CN111066403A

CN111066403A - Synchronous emission reduction CH4And N2O and method for improving soil fertility

Info

Publication number: CN111066403A
Application number: CN201911191040.8A
Authority: CN
Inventors: 朱义族; 郑宁国; 李雅颖; 姚槐应
Original assignee: Ningbo Urban Environment Observation And Research Station-Nueors Chinese Academy Of Sciences; Institute of Urban Environment of CAS
Current assignee: Ningbo Urban Environment Observation And Research Station-Nueors Chinese Academy Of Sciences; Institute of Urban Environment of CAS
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2020-04-28
Anticipated expiration: 2039-11-28
Also published as: CN111066403B

Abstract

The invention belongs to the technical field of environmental protection and agricultural soil improvement, and particularly relates to synchronous emission reduction CH₄And N₂O and improving soil fertility. The method comprises the following steps: crushing straws, uniformly throwing the straws on the surface of a rice field, and ploughing the straws into soil; and (4) guiding water to soak the field by adopting a gradual flooding mode, and gradually increasing the water content in the soil of the rice field until the height of the water surface is 1-5 cm. The gradual flooding mode comprises the following steps: during field soaking, water is introduced for irrigation for 2-4 times, and the interval time of each water introduction for irrigation is 3-8 days.

Description

Synchronous emission reduction CH4And N2O and method for improving soil fertility

Technical Field

The invention belongs to the technical field of environmental protection and agricultural soil improvement, and particularly relates to synchronous emission reduction CH₄And N₂O and improving soil fertility.

Background

CH₄And N₂O is the main greenhouse gas discharged by the ecological system of the farmland, and the potential for increasing the temperature of the gas is CO ₂25 times and 298 times, the emission of large amounts of greenhouse gases destroys the ozone layer, increasing the risk of global warming. At the same time, CH is produced in the farmland soil under the influence of human activities₄And N₂The O emissions, up to 52% and 60%, respectively, have a significant impact on global climate change.

The rice field ecosystem is an important component of the agricultural ecosystem. Due to the special production management mode, the rice field becomes the greenhouse gas CH₄And N₂An important source of O. Research aiming at the greenhouse gas emission reduction measures of the rice field is numerous, and mainly focuses on the change of the irrigation mode. Different irrigation patterns cause differences in soil moisture changes, thereby causing differences in greenhouse gas emissions. Studies have shown that in CH₄And N₂O production has a significant "" this trade off "" relationship with emissions. Conventional irrigation (i.e. long term flooding) of N₂O is completely denitrified to N₂Reduce N₂O discharge, but long term flooding leaves the soil in an anaerobic environment for a long period of time, which would promote CH₄Generation and discharge of (d); deep water irrigation is carried out, the flooding depth of the paddy field is higher than the normal irrigation depth (2 cm) and reaches 5cm to 10 cm, and the deeper water blocks CH generated in the anaerobic environment₄Transmitting from bottom to top, reducing CH₄The emission is carried out, but the operation is complex, a large amount of water is needed, and the method is not an ideal emission reduction method; the water-saving irrigation mode comprises intermittent irrigation, irrigation and alternate sunning, although the air permeability of the soil is increased, the oxidation-reduction potential of the soil is improved, and CH is enabled₄Is inhibited, but the soil is alternately wet and dry in the phase N₂Peak periods of O production and emissions. Therefore, the greenhouse gas CH is applied to different irrigation modes₄And N₂The potential for O abatement, which is usually not the case, can only be balanced.

Straw is an excellent renewable biomass resource, and returning the straw to the field is also a yield increase measure for improving fertility of the soil which is generally regarded as important. The straw is returned to the field, so that the crop material is fully utilizedImprove soil fertility, improve soil structure, and reduce greenhouse gas N₂Potential for O emissions. Researches show that the high C/N ratio of crop straws enables the crop straws to assimilate more inorganic nitrogen in the decomposition process, reduces the substrate for nitrification and denitrification of soil, and further reduces N₂And O. However, straw is also soil CH₄One of the main raw materials is the climate change special committee (IPCC) between the United nations governments, and the increase of CH is caused by the returning of the rice field straws₄And (4) discharging.

Therefore, how to effectively realize the greenhouse gas CH in the paddy field₄And N₂The comprehensive emission reduction of O reduces the generation and emission of greenhouse gases to the maximum extent, and becomes a problem worthy of further research and solution.

Disclosure of Invention

The invention provides a simple rice field greenhouse gas N₂O and CH₄The management method for synchronously reducing emission and improving soil fertility not only effectively realizes the greenhouse gas CH in the rice field by combining straw returning with water management measures of gradually flooding₄And N₂And O is synchronously reduced, the soil fertility can be improved, the soil structure is improved, the resource utilization of the waste straws is realized, and the optimal effect is achieved.

One purpose of the invention is realized by the following technical scheme:

synchronous emission reduction CH₄And N₂A method of improving soil fertility comprising the steps of:

crushing straws, uniformly throwing the straws on the surface of a rice field, and ploughing the straws into soil; guiding water to soak the field by adopting a gradual flooding mode, and gradually increasing the water content in the soil of the rice field until the height of the water surface is 1-5 cm;

the gradual flooding mode comprises the following steps: during field soaking, water is introduced for irrigation for 2-4 times, and the interval time of each water introduction for irrigation is 3-8 days. The interval of water diversion can be gradually shortened.

During the field soaking and soil preparation before rice transplanting, straws are smashed and directly returned to the field and turned over for burying, and then water is introduced to soak the field in a gradual flooding mode, so that the water content in the soil of the rice field is gradually increased, and the rice field is prevented from being soakedThe anaerobic environment which is formed rapidly by directly flooding and field soaking is realized, thereby inhibiting the growth of methane bacteria and reducing CH₄Discharging of (3); the gradual increase of the soil moisture content is beneficial to the growth and activity of aerobic microorganisms, accelerates the effective decomposition of the straws and improves the release of nutrient substances, thereby improving the soil fertility.

Preferably, the straws are one or more of rice straws, corn straws, wheat straws and sorghum straws.

Preferably, the straws are crushed to the length of less than or equal to 2 cm. After being crushed, the straw decomposition is accelerated, and the anaerobic environment is avoided.

Preferably, the throwing amount of the straws is 1000-8000 kg/ha. The throwing amount of the straws on the surface of the rice field needs to be proper, the straw amount is too small, the emission reduction and fertility increasing effects are not obvious, but the straw amount is too large, an anaerobic environment is easy to form, the straws are the main body for generating methane, the straw amount is too large, and the methane emission is increased.

Preferably, when water is first drawn for irrigation, the water drawing amount is such that the soil humidity of the rice field is 50% -65%. The water demand for first water diversion and field soaking is appropriate, if the water quantity is excessive, an anaerobic environment is easily formed, CH is increased₄Discharging; if the water amount is too small, the environment of the rice field can not be denitrified by N₂O is N₂Will increase N₂And (4) discharging O.

Preferably, the field soaking time is 11-25 days. Under the condition of progressive flooding, the microbial biomass carbon in the soil is related to the field soaking time, and the content of the microbial biomass carbon increases along with the increase of the field soaking time.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the straw is returned to the field and combined with simple and easily-implemented water management measures of gradual flooding, so that the resource utilization of the straw is realized on the one hand; on the other hand, on the premise of meeting the water demand in the field, the greenhouse gas CH can be avoided₄And N₂The O emission amount has the defect of 'eliminating the longest of the O emission amount' in a conventional irrigation mode, so that the O emission amount and the O emission amount are synchronously reduced; finally, straw returning is combined with a gradual flooding mode at 11-2Within 5 days of field soaking, the soil fertility is effectively improved.

Drawings

FIG. 1 shows CH of CK-F and CK-IF in culture cycle in example 1₄Comparing the change of the discharge rate;

FIG. 2 shows CH of RS-F and RS-IF in culture cycle in example 1₄Comparing the change of the discharge rate;

FIG. 3 shows N in the culture period of CK-F and CK-IF in example 1₂Comparing the change of the O discharge rate;

FIG. 4 shows N in the culture period of RS-F and RS-IF in example 1₂Comparing the change of the O discharge rate;

FIG. 5 is a comparison of the cumulative amount of Global Warming Potentials (GWP) of greenhouse gases in culture cycles for CK-F, CK-IF, RS-F and RS-IF in example 1.

Detailed Description

The technical solutions of the present invention will be further described and illustrated below by means of specific examples and drawings, however, these embodiments are exemplary, the disclosure of the present invention is not limited thereto, and the drawings used herein are only for better illustrating the disclosure of the present invention and do not have a limiting effect on the scope of protection. Unless otherwise specified, the raw materials used in the following specific examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art.

Example 1

1.1 test materials

The soil to be tested is taken from a paddy field in suburbs of Ningbo northern Lung, the soil type is yellow soil, the soil is dried and crushed before the experiment, and impurities such as stones, roots and the like are picked out. Rice straws are selected, dried before testing, mechanically crushed and sieved by a sieve with the aperture of 2 mm.

1.2 test devices

The transparent serum bottle is purchased from Shanghai Jing Ansheng Biotech limited, and has the specification: 500 ml; gas chromatograph (Agilent7890A, usa).

1.3 Experimental procedures

1) Weighing 1800g of air-dried rice soil, uniformly mixing the rice soil and the air-dried rice soil, and subpackaging the mixture into 12 clean transparent serum bottles, wherein each serum bottle contains about 150g of rice soil;

2) setting applied straw treatment (RS, straw addition amount is 1% (m/m)) and no straw Contrast (CK), wherein different water diversion modes including direct flooding (F) and progressive flooding (IF) are set, and finally obtaining combination of 2 × 2 ═ 4 treatment levels (respectively: applying straws-direct flooding RS-F, applying straws-incremental flooding RS-IF, no straws-direct flooding CK-F and no straws-incremental flooding CK-IF), setting 3 times of treatment, placing the mixture in a soil incubator at 25 ℃ for pre-culturing for 3 days, and enabling the conditions such as soil temperature to be stable;

3) after the preculture was completed, CH produced in the soil before the addition of water was measured by gas chromatography₄And N₂O, then adding 180ml of ultrapure water directly to the RS-F and CK-F treated serum bottles so as to completely submerge the soil in the serum bottles (the height of the water layer is about 1cm), adding 50ml of ultrapure water uniformly to the RS-IF and CK-IF treated serum bottles (the water content of the soil is about 51.06%), and continuing to culture in a 25 ℃ soil incubator for 7 days; the CH was then determined as required for each treatment day 1, 4, 7₄And N₂O production, calculating the discharge rate;

4) after the greenhouse gas content was measured on day 7, 60ml of ultrapure water (soil moisture content about 96.37%) was further added to the RS-IF and CK-IF treated serum bottles, and the RS-F and CK-F treated groups were kept in a flooded state and placed in a 25 ℃ soil incubator for 7 days; the CH on days 1, 4 and 7 (i.e., days 8, 11 and 14) after the second addition of water was determined for each treatment as required₄And N₂O production, calculating the discharge rate;

5) after the greenhouse gas content was measured on day 14, 70ml of ultrapure water was continuously added to the RS-IF and CK-IF treated serum bottles to keep the soil completely submerged (water layer about 1cm), and the RS-F and CK-F treated groups were kept submerged and cultured in a 25 ℃ soil incubator for 7 days; the CH on days 1, 4 and 7 (i.e., days 15, 18 and 21) after the third addition of water was determined for each treatment as required₄And N₂O production, calculating the discharge rate;

6) finally obtaining the greenhouse gas CH in the whole culture period₄And N₂The discharge rate of O varies and accumulates.

FIG. 1 shows CH of CK-F and CK-IF₄Discharge Rate, FIG. 2 CH for RS-F and RS-IF₄The discharge rate, as can be seen in the figure, applying straw and direct flooding greatly accelerates CH₄But with progressive flooding to reduce CH₄The discharge rate of (d); FIG. 3 shows N of CK-F and CK-IF₂O discharge Rate, N for RS-F and RS-IF in FIG. 4₂O-discharge rate, it can be seen from the figure that application of straw helps to reduce N₂The discharge rate of O is not very remarkable, but the application of straw in combination with the gradual flooding can greatly reduce N₂The discharge rate of O and the effect are obvious. FIG. 5 shows CH of CK-F, CK-IF, RS-F and RS-IF₄And N₂Cumulative amount of O discharged by calculating CH₄And N₂Accumulation of O throughout the culture period, and the RS-IF (straw application and progressive flooding) treated CH was found₄、N₂The cumulative amount of O discharged is significantly less than RS-F treated, CH₄And N₂The amount of O reduction achieved 1/63 and 1/5, respectively, and the Global Warming Potential (GWP) of the RS-IF treatment for greenhouse gases was significantly lower than that of the other treatments, about 1/4 for the RS-F treatment.

After the above laboratory tests, further field tests were carried out.

Example 2

The test was conducted on a rice field in the lower village of the greenfield of northern area of Nibo, Zhejiang province, which had a history of rice planting over many years and had typical southern rice soil characteristics. The average temperature of the land for many years is 16.5 ℃, and the average precipitation per year is about 1480 mm. In 2019, in 9 months, the method adopts straw application as main treatment and adopts a flooding mode as auxiliary treatment to carry out plot experiments. Making high ridges in the field to divide the field into A, B, C, D four regions (each region has an area of about 6m × 6 m-36 m)²) The areas A and B are control groups without straw and are treated by direct flooding (A) and gradual flooding (B), and the areas C and D are treatment groups with straw and are treated by direct floodingFlooding (C) and gradually flooding (D).

Drying the rice straws harvested in the farmland before throwing, and mechanically crushing the rice straws until the length of the rice straws is less than or equal to 2 cm.

Uniformly scattering the dried and crushed rice straws to the surfaces of the areas C and D, wherein the scattering amount is 0.4kg/m²Ploughing and burying soil, leveling the field, wherein the area A and the area B are used as control groups, and ploughing and preparing soil in the same way; on the 1 st day, water diversion irrigation is carried out on the areas B and D to ensure that the field soil is in a fully wet state, the final soil water content is measured to be about 50.26 percent, water diversion irrigation is directly carried out on the areas A and C to a flooded state, and the height of a water layer is about 4 cm; water is introduced for irrigation on day 8, so that the fields in the area B and the area D are extremely wet, the water content reaches a saturated state, the water content is measured to be about 98 percent, and meanwhile, water lost due to natural evaporation is supplemented to the area A and the area C until the water layer is about 4 cm; and (4) on the 15 th day, irrigating the areas B and D by water diversion until the water layer is flooded, wherein the height of the water layer is about 4cm, and supplementing the areas A and C with water lost due to natural evaporation.

Greenhouse gases generated in the test cells were collected by static box method and brought back to the laboratory for CH determination by gas chromatograph of Agilent7890A, usa₄And N₂The concentration of O gas. The gas sampling time is as follows: collecting gas on

days

1, 4, 7, 10, 13, 17 and 21, sampling in parallel by each treatment, repeating each treatment for 4 times, wherein each sampling time is between 9-10 am. Final measurement calculates the CH of four cells₄And N₂The cumulative amount of O emitted and its global warming potential are shown in Table 1.

Table 1 CH of four test cells₄And N₂Cumulative amount of O discharged and global warming potential GWP thereof

	CH₄Cumulative amount (g/m)²)	N₂Cumulative amount of O (g/m)²)	Total GWP (g CO)₂/m²)
				Zone A	0.395	8.26	2471
Zone B	0.0310	8.95	2667
				Region C	29.4	3.84	1879
Region D	0.610	1.13	351

As can be seen, the field test results are the same as the laboratory test results, which indicate that the simple water management measures of straw returning to field and gradual flooding are adopted to reduce CH₄The emission amount is also obviously reduced by N₂Discharge of O to realize CH₄And N₂And (4) synchronously reducing emission.

Meanwhile, soil samples were collected by the five-point layout method on the 7 th, 14 th and 21 st days, respectively, for determining soil microbial biomass carbon, and the experimental results are shown in table 2.

TABLE 2 soil microbial biomass carbon (mg/kg dry soil) of four test plots during field steeping

	7day	14day	21day
				Zone A	1254±66	1460±69	1540±70
Zone B	1171±53	1252±74	1440±83
				Region C	1408±53	1583±72	1812±73
Region D	1357±48	1842±63	2454±79

As can be seen from Table 1, microbial biomass carbon increased significantly in the treatment of zone D (straw application coupled with incremental flooding) and was much higher than the other treatments at the final submersion at day 21. And although the area C (applied straw and directly flooded) is applied with the straw, the microbial biomass carbon of the area C has no obvious difference compared with a control group without the straw, which shows that the effect of the application of the straw on improving the soil fertility is smaller by the water management of the direct flooding. The results show that the treatment mode of applying the straws and combining with gradual flooding is favorable for improving the soil fertility, particularly prolonging the field soaking time, and the microbial biomass carbon is obviously increased.

The invention combines the straw returning field with the simple and easy water management measures of gradual flooding, so that the straw waste is utilized, and CH is realized₄And N₂O is synchronously reduced, and the soil fertility is improved.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims

1. Synchronous emission reduction CH₄And N₂A method for increasing soil fertility, comprising the steps of:

the gradual flooding mode comprises the following steps: during field soaking, water is introduced for irrigation for 2-4 times, and the interval time of each water introduction for irrigation is 3-8 days.

2. The synchronous emission reduction CH of claim 1₄And N₂O and improving soil fertility, which is characterized in that the straws are one or more of rice straws, corn straws, wheat straws and sorghum straws.

3. According to claimSynchronous emission reduction CH as set forth in claim 1₄And N₂O and improving soil fertility, which is characterized in that the straws are crushed to a length of less than or equal to 2 cm.

4. The synchronous emission reduction CH of claim 1₄And N₂O and improving soil fertility, which is characterized in that the throwing amount of the straws is 1000-8000 kg/ha.

5. The synchronous emission reduction CH of claim 1₄And N₂O and improving soil fertility, characterized in that, when irrigating by water diversion for the first time, the water diversion amount is to make the soil humidity of paddy field 50% -65%.

6. The synchronous emission reduction CH of claim 1₄And N₂O and improving soil fertility, which is characterized in that the field soaking time is 11-25 days.