CN116076212A - A method of biogas slurry returning to field - Google Patents

Abstract

The invention relates to the technical field of resource utilization of agricultural waste, in particular to a method for returning biogas slurry to fields. The biogas slurry returning method provided by the present invention is divided into two steps: the biogas slurry returning to the field during the soil environment improvement period and the biogas slurry returning to the field during the corn planting period. The biogas slurry was returned to the field during the improvement period of the soil environment, and the simultaneous return of straw and biogas slurry was adopted. When the biogas slurry is returned to the field during the corn planting period, the biogas slurry is applied at the small bell mouth stage, the big bell mouth stage, the tasseling stage and the grain filling stage of the corn growth period. The field returning method provided by the invention can obviously improve the field soil environment, reduce the use of chemical fertilizers, and increase the yield of crops during the process of returning the biogas slurry to the field.

Description

A method of biogas slurry returning to field

technical field

The invention relates to the technical field of resource utilization of agricultural waste, in particular to a method for returning biogas slurry to fields.

Background technique

Soil fertility is the basis and primary guarantee for high grain yield. Fertilizer is known as the "grain" of grain. Fertilization not only increases crop yield, but also is an important way to improve soil fertility. The use of chemical fertilizers is a major achievement in China's agricultural production, especially grain production. According to statistics, 40% of my country's grain production comes from the increase in chemical fertilizer production. Behind the continuous increase in grain production is the continuous increase in chemical fertilizer consumption. Long-term application of chemical fertilizers has caused a series of hazards to the soil, such as long-term excessive application of chemical fertilizers, causing soil structure damage, compaction, acidification, nutrient imbalance, excessive heavy metals, etc. In recent years, with the increasing emphasis on the environment, the amount of chemical fertilizers has been gradually reduced.

As a large agricultural country, my country produces a large amount of straw every year, and returning straw to the field is an important utilization method and an important measure for sustainable agricultural development. Straw is mainly composed of lignin, cellulose, and hemicellulose. The content of carbon and nitrogen in the composition is high, and the moisture content is low, which leads to slow decomposition of straw and affects the sowing and growth of crops in the next season. It has become a technical bottleneck restricting the promotion and application of straw returning to the field. question. The autumn in northern my country is dry, the temperature is low, the moisture content of crop straw is lower, the degree of lignification and fibrosis is higher, and it is more difficult to rot and degrade when returning to the field.

As the consumption of meat, eggs and milk shows an upward trend, the animal husbandry industry develops rapidly. The annual output of livestock and poultry manure reaches 3.05 billion tons. According to the 70% collection coefficient, the amount of manure that needs to be processed every year reaches 2.135 billion tons, especially for large-scale farms. The manure contains a large amount of organic matter, nitrogen and phosphorus, etc., and the unreasonable application method can easily cause groundwater pollution. At the same time, biogas slurry is rich in amino acids, vitamins, proteins, gibberellins, auxins, sugars, nucleic acids, etc., and has dual functions of promoting crop growth and controlling disease occurrence. At present, biogas slurry is mainly used for flood irrigation and returning to the field, and the large amount is used, resulting in waste of resources. Long-term application leads to soil compaction, and the extension of biogas slurry irrigation time leads to excessive Cd and Pb content.

At present, the utilization of fertilizers is the main way of resource utilization of agricultural waste, among which returning straw to the field and making organic fertilizer from livestock and poultry manure is an important way, which is the basic guarantee to ensure the resource utilization of agricultural waste. Direct return to the field accounts for 39% of crop straw fertilizer utilization, but it has adverse effects on agricultural production. For example, it takes 3 years for the straw to completely decompose and decompose when it is directly returned to the field. The slow decomposition prevents the seeds from contacting the soil and affects the germination rate of the seeds. The emergence rate is low; the germs and insect eggs attached to the straw are implanted in the soil to reproduce and spread, causing the flood of diseases and insect pests.

At present, there is a lack of systematic research on the appropriate dosage and concentration of biogas slurry in the process of synergistic returning of biogas slurry and straw to the field at home and abroad, and the impact on soil environmental quality and crop yield is still unclear. Therefore, it is an urgent problem to develop a synergistic return method of biogas slurry and straw that can increase soil nutrients, reduce bulk density, optimize microbial community structure, promote biogas slurry consumption, reduce chemical fertilizer application, improve soil moisture, and ensure crop yield.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a method for returning biogas slurry to fields.

The biogas slurry returning method provided by the present invention is divided into two steps: biogas slurry returning to the field during the soil environment improvement period and biogas slurry returning to the field during the corn planting period, specifically including the following steps:

(1) Biogas slurry returning to the field during the soil environment improvement period adopts the method of synchronously returning straw and biogas slurry to the field, crushing corn stalks and root stubbles to a length of 3-5 cm and spreading them evenly in the field, and at the same time removing the stubble of weeds and rhizomes in the field soil After collection, the amount of straw returned to the field is 2.5-3 tons/mu; for the first rotary tillage operation, the broken straw scattered on the field is rotary-tilled to the plow layer soil, and the plowing depth is 20-25cm; the biogas slurry is evenly sprayed On the surface of the field, the amount of biogas slurry sprayed is 20-30 tons/mu; when the soil moisture in the field is saturated, the second rotary tillage is carried out, and the depth of rotary tillage is 10-15cm; 6 months;

(2) The biogas slurry is returned to the field during the corn planting period. After the corn is planted, 5-6 tons/mu of biogas slurry is applied in the small bell-mouth stage of corn growth, and 6-8 tons/mu of biogas slurry is applied in the big bell-mouth stage of corn growth. Apply biogas slurry 8-10 tons/mu, and apply biogas slurry 5-6 tons/mu during the grouting period.

Further, 6-7kg/mu of nitrogen fertilizer, 3-4kg/mu of phosphorus fertilizer and 3-4kg/mu of potassium fertilizer are applied in the field before corn planting.

Further, 5-7 kg/mu of potassium dihydrogen phosphate was applied during the small trumpet-mouth stage of corn growth.

Further, the biogas slurry is pig farm wastewater treated by UASB anaerobic reactor.

Compared with prior art, advantage and beneficial effect of the present invention are:

The method for synchronously returning straw and biogas slurry to the field provided by the present invention can solve the problems of large amount of corn straw after harvesting and difficulty in handling and transportation in the northern region; combined with biogas slurry returning to the field, the environmental risk of biogas slurry can be reduced, and the way to absorb biogas slurry can be increased .

The invention realizes simultaneous returning of straw and biogas slurry to the field, and improves the poor soil moisture after corn harvest in autumn in the northern region through the application of biogas slurry. The air is not easy to invade the soil and accelerate the degradation of straw in the soil. The biogas slurry returning method of the present invention can significantly improve soil fertility, especially improve soil bulk density and aggregate structure, increase soil air permeability, enrich soil microbial species and quantity, improve microbial activity, accelerate soil micro-ecological cycle, and increase soil organic matter, Nutrient content such as nitrogen, phosphorus and potassium. The present invention returns the biogas slurry to the field respectively in the soil improvement period and the crop planting period, and can obviously increase the yield of crops through tests.

Detailed ways

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

The following items should be paid attention to in the application process of the present invention: 1. Machinery selection: the straw returning machine should have a good crushing function, and mix the straw with the soil after crushing, so as to play the role of heat preservation, moisture conservation, loosening and ventilation. 2. Biogas slurry returning device: place the submersible sewage pump at the bottom of the storage pond, set a check valve above the submersible sewage pump, connect the check valve with the liquid inlet pipe, connect the main pipe with the liquid inlet pipe, and install it on the main pipe The quick pressure relief valve and gate valve on the road are connected to the main pipeline with several branch pipelines, and the main pipeline or branch pipelines are connected to the water outlet pile. The control valve installed on the water outlet pile is connected to the hose through the control valve. Sediment collection pipes are installed at the bottom of the low-lying part of the branch pipeline and at the corner at right angles, and exhaust valves are installed on the main pipeline and branch pipeline. 3. Biogas slurry standard: need to meet the "Agricultural Biogas Slurry" (GB/T 40750-2021) standard, that is, N+P ₂ O ₅ +K ₂ O≥8g/L and organic matter≥18g/L, pH value 5.5～8.5 between. 4. Balanced fertilization: According to the characteristics of different growth stages of corn, apply balanced nutrition to corn to improve the utilization rate of fertilizer. 5. Intertillage and weeding in time: Eliminate weeds that compete with crops for nutrition, improve soil air permeability, increase ground temperature and water storage and moisture conservation.

Example 1 Simultaneous return of straw and biogas slurry to the field

The Dabeinong (Yutian) Pig Scientific Experimental Center's demonstration base for breeding and breeding in Sun'anzi Village, Shijiuwo Town, Yutian County, Tangshan City, Hebei Province was selected. It is located at 117°37' east longitude and 39°29' north latitude. It has an eastern monsoon continental climate. Seasonal changes Meteorological factors such as light, temperature, rainfall, temperature and humidity change significantly, annual precipitation is 693mm, annual average temperature is 11.2°C, frost-free period is 193 days, annual sunshine is 2496.7 hours, annual average relative humidity is 48%, active accumulated temperature ≥10°C It is 2867°C. The soil type is fluvo-aquic soil with medium fertility level. The previous crop was the summer corn variety Jingyu 11, with a planting density of 4,500 plants/mu. Intertillage, irrigation and fertilization, and pest control were conducted in a timely manner.

The biogas slurry to be tested comes from the effluent of the UASB anaerobic reactor of the Dabeinong (Yutian) Pig Science Experimental Center. It is used after disinfection and precipitation. The raw material is pig manure. The fermentation time is 180 days, and there is no obvious foul smell. The physical and chemical properties of the biogas slurry are shown in Table 1. The biogas slurry composition analysis method is as follows: the pH value of the biogas slurry is measured by a calomel electrode pH meter (HJ1147-2020); the chemical oxygen demand (COD) is oxidized by potassium dichromate method (HG/T5964-2021); organic matter content in biogas slurry was determined by Shimadzu TOC-VCPH analyzer (NY/T1976-2010); total nitrogen content was determined by potassium persulfate oxidation-ultraviolet spectrophotometer (DB23/ T3310-2022); the total phosphorus content is determined by molybdenum antimony anti-ultraviolet spectrophotometry (HJ670-2013); the total potassium content is determined by flame photometry (NY/T1977-2010); the conductivity is determined by a precision conductivity meter (DDSJ- 318, Shanghai Leici) determination (HJ/T51-1999); content of arsenic, cadmium, lead, chromium and mercury in biogas slurry was determined by microwave digestion and inductively coupled plasma mass spectrometry (ICP-MS) (GB/T23349-2020 ).

Table 1 Physicochemical properties of biogas slurry

Synchronous returning method of straw and biogas slurry:

1) Use a crushing and spreading machine to crush corn stalks and root stubbles to 3-5 cm and evenly sprinkle them on the farmland. At the same time, collect the weeds and rhizomes in the soil after stubble removal. The amount of straw returned to the field is 2.5-3 tons/mu;

2) Use a large and medium-sized rotary tiller for the first rotary tillage operation, and rotate the straw scattered on the farmland to the soil of the plow layer, and the plowing depth is 20-25cm;

3) Use biogas slurry spraying equipment to spray anaerobic fermentation biogas slurry on the field and broken straw and root stubble. The amount of biogas slurry sprayed is 20-30 tons/mu; the surface water will dry naturally after 2-3 days without obvious water accumulation , when the soil moisture is saturated, carry out the second rotary tillage, and the depth of rotary tillage is 10-15cm;

4) Use the suppression device to comprehensively suppress and level the soil, and let it stand for 4 to 6 months. Realize the tight coverage of soil on straw and root stubble, and improve the degradation speed and effect of straw and root stubble;

The experiment will be carried out in October 2021. The biogas slurry will be returned to the field synchronously when the straw is crushed and plowed after the previous crop of corn is harvested, which is beneficial to soil moisture conservation and prevention of drought in early spring. During the experiment, a random block design was adopted, and the soil collected before the experiment was set to Control group, set 3 treatment groups after the test, CK-no fertilization control, NPK-application of chemical fertilizers (using nitrogen fertilizer is urea (N 46%), phosphorus fertilizer is double superphosphate (P ₂ O ₅ 46%), potassium fertilizer is sulfuric acid Potassium (K ₂ O 50%)), NPKSB-straw + biogas slurry (the total nitrogen content of biogas slurry and straw accounted for 60% of the total nitrogen), and biogas slurry returned to the field was insufficient. P and K were supplemented with chemical fertilizers, repeated 3 times, and the total There are 9 quadrats, each with an area of 1 mu (667m ² ), and the distance between two adjacent quadrats is 5m to prevent mutual influence. The nutrient supply of different treatment groups is shown in Table 2. The total amount of fertilization NP ₂ O ₅ -K ₂ O in NPK group and NPKSB group is 240-135-120kg/hm ² .

Table 2 Nutrient supply in different treatment groups

Before and after straw and biogas slurry were returned to the field simultaneously, soil samples were collected from the above treatment groups, and soil mechanical composition, soil physical and chemical properties, soil microbial quantity and soil enzyme activity were measured for the collected soil samples.

Soil sample collection: A total of 5 sampling points are set at the center point and 4 corner points of the 10m×10m sample plot, and the soil profile is excavated to remove surface impurities. Thoroughly mix the soil samples and use the quartering method to take 500-600g soil samples respectively, remove gravels, roots and other impurities with a diameter greater than 2mm, divide them into two parts, and take one part back to the laboratory for air-drying and grinding, and pass through a 100-mesh sieve to measure soil physical and chemical properties Characters; Another fresh soil sample was passed through a 100-mesh sieve, and refrigerated at 4°C to measure soil biological properties.

The soil mechanical composition was determined by the specific gravity method (NY/T1121.3-2006). Determination of the number of soil microorganisms: the number of viable soil microorganisms was counted by plate counting method (GB/T14643.4-2009); the number of soil bacteria was measured by plate counting method, and the medium was beef extract peptone medium (37°C, 3 days) (Xu Guanghui et al., Effects of glyphosate-resistant transgenic soybean (RRS) on the number and diversity of rhizosphere soil bacteria, 2009, Acta Ecologica Sinica); the number of soil fungi was sequenced using high-throughput sequencing (25°C, 3 days) (Zhang Tie et al. , the impact of the decomposition of fallen logs of common tree species in karst forests on the composition and distribution of soil fungal communities, 2022, Actinomyces Sinica); the number of soil actinomycetes was determined by the dilution plate separation and counting method (Yang Bin et al., the effect of microwave treatment on the separation of soil actinomycetes Impact, 2008, Journal of Applied Ecology).

Soil enzyme activity (URE) was measured by the phenol-sodium hypochlorite colorimetric method (Liu Shujuan et al., Soil urease activity at different vegetation succession stages in karst depressions in Northwest Guangxi, 2011, Acta Ecologica Sinica); soil dehydrogenase activity was measured by triphenyl chloride Determination of tetrazolium (TTC) method (ISO23573-1-2021); Soil acid phosphatase activity is determined by phenyl disodium phosphate colorimetric method (Li Yingfei et al., Comparison of soil acid phosphatase activity based on different methods, 2011, China Journal of Ecological Agriculture); Soil catalase activity was determined by potassium permanganate titration (Ningxia Chemical Analysis and Testing Association, 2020).

Determination of soil physical and chemical properties: soil organic matter was measured by potassium dichromate-sulfuric acid method (GB9834-1988); soil pH was measured by pH meter (NY/T1377-2007); soil total nitrogen was measured by semi-micro Kelvin method (GB7173- 1987); Soil bulk density was determined by ring knife method (NY/T1121.4-1996); Soil available phosphorus was extracted by sodium carbonate-molybdenum antimony colorimetric method (GB12297-1990); Soil available potassium ammonium acetate extraction-flame Photometer method (NY/T889-2004); Microbial carbon and nitrogen (MBC and MBN) using fumigation extraction method (GB/T39228-2020); Determination method of soil water-stable aggregate composition (NY/T1121.19-2008); Soil water content was determined by gravimetric method (LY/T1213-1999).

The soil mechanical composition measurement results are shown in Table 3. The clay content of different soil layers is about 40%, which shows that the soil viscosity in the test area is relatively large; the 0-20cm soil sand particles in the NPK group are 18.7% higher than the CK group, and the coarse silt particles are 43.0%. The fine silt content increased by 31.8%, and the clay content decreased by 3.2%; the 0-20cm soil sand, coarse silt and clay in the NPKSB group decreased by 15.1%, 7.4% and 9.6% respectively compared with the CK group, while the fine silt increased by 41.5% %; From the experimental results, the soil sand and clay in the NPKSB group showed a downward trend compared with the NPK group, transforming into more coarse silt and fine silt, which promoted the formation of a more rationalized soil mechanical composition to a certain extent; similarly, NPK group and NPKSB group had similar changes in soil mechanical composition between 20-40cm and 0-20cm, and NPKSB group had a better effect on improving soil texture.

Table 3 Mechanical composition of soil particles in different treatments (%)

The results of the determination of the number of soil microorganisms are shown in Table 4. After measurement, compared with the NPK group and the CK group, the amount of bacteria and fungi in the NPKSB group increased significantly, and the number of soil bacteria, fungi and actinomycetes in the NPKSB group increased by 58.5%, 29.9% and 17.4% respectively compared with the CK group, and the NPK group respectively Increased by 30.7%, 17.8% and 7.3%; the proportion of bacteria in the NPKSB group accounted for 78.6% of the total microorganisms, 1.7% and 5.3% higher than the NPK group and CK group respectively, the fungi and actinomycetes in the NPKSB group The ratio decreased, and the bacteria/fungi ratio increased to 45.43. A bacterial-dominated community was associated with a faster nitrogen cycle rate, accelerating nutrient activation; while fungi had a slow life cycle, resulting in more soil nitrogen retention and faster restoration of soil structure. And more resistant to drought. Therefore, the soil microbes in the NPKSB group were more active and accelerated the soil nutrient turnover rate.

Table 4 Different treatments on the number of soil microorganisms

The results of soil enzyme activity determination are shown in Table 5. The sucrase activity, urease activity, acid phosphatase activity and catalase activity in NPKSB group were higher than those in NPK group. Compared with NPK group and CK group, the activities of soil invertase, urease, acid phosphatase and catalase in NPKSB group increased by 50%, 43.0%, 64.0% and 40.0% respectively compared with CK group, and NPK group increased 37.8%, 26.7%, 33.4%, and 26.9%. Sucrase is closely related to soil organic matter, nitrogen and phosphorus content, microbial quantity and soil respiration intensity; the higher the urease activity, the stronger the soil organic nitrogen content and its transformation efficiency; the level of soil acid phosphatase activity directly affects the decomposition and conversion of organic phosphorus and the Effectiveness is an important index to evaluate the direction and intensity of phosphorus biotransformation; the activity of catalase indicates the degree of soil humification and the rate of organic matter conversion. The experimental results showed that the soil enzyme activity of the NPKSB group was significantly higher than that of the NPK group, so the effect of promoting soil organic matter and nitrogen and phosphorus conversion efficiency was significantly better than that of the NPK group, indicating that organic and inorganic fertilizers are more beneficial to soil health.

Table 5 Different treatments have different effects on soil enzyme activity

The test results of soil chemical properties are shown in Table 6. Compared with before returning to the field, the soil pH value of the NPKSB group decreased by 3.7%; the organic matter content of the NPK group only increased by 5.2%, while the NPKSB group increased by 16.5%, and the CK group did not change significantly; the total nitrogen content of the NPK group and the NPKSB group increased by 18.4% respectively and 43.7%, the total phosphorus content increased by 9.7% and 11.8% respectively, and the CK group decreased by 11.4%. NPK group.

Table 6 Effects of different treatments on soil chemical properties

See Table 7 for the soil bulk density of each treatment using the simultaneous returning of straw and biogas slurry to the field. Compared with the soil bulk density before returning to the field, the soil bulk density of the NPKSB group decreased by 9.4%, and that of the NPK group decreased by 6.3%. The previous soil bulk density decreased by 0.07g/cm ³ ; the results showed that the returning of straw and biogas slurry and the penetration of crop roots in the soil in the NPKSB group had the effect of increasing the organic matter content and reducing the soil bulk density, indicating that the effect of the NPKSB group was significantly better than that of the NPK group.

Table 7 Effects of different treatments on soil bulk density

See Table 8 for the composition of soil aggregates in each treatment using the simultaneous return of straw and biogas slurry to the field. Compared with the soil before returning to the field, the content of >5mm aggregates in the NPKSB group increased by 27.7%, while the content of 1-5mm, 0.5-1mm and 0.25-0.5mm aggregates did not change significantly; the NPK group >5mm, 1-5mm and The content of <0.25mm aggregates decreased by 5.0%, 11.2% and 8.4%, and the change of 0.5-1mm aggregates was not obvious, but the content of 0.25-0.5mm aggregates increased by 30.03%. The content of larger aggregates of 5 mm decreased, while the content of smaller aggregates of 0.5-1 mm, 0.25-0.5 mm and <0.25 mm increased, indicating that farmland cultivation without fertilization destroyed large aggregates and correspondingly increased the content of small aggregates. The results showed that the effect of NPKSB group was significantly better than that of NPK group and CK group.

Table 8 Effects of different treatments on soil aggregates

See Table 9 for the soil microbial carbon and nitrogen contents using the simultaneous returning of straw and biogas slurry to the field. Compared with the soil before returning to the field, the microbial carbon and nitrogen content of the NPKSB group increased, the soil microbial carbon content of the NPKSB group increased by 25.4%, and the NPK group only increased by 10.4%. Similarly, the soil microbial nitrogen content increased by 29.8% and 18.5% respectively; Compared with the control group, the soil microbial carbon content in the NPKSB group and the NPK group increased by 27.7% and 12.4%, respectively, and the microbial nitrogen content increased by 23.2%-34.9%; the microbial carbon and nitrogen content in the CK group decreased by 1.81% and 3.91% compared with the control group; The content of microbial carbon and nitrogen was significantly increased, indicating that the effect of the NPKSB group was significantly better than that of the NPK group.

Table 9 Effects of different treatments on soil microbial carbon and nitrogen content

Example 2 Biogas slurry returning to field during corn planting period

The corn planting method for the test: When the surface depth is 5cm and the ground temperature reaches 8-10℃, it is the suitable sowing time for corn. Summer corn is usually sown from April 20th to May 5th. Use full film seeder to sow, 2 to 3 seeds per hole, sowing depth 3 to 5cm, plant spacing 30 to 35cm, 4000 to 4500 seedlings per acre, that is, to suppress the sowing holes so that the seeds and the soil are tightly combined to prevent hanging seedlings and powder seed phenomenon. The tested corn was harvested in mid-October.

Method of returning biogas slurry to field during corn planting period: Plant corn in the second year after synchronous returning of straw and biogas slurry, and apply base fertilizer (N 6.4kg/mu, P ₂ O ₅ 3.6 kg/mu, K ₂ O 3.2kg/mu) evenly to ensure sufficient soil fertilizer supply capacity in the initial stage of crop growth, and the small trumpet-mouth period of corn (June 10) to return the biogas slurry to the field with sprinkler irrigation or drip irrigation, which can be combined with weeding Soil loosening, the application rate is 5-6 tons/mu; during the trumpet-mouth period of corn (July 10), return the biogas slurry to the field with sprinkler irrigation or drip irrigation, which can be combined with weeding and loosening soil and field pest management, and the application rate is 6-8 tons / mu, increase soil water content under drought conditions; corn tasseling period (August 15) drip irrigation biogas slurry can be combined with intertillage and pest management, the application rate is 8-10 tons / mu; corn filling period (end of August) Return the biogas slurry to the field with drip irrigation, and the application rate is 5-6 tons/mu. Among them, in addition to the application of biogas slurry in the small trumpet mouth period, 5-7kg/mu potassium dihydrogen phosphate needs to be applied to provide additional phosphorus and potassium elements for the soil, so as to avoid short plants and purple stems caused by the lack of phosphorus and potassium in corn. . See Table 10 for the physicochemical properties of the tested biogas slurry during the corn planting period.

Table 10 Physicochemical properties of biogas slurry tested during corn planting period

Test method: plant corn in the plots of CK group, NPK group, and NPKSB group in Example 1, and calculate the yield after the corn is harvested.

Yield measurement method of the test plot: measure and calculate the average row spacing of the yield measurement plot, randomly and continuously measure the width of 21 rows of corn and divide it by 20 to obtain the average single row spacing of the plot; measure and calculate the average row spacing of the yield measurement plot, and when necessary In the yield measurement plot, take 51 corn plants as a random continuous number, measure the length between the 51 corn plants and divide them by 50 to find the average plant spacing of the plot; calculate the average row spacing and the average plant spacing to calculate the number of plants per unit area; measure the average The number of ears per plant, that is, take 20 plants continuously, count the total number of ears and divide it by 20 to calculate the average number of ears per plant; measure the average number of grains per ear, that is, take 10 ears continuously, and count the number of grains per ear. Add and divide by 10 to calculate the average number of grains per ear of the ear; obtain the thousand-grain weight; calculate the yield per mu (number of plants per mu × average number of ears per plant × average number of grains per ear × thousand-grain weight)/1000000.

Table 11 Yield, number of grains per panicle, weight of 100 grains of different treatment groups

See Table 11 for the results of corn yield, number of grains per ear, and 100-grain weight using the simultaneous return of straw and biogas slurry to the field. Compared with the CK group, the NPK group and the NPKSB group corn yield increased by 73.7% and 99.5% respectively; similarly, the number of grains per spike increased by 23.9% and 36.2% respectively, and the hundred-grain weight increased by 36.2% and 48.2%. The biogas slurry returning method can significantly increase the yield of corn.

Claims (4)

1. The biogas slurry returning method is characterized by comprising two steps of returning biogas slurry in a soil environment improvement period and returning biogas slurry in a corn planting period, and specifically comprises the following steps of:

(1) The biogas slurry returning method adopts a method of synchronously returning straw and biogas slurry in the soil environment improvement period, corn straw and stubble are crushed to 3-5 cm in length and uniformly thrown into the field, meanwhile, weed rootstalk stubble in the field soil is collected after being cleared, and the straw returning amount is 2.5-3 tons/mu; carrying out first rotary tillage operation, namely rotary tillage is carried out on broken straws thrown on the field to plough layer soil, and the ploughing depth is 20-25 cm; uniformly spraying biogas slurry on the field surface, wherein the spraying amount of the biogas slurry is 20-30 tons/mu; carrying out secondary rotary tillage when the soil moisture of the field is in a saturated state, wherein the rotary tillage depth is 10-15 cm; comprehensively compacting and leveling soil, and standing for 4-6 months;

(2) After corn planting, applying 5-6 tons of biogas slurry to each mu in a small horn mouth period, applying 6-8 tons of biogas slurry to each mu in a large horn mouth period, applying 8-10 tons of biogas slurry to each mu in a male pulling period, and applying 5-6 tons of biogas slurry to each mu in a grouting period.

2. The biogas slurry returning method according to claim 1, wherein 6-7 kg/mu of nitrogenous fertilizer, 3-4 kg/mu of phosphate fertilizer and 3-4 kg/mu of potash fertilizer are applied to the field before corn planting.

3. The biogas slurry returning method according to claim 1, wherein the potassium dihydrogen phosphate is applied at a small bell mouth period of corn growth by 5-7 kg/mu.

4. The biogas slurry returning method according to claim 1, wherein the biogas slurry is pig farm wastewater treated by a UASB anaerobic reactor.