline-alkali soil; S24, after harvesting in spring, new crops are planted, and after harvesting crops in autumn, the soil salt content is detected, if it is greater than 0.2%, step S2 is repeated, and if it is less than or equal to 0.2%, step S3 is executed; S3, in the next autumn, after straw returning and ploughing in light saline-alkali soil, crops are sowed and covered with livestock and poultry manure; S31, crop straw in saline-alkali soil is returned and deep ploughed to 18-25cm; S32, crops are sowed in strips; S33, livestock and poultry manure is covered on the surface of the saline-alkali soil, and the proportion of the livestock and poultry manure covering the soil surface is greater than 90%; S34, after harvesting in spring, new crops are planted; S4, in the next autumn, crops are normally sowed; S41, deep ploughing is carried out, and crop straw in saline-alkali soil is turned into the soil together with livestock and poultry manure; S42, crops are sowed in strips.

2. The method for improving a severe coastal saline-alkali soil according to claim 1, characterized in that, In step S11, the laying height of the plant straw is not less than 20cm.

3. The method for improving a severe coastal saline-alkali soil according to claim 1, characterized in that, In step S13, the salt discharge pipe is installed on the upper surface of the adjacent non-water permeable layer below the blocking layer.

4. The method for improving a severe coastal saline-alkali soil according to claim 1, characterized in that, In step S23, when strong wind weather is encountered before the crops emerge, liquid mulching film is supplemented in time.

5. The method for improving a severe coastal saline-sodic soil according to claim 1, characterized in that, In step S12, the depth of ploughing is 1m.

6. The method for improving a severe coastal saline-sodic soil according to claim 1, characterized in that, In step S21, the depth of ploughing is 30cm.

7. The method for improving a severe coastal saline-sodic soil according to claim 1, characterized in that, In step S31, the depth of ploughing is 20cm.