Planting method for cultivating soil carbon-nitrogen bank in arid irrigated area

Abstract

The invention provides a planting method for cultivating a soil carbon-nitrogen library in an arid irrigated area, and belongs to the technical field of crop cultivation. According to the planting method, a spring wheat-common vetch-corn two-year-three-cropping planting system is implemented in an arid irrigated area, slow-release nitrogen fertilizer is used as base fertilizer for the spring wheat and the corn, and charcoal and / or attapulgite clay are / is applied in a mixed mode. According to the planting method, the soil carbon and nitrogen reserves can be remarkably improved, the nitrogen fertilizer utilization efficiency is improved, the nitrogen fertilizer application amount is reduced, the soil microenvironment is improved, the soil water and fertilizer retention capacity is enhanced, crop growth is promoted, the crop yield is increased, greenhouse gas emission is reduced, agricultural sustainable development is promoted, the farming system is optimized, and the farmland ecosystem service function is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of crop cultivation, and in particular relates to a planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas. Background Art

[0002] With the rise of global CO2 concentration and the intensification of climate warming, carbon fixation and carbon pool cultivation have gradually become hot topics in scientific research. As the largest carbon reservoir in the terrestrial system, soil has a carbon content that is 2 times and 2.5 times that of the atmospheric and terrestrial vegetation carbon pools. Changes in soil carbon pools play an important role in global climate change. As an important component of terrestrial ecosystems, farmland is strongly disturbed by human activities. Its carbon storage accounts for 8%-10% of terrestrial soils, providing a potential sink for atmospheric CO2. Small changes in soil carbon pools significantly affect the global carbon cycle and balance, especially the conversion processes such as soil organic carbon fixation and emission. According to statistics, the global agricultural emission reduction potential is as high as 5500-6000Mt CO2 equivalent per year, of which 89% comes from soil carbon fixation. Therefore, how to improve soil carbon sequestration and expand carbon pools has become the key to improving soil quality and achieving the "dual carbon" goals. Clarifying the soil carbon sequestration potential is an important part of scientifically evaluating the service functions of farmland ecosystems.

[0003] Nitrogen is one of the essential nutrients for crop growth. Nitrogen application plays an important role in increasing crop yields. However, excessive nitrogen application can easily lead to low utilization rate and excessive nitrogen accumulation in the soil. Excessive nitrogen fertilizer application not only leads to a large amount of nitrogen surplus and underground nitrate pollution, destroying the farmland ecological environment, but also reduces crop yield and agricultural product quality. At present, excessive nitrogen application and low nitrogen fertilizer utilization rate are common in agricultural production, which seriously affects the stability and sustainability of farmland ecosystems and is not conducive to the sustainable development of agriculture. Therefore, how to improve the utilization efficiency of nitrogen fertilizers and cultivate soil nitrogen pools to maintain soil health is an important direction of current agricultural research.

[0004] my country's dryland farmland accounts for 50% of the country's total cultivated land area. The dryland soil fertility is low, the input of organic materials is small, the soil carbon fixation and nitrogen retention capacity is poor, and it is in a low-level carbon balance state. There is a lack of discussion on effective measures to improve soil carbon and nitrogen reserves, and it is not clear how the farming system and agronomic measures affect the specific mechanism of soil carbon and nitrogen reserves. At present, the existing technology only solves one of the problems of soil carbon pool and nitrogen pool, and has not achieved the coordinated cultivation of soil carbon pool and nitrogen pool through integrated measures. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas, and to achieve the goal of increasing farmland crop yields in arid irrigation areas and synergizing the cultivation of soil carbon and nitrogen pools by integrating green manure with soil conditioners, slow-release nitrogen fertilizers and other measures.

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

[0007] A planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas, wherein a two-year three-crop planting system of spring wheat-arrow peas→corn is implemented in the arid irrigation areas; the spring wheat and corn use slow-release nitrogen fertilizer as base fertilizer, and are mixed with biochar and / or attapulgite clay.

[0008] Preferably, the spring wheat is fertilized with a slow-release nitrogen fertilizer of 124-128 kg / hm 2 , mixed with biochar 14.5-15.5t / hm 2 and / or attapulgite clay 29.5-30.5kg / hm 2 .

[0009] Preferably, the corn is fertilized with 250-254 kg / hm2 of slow-release nitrogen fertilizer. 2 , mixed with biochar 19.5-20.5t / hm 2 and / or attapulgite clay 44.5-45.5kg / hm 2 .

[0010] Preferably, the spring wheat and corn are tilled and the land is prepared after applying basal fertilizer, biochar and / or attapulgite clay, with the tillage depth being 15-20 cm in the spring wheat season and 20-30 cm in the corn season.

[0011] Preferably, the spring wheat is sown in mid-to-late March, using micro-ridge sowing technology, with a row spacing of 14-16 cm and a sowing rate of 445-455 kg / hm 2 .

[0012] Preferably, the arrow pea is planted after wheat is harvested, with a row spacing of 14-16 cm and a sowing rate of 145-155 kg / hm 2 .

[0013] Preferably, the corn is sown in early to mid-April, with wide and narrow row single grain precision sowing, the wide row spacing is 69-71 cm, the narrow row spacing is 39-41 cm, and the planting density is 93550-93850 plants / hm2. 2 .

[0014] More preferably, the corn is planted in an integrated manner of film covering, spraying, laying of drip irrigation tapes, and corn hole sowing.

[0015] Preferably, the straw of spring wheat and broadleaf pea is returned to the field after harvest, and the field is not tilled after harvest of corn, so as to achieve year-round surface coverage.

[0016] Preferably, after the corn is harvested, when spring wheat is rotated again, 4.3-4.7 t / hm2 of organic fertilizer is applied as base fertilizer. 2 .

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) Significantly increase soil carbon and nitrogen reserves: The synergistic application of slow-release nitrogen fertilizer, biochar and attapulgite clay significantly increased soil organic carbon and nitrogen reserves. The experimental results show that the soil organic carbon reserves of slow-release nitrogen fertilizer combined with biochar increased by 7.41%-10.97% and the soil nitrogen reserves increased by 56.95%-61.36% compared with traditional crop rotation. Biochar and attapulgite clay, as soil conditioners, can improve soil structure, increase soil organic matter content, promote soil microbial activity, and thus enhance the soil's ability to fix carbon and retain nitrogen.

[0019] (2) Improve nitrogen fertilizer utilization efficiency and reduce nitrogen fertilizer application: The use of slow-release nitrogen fertilizer combined with nitrogen reduction measures (reducing the local customary nitrogen application by 30%) significantly improved nitrogen fertilizer utilization efficiency, reduced excessive nitrogen fertilizer application, avoided nitrogen accumulation and loss in the soil, and reduced the risk of underground nitrate pollution. Nitrogen reduction measures alleviated the "nitrogen barrier" effect of leguminous green manure in a high-nitrogen environment and further promoted the coordinated cultivation of soil carbon and nitrogen pools.

[0020] (3) Improve soil microenvironment and enhance soil water and fertilizer retention capacity: The application of biochar and attapulgite clay significantly reduced soil bulk density and soil temperature, increased soil water retention capacity, and improved soil water and heat conditions. The combined application of slow-release nitrogen fertilizer and soil conditioner significantly reduced soil conductivity and salt content, effectively curbed soil salinization, and provided a superior soil microenvironment for crop growth.

[0021] (4) Promote crop growth and increase crop yield: Through the two-year three-crop planting system of spring wheat-arrow peas → corn, combined with straw return to the field and no-till measures, the surface is covered all year round, soil evaporation and wind erosion are reduced, and the soil's ability to retain water and soil is enhanced. The test results show that the corn grain yield reaches 9.8-10.5t / hm2 by using the planting method of the present invention. 2 , wheat grain yield reaches 4.5-5.0t / hm 2 , significantly higher than the traditional crop rotation system.

[0022] (5) Reduce greenhouse gas emissions and promote sustainable agricultural development: The combined application of slow-release nitrogen fertilizers and soil conditioners significantly reduced the activity of soil nitrate and nitrite reductases, inhibited soil greenhouse gas emissions, and reduced the loss of soil carbon and nitrogen reserves. Through straw return and no-till measures, the decomposition and carbon emissions of soil organic matter were reduced, and the soil carbon sequestration capacity was further enhanced, providing technical support for achieving the "dual carbon" goal.

[0023] (6) Optimizing the farming system and improving the service functions of farmland ecosystems: The present invention optimizes the farming system in arid irrigation areas and improves the service functions of farmland ecosystems by integrating green manure rotation, slow-release nitrogen fertilizers, soil conditioners and other measures, thus providing a scientific basis and technical support for the sustainable development of agriculture in arid irrigation areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The effects of soil conditioners and slow-release nitrogen fertilizers on soil carbon and nitrogen storage in a green manure rotation system; in the figure, N1-local customary nitrogen application rate reduced by 30%, N2-local customary nitrogen application rate, T-traditional chemical nitrogen fertilizer (urea), S-slow-release nitrogen fertilizer, A-attapulgite clay, B-biochar, C-no conditioner applied.

[0025] Figure 2 The intrinsic correlation between soil carbon fixation and nitrogen retention capacity and changes in soil environmental factors in the green manure rotation system; in the figure, (a) is principal component analysis, and (b) is Mantel test; N1-traditional nitrogen application, N2-traditional nitrogen application reduced by 30%, T-traditional chemical nitrogen fertilizer (urea), S-slow-release nitrogen fertilizer, A-attapulgite clay, B-biochar, C-no conditioner, EC-soil electrical conductivity, SSC-soil salinity, MBC / MBN-microbial carbon-nitrogen ratio, C / N-soil carbon-nitrogen ratio, NiRs-nitrite reductase, NR-nitrate reductase, SBD-soil bulk density, NO 3- - Nitrate nitrogen, NH4 + -ammonium nitrogen, MGY-maize grain yield, WGY-wheat grain yield, MBY-maize aboveground biomass, WBY-wheat aboveground biomass, pH-pH, SM-soil moisture, SOC-soil organic carbon, Ta-soil temperature, TN-soil total nitrogen, MBN-microbial biomass nitrogen, MBC-microbial biomass carbon, Ureas-soil urease, Sucrase-soil sucrase, α-glu-α glucosidase, Rub.-Rubisco enzyme.

[0026] Figure 3 The main pathways of soil carbon and nitrogen fixation in the integrated green manure rotation system strengthened by slow-release nitrogen fertilizer combined with soil conditioner; in the figure, (a) and (c) are structural equation models, (b) and (d) are the standardized total effects of each variable on soil carbon storage and soil nitrogen storage; SAM-soil conditioner, Type-nitrogen fertilizer type, NR-nitrogen application rate, Soil microenvironment-soil microenvironment, MBC / MBN-microbial carbon-nitrogen ratio, C / N-soil carbon-nitrogen ratio, NiR-nitrite reductase, NR-nitrate reductase, NO 3- - Nitrate nitrogen, NH4 + -ammonium nitrogen, Ureas-soil urease, SCS-soil carbon stock, SNS-soil nitrogen stock.

[0027] Figure 4 This is a conceptual diagram of soil carbon fixation and nitrogen conservation in the integrated green manure rotation system strengthened by slow-release nitrogen fertilizer combined with soil conditioner in the nitrogen reduction system; in the figure, "%" refers to the calculation relative to "no soil conditioner + traditional chemical nitrogen fertilizer" in the system at each nitrogen level, that is, it is the control N2TC in the non-nitrogen reduction system and the control N1TC in the nitrogen reduction system; the gray area in the figure is the increase or decrease coupling effect calculated with "no soil conditioner + traditional chemical nitrogen fertilizer + traditional nitrogen application rate" N2TC as the control. DETAILED DESCRIPTION

[0028] The present invention provides a planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas, wherein a two-year three-crop planting system of spring wheat, peas, and corn is implemented in the arid irrigation areas, and the method comprises the following steps:

[0029] In the present invention, spring wheat is treated with slow-release nitrogen fertilizer as base fertilizer, and mixed with biochar and / or attapulgite clay; preferably, after the beginning of spring, 124-128 kg / hm2 of slow-release nitrogen fertilizer is applied. 2 , mixed with biochar 14.5-15.5t / hm 2 and / or attapulgite clay 29.5-30.5kg / hm 2 ; Further preferably, slow-release nitrogen fertilizer 126kg / hm 2 , mixed with biochar 15t / hm 2 and / or attapulgite clay 30kg / hm 2 Preferably, the soil is tilled after applying basal fertilizer, biochar and / or attapulgite clay, with the tillage depth being 15-20 cm, more preferably 18 cm.

[0030] In the present invention, spring wheat is preferably sown in mid-to-late March, using micro-ridge sowing technology, with a row spacing of 14-16 cm, more preferably 15 cm, and a sowing rate of 445-455 kg / hm 2 , more preferably 450kg / hm 2. The spring wheat micro-ridge and furrow sowing technology described in the present invention, i.e., the integrated water and fertilizer technology of wheat shallow buried drip irrigation micro-ridge and furrow sowing, includes shallow buried drip irrigation: burying the drip irrigation belt 5-10 cm below the ground surface, and directly delivering water and fertilizer to the roots of crops through drippers; micro-ridge and furrow sowing: opening small furrows in the field, sowing seeds in the furrows to form micro-ridges; integrated water and fertilizer: mixing water and fertilizer, and applying them to the roots of crops synchronously through the irrigation system. The present invention does not specifically limit the specific technical details of the integrated water and fertilizer technology of wheat shallow buried drip irrigation micro-ridge and furrow sowing, and conventional means in the field may be used. As an implementable method, the specific technical details are as follows: (1) Micro-ridge construction: mechanical ridge-forming is used to form micro-ridges with a width of 30-40 cm and a height of 10-15 cm, with a ridge spacing of 60-70 cm, and 2-3 rows of wheat are sown on the ridge surface; (2) Shallow buried drip irrigation system: drip irrigation tape is laid along the ridge, with a burial depth of 5-10 cm, a drip head spacing of 20-30 cm, and a drip irrigation flow rate of 1.0-2.0 L / h to ensure that water and fertilizer accurately infiltrate the root layer; (3) Coordinated management of water and fertilizer: based on soil moisture conditions and fertilizer requirements during the growth period, liquid fertilizer is accurately applied during the tillering period, jointing period, and filling period, and the fertilizer is evenly transported to the roots of the plants along with water through the drip irrigation system.

[0031] In the present invention, it is preferred that the straw of spring wheat is crushed and returned to the field when the spring wheat is mature and harvested; it is further preferred that the wheat straw is crushed to a length of 3-5 cm.

[0032] In the present invention, after returning spring wheat straw to the field, peas are planted. Preferably, the row spacing of peas is 14-16 cm, more preferably 15 cm, and the sowing rate is 145-155 kg / hm 2 , more preferably 150kg / hm 2 .

[0033] In the present invention, it is preferred that the straw of the pea bean is crushed and returned to the field after harvest, so as to achieve year-round coverage, prevent evaporation and wind erosion, and play a role in water and soil conservation; it is further preferred that the pea bean bean be harvested during the frost season, and it is more preferred that the pea bean straw be crushed to a length of 3-5 cm.

[0034] In the present invention, corn is treated with slow-release nitrogen fertilizer as base fertilizer, and biochar and / or attapulgite clay are mixed; preferably, after the beginning of spring of the next year, 250-254 kg / hm2 of slow-release nitrogen fertilizer is applied. 2 , mixed with biochar 19.5-20.5t / hm 2 and / or attapulgite clay 44.5-45.5kg / hm 2 ; Further preferably, slow-release nitrogen fertilizer 252kg / hm 2 , mixed with biochar 20t / hm 2 and / or attapulgite clay 45kg / hm 2Preferably, the soil is tilled after applying basal fertilizer, biochar and / or attapulgite clay, with the tillage depth being 20-30 cm, more preferably 25 cm.

[0035] In the present invention, corn is preferably sown in early to mid-April, and wide and narrow rows and single grains are precisely sown. The wide row spacing is 69-71 cm, more preferably 70 cm, the narrow row spacing is 39-41 cm, more preferably 40 cm, and the planting density is 93550-93850 plants / hm2. 2 , and more preferably 93750 plants / hm 2 . It is more preferred that corn be planted in an integrated manner of film covering, spraying, laying drip irrigation tapes, and corn hole sowing. The present invention does not specifically limit the specific forms of corn film covering, spraying, and laying drip irrigation tapes, and conventional means in the art may be used. As an implementable embodiment, the specific technical details are as follows: the ground film is a white plastic film with a width of 1.4m and a thickness of 0.01mm; the pre-seedling under-film sealing drug is a highly effective and low-residue 72% ethyl ester of atypsum (dosage is 3.0-4.5L / hm 2 , need to add water 750-900kg / hm 2 ); The drip irrigation tape is laid in a one-film double-tape mode, with a tape spacing of 80cm and a distance of 20cm from the edge of the film; the selected drip irrigation tape is an inner-embedded patch type drip irrigation tape with a patch spacing of 20cm and a flow rate controlled at 1.38-2.0L / h.

[0036] In the present invention, it is preferred that no-tillage is performed after corn harvest to achieve year-round coverage to prevent evaporation and wind erosion, thereby playing a role in conserving water and soil.

[0037] In the present invention, it is preferred that after corn is harvested, when spring wheat is rotated again, the old film is recovered and organic fertilizer 4.3-4.7 t / hm is applied as base fertilizer. 2 , further preferably 4.5t / hm 2 .

[0038] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0039] Example 1

[0040] A planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas comprises the following steps:

[0041] Planting system: Implement a two-year three-crop rotation of spring wheat-arrow pea→corn.

[0042] (1) Spring wheat planting:

[0043] Base fertilizer: After the first spring, apply slow-release nitrogen fertilizer 124kg / hm 2 , mixed with biochar 14.5t / hm2 and attapulgite clay 29.5kg / hm 2 .

[0044] Tillage depth: 15cm.

[0045] Sowing: March 20, using micro-ridge sowing technology, row spacing 14cm, sowing rate 445kg / hm 2 .

[0046] Field management: After sowing, shallow buried drip irrigation technology is used. The drip irrigation tape is buried 5cm below the surface, and water and fertilizer are applied simultaneously.

[0047] Harvest: Spring wheat is harvested after maturity, and the straw is crushed to 3 cm and returned to the field.

[0048] (2) Multiple cropping of arrow pea:

[0049] Sowing: Replant immediately after spring wheat harvest, row spacing 14cm, sowing rate 145kg / hm 2 .

[0050] Harvest: Harvest in frost season. After harvest, the straw is crushed to 3cm and returned to the field for mulch, so that the ground can be covered all year round to prevent evaporation and wind erosion.

[0051] (3) Corn planting:

[0052] Base fertilizer: After the spring of the second year, apply 250kg / hm2 of slow-release nitrogen fertilizer 2 , mixed with biochar 19.5t / hm 2 and attapulgite clay 44.5kg / hm 2 .

[0053] Tillage depth: 20cm.

[0054] Sowing: April 10, using wide and narrow row single seed precision sowing (wide row 69cm, narrow row 39cm), planting density 93850 plants / hm 2 ; Film covering, spraying, laying of drip irrigation tape, and integrated corn hole planting.

[0055] Harvest: After the corn is harvested, no tillage is required and the ground is covered with straw to prevent evaporation and wind erosion.

[0056] (4) Recycle the old film and rotate spring wheat according to step (1), and apply organic fertilizer 4.3t / hm2 as base fertilizer 2 .

[0057] Example 2

[0058] A planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas comprises the following steps:

[0059] Planting system: Implement a two-year three-crop rotation of spring wheat-arrow pea→corn.

[0060] (1) Spring wheat planting:

[0061] Base fertilizer: After the first spring, apply slow-release nitrogen fertilizer 126kg / hm 2 , mixed with biochar 15t / hm 2 and attapulgite clay 30kg / hm 2 .

[0062] Tillage depth: 18cm.

[0063] Sowing: March 15, using micro-ridge sowing technology, row spacing 15cm, sowing rate 450kg / hm 2 .

[0064] Field management: After sowing, shallow buried drip irrigation technology is used. The drip irrigation tape is buried 8cm below the surface, and water and fertilizer are applied simultaneously.

[0065] Harvest: Spring wheat is harvested after maturity, and the straw is crushed to 4 cm and returned to the field.

[0066] (2) Multiple cropping of arrow pea:

[0067] Sowing: Replant immediately after spring wheat harvest, row spacing 15cm, sowing rate 150kg / hm 2 .

[0068] Harvest: Harvest in frost season. After harvest, the straw is crushed to 4 cm and returned to the field for mulch, so that the surface can be covered all year round to prevent evaporation and wind erosion.

[0069] (3) Corn planting:

[0070] Base fertilizer: After the spring of the second year, apply slow-release nitrogen fertilizer 252kg / hm 2 , mixed with biochar 20t / hm 2 and attapulgite clay 45kg / hm 2 .

[0071] Tillage depth: 25cm.

[0072] Sowing: April 15, using wide and narrow row single seed precision sowing (wide row 70cm, narrow row 40cm), planting density 93750 plants / hm 2 ; Film covering, spraying, laying of drip irrigation tape, and integrated corn hole planting.

[0073] Harvest: After the corn is harvested, no tillage is required and the ground is covered with straw to prevent evaporation and wind erosion.

[0074] (4) Recycle the old film and rotate spring wheat according to step (1), and apply organic fertilizer 4.5t / hm2 as base fertilizer2 .

[0075] Example 3

[0076] A planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas comprises the following steps:

[0077] Planting system: Implement a two-year three-crop rotation of spring wheat-arrow pea→corn.

[0078] (1) Spring wheat planting:

[0079] Base fertilizer: After the first spring, apply slow-release nitrogen fertilizer 128kg / hm 2 , mixed with biochar 15.5t / hm 2 and attapulgite clay 30.5kg / hm 2 .

[0080] Tillage depth: 20cm.

[0081] Sowing: March 25, using micro-ridge sowing technology, row spacing 16cm, sowing rate 455kg / hm 2 .

[0082] Field management: After sowing, shallow buried drip irrigation technology is used. The drip irrigation tape is buried 10cm below the surface, and water and fertilizer are applied simultaneously.

[0083] Harvest: Spring wheat is harvested after maturity, and the straw is crushed to 5 cm and returned to the field.

[0084] (2) Multiple cropping of arrow pea:

[0085] Sowing: Replant immediately after spring wheat harvest, row spacing 16cm, sowing rate 155kg / hm 2 .

[0086] Harvest: Harvest in frost season. After harvest, the straw is crushed to 5cm and returned to the field for mulch, so that the ground can be covered all year round to prevent evaporation and wind erosion.

[0087] (3) Corn planting:

[0088] Base fertilizer: After the spring of the second year, apply slow-release nitrogen fertilizer 254kg / hm 2 , mixed with biochar 20.5t / hm 2 and attapulgite clay 45.5kg / hm 2 .

[0089] Tillage depth: 30cm.

[0090] Sowing: April 5, using wide and narrow row single seed precision sowing (wide row 71cm, narrow row 41cm), planting density 93550 plants / hm 2; Film covering, spraying, laying of drip irrigation tape, and integrated corn hole planting.

[0091] Harvest: After the corn is harvested, no tillage is required and the ground is covered with straw to prevent evaporation and wind erosion.

[0092] (4) Recycle the old film and rotate spring wheat according to step (1), and apply organic fertilizer 4.7t / hm2 as base fertilizer 2 .

[0093] Example 4

[0094] This experiment adopted a randomized block design and took spring wheat-arrow pea→maize (W-CV→M) as the research object.

[0095] The main area was treated with three soil conditioner types: attapulgite clay (A), biochar (B), and no conditioner (C);

[0096] The split area was divided into 2 types of nitrogen fertilizers: traditional chemical nitrogen fertilizer (T) and slow-release nitrogen fertilizer (S);

[0097] There were two nitrogen application levels in the fissure zone: 30% reduction of local customary nitrogen application (N1) and local customary nitrogen application (N2).

[0098] Taking the traditional wheat-corn rotation system (no soil conditioners, only traditional chemical nitrogen fertilizers) as the control, a total of 12 treatments, including N1TA, N1TB, N1TC, N1SA, N1SB, N1SC, N2TA, N2TB, N2TC, N2SA, N2SB and N2SC, were set up with 3 replications and 36 plots.

[0099] The experiment started in 2022. Soil organic carbon and total nitrogen were collected after corn harvest in 2023. The calculation formulas of soil carbon and nitrogen storage are shown in (1) and (2):

[0100] SCS=SOC content ×BD×H×10 -1 (1);

[0101] SNS=NT content ×BD×H×10 -1 (2);

[0102] SCS and SNS represent soil carbon storage (mg·ha -1 ) and soil nitrogen storage (mg·ha -1 ), SOC content and NT content Represents SOC content (g kg -1 ) and soil total nitrogen content (g·kg -1 BD is the soil bulk density (g·cm -3 ).

[0103] Test results:

[0104] like Figure 1 As shown in the results, the application of soil conditioners (biochar and attapulgite clay) combined with slow-release nitrogen fertilizer significantly increased the soil organic carbon storage in the green manure rotation system. Among them, the slow-release nitrogen fertilizer combined with biochar had the best effect on improving soil organic carbon storage, and the average soil carbon storage of N1SB and N2SB increased by 7.41% and 10.97% compared with the control treatment (N2TC). Similarly, the combined application of slow-release nitrogen fertilizer and biochar significantly increased soil nitrogen storage. The soil nitrogen storage of N1SB and N2SB treatments was still higher than that of the control treatment, increasing by 56.95% and 61.36%, respectively, indicating that the combined application of slow-release nitrogen fertilizer and biochar can still significantly enhance the soil's carbon and nitrogen retention capacity under the condition of reducing nitrogen fertilizer by 30%.

[0105] Example 5

[0106] The experiment adopted a double sequence design.

[0107] The main area of ​​the spring wheat experiment was treated with three types of soil conditioners: biochar (15 t·hm -2 ), attapulgite clay (30kg·hm -2 ), no conditioner was applied; two types of nitrogen fertilizer were applied to the split area: traditional chemical nitrogen fertilizer (urea N: P2O5: K2O = 46: 0: 0) and slow-release nitrogen fertilizer (slow-release blended fertilizer N: P2O5: K2O = 26: 20: 0); two nitrogen application levels were applied to the split area: local customary nitrogen application rate (180 kg·hm -2 ) and local customary nitrogen application reduction by 30% (126 kg·hm -2 ).

[0108] The main area of ​​the corn experiment was treated with three soil conditioner types: biochar (application rate: 20 t·hm -2 ), attapulgite clay (application amount: 45kg·hm -2 ), no conditioner was applied; two types of nitrogen fertilizer were applied to the split area: traditional chemical nitrogen fertilizer (urea N: P2O5: K2O = 46: 0: 0) and slow-release nitrogen fertilizer (slow-release blended fertilizer N: P2O5: K2O = 28: 17: 0); two nitrogen application levels were applied to the split area: local customary nitrogen application rate (360 kg·hm -2 ), local customary nitrogen application reduction by 30% (252kg·hm -2 ).

[0109] The experiment will start in 2022, and after the corn harvest in 2023, sampling and measurement of various indicators will be carried out according to Table 1.

[0110] Table 1 Sampling time and determination method of each index

[0111]

[0112]

[0113] Test results:

[0114] like Figure 2 As shown in the figure, the combined application of slow-release nitrogen fertilizer and soil conditioner significantly reduced soil bulk density and soil temperature, thereby improving soil water holding capacity; at the same time, it significantly reduced soil electrical conductivity and salt content, effectively curbed soil salinization, and provided an excellent soil microenvironment for crop growth. Among them, the effect of biochar combined with slow-release nitrogen fertilizer on improving soil quality is more prominent ( Figure 2 a). The effect of combined application of slow-release nitrogen fertilizer and soil conditioner on soil carbon and nitrogen storage is mainly controlled by soil bulk density, carbon and nitrogen turnover enzyme activity and changes in microbial biomass carbon and nitrogen ( Figure 2 b).

[0115] One of the main ways for the soil to fix carbon and nitrogen in the integrated green manure rotation system is that the coupling effect of the slow-release nitrogen fertilizer combined with soil conditioners improves the soil water and heat conditions and reduces the soil carbon-nitrogen ratio. It significantly increases the soil urease activity and reduces the soil nitrate and nitrite reductase activities, inducing the soil to produce a "positive excitation" effect and inhibiting the emission of soil greenhouse gases, thereby reducing the loss of soil carbon and nitrogen reserves. Figure 3 shown.

[0116] Another major pathway is that nitrogen fertilizer reduction increases the sensitivity of slow-release nitrogen fertilizer combined with soil conditioners to soil carbon and nitrogen storage capacity. The slow-release nitrogen fertilizer combined with soil conditioners in the nitrogen reduction system significantly increases soil microbial biomass carbon and nitrogen, soil nitrate nitrogen and ammonium nitrogen than the non-nitrogen reduction system. It can be seen that nitrogen reduction to alleviate the "nitrogen barrier" of leguminous green manure in a high nitrogen environment is another core mechanism for the integrated green manure rotation system with soil conditioners to enhance soil carbon fixation and nitrogen conservation. Figure 4 shown.

[0117] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A planting method for cultivating soil carbon and nitrogen pools in arid irrigation areas, characterized in that: A two-year three-crop planting system of spring wheat-arrow pea→corn is implemented in arid irrigation areas; the spring wheat and corn use slow-release nitrogen fertilizer as base fertilizer, and are mixed with biochar and / or attapulgite clay.

2. The planting method according to claim 1, characterized in that: The spring wheat is fertilized with slow-release nitrogen fertilizer 124-128 kg / hm 2 , mixed with biochar 14.5-15.5t / hm 2 and / or attapulgite clay 29.5-30.5kg / hm 2 .

3. The planting method according to claim 1, characterized in that: The corn is fertilized with slow-release nitrogen fertilizer 250-254 kg / hm 2 , mixed with biochar 19.5-20.5t / hm 2 and / or attapulgite clay 44.5-45.5kg / hm 2 .

4. The planting method according to any one of claims 1 to 3, characterized in that: The spring wheat and corn are fertilized with basal fertilizer, biochar and / or attapulgite clay and then the land is tilled and prepared, with the tillage depth being 15-20 cm in the spring wheat season and 20-30 cm in the corn season.

5. The planting method according to claim 1, characterized in that: The spring wheat was sown in mid-to-late March using micro-ridge sowing technology, with a row spacing of 14-16 cm and a sowing rate of 445-455 kg / hm2. 2 .

6. The planting method according to claim 1, characterized in that: The arrow pea is planted after wheat is harvested, with a row spacing of 14-16 cm and a sowing rate of 145-155 kg / hm2. 2 .

7. The planting method according to claim 1, characterized in that: The corn was sown in early to mid-April, using wide and narrow row single seed precision sowing, with wide row spacing of 69-71 cm, narrow row spacing of 39-41 cm, and planting density of 93550-93850 plants / hm2. 2 .

8. The planting method according to claim 1, characterized in that: The corn is planted in an integrated manner including film covering, spraying pesticides, laying drip irrigation tapes, and corn hole sowing.

9. The planting method according to claim 1, characterized in that: After the spring wheat and arrowroot peas are harvested, the straw is returned to the fields, and after the corn is harvested, the field is not tilled, so that the ground is covered all year round.

10. The planting method according to claim 1, characterized in that: After the corn is harvested, when it is rotated to spring wheat again, 4.3-4.7t / hm2 of organic fertilizer is applied as base fertilizer 2 .

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