CN108450108B

CN108450108B - Method for determining semi-quantitative irrigation amount of biogas slurry of double-cropping cane shoots and irrigation method

Info

Publication number: CN108450108B
Application number: CN201810112290.7A
Authority: CN
Inventors: 陈贵; 程旺大; 张红梅; 沈亚强
Original assignee: Jiaxing Academy Of Agricultural Sciences Zhejiang Province
Current assignee: JIAXING ACADEMY OF AGRICULTURAL SCIENCES
Priority date: 2018-02-05
Filing date: 2018-02-05
Publication date: 2020-10-13
Anticipated expiration: 2038-02-05
Also published as: CN108450108A

Abstract

The invention relates to a method for determining semi-quantitative irrigation quantity of biogas slurry of double-cropping water bamboo and an irrigation method, belonging to the technical field of agricultural production. The method for irrigating the double-cropping water bamboo by using the semi-quantitative biogas slurry provided by the invention is characterized in that three biogas slurry irrigation processes are respectively set in autumn and spring, and the operation is simple, the growth inhibition rate of the water bamboo is low, the yield is high and the quality is high through the measurement of ammonium nitrogen concentration in the biogas slurry, the biogas slurry irrigation amount and the setting of field water level before and after irrigation in each irrigation process.

Description

Method for determining semi-quantitative irrigation amount of biogas slurry of double-cropping cane shoots and irrigation method

Technical Field

The invention relates to the technical field of agricultural production, in particular to a method for determining semi-quantitative irrigation quantity of biogas slurry of double-cropping water bamboo and an irrigation method.

Background

The growth of ecological cycle agriculture in combination with cultivation is a key measure for solving the sustainable and mutually coordinated development of livestock and poultry breeding and agricultural production in China, and is also a main way for solving the current environmental pollution problem of agriculture and rural areas in China. Various planting and breeding combination modes such as 'livestock-biogas manure-grain', 'livestock-organic manure-grain', livestock-biogas manure-dish and the like are actively promoted by government agencies all over the country. The biogas slurry is an accessory product of biogas generated by livestock and poultry breeding or planting waste anaerobic fermentation, is a high-quality nutrient material, contains abundant macronutrient, secondary nutrient and micronutrient elements and multiple nutrient substances, and has a nitrogen retention rate of over 90 percent. Therefore, in agricultural production, biogas slurry is generally used as a high-quality liquid nitrogen fertilizer to be irrigated and applied to farmland vegetable fields, forest lands and the like.

Zizania latifolia is aquatic vegetable of perennial root of Zizania of Gramineae, and is rich in various nutrients such as protein and carbohydrateThe vegetable dish is fresh and tender in texture, sweet in taste and the like, is regarded as a good product in vegetables and is popular with the masses. The wild rice shoots are widely planted in China, particularly the planting area is continuously enlarged for more than 10 years, and the planting area of the wild rice shoots is about 7 kilohm at present in China². The wild rice stem needs to absorb a large amount of water and nutrients in the whole growth period. The biogas slurry used as high-quality liquid nitrogen fertilizer for irrigating the water bamboo can not only provide water and a flooding environment required by the growth of the water bamboo, but also meet the requirements of the water bamboo on nitrogen and other nutrient elements. In actual agricultural production, some farmers have begun to irrigate zizania with biogas slurry instead of part or all of the nitrogen fertilizer. However, most biogas digesters in China currently adopt a normal-temperature anaerobic fermentation mode, so that the fermentation temperature and degree are greatly influenced by the environmental temperature. In addition, the nitrogen concentration in the fermented biogas slurry is greatly changed by factors such as the nitrogen content difference of different batches of feeds, the nitrogen content difference of livestock and poultry manure, the water-manure-urine ratio difference of the fermented liquid, the difference of the fermentation time and the like. Many research reports show that the content of the methane liquid in different batches in the same methane tank and the content of the methane liquid in different methane tanks are larger in increasing range.

It is known that ammonium nitrogen is the most important inorganic nitrogen for crop growth besides nitrate nitrogen, and plants can directly participate in nitrogen circulation and substance metabolism in vivo after absorbing ammonium nitrogen. However, too high a concentration of ammonium nitrogen is likely to poison crops, and the crops are slow to grow in the mild case and die in the severe case. In a laboratory hydroponic system, ammonium poisoning effects are produced by a concentration of 5mmol/L (i.e., 90mg/L) of ammonium nitrogen even under other nutrient-rich conditions. The method brings great difficulty to biogas slurry agriculture, and the situation that the growth of the zizania latifolia is inhibited due to high nitrogen concentration and large irrigation amount in the biogas slurry can be frequently encountered by zizania latifolia farmers in the process of irrigating the zizania latifolia with the biogas slurry, so that the positivity of applying the biogas slurry by the zizania latifolia farmers is hindered to a great extent. The prior art does not provide a normative method for irrigating zizania latifolia with biogas slurry efficiently.

Disclosure of Invention

The invention aims to provide a method for determining semi-quantitative irrigation quantity of biogas slurry of double-cropping water bamboo and an irrigation method. The determination method provided by the invention is simple, the determined irrigation amount is safe for growth of the cane shoots, the yield of the cane shoots can be increased, and the irrigation efficiency can be improved.

The invention provides a method for determining semi-quantitative irrigation quantity of biogas slurry of double-cropping water bamboo, which comprises the following steps:

measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the biogas slurry through a formula shown in formula I:

wherein the unit of the irrigation amount of the biogas slurry is t, the unit of the application amount (pure) of the nitrogen fertilizer is kg N/mu, and the unit of the concentration of ammonium nitrogen in the biogas slurry is mg/L.

The invention also provides a double-cropping water bamboo irrigation method based on the determination method of the technical scheme, which comprises the following steps:

1) transplanting water bamboo from late 6 months to early 7 months, extracting new leaves of more than 95% of the transplanted plants, measuring the ammonium nitrogen concentration in the biogas slurry when tillering buds appear, setting the application amount of the first nitrogen fertilizer to be 10.5 kgN/mu, determining the irrigation amount of the first biogas slurry according to a formula shown in a formula I, irrigating the first biogas slurry, and controlling the field water level to be 15-20 cm after the irrigation;

2) in the middle ten 9 months, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the second biogas slurry by using the application amount of the second nitrogen fertilizer as 9 kgN/mu; irrigating with secondary biogas slurry, wherein the field water level is 15-20 cm after irrigation;

3) in the middle 10 th month, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the third biogas slurry by using the application amount of the third nitrogen fertilizer as 10.5 kgN/mu; irrigating with the third biogas slurry, wherein the field water level is more than 20cm after irrigation;

4) in the second year, when the wild rice stem plants grow to 33-37 cm, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the fourth biogas slurry by taking the fourth nitrogen fertilizer application amount as 11 kgN/mu; irrigating with fourth biogas slurry, wherein the field water level is 13-17 cm after irrigation;

5) in the middle ten days of 5 months, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the fifth biogas slurry by using the application amount of the fifth nitrogen fertilizer as 9.5 kgN/mu; irrigating with fifth biogas slurry, wherein the field water level is 15-20 cm after irrigation;

6) measuring the concentration of ammonium nitrogen in the biogas slurry from the last ten days of 5 months to the last ten days of 6 months, and determining the irrigation amount of the sixth biogas slurry by taking the application amount of the sixth nitrogen fertilizer as 11kg N/mu; and irrigating with sixth biogas slurry, wherein the field water level is more than 20cm after irrigation.

Preferably, the first biogas slurry irrigation is carried out 25-35 d after the transplanting in the step 1).

Preferably, the fourth biogas slurry irrigation is performed in the step 4) from late 3 th to last 4 th of month.

Preferably, before each biogas slurry irrigation, the method also comprises stabilizing and heightening the field ridge.

Preferably, the ridge is more than 35cm in height.

Preferably, when the growth condition of the wild rice stem is poor, the method further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer.

Preferably, the zizania latifolia plants are irrigated without alignment of the biogas slurry every time the zizania latifolia plants are irrigated.

Preferably, before the biogas slurry is irrigated, the field water level before the irrigation is determined by a formula shown in a formula II:

wherein the unit of the field water level before irrigation is cm/mu, and the unit of the biogas slurry irrigation amount is t/mu.

Preferably, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, and the plant spacing of the zizania latifolia is 45-50 cm.

The invention provides a method for determining semi-quantitative irrigation quantity of biogas slurry of double-cropping water bamboo. The determination method provided by the invention firstly detects the concentration of ammonium nitrogen in the biogas slurry, and then obtains the irrigation amount of the biogas slurry through a determination formula. By utilizing the determination method, the obtained irrigation amount is closer to the nitrogen nutrient amount required by growth of the water bamboo, the water bamboo plants grow normally after irrigation, the yield is not influenced, and the quality is improved. The determination method provided by the invention can effectively avoid the problems of cane shoot growth inhibition, yield reduction and the like caused by blind irrigation of biogas slurry; the positivity of the biogas slurry applied by cane shoot farmers is promoted, the application amount of chemical nitrogen fertilizers and phosphorus and potassium is reduced, and the development of planting and breeding combined ecological cycle agriculture is promoted.

Drawings

FIG. 1 is a graph showing the effect of biogas slurry dosage on yield;

FIG. 2 is a comparison result chart of yield of Zizania latifolia under different treatment methods provided in example 4 of the present invention;

FIG. 3 is a graph showing the cumulative comparison of the dry matter on the aerial parts of zizania latifolia plants under different treatment methods provided in example 4 of the present invention;

FIG. 4 is a diagram showing the comparison of plant heights of zizania latifolia plants under different treatment methods provided in example 4 of the present invention;

FIG. 5 is a comparison result chart of leaf length of zizania latifolia plants under different treatment methods provided in example 4 of the present invention;

FIG. 6 is a graph showing the comparison result of ammonium nitrogen in water of Zizania latifolia field surface under different treatment methods provided in example 4 of the present invention.

Detailed Description

wherein the unit of the irrigation amount of the biogas slurry is t, the unit of the application amount of the nitrogen fertilizer is kg N/mu, and the unit of the concentration of ammonium nitrogen in the biogas slurry is mg/L.

The invention can treat NH in the biogas slurry₄ ⁺The method for measuring the concentration of-N is not particularly limited, and NH well known to those skilled in the art is used₄ ⁺the-N concentration measurement product can be used for measuring, for example, NH in the biogas slurry is determined by utilizing a rapid ammonium nitrogen detection product in water widely sold in the market₄ ⁺The concentration of-N is enough, because the water sample needs to be detected when the total nitrogen is detectedDigestion and color display are avoided, so that no total nitrogen detection product exists in the market at present.

In the present invention, the nitrogen fertilizer application amount refers to the amount of nitrogen fertilizer converted into pure nitrogen (N) per application, i.e. the amount of pure nitrogen required to apply the nitrogen fertilizer. In the present invention, the nitrogen fertilizer is preferably urea. In the present invention, the value of 0.65 in the formula is selected as follows: NH in the biogas slurry₄ ⁺The TN content of-N is determined at 65%.

The formula of the invention is obtained by assuming NH in the biogas slurry₄ ⁺The concentration of N is 65-95% of TN concentration. The nitrogen concentration value is obtained by detecting the nitrogen content of the actual biogas slurry and the nitrogen content of the reference biogas slurry together, and the process for obtaining the nitrogen concentration value is as follows:

the determination scheme of the nitrogen content range in the biogas slurry comprises the following steps: collecting biogas slurry samples after fermentation of biogas digesters of 8 live pig breeding plants in Jiaxing area is completed in two times (9 months and 12 months) in the same year, and analyzing the content of ammonium nitrogen, nitrate nitrogen, total nitrogen and nitrogen in different forms in the total nitrogen proportion. In addition, the biogas liquid nitrogen content has been reported by consulting literature data. The two approaches are combined to determine the variation range of the nitrogen content in the biogas slurry.

The irrigation amount determination scheme for safely and ecologically irrigating zizania latifolia with biogas slurry comprises the following steps: through the field test of irrigating the double-cropping water bamboo with the double-cropping biogas slurry, the normal growth of the autumn water bamboo and summer water bamboo plants can be ensured, and the maximum biogas slurry irrigation amount and irrigation range without reducing the yield are ensured. The field test scheme is as follows: the dosage of the urea (nitrogen fertilizer) of the autumn wild rice shoots (the autumn wild rice shoots for short) is 65 kg/mu and the dosage of the urea of the summer wild rice shoots (the summer wild rice shoots for short) is 69 kg/mu. The urea application periods and proportions were: the autumn water bamboo seedling separating fertilizer, the tillering and high-pulling fertilizer and the pregnant water bamboo fertilizer have the application proportion of 35%: 30%: 35 percent; the application proportion of the summer zizania latifolia seedling tillering fertilizer, the pulling-up fertilizer and the pregnant zizania latifolia fertilizer is 35%: 30%: studies were performed with 35% as basal control. Wherein 65 kg/mu of autumn zizania latifolia and 69 kg/mu of summer zizania latifolia are applied, and the application period and the application proportion of the urea are determined by carrying out extensive investigation and reference on a large number of literatures on double-cropping zizania latifolia farmers. A series of biogas slurry irrigation amount treatments from low to high are designed on the basis of 65 kg/mu of autumn wild rice stem urea and 69 kg/mu of summer wild rice stem urea, and the method comprises the following steps: 50% of urea is applied, and the other half of urea is replaced by biogas slurry with the same nitrogen content (0.5N); urea is not applied, and all urea is replaced by biogas slurry with the same nitrogen content (1N); no urea is applied, and the dosage of the biogas slurry is as follows: the nitrogen content in the biogas slurry is 1.5 times (1.5N) of the urea nitrogen content; no urea is applied, and the dosage of the biogas slurry is as follows: the nitrogen content in the biogas slurry is 2 times (2N) of the urea nitrogen content; no urea is applied, and the dosage of the biogas slurry is as follows: the nitrogen content in the biogas slurry is 2.7 times (2.7N) of the urea nitrogen content. Sampling and measuring the total nitrogen content (mg/L) in the biogas slurry before each biogas slurry irrigation, and determining the biogas slurry irrigation amount. The usage of the phosphate fertilizer and the potash fertilizer in each treatment in the field test is kept consistent. The field test leads to the conclusion that: when urea is not applied and the amount of the biogas slurry is 2 times of the nitrogen amount of the urea, the growth of the zizania latifolia plants starts to be inhibited to a certain extent, and the yield is reduced to a certain extent. The inhibition effect is more obvious when the amount of the biogas slurry is 2.7 times of the nitrogen amount of the urea when the urea is not applied and the nitrogen amount in the biogas slurry is 2.7 times of the nitrogen amount of the urea. When urea is not applied and the amount of the biogas slurry is within 1.5 times of the nitrogen amount of the urea, the production and the yield of the cane shoot plants are basically not influenced, and the influence result of the amount of the biogas slurry on the yield is shown in figure 1 (note: CK is the application treatment of pure chemical fertilizer). However, considering that (1) the biogas slurry contains a certain amount of heavy metal elements, the irrigation amount greatly increases the risk of environmental pollution; (2) the field water level is high when the biogas slurry nitrogen concentration is high and the irrigation amount is large, the digestion time is long, and the pollution risk to the surface water body is increased. Therefore, the upper limit of the biogas slurry irrigation amount is set to be 1 time of the amount of the fertilizer nitrogen.

The technical scheme has the following results:

the determination scheme of the nitrogen content range in the biogas slurry comprises the following steps:

the nitrogen content of biogas slurry samples after the fermentation of biogas digesters of 8 pig breeding plants is completed is characterized in that:

1. total Nitrogen (TN): the nitrogen concentration variation amplitude in the biogas slurry in 9 months is 320-1358 mg/L (903 mg/L on average), and the coefficient of variation is 40.2%; the variation range of the collection in 12 months is 260-779 mg/L (average 600mg/L), and the coefficient of variation is 28.1%. When the same methane tank is collected at different time points, the nitrogen concentration in the methane liquid is greatly changed and is 46.1-731 mg/L (mean 427mg/L), and the coefficient of variation is 55.6%;

2. ammonium Nitrogen (NH)₄ ⁺-N): when the ammonium Nitrogen (NH) in the biogas slurry of the biogas digesters of 8 breeding plants is collected at the same time₄ ⁺N) the variation of the concentration in 9 months is 246-1196 mg/L (784 mg/L on average), and the coefficient of variation is 41.4%; the amplitude of 12 months is 236-692 mg/L (528 mg/L on average), and the coefficient of variation is 28.2%. When the same methane tank collects at different time points, NH in the methane liquid₄ ⁺The N concentration is also greatly changed and is 46.5-682 mg/L (378 mg/L on average), and the coefficient of variation is 57.7%;

3. nitrate Nitrogen (NO)₃ ^--N): nitrate Nitrogen (NO) in biogas slurry of 8 biogas digesters of aquaculture plant collected at the same time₃ ^--N) the variation of concentration at 9 months is 6.60-27.4 mg/L (average 18.7mg/L), the coefficient of variation is 40.4%, the variation at 12 months is 3.95-20.6 mg/L (average 12.9mg/L), and the coefficient of variation is 44.0%. When the same methane tank is collected at different time points, NO in the methane liquid₃ ^-The N concentration varies from 0.82 to 17.0mg/L (average 6.23mg/L), and the coefficient of variation is 96.8%.

Ammonium Nitrogen (NH) measured from biogas slurry of 8 biogas digesters of aquaculture plants in 9 and 12 months of the same year₄ ⁺-N), nitrate Nitrogen (NO)₃ ^-The average percentages of-N) to Total Nitrogen (TN) content were 87.2% and 2.93%, respectively. This indicates that the most predominant form of nitrogen in biogas slurry is ammonium Nitrogen (NH)₄ ⁺-N) is dominant. Meanwhile, part of soluble organic nitrogen exists, and the content of nitrate nitrogen is lower.

From the reported content of biogas liquid nitrogen in literature data, the nitrogen content in the biogas slurry fluctuates greatly, and the amplitude is 189-1680 mg/L. The total nitrogen content in the biogas slurry samples of the same biogas digester at different collection times, or different biogas digesters, or different sources of biogas digesters has larger difference. In addition, ammonium Nitrogen (NH) is contained₄ ⁺Reports of literature on-N) content of NH can also be found₄ ⁺N is the most predominant nitrogen form in biogas slurry.

Table 1 shows the nitrogen content of biogas slurry

By combining the nitrogen concentration of 260-1358 mg/L in the biogas slurry pool of 8 live pig breeding plants in the Jiaxing southern lake region, the nitrogen concentration of 189-1680 mg/L in the biogas slurry is reported in literature data. The nitrogen concentration in the biogas slurry can be basically judged to be within 2000mg/L, and the lowest concentration is basically about 100 mg/L. In addition, NH in biogas slurry pools of 8 live pig breeding plants in Jiaxing south lake region is combined₄ ⁺76.9 to 92.9 percent of N (average is 87.2 percent) and literature data report that NH in biogas slurry₄ ⁺N accounts for 65.6-92.8% of nitrogen, and NH in the biogas slurry can be basically determined₄ ⁺The N concentration can be 65-95% (on average about 80%) of the nitrogen concentration.

The method utilizes the ammonium nitrogen in the water widely sold in the market to rapidly detect the product to determine the concentration value or range of the ammonium nitrogen in the biogas slurry, and uses NH in the biogas slurry₄ ⁺N accounts for 65-95% of TN content, the total nitrogen content range in the biogas slurry is determined, but in consideration of reducing negative influence on growth of cane shoots caused by excessive irrigation of high-concentration biogas slurry as far as possible, NH in the biogas slurry₄ ⁺The content of-N in TN is calculated as 65%, and the nitrogen amount in the irrigated biogas slurry is calculated to be the same as the pure nitrogen amount applied by nitrogen fertilizer.

The invention provides a double-cropping water bamboo irrigation method based on the determination method of the technical scheme, which comprises the following steps:

Transplanting cane shoots in the first ten days of 6 months to the last ten days of 7 months, extracting new leaves of more than 95% of the plants after transplanting, measuring the ammonium nitrogen concentration in the biogas slurry when tillering buds appear, setting the application amount of the first nitrogen fertilizer to be 10.5 kgN/mu, determining the irrigation amount of the first biogas slurry according to a formula shown in a formula I, irrigating the first biogas slurry, and controlling the field water level to be 15-20 cm after irrigating. In the invention, the field water level after irrigation is preferably 16 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 10.5 kgN/mu.

In the invention, before the biogas slurry is irrigated, the field water level before the irrigation is preferably determined by a formula shown in formula II:

wherein the unit of the field water level before irrigation is cm/mu, and the unit of the biogas slurry irrigation amount is t/mu. In the present invention, 667 in the formula is 1 acre of land area.

In the invention, the first biogas slurry irrigation can apply seedling fertilizer to the wild rice shoots, and the transplanted wild rice shoots are in a seedling revival stage, preferably, when more than 95% of the transplanted wild rice shoots have new leaves and are accompanied with tillering buds, the first biogas slurry irrigation is carried out, and more preferably, the first biogas slurry irrigation is carried out after the wild rice shoots are transplanted for 25-35 days. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

In the middle ten 9 months, the concentration of ammonium nitrogen in the biogas slurry is measured, and the irrigation amount of the second biogas slurry is determined by taking the application amount of the second nitrogen fertilizer as 9 kgN/mu; and irrigating with secondary biogas slurry, wherein the field water level is 15-20 cm after irrigation. In the invention, the water level in the field after irrigation is preferably 18 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 9 kgN/mu.

In the invention, the tillering and the pulling up of the wild rice stem plant can be promoted by irrigating the second biogas slurry. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

In 10 middle ten months, the concentration of ammonium nitrogen in the biogas slurry is measured, and the irrigation amount of the third biogas slurry is determined according to the application amount of the third nitrogen fertilizer being 10.5kg N/mu; and irrigating with the third biogas slurry, wherein the field water level is more than 20cm after irrigation. In the invention, the water level of the field after irrigation is preferably 22-25 cm, and more preferably 24 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 10.5 kgN/mu.

In the invention, the third biogas slurry irrigation can promote the growth of the pregnant zizania latifolia. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

In the second year, when the wild rice stem plants grow to 33-37 cm, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the fourth biogas slurry by taking the fourth nitrogen fertilizer application amount as 11 kgN/mu; and (4) irrigating with fourth biogas slurry, wherein the field water level is 13-17 cm after irrigation. In the present invention, the post-irrigation water level is preferably 15 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 11 kgN/mu.

In the invention, after the air temperature rises again in 3 months, new buds grow on the water bamboo piers of the autumn water bamboos in the last half year, and when the plants grow to 33-37 cm, more preferably to 35cm, the fourth biogas slurry irrigation is carried out. In the invention, the fourth biogas slurry irrigation is used for promoting the reversion and tillering of the cane shoot plants. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

In the middle ten days of 5 months, the concentration of ammonium nitrogen in the biogas slurry is measured, and the irrigation amount of the fifth biogas slurry is determined according to the application amount of the fifth nitrogen fertilizer of 9.5kg N/mu; and (5) irrigating with fifth biogas slurry, wherein the field water level is 15-20 cm after irrigation. In the invention, the water level in the field after irrigation is preferably 18 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 9.5kg N/mu.

In the invention, the fifth biogas slurry irrigation is used for promoting growth and height drawing of the cane shoot plants. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

In the last ten days of 5 months to the last 6 months, the concentration of ammonium nitrogen in the biogas slurry is measured, and the irrigation amount of the sixth biogas slurry is determined by taking the application amount of the sixth nitrogen fertilizer as 11 kgN/mu; and irrigating with sixth biogas slurry, wherein the field water level is more than 20cm after irrigation. In the invention, the water level of the field after irrigation is preferably 22-25 cm, and more preferably 24 cm. In the invention, the transplanting density of the zizania latifolia is 1500-1600 plants/mu, more preferably 1550 plants/mu, the row spacing of the zizania latifolia is 80-100 cm, more preferably 90cm, the plant spacing of the zizania latifolia is 45-50 cm, more preferably 48cm, and the zizania latifolia is planted with wide rows and narrow plants. After the concentration of ammonium nitrogen in the biogas slurry is measured, the irrigation amount of the biogas slurry is determined by a formula shown in a formula I:

wherein the application amount of the nitrogen fertilizer is 11 kgN/mu.

In the invention, the sixth biogas slurry irrigation is used for promoting the growth of the pregnant wild rice shoots in summer. According to the invention, before the biogas slurry is irrigated, the field ridge is preferably stabilized and heightened, so that the risk of biogas slurry outflow is reduced. In the present invention, the height of the ridge is preferably 35cm or more. In the invention, when the growth condition of the wild rice stem is poor, the method preferably further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer. In the invention, biogas slurry does not align with the wild rice stem plants to irrigate each time of biogas slurry irrigation, so as to avoid damage to the wild rice stem plants. The invention has no special limitation on the irrigation mode of the biogas slurry, and can be implemented by adopting a conventional biogas slurry application mode, such as directly irrigating the biogas slurry or mixing the biogas slurry and water and then irrigating the mixture into the field. If continuous rainy days occur or heavy rain in a short period is foreseen, the water bamboo is not irrigated, or the irrigation amount of biogas slurry is reduced, and the risk of biogas slurry outflow is reduced.

According to the invention, the maximum irrigation quantity value is set at each irrigation stage, so that the phenomenon that the growth of the cane shoots is inhibited or the cane shoots are pregnant due to high nitrogen concentration of biogas slurry is avoided, and meanwhile, the risk of water environment and soil environment pollution is reduced.

In the present invention, the principle of the irrigation method is as follows: the nitrogen fertilizer application amount of the autumn wild rice shoots in the whole growth period is 450kgN/ha (65kg urea/mu), and the application proportion of the seedling fertilizer (first biogas slurry irrigation), the tillering and high-pulling fertilizer (second biogas slurry irrigation) and the pregnant wild rice shoot fertilizer (third biogas slurry irrigation) is 35%: 30%: 35% as reference; the application rate of nitrogenous fertilizer application amount of wild rice stem in summer is 475kgN/ha (69kg urea/mu), the application proportion of tillering fertilizer (fourth biogas slurry irrigation), high-pulling fertilizer (fifth biogas slurry irrigation) and pregnant wild rice stem fertilizer (sixth biogas slurry irrigation) is 35%: 30%: 35% as reference. And combining the following two formulas to obtain the numerical values of each stage in the biogas slurry irrigation method. The calculation formula of the biogas slurry irrigation amount and the water lifting height of the field surface after irrigation is as follows:

biogas slurry irrigation amount (W) calculation formula: application amount of nitrogen fertilizer (pure, unit: kgN/mu) ÷ (NH is determined by colorimetric card)₄ ⁺-N concentration ÷ 0.65 × 0.001) (unit: t/mu);

the water rise (H) of the field surface after irrigation (unit: cm/mu) is calculated by the following formula: biogas slurry irrigation amount (unit: t/mu) ÷ 667 (unit: m)²)×100。

In the invention, the water level height of the field surface water before irrigation is preferably adjusted according to the irrigation amount of the biogas slurry and the water level rising height of the field surface water before irrigation, under the condition of the same irrigation amount of the biogas slurry, the water amount of the field surface water before irrigation of the biogas slurry can be properly reduced when the concentration of the biogas slurry is lower, and the water amount of the field surface water can be properly increased when the concentration of the biogas slurry is high.

The calculation method and irrigation method for semi-quantitative irrigation amount of the double-cropping zizania latifolia biogas slurry are further described in detail with reference to specific examples, and the technical scheme of the invention includes but is not limited to the following examples.

Example 1

In autumn:

(1) and (3) seedling fertilizer irrigation amount: and (3) extracting new leaves of the wild rice stem plants 26 days after the transplanting, accompanying with tillering buds, determining the ammonium nitrogen concentration in the biogas slurry to be 330mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in a formula I by using the first nitrogen fertilizer application amount to be 10.5kg N/mu:

determining the irrigation amount of the first biogas slurry to be 20.6 t/mu; and (4) irrigating with first biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at 15 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the wild rice stem raised by the biogas slurry irrigation of 1 mu of the field is about 3.1cm, and the water level of the field surface before the biogas slurry irrigation is 11.9 cm;

(2) and (3) tillering and high-fertilizer-pulling irrigation amount: and 9 months and 9 days, determining the ammonium nitrogen concentration in the biogas slurry to be 700mg/L, determining the biogas slurry irrigation amount according to a formula shown in the formula I by taking the second nitrogen fertilizer application amount to be 9 kgN/mu:

determining the irrigation amount of the second biogas slurry to be 8.3 t/mu; and (3) irrigating with second biogas slurry to promote tillering and pulling of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 20cm after biogas slurry irrigation.

Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the wild rice stem raised by the biogas slurry irrigation of 1 mu of the field is about 1.3cm, and the water level of the field surface water before the biogas slurry irrigation is 18.7 cm;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: and (4) determining the ammonium nitrogen concentration in the biogas slurry to be 1500mg/L at 8 days in 10 months, determining the biogas slurry irrigation amount according to a formula shown in a formula I by taking the third nitrogen fertilizer application amount to be 10.5 kgN/mu:

and determining that the third biogas slurry irrigation amount is 4.5 t/mu, performing third biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field at 22cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

and obtaining that the height of the water level of the field surface of the cane shoots is 0.7cm when 1 mu of field is irrigated by biogas slurry, and the water level of the field surface before the field is irrigated by the biogas slurry is 21.3 cm.

Summer season

And after the air temperature rises again in 3 months, new buds grow on the water bamboo piers of autumn water bamboos in the last year, and the biogas slurry irrigation is started when the height of plants is as long as 35cm and the time is about 3 mid-ten days.

(1) And (3) fertilizing amount of the tillers: the wild rice stem plants grow to 35cm height, the concentration of ammonium nitrogen in the measured biogas slurry is 450mg/L, the fourth nitrogen fertilizer application amount is 11 kgN/mu, and the biogas slurry irrigation amount is determined according to a formula shown in formula I:

determining the irrigation quantity of the fourth biogas slurry to be 15.8 t/mu;

and (4) irrigating with fourth biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at 15 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the wild rice stem is raised by the biogas slurry irrigation for 1 mu of the field is 2.4cm, the water level of the field surface water before the biogas slurry irrigation is 12.6cm, and then irrigating;

(2) drawing up the fertilizer and watering amount: and 5, 12 days in 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 800mg/L, determining the biogas slurry irrigation amount according to a formula shown in the formula I by using the fifth nitrogen fertilizer application amount to be 9.5 kgN/mu:

and determining that the fifth biogas slurry irrigation amount is 7.7 t/mu, performing fifth biogas slurry irrigation to promote growth of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 18cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the zizania latifolia field is increased by 1 mu of field biogas slurry irrigation is 1.2cm, the water level of the field surface water before the zizania latifolia field is irrigated is 16.8cm, and then the zizania latifolia field is irrigated;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: in late 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 1100mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in formula I by using the sixth nitrogen fertilizer application amount to be 11 kgN/mu:

and determining that the sixth biogas slurry irrigation amount is 6.5 t/mu, performing sixth biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field at 22cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

and (3) obtaining that the height of the water level of the field surface of the cane shoots is 1cm when 1 mu of field is irrigated by biogas slurry, and the water level of the field surface before the field surface is irrigated by the biogas slurry is 21cm, and then irrigating.

Example 2

In autumn:

(1) and (3) seedling fertilizer irrigation amount: and (3) after the wild rice stem is transplanted for 26 days, extracting new leaves, forming partial tillering buds, determining the ammonium nitrogen concentration in the biogas slurry to be 620mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in a formula I by using the first nitrogen fertilizer application amount to be 10.5kg N/mu:

determining the irrigation amount of the first biogas slurry to be 11 t/mu;

and (4) irrigating with first biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at 16 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the wild rice stem is increased by 1 mu of field biogas slurry for irrigation is about 1.7cm, the water level of the field surface water before the field surface is irrigated by the biogas slurry is 14.3cm, and then irrigating;

(2) and (3) tillering and high-fertilizer-pulling irrigation amount: and 9 months and 9 days, determining the ammonium nitrogen concentration in the biogas slurry to be 1200mg/L, determining the biogas slurry irrigation amount according to a formula shown in formula I by taking the second nitrogen fertilizer application amount to be 9 kgN/mu:

and determining that the second biogas slurry irrigation amount is 4.8 t/mu, performing second biogas slurry irrigation to promote tillering and pulling of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 18cm after the zizania latifolia field is irrigated by biogas slurry. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface of the wild rice stem is increased by 1 mu of field biogas slurry for irrigation is about 0.7cm, the water level of the field surface water before the field surface is irrigated by the biogas slurry is 17.3cm, and then irrigating;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: and (4) determining that the concentration of ammonium nitrogen in the biogas slurry is 730mg/L and the application amount of a third nitrogen fertilizer is 10.5 kgN/mu in 8 days after 10 months, and determining the irrigation amount of the biogas slurry according to a formula shown in a formula I:

and determining that the third biogas slurry irrigation amount is 9.3 t/mu, performing third biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field at 23cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

and obtaining that the height of the water level of the field surface of the cane shoots is 1.4cm when 1 mu of field is irrigated by biogas slurry, and the water level of the field surface before the field surface is irrigated by the biogas slurry is 21.6cm, and then irrigating.

Summer season

(1) And (3) fertilizing amount of the tillers: the wild rice stem plants grow to 35cm in height, the concentration of ammonium nitrogen in the measured biogas slurry is 380mg/L, the fourth nitrogen fertilizer application amount is 11 kgN/mu, and the biogas slurry irrigation amount is determined according to a formula shown in formula I:

determining the irrigation quantity of the fourth biogas slurry to be 18.8 t/mu; and (4) irrigating with fourth biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at 15 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is raised by 1 mu of field biogas slurry for 2.8cm, the water level of the field surface water before the field surface water is irrigated by the biogas slurry with the application amount of the nitrogen fertilizer is 12.2cm, and then irrigating;

(2) drawing up the fertilizer and watering amount: and 5, 12 days in 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 840mg/L, determining the biogas slurry irrigation amount according to a formula shown in the formula I by using the fifth nitrogen fertilizer application amount to be 9.5 kgN/mu:

determining the irrigation quantity of the fifth biogas slurry to be 7.3 t/mu; and (4) irrigating with fifth biogas slurry to promote growth of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 16cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is increased by 1 mu of field biogas slurry irrigation is 1.1cm, the water level of the field surface water before the field surface water of the wild rice stem is irrigated by the biogas slurry with the nitrogen fertilizer application amount is 14.9cm, and then irrigating;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: in late 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 280mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in formula I by using the sixth nitrogen fertilizer application amount to be 11 kgN/mu:

and determining that the sixth biogas slurry irrigation amount is 25.5 t/mu, performing sixth biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field at 22cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

and obtaining that the height of the water level of the field surface of the cane shoots is increased by 1 mu of field biogas slurry for irrigation to be about 3.8cm, and the water level of the field surface water before the field surface is irrigated by the biogas slurry is 18.2cm, and then irrigating.

Example 3

In autumn:

(1) and (3) seedling fertilizer irrigation amount: and (3) after the wild rice stem is transplanted for 26 days, extracting new leaves, forming partial tillering buds, determining the ammonium nitrogen concentration in the biogas slurry to be 370mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in a formula I by using the first nitrogen fertilizer application amount to be 10.5kg N/mu:

determining the irrigation amount of the first biogas slurry to be 18.4 t/mu; and (3) irrigating with first biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at 20 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is raised by 1 mu of field biogas slurry for 2.8cm, the water level of the field surface water before the field surface water is irrigated by the biogas slurry with the application amount of the nitrogen fertilizer is 17.2cm, and then irrigating;

(2) and (3) tillering and high-fertilizer-pulling irrigation amount: and 9 months and 9 days, determining the ammonium nitrogen concentration in the biogas slurry to be 730mg/L, determining the biogas slurry irrigation amount according to a formula shown in a formula I by taking the second nitrogen fertilizer application amount to be 9 kgN/mu:

and determining that the second biogas slurry irrigation amount is 4.2 t/mu, performing second biogas slurry irrigation to promote tillering and pulling of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 18cm after the zizania latifolia field is irrigated by biogas slurry. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is increased by 1 mu of field biogas slurry for irrigation is about 0.7cm, the water level of the field surface water before the field surface water of the wild rice stem is irrigated by the biogas slurry with the nitrogen fertilizer application amount is 17.3cm, and then irrigating;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: and (4) determining the ammonium nitrogen concentration in the biogas slurry to be 1000mg/L at 8 days in 10 months, determining the irrigation amount of the biogas slurry according to a formula shown in a formula I by using the third nitrogen fertilizer application amount to be 10.5 kgN/mu:

and determining that the third biogas slurry irrigation amount is 6.8 t/mu, performing third biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field at 21cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

and (3) obtaining that the water level of the field surface water of the cane shoots is raised by 1 mu of field biogas slurry for irrigation to be about 1cm, and the water level of the field surface water before the field surface water is irrigated by the biogas slurry with the nitrogen fertilizer application amount is 20cm, and then irrigating.

Summer season

(1) And (3) fertilizing amount of the tillers: the height of the wild rice stem plant is 35cm, the ammonium nitrogen concentration in the measured biogas slurry is 870mg/L, the fourth nitrogen fertilizer application amount is 11 kgN/mu, and the biogas slurry irrigation amount is determined according to a formula shown in formula I:

determining the fourth biogas slurry irrigation amount to be 8.2 t/mu;

and (4) irrigating with fourth biogas slurry, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation, so that the total water level height of the zizania latifolia field after biogas slurry irrigation is kept at about 15 cm. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is increased by 1 mu of field biogas slurry for irrigation is about 1.2cm, the water level of the field surface water before the field surface water of the wild rice stem is irrigated by the biogas slurry with the nitrogen fertilizer application amount is 13.8cm, and then irrigating;

(2) drawing up the fertilizer and watering amount: and 5, 12 days in 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 630mg/L, determining the biogas slurry irrigation amount according to a formula shown in formula I by using the fifth nitrogen fertilizer application amount to be 9.5 kgN/mu:

determining the irrigation quantity of the fifth biogas slurry to be 9.8 t/mu;

and (4) irrigating with fifth biogas slurry to promote growth of the zizania latifolia plants, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation so as to keep the total water level height of the zizania latifolia field at 16cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

obtaining that the height of the water level of the field surface water of the wild rice stem is increased by 1 mu of field biogas slurry for irrigation is about 1.5cm, the water level of the field surface water before the field surface water of the wild rice stem is irrigated by the biogas slurry with the nitrogen fertilizer application amount is 14.5cm, and then irrigating;

(3) fertilizing and irrigating amount of pregnant zizania aquatica: in late 5 months, determining the ammonium nitrogen concentration in the biogas slurry to be 1050mg/L, determining the irrigation amount of the biogas slurry according to a formula shown in formula I by using the sixth nitrogen fertilizer application amount to be 11 kgN/mu:

and determining that the sixth biogas slurry irrigation amount is 6.8 t/mu, performing sixth biogas slurry irrigation to promote the growth of the pregnant zizania latifolia, and properly regulating and controlling the water level height of the zizania latifolia field according to the biogas slurry irrigation amount before irrigation to keep the total water level height of the zizania latifolia field to be more than 22cm after biogas slurry irrigation. Determining the field water level before irrigation by using a formula shown in formula II:

according to the formula: biogas slurry irrigation volume and irrigation wild rice stem field area (unit: m)²) × 100 (unit: cm), obtaining that the height of the water level of the water surface of the cane shoot field is about 1cm when 1 mu of field biogas slurry is irrigated, the water level of the water surface of the cane shoot field before the nitrogen fertilizer application amount biogas slurry is irrigated is 21cm, and then irrigating.

Example 4

The results of comparison of the effects of the method of example 1 and the conventional fertilizer application method (150 kg 15-15-15 compound fertilizer and 20 kg urea per mu) and the method of applying biogas slurry without the method of the invention (the method is applied by farmers according to experience, the first application is 8 t/mu biogas slurry, the second application is 11 t/mu biogas slurry, and the third application is 10 t/mu biogas slurry) in the irrigation of wild rice shoots are as follows:

the yield and the dry matter accumulation result of the overground part of the water bamboo plant are shown in figures 2 and 3, wherein figure 2 is a comparison result chart of the yield of the water bamboo under different treatment methods, and figure 3 is a comparison result chart of the overground part dry matter accumulation of the water bamboo plant under different treatment methods.

As can be seen from figure 2, the yield of the wild rice stem after the wild rice stem is irrigated by the biogas slurry irrigation method is 30.9 t/ha. The yield of the wild rice shoots is 29.8t/ha when the conventional fertilizer is applied, and the yield of the wild rice shoots is even higher than that of the wild rice shoots applied by the conventional fertilizer by adopting the technical method. However, when the zizania latifolia is irrigated without the biogas slurry, the yield of the zizania latifolia is 23.8t/ha, and compared with the method adopting the technology, the yield of the zizania latifolia is reduced by 23.0% when the zizania latifolia is irrigated without the technology.

As can be seen from figure 3, the dry matter accumulation of the overground part of the wild rice stem plant is 11.9t/ha after the irrigation method of the technology is adopted. When the conventional fertilizer is applied, the accumulated amount of dry matter on the upper part of the wild rice stem is 11.4 t/ha. The dry matter accumulation amount of the overground part is even higher than that of the conventional fertilizer application by adopting the technical method. However, when the zizania latifolia is irrigated without the biogas slurry, the accumulation amount of dry matters on the upper part of the zizania latifolia is 9.15t/ha, and compared with the irrigation method adopting the technology, the accumulation amount of dry matters on the upper part of the zizania latifolia is reduced by 23.1%.

The plant height and leaf length results of the zizania latifolia plants are shown in fig. 4 and 5, wherein fig. 4 is a comparison result graph of the plant heights of the zizania latifolia plants under different treatment methods, and fig. 5 is a comparison result graph of the leaf lengths of the zizania latifolia plants under different treatment methods.

As can be seen from figure 4, when the zizania latifolia is irrigated by the biogas slurry irrigation method of the technology, the plant height of the zizania latifolia plants is 198 cm. When the fertilizer is applied conventionally, the plant height of the wild rice stem is 197 cm. The height of the zizania latifolia plant adopting the technical method is even higher than that of the zizania latifolia plant applied with a conventional chemical fertilizer. However, when the zizania latifolia is irrigated without the biogas slurry, the height of the zizania latifolia plants is 164cm, and compared with the irrigation method adopting the technology, the height of the zizania latifolia plants is reduced by 17.2 percent.

As can be seen from FIG. 5, when the irrigation method of the technology is adopted, the leaf length of the cane shoot plant is 3.67 cm. When the fertilizer is applied conventionally, the leaf length of the cane shoot plant is 3.67 cm. The length of the leaves by adopting the technical method is even higher than that of the leaves of the zizania latifolia plants applied with the conventional chemical fertilizer. However, when the zizania latifolia is irrigated without the biogas slurry, the leaf length of the zizania latifolia plant is 3.22cm, and compared with the irrigation method adopting the technology, the leaf length of the zizania latifolia plant is reduced by 12.3%.

FIG. 6 is a graph showing the comparison result of ammonium nitrogen in water in the field surface of Zizania latifolia under different treatment methods. As can be seen from FIG. 6, the biogas slurry is used for irrigating the wild rice stem field in the irrigation method of the technologyThe content of ammonium Nitrogen (NH) in the water of the wild rice stem field surface in two days₄ ⁺-N) are respectively 121mg/L, which is obviously lower than NH in water of the field surface of the zizania latifolia when the zizania latifolia is irrigated without biogas slurry₄ ⁺N content (203 mg/L). Thus, NH in the surface water when the technical method is not adopted₄ ⁺The N content is high, and the environmental hazard risk of the turnover water body is aggravated when the runoff event happens due to rainfall or poor management. In addition, ammonia (NH) was also increased₃) And (4) volatilization amount. (Note: biogas slurry irrigating water NH in the surface water of the wild rice stem field₄ ⁺The N content is higher than NH in the surface water only applied by chemical fertilizers (such as urea, compound fertilizer and the like)₄ ⁺The N content is of normal embodiment).

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The double-cropping water bamboo watering method based on the double-cropping water bamboo biogas slurry semi-quantitative watering amount determination method comprises the following steps:

formula I;

wherein the unit of the irrigation amount of the biogas slurry is t/mu, the unit of the application amount of the nitrogen fertilizer is kg N/mu, and the unit of the concentration of ammonium nitrogen in the biogas slurry is mg/L;

the irrigation method comprises the following steps:

1) transplanting water bamboo from late 6 months to early 7 months, extracting new leaves of more than 95% of the transplanted plants, measuring the ammonium nitrogen concentration in the biogas slurry when tillering buds appear, setting the application amount of the first nitrogen fertilizer to be 10.5kg N/mu, determining the irrigation amount of the first biogas slurry according to a formula shown in a formula I, irrigating the first biogas slurry, and controlling the field water level to be 15-20 cm after irrigating;

2) measuring the concentration of ammonium nitrogen in the biogas slurry in the middle ten 9 months, and determining the irrigation amount of the second biogas slurry by using the application amount of the second nitrogen fertilizer as 9kg N/mu; irrigating with secondary biogas slurry, wherein the field water level is 15-20 cm after irrigation;

3) in the middle 10 th of the month, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the third biogas slurry by using the application amount of the third nitrogen fertilizer as 10.5kg N/mu; irrigating with the third biogas slurry, wherein the field water level is more than 20cm after irrigation;

4) in the second year, when the wild rice stem plants grow to 33-37 cm, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of a fourth biogas slurry by taking the fourth nitrogen fertilizer application amount as 11kg N/mu; irrigating with fourth biogas slurry, wherein the field water level is 13-17 cm after irrigation;

5) in the middle ten days of 5 months, measuring the concentration of ammonium nitrogen in the biogas slurry, and determining the irrigation amount of the fifth biogas slurry by using the application amount of the fifth nitrogen fertilizer as 9.5kg N/mu; irrigating with fifth biogas slurry, wherein the field water level is 15-20 cm after irrigation;

2. The method for irrigating double-cropping water bamboo according to claim 1, wherein the first biogas slurry irrigation is performed 25 days after the transplanting in step 1).

3. The method for irrigating double cropping water bamboo according to claim 1, wherein in the step 4), fourth biogas slurry irrigation is performed from 3 to 4 last days of month.

4. The method for irrigating the double-cropping water bamboo according to claim 1, wherein stabilizing and heightening field ridges are further performed before each biogas slurry irrigation.

5. The method for irrigating double cropping water bamboo according to claim 4, wherein the ridge is more than 35cm in height.

6. The method for irrigating double cropping water bamboo according to claim 1, wherein when the water bamboo is in poor growth condition, the method further comprises the following steps: supplementing nitrogen, phosphorus and potassium single mineral fertilizer or nitrogen, phosphorus and potassium compound fertilizer.

7. The method of claim 1, wherein biogas slurry is not directed to water the Zizania latifolia plants each time the biogas slurry is irrigated.

8. The method for irrigating double-cropping water bamboo according to claim 1, wherein before biogas slurry irrigation, the field water level before irrigation is determined by a formula shown as formula II:

formula II;

9. The method for irrigating the double-cropping water bamboos as claimed in claim 1, wherein the transplanting density of the water bamboos is 1500-1600 plants/mu, the row spacing of the water bamboos is 80-100 cm, and the plant spacing of the water bamboos is 45-50 cm.