CN103960037B - The alternating method of a kind of clover and awnless brome - Google Patents

Abstract

The invention relates to the technical field of agricultural planting, and particularly discloses a crop rotation method of alfalfa and brome without awn. The crop rotation method of alfalfa and awnless brome comprises the following steps: after the awnless brome is planted for 5 to 6 years, the alfalfa is overturned and planted for 5 to 6 years, and then the awnless brome is overturned and planted again, and the crop rotation is repeated. The beneficial effect of the present invention is: increase the yield and soil fertility of high-quality pasture per unit area by means of crop rotation, and improve soil physical and chemical properties; the root nodules of alfalfa can also fix nitrogen in the atmosphere and improve soil fertility, which can reduce fertilization accordingly The amount of manpower and fertilizer input can be reduced, and the fertilizer input for the next round of awnless brome planting can be reduced, the output of awnless brome can be increased, the land utilization rate and yield per mu can be further improved, and economic benefits can be increased.

Description

A kind of crop rotation method of alfalfa and awnless brome

(1) Technical field

The invention relates to the technical field of agricultural planting, in particular to a method for crop rotation of alfalfa and brome without awn.

(2) Background technology

Alfalfa (Medicagosativa) is a perennial herb of the legume family Alfalfa, known as the "King of Grass". Alfalfa has strong stress resistance, wide distribution, large cultivation area, high yield, good quality, good palatability and high economic value. Alfalfa likes warm, semi-dry, semi-humid climate conditions and dry, loose, well-drained and high-calcium soil. The annual precipitation in the planting area is 600mm-800mm is the most suitable. Alfalfa does not have strict requirements on the soil, and it can grow except for the soil that is too sticky, the extremely poor sandy soil, or the soil that is too acidic or too alkaline. With the continuous deepening of my country's grassland ecological restoration and environmental protection, and the continuous improvement of the industrialization of alfalfa, the alfalfa planting area is increasing. Forage species of promotional value.

Bromusinermis (Bromusinermis) is a perennial herb with transverse rhizomes. It is widely distributed in provinces such as Guizhou and Guizhou, and is the dominant grass species in mountain meadow grasslands of 1000m to 3500m. Bromegrass has strong adaptability and is suitable for cold and dry climates. It is suitable for areas with a growth temperature of 20°C to 26°C, an annual average temperature of 3°C to 10°C, and an annual precipitation of 400mm to 500mm. Bromegrass is an excellent forage grass with high nutritional value, large yield, good palatability, long use season, cold and drought tolerance, and grazing tolerance. It has been introduced and cultivated all over the world. It grows in fertile loam and clay loam, but it is not resistant to strong acid and alkali soil and saline-alkali soil.

At present, alfalfa is mainly used as protein forage in planting. Planting for many years can improve soil fertility. However, alfalfa has self-toxicity, and the grassland planted with alfalfa cannot be planted continuously. Low, poor economic benefits.

(3) Contents of the invention

In order to make up for the deficiencies of the prior art, the present invention provides a crop rotation method for improving soil physical and chemical properties, increasing soil fertility, reducing fertilization, high land utilization rate, high yield per mu, and good economic benefits of alfalfa and brome awnless.

The present invention is achieved through the following technical solutions:

A crop rotation method for alfalfa and awnless brome comprises the following steps: after the awnless brome is planted for 5 to 6 years, the alfalfa is overturned for 5 to 6 years, and then the awnless brome is overturned for 5 to 6 years, and the crop rotation is repeated.

The crop rotation method of the alfalfa and the brome without awns specifically comprises the following steps:

Ⅰ) Pressing and planting of awnless brome and planting alfalfa: 5 to 6 years after planting of awnless brome and planting alfalfa for 5 to 6 years, the specific method is as follows:

(Ⅰ-a) Tilling: When cropping with alfalfa, turn over the mansless brome in the middle and late September. The wheat field is plowed deeply, and the plowing depth is more than 20cm;

(I-b) Weeding: After plowing, dry the ground for 9-11 days, and spray glyphosate or paraquat to remove the surviving grass after the seeds or roots in the soil grow new shoots;

(Ⅰ-c) Alfalfa planting: sow in the middle and late May, alfalfa naked seeds are sown at a rate of 1.2kg/mu, and coated seeds are sown at a rate of 1.5kg/mu. The sowing method is carried out with a row spacing of 25cm, and the soil is immediately suppressed. ; Apply diamine phosphate in the furrow while sowing, the fertilization rate is 10kg/mu or the mixed fertilizer of urea, superphosphate and potassium sulfate, wherein the weight percentage of N is ≥ 8%, and the weight percentage of P is ≥ 25 %, the weight percentage of K≥10%, and the fertilization rate is 30kg/mu;

(I-d) Field management:

① Weed control: Spray twice for the control of weeds in the alfalfa field. The time of the first spraying is when the alfalfa grows 3-5cm above the ground or 3-4 branches/branches. Mix 120ml of alfalfa net, 100ml of quizalofop-p-ethyl and 30kg of water before spraying; the second spraying time is when the seedling height is 15-20cm, and the spraying amount is 120ml of Mix Heling 100ml and water 30kg thoroughly before spraying;

②Water and fertilizer management: Irrigate at the branching stage with a plant height of 15-20cm, and apply superphosphate and potassium sulfate after irrigation. , calcium superphosphate, and potassium sulfate mixed fertilizer, wherein the weight percentage of N ≥ 8%, the weight percentage of P ≥ 25%, the weight percentage of K ≥ 10%, and the fertilization amount is not less than 80kg/mu;

(Ⅰ-e) The alfalfa harvest time is from mid-early July to mid-to-late September, and the number of alfalfa harvests is several times;

Ⅱ) Pressing alfalfa and planting brome without awns: After 5-6 years of alfalfa planting, brome without awns is planted with pressure for 5-6 years. The specific method is as follows:

(II-a) Tillage: In the middle and late September, the alfalfa is turned over, and the above-ground part is cut first, so that the stubble of the alfalfa is 5-10 cm, and then the alfalfa field is deeply plowed, and the plowing depth is more than 30 cm;

(II-b) Weeding: After overturning, dry the ground for 9-11 days. After the seeds or roots in the soil grow new shoots, spray glyphosate or paraquat to remove the surviving grass;

(Ⅱ-c) Planting of brome without awns: sow in the middle and late May. The naked brome without awns is sown at a seeding rate of 1.5-2kg/mu. Carry out sowing, immediately cover soil and suppress; apply nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer in the furrow at the same time of sowing.

(Ⅱ-d) Field management:

① Weed control: When there are few weeds, weeding can be done manually. When there are many weeds, 2,4-D butyl ester can be sprayed for weeding. The spraying amount is 40-60ml of 2,4-D butyl ester and 50 ～60kg is fully mixed and then sprayed;

②Water and fertilizer management: timely irrigate brome without awns; and topdress nitrogen fertilizer (such as urea) in time after each cutting, and the fertilization rate is 10kg/mu of urea;

③ Grassland rejuvenation: 3 to 4 years after planting Bromegrass, cut the rhizomes with a rake, loosen the soil layer, improve the soil permeability of the grassland, and rejuvenate the grassland;

(Ⅱ-e) The harvest time of brome without awns is from mid-early July to mid-to-late September, and the number of harvests of brome without awns is several times;

After 5 to 6 years of planting the awnless brome, turn over and plant alfalfa, repeat steps I) and II) to implement the next round of alfalfa and awnless brome crop rotation.

The specific method of plowing in the step (I-a) is: first use a heavy-duty harrow to harrow 2 times, then use a rotary tiller to do 2 times, and then use a nail-toothed harrow to remove the root system and the above-ground part left in the soil. After the soil is air-dried for 1-2 days, use a nail-toothed rake to rake the grass roots twice.

The amount of glyphosate used in the step (I-b) is: use 150-200ml of 30% glyphosate water per mu, mix with 15-20kg of water and spray evenly.

The amount of paraquat used in the step (I-b) is: 150-200 ml of 20% paraquat water solution per mu, mixed with 50 kg of water and sprayed evenly.

The specific method of plowing in the step (II-a) is as follows: first use a heavy-duty rake to deeply harrow twice, then use a rotary tiller to do two times of rotary tillage, and then use a nail-toothed harrow to remove the root system and the above-ground parts left in the soil. After the soil is air-dried for 1-2 days, use a nail-toothed rake to rake the grass roots twice.

In the step (II-a), the alfalfa is mowed and turned over before the initial flowering stage of the alfalfa.

The amount of glyphosate used in the step (II-b) is: 150-200 ml of 30% glyphosate water per mu, mixed with 15-20 kg of water and sprayed evenly.

The amount of paraquat used in the step (II-b) is: 150-200 ml of 20% paraquat water solution per mu, mixed with 50 kg of water and sprayed evenly.

The beneficial effects of the method for crop rotation of alfalfa and brome without awns in the present invention are as follows: the yield and soil fertility of high-quality forage grass per unit area are improved by means of crop rotation, the mode of alternate planting of alfalfa and brome without awns is adopted, and the well-developed root nodules of alfalfa are used as soil Provide a large amount of organic matter, and can absorb calcium from the deep layer of the soil, and can also decompose phosphate, so that the decomposed phosphate remains in the cultivation layer, and forms organic colloid after decomposition, which can make the soil form a stable Agglomerates, thereby improving soil physical and chemical properties; alfalfa root nodules can also fix nitrogen in the atmosphere and improve soil fertility, so that the amount of fertilization can be reduced accordingly, the input of labor and chemical fertilizers can be reduced, and the next round of awnless brome can also be reduced. The input of fertilizers during planting increases the yield of brome without awns, further improves the land utilization rate and yield per mu, and increases economic benefits.

(4) Specific implementation methods

The present invention will be further described below in conjunction with the examples, but the present invention is not limited thereto.

Example 1:

The crop rotation method of alfalfa and awnless brome comprises the following steps: after the awnless brome is planted for 5 to 6 years, the alfalfa is overturned and planted for 5 to 6 years, and then the awnless brome is overturned and planted again, and the crop rotation is repeated. Except the following crop rotation method of the present invention, the planting method of all the other alfalfa and awnless brome is the same as the planting method of conventional alfalfa and awnless brome.

The crop rotation method of the alfalfa and the brome without awns specifically comprises the following steps:

Ⅰ) Pressing and planting of awnless brome and planting alfalfa: 5 to 6 years after planting of awnless brome and planting alfalfa for 5 to 6 years, the specific method is as follows:

(Ⅰ-a) Tillage: When cropping with alfalfa, turn over the awnless brome in mid-September, first mow the aboveground part, so that the awnless brome stubble is 10-15cm, and then use a tiller to plow it Deep plowing of brome without awns, the plowing depth is more than 20cm, because the brome without awns planted for many years has well-developed fibrous roots, which are mainly concentrated at 10-20cm of the surface soil and the root system is closely connected with the soil. The specific method of plowing is as follows: first Use a heavy-duty rake (model 1BZ-2.5) to rake deeply twice, and then use a rotary tiller (1GKNBM-220) to till it twice. Rake off the root system and the aboveground part in the grass, and after the soil is aired for 1-2 days (sunny), then use a nail-toothed rake to rake the grass roots twice;

(I-b) Weeding: After plowing, dry the ground for 10 days, and spray glyphosate to remove the surviving grass after the seeds or roots remaining in the soil grow new shoots. The dosage of glyphosate is: 150-200ml of 30% glyphosate water solution for mu, mixed with 15-20kg of water and sprayed evenly;

(I-c) alfalfa planting: sowing in mid-May, alfalfa bare seeds are planted at a rate of 1.2kg/mu, and coated seeds are pressed at a rate of 1.5kg/mu, and the seeding method is adopted, with a row spacing of 25cm, and immediately covered with soil for suppression; Apply diamine phosphate in the furrow at the same time of sowing, the fertilization rate is 10kg/mu or a mixed fertilizer made of urea, superphosphate, and potassium sulfate, wherein the weight percentage of N is ≥ 8%, and the weight percentage of P is ≥ 25%. , K weight percentage ≥ 10%, fertilization rate is 30kg/mu;

(I-d) Field management:

① Weed control: Spray twice for the control of weeds in the alfalfa field. The time of the first spraying is when the alfalfa grows 3-5cm above the ground or 3-4 branches/branches. Mix 120ml of alfalfa net, 100ml of quizalofop-p-ethyl and 30kg of water before spraying; the second spraying time is when the seedling height is 15-20cm, and the spraying amount is 120ml of Mix Heling 100ml and water 30kg thoroughly before spraying;

②Water and fertilizer management: Irrigate at the branching stage with a plant height of 15-20cm, and apply phosphorus fertilizer and potassium fertilizer after irrigation. A mixed fertilizer made of potassium, wherein the weight percentage of N is ≥ 8%, the weight percentage of P is ≥ 25%, and the weight percentage of K is ≥ 10%, and the fertilization amount is not less than 80kg/mu;

(Ⅰ-e) The alfalfa harvest time is from mid-early July to mid-to-late September, and the number of alfalfa harvests is several times;

Ⅱ) Pressing alfalfa and planting brome without awns: After 5-6 years of alfalfa planting, brome without awns is planted with pressure for 5-6 years. The specific method is as follows:

(Ⅱ-a) Tilling: before the early flowering stage of alfalfa in mid-September, the alfalfa is turned over, and the above-ground part is cut first, so that the stubble of the alfalfa is 5 to 10 cm, and then the alfalfa field is deeply plowed and plowed with a tiller. The depth should be more than 30cm to cut off the root system of alfalfa, because the main root of the alfalfa that has been planted for many years is well-developed, and the length of the main root can reach more than 40cm; the specific method of plowing is: first use a heavy-duty rake (model 1BZ-2.5) to rake deeply twice, and then use rotary tillage Machine (1GKNBM-220) rotary tillage twice, then use nail-toothed rake to rake off the roots and aboveground parts left in the soil, after the soil is aired for 1-2 days (sunny day), then use nail-toothed rake to rake the grass roots twice ;

(Ⅱ-b) Weeding: after turning over, put the ground in the sun for 10 days, after the seeds or root system remaining in the soil grow new shoots, spray glyphosate to get rid of the surviving grass. The dosage of glyphosate is: 150-200ml of 30% glyphosate water solution for mu, mixed with 15-20kg of water and sprayed evenly;

(Ⅱ-c) Planting of brome without awns: sow in mid-May. The naked brome without awns is sown at a seeding rate of 1.5-2kg/mu in a drill, with a depth of 1-2cm and a row spacing of 20-30cm. Sowing, immediately cover with soil and suppress; apply nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer in the furrow at the same time of sowing.

(Ⅱ-d) Field management:

① Weed control: Brome awns grows slowly in the year of sowing and is vulnerable to weed damage. Pay attention to weeding in the year of sowing. Weeding can be done manually when there are few weeds, and 2,4-D butyl ester can be sprayed for weeding when there are many weeds. The amount of spraying is 40-60ml of 2,4-D butyl ester and 50-60kg of water per mu of land, and then spraying after fully mixing;

②Water and fertilizer management: timely irrigate brome without awns; and topdress urea in time after each cutting, and the fertilization rate is 10kg/mu of urea;

③Grassland rejuvenation: After three and a half years of planting brome without awns, the underground rhizomes tend to form hard flocculent turf, resulting in solid soil surface, poor ventilation and water permeability, slow decomposition of organic matter, and decreased grass production. , use a disc harrow to cut the rhizomes, loosen the soil layer, improve the soil permeability of the grassland, and rejuvenate the grassland;

(Ⅱ-e) The harvest time of brome without awns is from mid-early July to mid-to-late September, and the number of harvests of brome without awns is several times;

After 5 to 6 years of planting the awnless brome, turn over and plant alfalfa, repeat steps I) and II) to implement the next round of alfalfa and awnless brome crop rotation.

Example 2:

The crop rotation method of alfalfa and awnless brome comprises the following steps: after the awnless brome is planted for 5 to 6 years, the alfalfa is overturned and planted for 5 to 6 years, and then the awnless brome is overturned and planted again, and the crop rotation is repeated. Except the following crop rotation method of the present invention, the planting method of all the other alfalfa and awnless brome is the same as the planting method of conventional alfalfa and awnless brome.

The crop rotation method of the alfalfa and the brome without awns specifically comprises the following steps:

Ⅰ) Pressing and planting of awnless brome and planting alfalfa: 5 to 6 years after planting of awnless brome and planting alfalfa for 5 to 6 years, the specific method is as follows:

(Ⅰ-a) Tilling: When cropping with alfalfa, turn over the awnless brome at the end of September, and cut the aboveground part first, so that the stubble of awnless brome is 10-15cm, and then use a tiller to plow it Deep plowing of brome without awns, the plowing depth is more than 20cm, because the brome without awns planted for many years has well-developed fibrous roots, which are mainly concentrated at 10-20cm of the surface soil and the root system is closely connected with the soil. The specific method of plowing is as follows: first Use a heavy-duty rake (model 1BZ-2.5) to rake deeply twice, and then use a rotary tiller (1GKNBM-220) to till it twice. Rake off the root system and the aboveground part in the grass, and after the soil is aired for 1-2 days (sunny), then use a nail-toothed rake to rake the grass roots twice;

(I-b) Weeding: After plowing, dry the ground for 11 days. After the seeds or roots remaining in the soil grow new shoots, spray paraquat to remove the surviving grass. The dosage of paraquat is: 150-200ml of 20% paraquat water solution, mixed with 50kg of water and sprayed evenly;

(I-c) alfalfa planting: sowing in late May, alfalfa bare seeds are planted at a rate of 1.2kg/mu, and coated seeds are pressed at a rate of 1.5kg/mu, and the seeding method is adopted with a row spacing of 25cm, and the soil is immediately suppressed; Apply diamine phosphate in the furrow at the same time of sowing, the fertilization rate is 10kg/mu or a mixed fertilizer made of urea, superphosphate, and potassium sulfate, wherein the weight percentage of N is ≥ 8%, and the weight percentage of P is ≥ 25%. , K weight percentage ≥ 10%, fertilization rate is 30kg/mu;

(I-d) Field management:

① Weed control: Spray twice for the control of weeds in the alfalfa field. The time of the first spraying is when the alfalfa grows 3-5cm above the ground or 3-4 branches/branches. Mix 120ml of alfalfa net, 100ml of quizalofop-p-ethyl and 30kg of water before spraying; the second spraying time is when the seedling height is 15-20cm, and the spraying amount is 120ml of Mix Heling 100ml and water 30kg thoroughly before spraying;

②Water and fertilizer management: Irrigate at the branching stage with a plant height of 15-20cm, and apply superphosphate and potassium sulfate after irrigation. , calcium superphosphate, and potassium sulfate mixed fertilizer, wherein the weight percentage of N ≥ 8%, the weight percentage of P ≥ 25%, the weight percentage of K ≥ 10%, and the fertilization amount is not less than 80kg/mu;

(Ⅰ-e) The alfalfa harvest time is from mid-early July to mid-to-late September, and the number of alfalfa harvests is several times;

Ⅱ) Pressing alfalfa and planting brome without awns: After 5-6 years of alfalfa planting, brome without awns is planted with pressure for 5-6 years. The specific method is as follows:

(Ⅱ-a) Tilling: before the early flowering stage of alfalfa in late September, the alfalfa is turned over, and the above-ground part is cut first, so that the stubble of the alfalfa is 5 to 10 cm, and then the alfalfa field is deeply plowed and plowed with a tiller. The depth should be more than 30cm to cut off the root system of alfalfa, because the main root of the alfalfa that has been planted for many years is well-developed, and the length of the main root can reach more than 40cm; the specific method of plowing is: first use a heavy-duty rake (model 1BZ-2.5) to rake deeply twice, and then use rotary tillage Machine (1GKNBM-220) rotary tillage twice, then use nail-toothed rake to rake off the roots and aboveground parts left in the soil, after the soil is aired for 1-2 days (sunny day), then use nail-toothed rake to rake the grass roots twice ;

(Ⅱ-b) Weeding: After turning over the soil, dry the ground for 11 days. After the seeds or roots in the soil grow new shoots, spray paraquat to remove the surviving grass. The dosage of paraquat is: 150-200ml of 20% paraquat water solution, mixed with 50kg of water and sprayed evenly;

(Ⅱ-c) Planting of brome without awns: sow in late May. The naked brome without awns is sown at a seeding rate of 1.5-2kg/mu, and the sowing depth is 1-2cm, and the row spacing is 20-30cm. Sowing, immediately cover with soil and suppress; apply nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer in the furrow at the same time of sowing.

(Ⅱ-d) Field management:

① Weed control: Brome awns grows slowly in the year of sowing and is vulnerable to weed damage. Pay attention to weeding in the year of sowing. Weeding can be done manually when there are few weeds, and 2,4-D butyl ester can be sprayed for weeding when there are many weeds. The amount of spraying is 40-60ml of 2,4-D butyl ester and 50-60kg of water per mu of land, and then spraying after fully mixing;

②Water and fertilizer management: timely irrigate brome without awns; and topdress urea in time after each cutting, and the fertilization rate is 10kg/mu of urea;

③Grassland rejuvenation: After 4 years of planting Bromegrass, the underground rhizomes tend to form hard flocculent turf, resulting in solid soil surface, poor ventilation and water permeability, slow decomposition of organic matter, and decreased grass production. In order to maintain grass production, Cut the rhizomes with a disc harrow, loosen the soil layer, improve the soil permeability of the grassland, and rejuvenate the grassland;

(Ⅱ-e) The harvest time of brome without awns is from mid-early July to mid-to-late September, and the number of harvests of brome without awns is several times;

After 5 to 6 years of planting the awnless brome, turn over and plant alfalfa, repeat steps I) and II) to implement the next round of alfalfa and awnless brome crop rotation.

Implementation Effect:

In the traditional model of only planting alfalfa, within 1 to 5 years of planting, the alfalfa yield per mu is 400 kg. Calculated at 2 yuan per kilogram, the output value per mu is 800 yuan. After 5 to 10 years of planting, the average yield per mu is only 160 kg. The output value per mu is 320 yuan; in the traditional mode of only planting brome without awns, the yield of brome without awns per mu is 300 kg within 1 to 5 years. Over 10 years, the average yield per mu is 150-180 kg, and the output value per mu is 225-270 yuan.

The gross production value per unit area of land can be effectively increased after being planted by the rotation method of the alfalfa and the awnless brome of the present invention. Due to the interaction effect of gramineous and leguminous pastures in the crop rotation method, the gross production value per unit area of land can reach 1,400 yuan/mu. Alfalfa is 1120 yuan/mu, and brome without awns is 700 yuan/mu, and the economic benefits have increased by 25% and 100% respectively. Since the perennial pasture has the characteristics of being put into use for many years in one year, after deducting the average annual miscellaneous expenses per unit of land area (pesticides, fertilizers, fuel power, hired labor, etc.) Under the method, the net benefits per mu are 900 yuan, 480 yuan and 1180 yuan respectively.

Claims (8)

1. A method for crop rotation of alfalfa and awnless brome, which is characterized in that: comprising the following steps: planting alfalfa for 5 to 6 years after the awnless brome is planted for 5 to 6 years, and then turning over and planting awnless brome Wheat, repeated crop rotation; specifically include the following steps: Ⅰ) Pressing and planting of awnless brome and planting alfalfa: 5 to 6 years after planting of awnless brome and planting alfalfa for 5 to 6 years, the specific method is as follows: (Ⅰ-a) Tilling: When cropping with alfalfa, turn over the mansless brome in the middle and late September. The wheat field is plowed deeply, and the plowing depth is more than 20cm; (I-b) Weeding: After plowing, dry the ground for 9-11 days, and spray glyphosate or paraquat to get rid of the surviving grass after the seeds or roots that remain in the soil grow new shoots; (Ⅰ-c) Alfalfa planting: Sow in the middle and late May. The sowing rate of naked alfalfa seeds is 1.2kg/mu, and that of coated seeds is 1.5kg/mu. The sowing method is carried out with a row spacing of 25cm, and the soil is pressed in time. ; Apply diamine phosphate in the furrow while sowing, the fertilization rate is 10kg/mu or the mixed fertilizer of urea, superphosphate and potassium sulfate, wherein the weight percentage of N is ≥ 8%, and the weight percentage of P is ≥ 25 %, the weight percentage of K≥10%, and the fertilization rate is 30kg/mu; (I-d) Field management: ① Weed control: Spray twice for the control of weeds in the alfalfa field. The time of the first spraying is when the alfalfa grows 3-5cm above the ground or 3-4 branches/branches. Mix 120ml of alfalfa net, 100ml of quizalofop-p-ethyl and 30kg of water before spraying; the second spraying time is when the seedling height is 15-20cm, and the spraying amount is 120ml of Mix Heling 100ml and water 30kg thoroughly before spraying; ②Water and fertilizer management: Irrigate at the branching stage with a plant height of 15-20cm, and apply superphosphate and potassium sulfate after irrigation. , calcium superphosphate, and potassium sulfate mixed fertilizer, wherein the weight percentage of N ≥ 8%, the weight percentage of P ≥ 25%, the weight percentage of K ≥ 10%, and the fertilization amount is not less than 80kg/mu; (Ⅰ-e) The alfalfa harvest time is from mid-early July to mid-to-late September, and the number of alfalfa harvests is several times; Ⅱ) Pressing alfalfa and planting brome without awns: After 5-6 years of alfalfa planting, brome without awns is planted with pressure for 5-6 years. The specific method is as follows: (II-a) Tillage: In the middle and late September, the alfalfa is turned over, and the above-ground part is cut first, so that the stubble of the alfalfa is 5-10 cm, and then the alfalfa field is deeply plowed, and the plowing depth is more than 30 cm; (II-b) Weeding: After overturning, dry the ground for 9 to 11 days, and after the seeds or root systems remaining in the soil grow new shoots, spray glyphosate or paraquat to remove the surviving grass; (Ⅱ-c) Planting of brome without awns: sow in the middle and late May. The naked brome without awns is sown at a seeding rate of 1.5-2kg/mu. Carry out sowing, cover soil and suppress in time; apply urea, superphosphate and potassium sulfate in the furrow at the same time of sowing. mu; (Ⅱ-d) Field management: ① Weed control: manual weeding when there are few weeds, and spraying 2,4-D butyl ester for weeding when there are many weeds. The spraying amount is 40-60ml of 2,4-D butyl ester and 50-60kg of water per mu Spray after mixing thoroughly; ②Water and fertilizer management: timely irrigate brome without awns; and topdress urea in time after each cutting, and the fertilization rate is 10kg/mu of urea; ③ Grassland rejuvenation: 3 to 4 years after planting Bromegrass, cut the rhizomes with a rake, loosen the soil layer, improve the soil permeability of the grassland, and rejuvenate the grassland; (Ⅱ-e) The harvest time of brome without awns is from mid-early July to mid-to-late September, and the number of harvests of brome without awns is several times; After 5 to 6 years of planting the awnless brome, turn over and plant alfalfa, repeat steps I) and II) to implement the next round of alfalfa and awnless brome crop rotation. 2. The crop rotation method of a kind of alfalfa and awnless brome according to claim 1 is characterized in that: the specific method of plowing in the step (I-a) is: at first adopt heavy-duty rake deep rake 2 times, then use rotary Rotate the tiller twice, then use a nail-toothed rake to remove the roots and aboveground parts left in the soil, and then use a nail-toothed rake to rake the grass roots twice after the soil has been aired for 1-2 days. 3. the crop rotation method of a kind of alfalfa according to claim 1 and awnless brome, it is characterized in that: the consumption of glyphosate used in the step (I-b) is: every mu uses 30% glyphosate water 150-200ml, mixed with 15-20kg of water and sprayed evenly. 4. The crop rotation method of a kind of alfalfa and brome without awns according to claim 1, it is characterized in that: the consumption of paraquat used in the step (I-b) is: every mu uses 20% paraquat aqueous solution 150～ 200ml, mixed with 50kg of water and sprayed evenly. 5. The crop rotation method of a kind of alfalfa and brome without awns according to claim 1, it is characterized in that: the specific method of plowing in the step (II-a) is: first adopt heavy rake deep rake 2 times, then use rotary Rotate the tiller twice, then use a nail-toothed rake to remove the roots and aboveground parts left in the soil, and then use a nail-toothed rake to rake the grass roots twice after the soil has been aired for 1-2 days. 6. The crop rotation method of a kind of alfalfa and awnless brome according to claim 1, characterized in that: in the step (II-a), the alfalfa is mowed and turned over before the initial flowering stage of the alfalfa. 7. The crop rotation method of a kind of alfalfa and brome without awns according to claim 1 is characterized in that: the consumption of glyphosate used in the step (II-b) is: every mu uses 30% glyphosate water 150-200ml, mixed with 15-20kg of water and sprayed evenly. 8. A method for crop rotation of alfalfa and brome awnless according to claim 1, characterized in that: the amount of paraquat used in the step (II-b) is: 20% paraquat aqueous solution 150-100% per mu 200ml, mixed with 50kg of water and sprayed evenly.