A rice nitrogen-saving planting method

Abstract

The invention provides a rice nitrogen-saving planting method, which belongs to the technical field of rice nutrition and fertilization. The rice nitrogen-saving planting method of the invention comprises the following steps: turning over leguminous green manure and returning rice straw to the field; before turning over the leguminous green manure, investigating the earthworm population density X in the field, designing the nitrogen percentage Y in the rice growing season, and Y 2 =17.5×10 ‑4 X+0.0225, field irrigation to make earthworms migrate out, and then leguminous green manure is turned over; the nitrogen application amount S in the rice growing season = the customary nitrogen application amount M×(1-rice growing season nitrogen percentage Y). The present invention utilizes the biological nitrogen fixation function of leguminous green manure and the fertilization function of earthworms, and through the synergistic effect of "green manure nitrogen fixation-earthworm nitrogen promotion-rice nitrogen reduction", reduces the amount of nitrogen fertilizer and improves the utilization rate of rice nitrogen fertilizer.

Description

Technical Field

[0001] The invention belongs to the technical field of rice nutrition and fertilization, and in particular relates to a rice nitrogen-saving planting method. Background Art

[0002] In recent years, driven by a series of policies such as the "Straw Burning Ban and Two Reduction Actions", returning straw to the fields and planting green manure in winter have become the main measures to reduce nitrogen in rice fields, making the use of chemical nitrogen fertilizers in rice cultivation show a downward trend year by year. However, there are problems such as slow release of organic nitrogen and low utilization rate, which limits the space for nitrogen reduction during the rice growing season.

[0003] In addition, the fertilization method in rice production is mostly basal fertilizer: topdressing = 6:4 or 7:3. Some farmers even directly use a one-time fertilization method. The amount of fertilizer required in the rice seedling stage is small. Under the condition of heavy basal fertilizer application, nitrogen fertilizer is easy to enter the atmosphere and rivers through ammonia volatilization and surface runoff, which further squeezes the nitrogen reduction space during the rice growing season and easily causes serious resource waste and environmental pollution. Earthworms are called "ecosystem engineers". Through biological disturbance processes such as feeding, digging, digestion, and defecation, they improve soil pore structure, accelerate organic material nutrient circulation, increase soil fast-acting nutrient pool capacity, and optimize soil microbial community structure. They provide important service functions in the cultivation of healthy soil, soil productivity improvement, and sustainable crop production. Wang Xia et al. studied the effects of earthworms on soil carbon and nitrogen in dryland rice fields under different straw return methods (Effects of earthworms on soil carbon and nitrogen in dryland rice fields under different straw return methods [J]. Ecological Environment, 2003 (04)), but did not involve how to establish the relationship between rice field earthworms and rice nitrogen application. Under existing technologies, paddy field soil fertilization is mainly achieved through measures such as increasing the application of organic fertilizers, returning straw to the fields, and reducing tillage and avoiding tillage, while ignoring the regulation of soil functions by soil animals. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a rice nitrogen-saving planting method, which reduces the amount of nitrogen fertilizer and improves the utilization rate of rice nitrogen fertilizer through the synergistic effect of "green manure nitrogen fixation-earthworm nitrogen promotion-rice nitrogen reduction".

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A rice nitrogen-saving planting method comprises the following steps: turning over leguminous green manure and returning rice straw to the field;

[0007] Before turning over the leguminous green manure, investigate the earthworm population density X in the field, design the nitrogen percentage Y, Y in the rice growing season 2 =17.5×10 -4 X+0.0225, water the field to make the earthworms migrate out, and then turn over the leguminous green manure;

[0008] The nitrogen application amount S during the rice growing season=the customary nitrogen application amount M×(1-the nitrogen percentage Y during the rice growing season).

[0009] Preferably, the leguminous green manure is astragalus, which is planted 2 to 3 days before the previous rice harvest at a rate of 30 to 45 kg / hm 2 Intercropping.

[0010] More preferably, the leguminous green manure is turned over during the flowering period, with a turning depth of 12 to 15 cm.

[0011] Preferably, when returning the rice straw to the field, a stubble of 20 to 30 cm is left, and the rice straw is crushed to 5 to 8 cm and scattered back into the field.

[0012] Preferably, it also includes applying 3000-4500kg / hm2 of organic fertilizer before the winter solstice. 2 .

[0013] Preferably, after the previous rice crop is harvested, "three furrows" are dug with a width of 15 to 20 cm, a depth of 12 to 14 cm in the middle of the field, and a depth of 16 to 18 cm near the drainage outlet.

[0014] Preferably, the field irrigation depth is 4 to 6 cm.

[0015] Preferably, the rice planting density is increased by 10% to 30%.

[0016] Preferably, nitrogen is applied during the rice growth period according to the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2.

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

[0018] The present invention utilizes the biological nitrogen fixation function of leguminous green manure, and realizes carbon-nitrogen mutual assistance through the coordinated fertilization of leguminous green manure (low carbon-nitrogen ratio) and rice straw (high carbon-nitrogen ratio), thereby increasing the input of soil organic nitrogen, reducing the input of chemical nitrogen fertilizers, and effectively improving the utilization rate of nitrogen fertilizers.

[0019] The present invention is based on the biological fertilization function of earthworms. Earthworms feed on organic materials such as fallen leaves of leguminous green manure and rice straw, and excrete them out of the body in the form of earthworm feces through biological transformation in the earthworm intestines, thereby accelerating the decomposition of organic materials in rice fields, promoting the rapid release of nutrients, and enhancing the availability of nutrients.

[0020] The main ways to reduce the application of chemical nitrogen fertilizers are organic fertilizer substitution, returning straw to the field, and winter planting of green manure, but there are problems such as slow release of organic nitrogen and low utilization rate, which limits the space for reducing nitrogen in chemical fertilizers. The present invention makes full use of the biological transformation function of earthworms, and on the basis of biological nitrogen fixation of astragalus, promotes the conversion of organic nitrogen into inorganic nitrogen, increases the capacity of the soil's available nitrogen reservoir, and provides favorable conditions for nitrogen reduction during the rice season. The nitrogen reduction percentage and earthworm density show a parabolic relationship that opens to the right, realizing the synergy of "astragalus nitrogen fixation-earthworm nitrogen promotion-rice nitrogen reduction" (abbreviated as fixation-promotion-reduction), which is of great significance for the sustainable utilization of paddy field soil.

[0021] The present invention further increases the nitrogen reduction space of rice fields through the synergy of solidification, promotion and reduction, and reduces the application ratio of base fertilizer and increases the application ratio of ear fertilizer to carry out forward nitrogen and backward movement, thereby reducing nitrogen loss in the early growth period of rice, increasing nutrient supply in the middle and late growth period, improving the ear formation rate, and promoting the formation of large ears. By appropriately increasing the density, a "few evils, many ears, and large ears" group is constructed, which alleviates the contradiction between individual quality and group quality to the greatest extent, and promotes the development of resource-saving and environmentally friendly rice farming technology. DETAILED DESCRIPTION

[0022] The invention provides a rice nitrogen-saving planting method, comprising the following steps: turning over leguminous green manure and returning rice straw to the field; before turning over the leguminous green manure, investigating the earthworm population density X in the field, designing the nitrogen percentage Y in the rice growing season, and Y 2 =17.5×10 -4 X+0.0225, field irrigation to make earthworms migrate out, and then legume green manure is turned over; the nitrogen application amount S in the rice growing season = the customary nitrogen application amount M×(1-nitrogen percentage Y in the rice growing season). Among them, the earthworm population density X is in units of worms / m 2 ; Rice customary nitrogen application rate M refers to the customary nitrogen application rate for the current plot and current rice variety, in kg / hm 2 .

[0023] The present invention adopts a five-point sampling method to investigate the population density of earthworms in the field before turning over the leguminous green manure. The investigation is carried out by digging and hand counting method. The digging depth is 20-30cm, and the statistics are 1m 2 (1m×1m)The number of earthworms in the soil.

[0024] The leguminous green manure of the present invention includes astragalus, pea, broad bean, alfalfa, etc., which can increase the content of mineral nutrients such as nitrogen, phosphorus, potassium and organic matter in the soil, improve the soil structure, and especially have the ability to "capture" free nitrogen in the air, and form a symbiotic nitrogen fixation system with rhizobia to fix nitrogen in the air, which is then turned over and used for the next rice crop. The leguminous green manure of the present invention is preferably astragalus, which is applied 2 to 3 days before the previous rice crop is harvested at a rate of 30 to 45 kg / hm 2Interplanting; further preferred interplanting density 40kg / hm 2 The leguminous green manure is preferably turned over during the flowering period, with a turning depth of 12 to 15 cm; more preferably, the turning depth is 14 cm.

[0025] Rice straw contains rich organic matter and nitrogen, phosphorus and potassium nutrients, which can make the soil loose and breathable. Therefore, returning rice straw to the field can improve soil fertility and increase yield. In the present invention, when returning rice straw to the field, the stubble of the previous rice crop is preferably 20 to 30 cm, more preferably 25 cm, and the rice straw is crushed to 5 to 8 cm and scattered back to the field, more preferably crushed to 6 cm.

[0026] The present invention preferably includes applying 3000-4500 kg / hm2 of organic fertilizer before the winter solstice during the rice growth period. 2 It can not only increase the organic matter content in rice fields, but also provide sufficient food for the growth and reproduction of earthworms.

[0027] The present invention preferably digs "three furrows" (side furrow, waist furrow, and surrounding furrow) after the previous rice crop is harvested. As an implementable method, a "bow" type furrow digging method is adopted. The present invention preferably has a furrow width of 15 to 20 cm, and more preferably 18 cm; the furrow depth preferably increases step by step from the middle of the field to the drainage outlet, with a furrow depth of 12 to 14 cm in the middle of the field, more preferably 13 cm, and a furrow depth of 16 to 18 cm near the drainage outlet, more preferably 17 cm.

[0028] The present invention preferably sets the field irrigation depth at 4-6 cm to promote the migration of earthworms; after all the earthworms are transferred to the surrounding habitats such as the field ridges, the leguminous green manure is turned over and returned to the field.

[0029] The present invention preferably increases the rice planting density by 10% to 30%, and further preferably increases it by 20%. Preferably, nitrogen is applied during the rice growth period according to the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2, and the ear fertilizer application ratio is increased to move nitrogen application forward and backward, thereby reducing nitrogen loss in the early growth period of rice, increasing nutrient supply in the middle and late growth period, improving ear formation rate, and promoting large ear formation. By appropriately increasing the density, a "few evils, many ears, and large ears" population is constructed, and the contradiction between individual quality and population quality is alleviated to the greatest extent.

[0030] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0031] Example 1

[0032] A rice nitrogen-saving planting method comprises the following steps:

[0033] (1) 2-3 days before rice harvest, use drones to sow astragalus membranaceus at 40 kg / hm2 2 .

[0034] (2) After rice harvest, leave 25 cm of stubble, crush rice straw to 6 cm in length and evenly spread it back into the field, and apply 4000 kg / hm2 of organic fertilizer before the winter solstice. 2 , providing sufficient food for the growth and reproduction of earthworms.

[0035] (3) After the rice is harvested, the “bow”-shaped trenching method is used to dig the side trenches, waist trenches, and perimeter trenches in a timely manner. The trench width is 18 cm, and the trench depth increases step by step from the center of the field to the drainage outlet. The trench depth in the middle of the field is 13 cm, and the trench depth near the drainage outlet is 17 cm. This ensures that the “three trenches” are unobstructed and can be irrigated and drained, providing a suitable moist environment for the growth of asparagus and earthworms.

[0036] (4) During the flowering period of astragalus, water the field to a depth of 5 cm to force the earthworms to migrate out. After all the earthworms have moved to the surrounding habitats such as the ridges of the field, turn the astragalus back into the field at a turning depth of 14 cm.

[0037] (5) Before planting rice, the nitrogen saving percentage Y during the rice growing season is designed based on the earthworm population density X in the field before turning over the astragalus. The nitrogen saving percentage Y 2 =17.5×10 -4 X+0.0225, the unit of X is bar / m 2 , the amount of nitrogen applied during the rice growing season (pure nitrogen) S = M (1-Y), where M is the customary amount of nitrogen applied and the unit of nitrogen application is kg / hm 2 .

[0038] (6) During the rice growing season, under nitrogen-saving conditions, the transplanting density can be appropriately increased by 20%, and nitrogen fertilizer can be applied at the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2. By appropriately applying nitrogen fertilizer in the front and back positions, the ear formation rate can be increased, the formation of large ears can be promoted, and a high yield of rice can be ensured.

[0039] Example 2

[0040] A rice nitrogen-saving planting method comprises the following steps:

[0041] (1) 2-3 days before rice harvest, use drones to sow astragalus membranaceus at 30 kg / hm2 2 .

[0042] (2) After rice harvest, leave 20 cm of stubble, crush rice straw to 5 cm in length and evenly spread it back into the field, and apply 3000 kg / hm2 of organic fertilizer before the winter solstice. 2 , providing sufficient food for the growth and reproduction of earthworms.

[0043] (3) After rice harvest, the “bow” shaped trenching method is used to dig the side trenches, waist trenches and perimeter trenches in a timely manner. The trench width is 15 cm, and the trench depth increases gradually from the middle of the field to the drainage outlet. The trench depth in the middle of the field is 12 cm, and the trench depth near the drainage outlet is 16 cm. This ensures that the “three trenches” are unobstructed and can be irrigated and drained, providing a suitable moist environment for the growth of astragalus and earthworms.

[0044] (4) During the flowering period of astragalus, water the field to a depth of 4 cm to force the earthworms to migrate out. After all the earthworms have moved to the surrounding habitats such as the ridges of the field, turn the astragalus back into the field at a depth of 12 cm.

[0045] (5) Before planting rice, the nitrogen saving percentage Y during the rice growing season is designed based on the earthworm population density X in the field before turning over the astragalus. The nitrogen saving percentage Y 2 =17.5×10 -4 X+0.0225, the unit of X is bar / m 2 , the amount of nitrogen applied during the rice growing season (pure nitrogen) S = M (1-Y), where M is the customary amount of nitrogen applied and the unit of nitrogen application is kg / hm 2 .

[0046] (6) During the rice growing season, under nitrogen-saving conditions, the transplanting density can be appropriately increased by 10%, and nitrogen fertilizer can be applied at the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2. By appropriately applying nitrogen fertilizer in the front and back positions, the ear formation rate can be increased, the formation of large ears can be promoted, and a high yield of rice can be ensured.

[0047] Example 3

[0048] A rice nitrogen-saving planting method comprises the following steps:

[0049] (1) 2-3 days before rice harvest, use drones to sow astragalus membranaceus at 45 kg / hm2 2 .

[0050] (2) After rice harvest, leave 30 cm of stubble, crush the rice straw to 8 cm in length and evenly spread it back into the field. Apply 4500 kg / hm2 of organic fertilizer before the winter solstice. 2 , providing sufficient food for the growth and reproduction of earthworms.

[0051] (3) After rice harvest, the “bow” shaped trenching method is used to dig the side trenches, waist trenches and surrounding trenches in a timely manner. The trench width is 20 cm, and the trench depth increases gradually from the middle of the field to the drainage outlet. The trench depth in the middle of the field is 14 cm, and the trench depth near the drainage outlet is 18 cm. Ensure that the “three trenches” are unobstructed and can be irrigated and drained, providing a suitable moist environment for the growth of asparagus and earthworms.

[0052] (4) During the flowering period of astragalus, water the field to a depth of 6 cm to force the earthworms to migrate out. After all the earthworms have moved to the surrounding habitats such as the ridges of the field, turn the astragalus back into the field at a turning depth of 15 cm.

[0053] (5) Before planting rice, the nitrogen saving percentage Y during the rice growing season is designed based on the earthworm population density X in the field before turning over the astragalus. The nitrogen saving percentage Y 2 =17.5×10 -4 X+0.0225, the unit of X is bar / m 2 , the amount of nitrogen applied during the rice growing season (pure nitrogen) S = M (1-Y), where M is the customary amount of nitrogen applied and the unit of nitrogen application is kg / hm 2 .

[0054] (6) During the rice growing season, under nitrogen-saving conditions, the transplanting density can be appropriately increased by 30%, and nitrogen fertilizer can be applied at the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2. By appropriately applying nitrogen fertilizer in the front and back positions, the ear formation rate can be increased, the formation of large ears can be promoted, and a high yield of rice can be ensured.

[0055] Example 4

[0056] Based on the previous experiments, when there is no earthworm activity in the field, replacing 15% of the fertilizer nitrogen by returning astragalus to the field will not lead to a reduction in rice production. Subsequently, under the premise of ensuring that the yield is comparable to that of traditional farmers, the rate of increase in nitrogen saving percentage during the rice growing season gradually decreases with the increase in earthworm density, that is, the rate of increase in nitrogen saving percentage per unit earthworm density gradually decreases, and eventually stabilizes, approaching zero increase, which is consistent with the curve equation "Y 2 =17.5×10 -4 X+0.0225”, and the specific rice nitrogen saving percentage settings are shown in Table 1.

[0057] Table 1 Setting of rice nitrogen saving percentage under different earthworm population densities

[0058]

[0059]

[0060] Table 1 shows that the nitrogen saving percentage Y in the rice growing season is designed according to the earthworm population density X in the field before turning over the astragalus. 2 =17.5×10 -4 X+0.0225, when the earthworm population density increases from 0 / m 2 Increase to 80 / m 2 During the rice growing season, the nitrogen percentage increased from 15.0% to 40.3%.

[0061] Example 5

[0062] The traditional winter fallow-rice model was used as the control, that is, no astragalus was planted, and the nitrogen application rate for rice was 225 kg / hm 2 In the Chinese milk vetch-rice model, the average amount of Chinese milk vetch returned to the field is 30,000 kg / hm2.2 Before turning over the astragalus, the earthworm population density was investigated in different plots, and the earthworm density was selected as 0, 10±2, 20±2, 30±3, 40±3, 50±3, 60±4, 70±4, and 80±4 / m 2 There was one plot in each field, and each plot was divided into three equal parts, equivalent to three repetitions. The amount of nitrogen fertilizer was set based on the earthworm density and nitrogen reduction percentage in Table 1, and other field management measures of each plot remained consistent.

[0063] During the rice maturity period, harvesters were used in each plot to measure the yield and calculate the agronomic utilization efficiency of nitrogen. At the same time, the five-point sampling method was used to select five rice plants for testing, and yield factors such as effective ears, number of grains per ear, fruit setting rate, and 1,000-grain weight were examined to calculate the theoretical yield.

[0064] Table 2 Effects of nitrogen-saving cultivation on the biological characteristics of rice under earthworm bio-tillage in Astragalus membranaceus-rice system

[0065]

[0066]

[0067] Table 2 shows that under the condition of winter planting of astragalus, based on the earthworm population density in the field before turning over of astragalus in Table 1, the nitrogen saving percentage during the rice growing season was designed. When the earthworm population density was 0 / m 2 Increase to 80 / m 2 When the nitrogen fertilizer application rate of rice is 191.3kg / hm 2 Correspondingly reduced to 134.3kg / hm 2 In general, the ear formation rate and fruiting rate showed an increasing trend, while the effective ear showed a decreasing trend. The number of grains per ear showed a trend of increasing first and then decreasing. There was no significant difference in the thousand-grain weight. The final yield showed a trend of increasing first and then decreasing. The combination with the highest yield was the combination of returning astragalus to the field at a rate of 30,000 kg / hm2. 2 + 30 earthworms / hm 2 + Nitrogen (N) fertilizer dosage 163.4kg / hm 2 , an increase of 8.1% over the control, and the final nitrogen agronomic utilization rate showed an increasing trend with the decrease of nitrogen fertilizer application. From the average value of each combination of winter-sown astragalus, the average earthworm density was 40 / hm 2 The average nitrogen (N) fertilizer application rate was 159.0 kg / hm 2Although the average effective panicle decreased by 5.2% compared with the control, the average panicle rate, average number of grains per panicle, and average fruiting rate increased by 21.8%, 2.8%, and 2.8% respectively, and the average yield and average nitrogen agronomic utilization rate increased by 2.9% and 27.2% respectively. This shows that under the conditions of winter planting of astragalus, earthworm biological farming can further increase the nitrogen saving space in the rice season, achieve the synergy of nitrogen saving and yield increase, and thus greatly improve the nitrogen agronomic utilization efficiency.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A rice nitrogen-saving planting method, characterized in that: The following steps are involved: Carry out turning over of leguminous green manure and returning rice straw to the fields; Before turning over the leguminous green manure, investigate the earthworm population density X in the field, design the nitrogen percentage Y, Y in the rice growing season 2 =17.5×10 -4 X+0.0225, water the field to make the earthworms migrate out, and then turn over the leguminous green manure; The nitrogen application amount S during the rice growing season = the customary nitrogen application amount M×(1-nitrogen percentage Y during the rice growing season); Among them, the earthworm population density X is in units of pieces / m 2 ; Rice customary nitrogen application rate M refers to the customary nitrogen application rate for the current plot and current rice variety, in kg / hm 2 ; The unit of nitrogen application S during the rice growing season is kg / hm 2 .

2. The rice nitrogen-saving planting method according to claim 1, characterized in that: The leguminous green manure is astragalus, which is applied 2 to 3 days before the previous rice harvest at a rate of 30 to 45 kg / hm2. 2 Intercropping.

3. The rice nitrogen-saving planting method according to claim 1 or 2, characterized in that: The leguminous green manure is turned over during the flowering period, with a turning depth of 12 to 15 cm.

4. The rice nitrogen-saving planting method according to claim 1, characterized in that: When returning the rice straw to the field, 20 to 30 cm of stubble is left, and the rice straw is crushed to 5 to 8 cm and scattered back into the field.

5. The rice nitrogen-saving planting method according to claim 1, characterized in that: It also includes applying organic fertilizer of 3000-4500kg / hm before the winter solstice. 2 .

6. The rice nitrogen-saving planting method according to claim 1, characterized in that: After the previous rice crop is harvested, "three trenches" are dug with a width of 15 to 20 cm, a depth of 12 to 14 cm in the middle of the field, and a depth of 16 to 18 cm near the drainage outlet.

7. The rice nitrogen-saving planting method according to claim 1, characterized in that: The field irrigation depth is 4 to 6 cm.

8. The rice nitrogen-saving planting method according to claim 1, characterized in that: The rice planting density is increased by 10% to 30%.

9. The rice nitrogen-saving planting method according to claim 1, characterized in that: The nitrogen application during the rice growth period is based on the ratio of base fertilizer: topdressing: ear fertilizer = 5:3:2.

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