Rice-fish-water spinach green co-culture system for controlling greenhouse gas emissions of rice-fish system and field management method therefor

Abstract

A rice-fish-water spinach co-culture system and a field management method therefor. A plurality of fish ponds are provided in a rice field, the rice field being planted with rice, and fishes and water spinach being grown in the fish ponds, such that a rice-fish-water spinach co-culture system is formed in which rice and water spinach are intercropped on a horizontal structure, and rice, water spinach and fish breeding are combined on a vertical structure. The system can reduce the risk of the agricultural non-point source pollution of water bodies, improves the nutrient recycling efficiency of the system, produces diversified agricultural products, and protects the ecological environment of rice fields.

Description

A rice-fish-water spinach green farming system for controlling greenhouse gas emissions from the rice-fish system and its field management method Technical Field

[0001] The present invention relates to the field of agricultural planting technology, and in particular to a rice-fish-water spinach green co-cultivation system for controlling greenhouse gas emissions from the rice-fish system and a field management method thereof. Background Art

[0002] Rice-fish farming is a typical ecological agricultural model in my country, a prime example of integrating grain production with aquaculture. Fish not only eat pests, but their excrement also serves as fertilizer for the growing rice. The fish's movement in the water loosens the soil, promoting the growth of rice roots. The mature rice provides an ideal shelter for the fish from predators. Rice-fish farming not only provides food and fish products, conserves water and soil resources, but also generates positive social and ecological benefits, making it widely practiced throughout China.

[0003] However, the current rice-fish farming model still has the following problems, and the rice-fish farming technology needs to be improved.

[0004] On the one hand, rice paddies are a major source of greenhouse gas emissions, including carbon dioxide, methane, and nitrous oxide. Numerous reports suggest that raising fish in rice paddies can exacerbate greenhouse gas emissions, further exacerbating environmental pollution (e.g., 10.1016 / j.agee.2008.09.003). However, numerous reports suggest that raising fish in rice paddies can reduce greenhouse gas emissions. However, the influencing factors and mechanisms remain unclear and inconclusive. Therefore, for rice-fish systems, which can exacerbate greenhouse gas emissions from rice paddies, controlling greenhouse gas emissions is a pressing issue.

[0005] On the other hand, the conflict between fish farming and rice cultivation is difficult to resolve. While fish in rice paddies can prey on some pests, this effectiveness is limited, and they also take up some rice paddy resources. Therefore, to ensure high rice yields, chemical fertilizers and pesticides are still required. However, chemical fertilizers and pesticides alter water and soil structure, causing agricultural non-point source pollution, deteriorating water quality, and soil nutrient loss. This prevents fish from providing a long-term, optimal living environment, leading to fish mortality and reduced yields. Studies have shown that co-cultivation of rice and vegetables can boost rice yields and reduce the use of chemical fertilizers. After applying base fertilizer, topdressing is not required. However, this approach, without topdressing, can lead to phosphorus deficiencies in the soil later in the crop's lifespan. Rice, on the other hand, requires phosphorus even more during its later growth stages. Phosphorus is essential throughout rice's growth cycle, promoting root growth, increasing tillering, enhancing stress resistance, promoting early maturity, and increasing per-acre yield. It is a crucial nutrient. Furthermore, while fish production is currently increased through feeding, this feed ultimately impacts rice production, making this approach unpopular given the priority of ensuring rice production. Therefore, achieving a double increase in both rice and fish production without requiring topdressing in the later stages of the rice-fish system and ensuring that the soil is phosphorus-deficient is another challenge facing the system.

[0006] Summary of the Invention

[0007] In order to solve the problems of increased greenhouse gas emissions, water pollution and loss of soil nutrients, especially phosphorus, caused by topdressing and pesticide application in existing rice-fish farming technology, the present invention provides a rice-fish-water spinach farming system for growing water spinach in fish pits and a field management method thereof. The rice-fish-water spinach farming system can ensure the yield of rice and fish while only applying base fertilizer, no topdressing, no pesticide application, and no feeding of fish feed. More importantly, the system can significantly control the problem of increased greenhouse gas emissions caused by the rice-fish system.

[0008] The first object of the present invention is to provide a rice-fish-water spinach co-cultivation system.

[0009] The second object of the present invention is to provide an application of the rice-fish-water spinach cooperative system in controlling agricultural non-point source pollution and reducing greenhouse gas emissions in the rice-fish cooperative system.

[0010] The third object of the present invention is to provide an application of the rice-fish-water spinach cooperative farming system in reducing soil nutrient loss and / or increasing soil nutrient content in the rice-fish cooperative farming system.

[0011] The fourth object of the present invention is to provide a field management method for the rice-fish-water spinach co-cultivation system.

[0012] In order to achieve the above object, the present invention is implemented through the following scheme:

[0013] The present invention constructs a "strip-shaped" rice field fish pit-rice planting area structure, and plants water spinach in the fish pit, forming a rice-fish-water spinach co-cultivation system in which rice and water spinach are intercropped in the horizontal structure and rice, water spinach and fish are raised in the vertical structure. This system increases efficiency and reduces emissions, significantly reduces greenhouse gas emissions and agricultural non-point source pollution of water bodies, increases the nutrient content in the soil, and increases the total output of rice field agricultural products. The "strip-shaped" rice field fish pit-rice planting area structure is achieved by building a number of fish pits in the rice field, dividing the rice field into a number of rice planting areas. A narrower fish pit is combined with a wider rice planting area. The fish pit and the rice planting area form a "wide and narrow" combination, so that the rice field presents a "strip-shaped" distribution spatial structure.

[0014] A rice-fish-water spinach cooperative farming system comprises a rice field provided with a plurality of fish pits; the rice field is planted with rice, and fish and water spinach are grown in the fish pits, forming a rice-fish-water spinach cooperative farming system in which rice and water spinach are intercropped in a horizontal structure, and rice, water spinach and fish are cultivated in a vertical structure.

[0015] Preferably, the fish pit is a strip-type fish pit.

[0016] More preferably, the long side of the fish pond is parallel to the long side of the rice field.

[0017] Preferably, the long side of the fish pond is the same length as the long side of the rice field.

[0018] Preferably, the width of the fish pond is 6% to 10% of the width of the rice field.

[0019] More preferably, the width of the fish pond is 10% of the width of the rice field.

[0020] Preferably, the area occupied by the fish pond is 6% to 10% of the total area of ​​the rice field.

[0021] More preferably, the area of ​​the fish pond is 10% of the total area of ​​the rice field.

[0022] In addition, when the rice field is large, several fish ponds can be set up in parallel.

[0023] The water in the rice fields and the water in the fish ponds can be connected to each other, and fish can swim back and forth between the rice fields and the fish ponds.

[0024] Preferably, the depth of the water surface in the rice field where rice is grown is 0 cm to 20 cm; and in the fish pond area, the depth from the water surface to the bottom of the fish pond is 70 cm to 100 cm.

[0025] More preferably, before transplanting rice seedlings, the depth of water on the surface of the rice field where rice is planted is 5 cm to 7 cm.

[0026] More preferably, except for the field drying, the depth of the water on the surface of the rice field where rice is grown is 6 cm to 8 cm.

[0027] More preferably, from the time of rice transplanting to the effective tillering stage of rice, the depth of the water on the surface of the rice field where rice is planted is 15 cm to 20 cm.

[0028] More preferably, before rice seedlings are transplanted, the depth from the water surface to the bottom of the fish pond in the fish pond area is 85 cm to 87 cm.

[0029] More preferably, from the rice transplanting stage to the effective tillering stage of the rice, the depth from the water surface to the bottom of the fish pond in the fish pond area is 82 cm to 84 cm.

[0030] More preferably, from the late tillering stage of rice to one week before the rice maturity stage, the depth from the water surface to the bottom of the fish pond in the fish pond area is 95 cm to 100 cm.

[0031] More preferably, the field water in the rice planting area is drained and the fields are dried one week before the rice matures, and the depth from the water surface to the bottom of the fish pond in the fish pond area is maintained at 70 cm to 75 cm.

[0032] More preferably, after catching the fish, the water depth in the fish pit is 70 cm to 75 cm.

[0033] Preferably, the ratio of the number of rice plants, the number of water spinach plants and the number of fish released is (905-985) plants:60 plants:(28-35) fish.

[0034] More preferably, the ratio of the number of rice plants, the number of water spinach plants and the number of fish released is 945 plants:60 plants:32 fish.

[0035] Preferably, in the rice-fish-water spinach co-cultivation system, the rice planting density is 20 plants / m 2 ~30 plants / m 2 .

[0036] More preferably, in the rice-fish-water spinach co-cultivation system, the rice planting density is 25 plants / m 2 .

[0037] Preferably, in the rice-fish-water spinach co-cultivation system, the water spinach planting density is 12 plants / m 2 ~16 plants / m 2 .

[0038] More preferably, in the rice-fish-water spinach co-cultivation system, the water spinach planting density is 100 plants / 7m 2 .

[0039] Preferably, in the rice-fish-water spinach co-cultivation system, the fish stocking density is 400 to 600 fish per mu.

[0040] More preferably, in the rice-fish-water spinach co-cultivation system, the stocking density of the fish is 500 fish per mu.

[0041] Preferably, the fish species is grass carp.

[0042] Preferably, the planting row spacing of the water spinach is 18 cm to 22 cm.

[0043] More preferably, the planting row spacing of the water spinach is 20 cm.

[0044] Preferably, the water spinach is planted on a floating board.

[0045] Preferably, the rice is indica rice.

[0046] More preferably, the rice varieties are Huahang 57, Huanghuazhan, Meixiangzhan, Yuehe Si Miao, 19xiang, Yuenong Si Miao, Jinnong Si Miao, Wushan Si Miao, Hemeizhan and / or Huangguangyouzhan.

[0047] More preferably, the rice is early rice and / or late rice.

[0048] Further preferably, the variety of early rice is Yuehe Si Miao.

[0049] Further preferably, the late rice variety is China Airlines 57.

[0050] Further preferably, the rice fields are rotated to grow early rice and late rice.

[0051] More preferably, the rice fields are planted with early rice first and then with late rice. Preferably, the rice fields are located in southern my country.

[0052] The application of any of the rice-fish-water spinach cooperative farming systems in agricultural planting of rice-fish cooperative farming systems should also be within the scope of protection of the present invention.

[0053] The application of any of the field management methods in controlling agricultural non-point source pollution in rice-fish farming systems should also be within the scope of protection of the present invention.

[0054] Preferably, the controlling of agricultural non-point source pollution in the rice-fish farming system includes reducing greenhouse gas emissions and / or improving water quality.

[0055] More preferably, the greenhouse gas is one or more of CH4, CO2 or N2O.

[0056] Preferably, the improvement in water quality includes an improvement in self-purification capacity.

[0057] More preferably, the improvement in self-purification capacity includes a decrease in dissolved oxygen content in the water body and / or an increase in total nitrogen content in the water body.

[0058] The application of any of the rice-fish-water spinach cooperative farming systems to reduce soil nutrient loss and / or increase soil nutrient content in the rice-fish cooperative farming system should also fall within the scope of protection of the present invention.

[0059] Preferably, the rice-fish farming system is a rice-fish farming system in which only base fertilizer is applied, no topdressing, no pesticides are applied, and no feed is fed.

[0060] Preferably, the soil nutrients include the phosphorus, nitrogen and / or potassium content of the soil.

[0061] More preferably, the soil nutrients include the phosphorus, nitrogen and / or potassium content of paddy soil.

[0062] Application of any of the rice-fish-water spinach cooperative farming systems in increasing the yield of agricultural products in the rice-fish cooperative farming system.

[0063] Preferably, the total output of agricultural products in the rice-fish farming model is increased.

[0064] Preferably, the agricultural products include rice, fish products and water spinach.

[0065] The field management method of any of the rice-fish-water spinach co-cultivation systems comprises the following steps:

[0066] The method comprises applying base fertilizer to the rice field 2 to 4 days before transplanting rice seedlings; planting water spinach 1 to 2 days before transplanting rice seedlings; putting fish into the fish pond in the late tillering stage of rice; cultivating rice, fish and water spinach together; and harvesting the agricultural products separately, namely harvesting the rice, fish products and water spinach separately.

[0067] Preferably, the base fertilizer comprises organic fertilizer.

[0068] More preferably, the organic fertilizer comprises decomposed organic fertilizer chicken manure.

[0069] Preferably, 2 to 4 days before rice transplanting, the amount of water used should be 4000 kg / hm2. 2 ~5000kg / hm 2 The rice fields are treated with decomposed organic fertilizer chicken manure.

[0070] More preferably, 3 days before rice transplanting, the amount of water used should be 4000 kg / hm2. 2 ~5000kg / hm 2 The rice fields are treated with decomposed organic fertilizer chicken manure.

[0071] More preferably, 2 to 3 days before rice transplanting, the amount of water used should be 4500 kg / hm2. 2 The rice fields are treated with decomposed organic fertilizer chicken manure.

[0072] More preferably, 3 days before rice transplanting, the 2The rice fields are treated with decomposed organic fertilizer chicken manure.

[0073] More preferably, no topdressing, no pesticides and no herbicides are applied during the entire rice planting period.

[0074] Preferably, water spinach is planted 1 to 2 days before rice seedlings are transplanted.

[0075] More preferably, water spinach is planted 1 day before rice transplanting.

[0076] Preferably, the water spinach is grown using a floating board.

[0077] More preferably, the floating plate has a width of 40 cm and a length of 100 cm.

[0078] More preferably, the floating plate is provided with a plurality of planting baskets.

[0079] Further preferably, the diameter of the planting basket is 8 cm.

[0080] Further preferably, the floating plate is provided with two rows of planting baskets arranged in parallel with a row spacing of 20 cm.

[0081] Preferably, before transplanting rice seedlings, the rice planting area is plowed and leveled, and the rice planting area is the area in the rice field where rice is planted.

[0082] Preferably, the depth of the surface water in the rice-growing area is 0 cm to 20 cm.

[0083] Preferably, the depth of the water on the surface of the rice-growing area is 5 cm to 7 cm from plowing to before rice transplanting.

[0084] More preferably, after transplanting the rice seedlings, flooding irrigation is adopted. Except for sun-drying the fields, the depth of water on the surface of the rice-growing area is 6 cm to 8 cm.

[0085] More preferably, from rice transplanting to the effective tillering stage of rice, shallow water is used for transplanting and thin water for tillering, and the depth of surface water in the rice planting area is 15 cm to 20 cm.

[0086] More preferably, the rice-growing area is drained of surface water one week before the rice matures, and the fields are dried under the sun.

[0087] More preferably, before rice seedlings are transplanted, the depth from the water surface to the bottom of the fish pond in the fish pond area is 85 cm to 87 cm.

[0088] More preferably, from the rice transplanting stage to the effective tillering stage of the rice, the depth from the water surface to the bottom of the fish pond in the fish pond area is 82 cm to 84 cm.

[0089] More preferably, from the late tillering stage of rice to one week before the rice maturity stage, the depth from the water surface to the bottom of the fish pond in the fish pond area is 95 cm to 100 cm.

[0090] More preferably, the field water in the rice planting area is drained and the fields are dried one week before the rice matures, and the depth from the water surface to the bottom of the fish pond in the fish pond area is maintained at 70 cm to 75 cm.

[0091] More preferably, after catching the fish, the water depth in the fish pit is 70 cm to 75 cm.

[0092] Preferably, the rice is harvested after it matures; and the fish is caught after the rice matures.

[0093] Due to the meristematic nature of water spinach, it will continue to regenerate stems and leaves after harvesting, so water spinach can be continuously picked during the rice planting period. Preferably, the water spinach is picked when the plant height is 25cm to 30cm.

[0094] Preferably, no fish feed is fed during the fish farming period.

[0095] Compared with the prior art, the present invention has the following beneficial effects:

[0096] The present invention provides a rice-fish-water spinach co-cultivation model, which can reduce greenhouse gas (such as CH4, N2O and CO2) emissions, promote the fixed accumulation of carbon and nitrogen resources in the soil, improve the nutrient content in the soil, increase the dissolved oxygen content of paddy field water and reduce the total nitrogen content of paddy field water, reduce the risk of agricultural non-point source pollution of water bodies, and improve the nutrient recycling efficiency in the system and the agricultural product output of the paddy field ecosystem. During the entire planting period, there is no need to feed fish feed additionally and apply fertilizers, pesticides and herbicides, achieving the agricultural production goal of production and protection at the same time, producing diversified agricultural products and protecting the paddy field ecological environment. It is an environmentally friendly agricultural production technology worthy of vigorous promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 is a schematic diagram of the planting design of the experimental plots with four treatments (vertical cross-section); a is rice monoculture; b is rice-fish farming; c is rice-fish-water chestnut farming; d is rice-fish-water spinach farming.

[0098] Figure 2 shows field photos of the experimental plots with four different treatments; a is rice monoculture; b is rice-fish farming; c is rice-fish-water chestnut farming; d is rice-fish-water spinach farming.

[0099] Figure 3 shows the dissolved oxygen content in water under different farming patterns; DZ is rice monoculture; CK is rice-fish farming; LJ is rice-fish-water chestnut farming; WC is rice-fish-water spinach farming.

[0100] Figure 4 shows the total nitrogen content in water bodies under different farming patterns; DZ is rice monoculture; CK is rice-fish farming; LJ is rice-fish-water chestnut farming; WC is rice-fish-water spinach farming. DETAILED DESCRIPTION

[0101] The present invention is further described in detail below with reference to the accompanying drawings and specific examples. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0102] The test site of the present invention is located in Zengcheng Teaching and Research Base of South China Agricultural University, Zengcheng District, Guangzhou City, Guangdong Province (23°14′N, 113°37′E). The base is located in the southwest of Zengcheng District, Guangzhou City, in the low mountain and hilly area. It has a southern subtropical monsoon humid climate with sufficient sunlight, mild climate, abundant rainfall and rich heat. The experimental plot is located in an interhill basin with an altitude of 18m to 329m. The total annual rainfall in the year of the experiment was 1507.2mm, the sunshine hours were 1986.6h, and the average temperature was 25.1°C. The experimental field is paddy soil developed from red soil, and is mainly used to grow double-season rice (early rice is from March to July, and late rice is from August to November). In the early stage of the experiment, the plot was sorted and trimmed, and 15 evenly distributed experimental plots with a length of 6m and a width of 7m were set up, and 50cm high ridges were set around the plots.

[0103] The test materials of the present invention include:

[0104] Rice (Oryza sativa L.): The early rice variety tested was Yuehe Si Miao, an indica conventional rice with an average growing period of 123.1 days, a moderate plant shape, upright leaves, medium tillering ability, colorless palea tips, large panicles with many grains, a high fruit set rate, low 1000-grain weight, and good color change at maturity. It was provided by the Guangdong Academy of Agricultural Sciences. The late rice variety tested was Huahang 57, an indica conventional rice with an average full growing period of 111 to 112 days, a medium plant shape, medium tillering ability and lodging resistance, and medium-weak cold resistance. It was purchased from the Zengcheng Farmers' Market.

[0105] Fish (Cyprinus carpio): Rice flower carp (Cyprinus carpio), purchased from Guangdong Qingyuan Green Source Fishery Technology Co., Ltd., the size of the fry is about 45g to 55g each, and the stocking density is 500 per mu.

[0106] Water chestnut (Trapa species) was selected from local water chestnuts and planted by direct seeding 10 days before rice transplanting. The row spacing and hole spacing of water chestnuts were 1.5m and 2 to 3 plants were planted in each hole.

[0107] Water spinach (Ipomoea aquatica Forsk) was purchased from Shouguang Xinxinran Horticulture Co., Ltd. This species has shiny, strong, long, upright stems and narrow, slender, emerald green leaves. It is resistant to disease and has excellent quality, low fiber content, and a pleasant taste, allowing for multiple harvests. Water spinach was planted on a 40 cm wide x 100 cm long floating board. Two rows of 8 cm diameter circular water spinach planting baskets were installed in the center of the board, spaced 20 cm apart and evenly spaced. Two water spinach seedlings were planted in each basket.

[0108] Example 1 A Rice-Fish-Water Spinach Co-cultivation System and Field Management Method

[0109] 1. Construction of a rice-fish-water spinach cooperative farming system

[0110] A strip-shaped fish pit with a depth of 80 cm is set up in the middle of the rice field. The long side of the fish pit is parallel to the long side of the rice field and has the same length. The area of ​​the fish pit accounts for 10% of the total area of ​​the rice field.

[0111] The paddy fields are planted with early rice, with a planting density of 24 plants / m 2 The fish pond is used to raise grass carp, with a stocking density of 400 grass carp per mu in the rice-fish-water spinach system. Water spinach is also planted on floating boards on the water surface, with a planting density of 100 plants per 7m2. 2 . Form a horizontal structure of intercropping of early rice and water spinach, and a vertical structure of combining rice, water spinach, grass carp and other crops.

[0112] During the early rice planting period, the water in the rice fields is connected to the water in the fish ponds, and fish can swim back and forth between the rice fields and the fish ponds.

[0113] 2. Field management methods for the rice-fish-water spinach system

[0114] (1) Tillage and fertilization

[0115] Three days before transplanting early rice, the paddy field was plowed and decomposed chicken manure organic fertilizer (4500kg / hm2) was applied. 2 ), and no chemical fertilizers, pesticides or herbicides will be applied during the entire planting period.

[0116] (2) Planting and placement

[0117] After fertilization, water spinach is planted in the fish pond using floating boards with a row spacing of 20 cm; then the early rice after seedling cultivation is transplanted into the rice field with a planting specification of plant spacing × row spacing of 20 cm × 20 cm; in the late stage of rice tillering, grass carp fry are put into the fish pond and raised without feeding fish feed before harvest.

[0118] (3) Water level management

[0119] Water levels should be managed according to conventional rice cultivation requirements. After transplanting the seedlings, flooding should be the primary method of irrigation. Except for sun-drying, the paddy field should be kept at a water depth of 6cm to 8cm. From plowing to transplanting of early rice, the water depth of the rice field surface is 5-7cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 85cm-87cm; from transplanting early rice to the effective tillering period of early rice, shallow water transplanting and thin water tillering are insisted on, and the water depth of the rice field surface is kept at 2cm-4cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 82cm-84cm; from the late tillering period of early rice to one week before the maturity of early rice, deep water irrigation is insisted on, and the water depth of the rice field surface is kept at 15cm-20cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 95cm-100cm; one week before the maturity of early rice, the water surface of the rice planting area is drained for drying the fields, and the water depth of the fish pit is kept at 70cm-75cm; after catching grass carp, the water depth of the fish pit (from the water surface to the bottom of the fish pit) is restored to 70cm-75cm.

[0120] (4) Picking and harvesting

[0121] During the early rice planting period, water spinach is picked routinely and harvested once when the plant height is 25cm to 30cm until harvest.

[0122] After the early rice matures, the early rice, grass carp and water spinach are harvested.

[0123] Example 2 A Rice-Fish-Water Spinach Co-cultivation System and Field Management Method

[0124] 1. Construction of a rice-fish-water spinach cooperative farming system

[0125] A strip-shaped fish pit with a depth of 80 cm is set up in the middle of the rice field. The long side of the fish pit is parallel to the long side of the rice field and has the same length. The area of ​​the fish pit accounts for 10% of the total area of ​​the rice field.

[0126] The paddy field is planted with late rice, with a planting density of 26 plants / m 2 The fish pond is stocked with 600 carp per mu. Water spinach is planted on floating boards on the water surface. The planting density of water spinach in the rice-fish-water spinach system is 100 plants per 7m2. 2 . Form a horizontal structure of intercropping of late rice and water spinach, and a vertical structure of combining rice, water spinach, grass carp and fish farming.

[0127] During the late rice planting period, the water in the rice fields is connected to the water in the fish ponds, and fish can swim back and forth between the rice fields and the fish ponds.

[0128] 2. Field management methods for the rice-fish-water spinach system

[0129] (1) Tillage and fertilization

[0130] Three days before transplanting late rice, the paddy field was plowed and decomposed chicken manure organic fertilizer (4500kg / hm2) was applied. 2), and no chemical fertilizers, pesticides or herbicides will be applied during the entire planting period.

[0131] (2) Planting and placement

[0132] After fertilization, water spinach is planted in the fish pond using floating boards with a row spacing of 20 cm; then the late rice after seedling cultivation is transplanted into the rice field with a planting specification of plant spacing × row spacing of 20 cm × 20 cm; in the late stage of rice tillering, grass carp fry are put into the fish pond and raised without feeding fish feed before harvest.

[0133] (3) Water level management

[0134] Manage paddy field water levels according to conventional rice cultivation requirements. After transplanting the seedlings, flooding is the primary method of irrigation. Except for sun-drying, the paddy field should be kept at a water depth of 6cm to 8cm. From plowing to transplanting of late rice, the water depth of the rice field surface is 5cm~7cm, and the water depth of the fish pond (from the water surface to the bottom of the fish pond) is 85cm~87cm; from transplanting late rice to the effective tillering period of rice, shallow water transplanting and thin water tillering are insisted on, and the water depth of the rice field surface is kept at 2cm~4cm, and the water depth of the fish pond (from the water surface to the bottom of the fish pond) is 82cm~84cm; from the late tillering period of late rice to one week before rice maturity, deep water irrigation is insisted on, and the water depth of the rice field surface is kept at 15cm~20cm, and the water depth of the fish pond (from the water surface to the bottom of the fish pond) is 95cm~100cm; one week before late rice matures, the water surface of the rice planting area is drained for drying the fields, and the water depth of the fish pond is kept at 70cm~75cm; after catching grass carp, the water depth of the fish pond (from the water surface to the bottom of the fish pond) is restored to 70cm~75cm.

[0135] (4) Picking and harvesting

[0136] During the late rice planting period, water spinach is picked routinely and harvested once when the plant height is 25cm to 30cm until harvest.

[0137] After the late rice matures, the late rice, grass carp and water spinach are harvested.

[0138] Example 3 A Rice-Fish-Water Spinach Co-cultivation System and Field Management Method

[0139] 1. Construction of a rice-fish-water spinach cooperative farming system

[0140] A strip-shaped fish pit with a depth of 80 cm is set up in the middle of the rice field. The long side of the fish pit is parallel to the long side of the rice field and has the same length. The area of ​​the fish pit accounts for 10% of the total area of ​​the rice field.

[0141] The paddy fields are planted with early rice and late rice in rotation, with a planting density of 25 plants / m 2 The fish pond is stocked with 500 carp per mu. Water spinach is planted on floating boards on the water surface. The planting density of water spinach in the rice-fish-water spinach system is 100 plants per 7m2. 2. Form a horizontal structure of intercropping of rice and water spinach, and a vertical structure of combining rice, water spinach, grass carp and fish farming.

[0142] During the planting period of early rice and late rice, the water in the rice fields is connected to the water in the fish ponds, and fish can swim back and forth between the rice fields and the fish ponds.

[0143] 2. Field management methods for the rice-fish-water spinach system

[0144] (1) Tillage and fertilization

[0145] Three days before transplanting early rice, the paddy field was plowed for the first time and decomposed chicken manure organic fertilizer (4500kg / hm2) was applied for the first time. 2 ); 3 days before transplanting late rice, the paddy field was plowed for the second time and decomposed chicken manure organic fertilizer (4500kg / hm2) was applied for the second time. 2 ). In addition, no chemical fertilizers, pesticides or herbicides are applied during the entire planting period of early and late rice.

[0146] (2) Planting and placement

[0147] After the first tillage and fertilization, water spinach is planted in the fish pond using a floating board with a row spacing of 20 cm; then the early rice after seedling cultivation is transplanted into the rice field with a planting specification of plant spacing × row spacing of 20 cm × 20 cm; in the late tillering stage of the early rice, grass carp fry are put into the fish pond for the first time and are raised without feeding fish feed until harvest.

[0148] After the early rice season is over, late rice is planted in the rice fields and water spinach is not replanted.

[0149] After the second plowing and fertilizing, the late rice after seedling cultivation is transplanted into the rice field with a planting specification of 20 cm × 20 cm spacing between rows. At the late tillering stage of the late rice, grass carp fry are put into the fish pond for the second time and are raised without feeding fish feed before harvest.

[0150] (3) Water level management

[0151] Water levels for early and late rice should be managed according to conventional rice cultivation requirements. After transplanting the seedlings, flooding should be the primary irrigation method. Except for sun-drying, the paddy field should be kept at a water depth of 6cm to 8cm. From plowing to before rice transplanting, the water depth of the rice field surface is 5cm~7cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 85cm~87cm; from rice transplanting to the effective tillering period of rice, shallow water transplanting and thin water tillering are insisted, and the water depth of the rice field surface is kept at 2cm~4cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 82cm~84cm; from the late rice tillering period to one week before rice maturity, deep water irrigation is insisted, and the water depth of the rice field surface is kept at 15cm~20cm, and the water depth of the fish pit (from the water surface to the bottom of the fish pit) is 95cm~100cm; one week before rice maturity, the water in the rice-growing area is drained for field drying, and the water depth of the fish pit is kept at 70cm~75cm; after catching grass carp, the water depth of the fish pit (from the water surface to the bottom of the fish pit) is restored to 70cm~75cm.

[0152] (4) Picking and harvesting

[0153] During the planting period of early rice and late rice, water spinach is picked regularly and harvested once when the plant height is 25cm to 30cm until the late rice is harvested.

[0154] After the early rice matures, the early rice and the first stock of grass carp are harvested; after the late rice matures, the late rice, the second stock of grass carp and water spinach are harvested.

[0155] Application Example 1 Field Experiment Design and Field Management

[0156] 1. Experimental Design

[0157] The field trial of the present invention was carried out from March 2022 to December 2022, and the rice-fish-water spinach co-cultivation system described in Example 3 was constructed. The specific method is as follows:

[0158] The infrastructure construction of the test plot will be carried out from March 1 to March 5, 2022. Each test plot is 6m long and 7m wide, that is, the test plot area is 42m 2 The ridges were pre-raised and reinforced, with a height and width of 0.5 m. Fish barriers were installed at the inlets and outlets to prevent fish from escaping and the entry of unwanted fish. A ridge was laid in the middle of the field in the ditch treatment area. The rice planting area was plowed and leveled. An excavator was used to build a strip fish pit between two adjacent rice planting areas. The length of the fish pit was equal to the length of the rice planting area (6 m long), 0.7 m wide, and 0.8 m deep. The fish pit area accounted for 10% of the total area of ​​the experimental area.

[0159] 2. Experimental plot

[0160] Four treatments were set up, including rice monoculture (DZ), rice-fish co-cultivation (CK), rice-fish-water chestnut co-cultivation (LJ), and rice-fish-water spinach co-cultivation (WC). Each treatment was replicated three times, resulting in 12 experimental plots with an area of ​​42 m2 per plot. 2 (6m×7m), and each experimental plot was randomly distributed.

[0161] The planting design schematics of the experimental plots with the four treatments are shown in a–d in Figure 1 , and the actual scenes are shown in a–d in Figure 2 . Rice was planted in the paddy fields of DZ, CK, LJ, and WC, fish were grown in the fish ponds of CK, LJ, and WC, water caltrops were grown in the fish pond of LJ, and water spinach was grown in the fish pond of WC.

[0162] 3. Field management

[0163] Carry out corresponding field management for each treatment according to the following time points:

[0164] (1) Planting and harvesting

[0165] The early rice was sown and raised on March 3, 2022, water chestnuts were planted on March 10, the land was plowed and fertilized on March 20, water spinach was planted on March 22, rice seedlings were transplanted on March 23, fish fry were placed on April 15 (late stage of rice tillering), rice was harvested on July 6 (rice maturity period), and field fish were harvested on July 15.

[0166] After the early rice is harvested, late rice is planted in the rice fields.

[0167] For late rice, rice seedlings will be raised on July 22, 2022, the land will be plowed and fertilized on August 3, rice seedlings will be transplanted on August 6, water chestnuts will be harvested on August 15 (early stage of rice tillering), fish fry will be released on September 1 (late stage of rice tillering), rice will be harvested on November 8 (rice maturity period), and field fish will be harvested on November 13.

[0168] The experimental rice seedlings were raised in soft trays and transplanted manually. The rice planting specifications were 20 cm × 20 cm. All experimental plots were plowed and fertilized with decomposed chicken manure organic fertilizer (4500 kg / hm2) 3 days before transplanting the rice. 2 ), and no chemical fertilizers, pesticides or herbicides will be applied during the entire planting period.

[0169] During the trial, water spinach and water caltrops were harvested regularly: water spinach was harvested every three weeks (or when the plant height reached 25-30 cm), and water caltrops were harvested every seven days after they matured. All late rice was harvested at once after it matured.

[0170] (2) Feeding fish feed

[0171] No fish feed was given during the experiment.

[0172] (3) Water level management

[0173] In all experimental plots, field management followed conventional rice cultivation practices. After transplanting the seedlings, flooding was the primary method of irrigation. Except for sun-drying, the paddy fields were kept at a water depth of 6 to 8 cm. Before rice is transplanted, the water depth in the rice planting area is 5cm to 7cm, and the water depth in the fish pond (from the water surface to the bottom of the fish pond) is 85cm to 87cm; from rice transplanting to the effective tillering period of rice, shallow water transplanting and thin water tillering are insisted, and the water depth in the rice planting area is maintained at 2cm to 4cm, and the water depth in the fish pond (from the water surface to the bottom of the fish pond) is 82cm to 84cm; from the late rice tillering period to one week before rice maturity, deep water irrigation is insisted, and the water depth in the rice planting area is maintained at 15cm to 20cm, and the water depth in the fish pond (from the water surface to the bottom of the fish pond) is 95cm to 100cm; one week before rice maturity, the surface water in the rice planting area is drained for field sun-drying, and the water depth in the fish pond is maintained at 70cm to 75cm; after catching grass carp, the water depth of the fish pond is immediately restored to 70cm to 75cm until the late season rice fields are plowed.

[0174] Clean up debris on the fish nets at the water inlet and outlet in a timely manner, reinforce the fish protection facilities, keep the water in and out unobstructed, and promptly drive away common natural enemies and biological hazards in the fields.

[0175] Application Example 2: Impact of different farming models on greenhouse gas emissions

[0176] 1. Experimental methods

[0177] (1) Sampling

[0178] Greenhouse gases were collected from the experimental plot corresponding to Example 1 every 6 to 10 days using the static chamber-gas chromatograph method.

[0179] The static chamber is 40 cm long, 40 cm wide, and 60 cm or 1.2 m high (the height is adjusted based on the height of the rice plants). The interior is made of PVC board, and the outer layer of the chamber is wrapped with a 0.5 cm thick sponge and reflective insulation film to prevent the temperature inside the chamber from rising too quickly due to sunlight. A small 12V fan is installed on the top of the chamber to prevent uneven air flow inside the chamber. The top of the chamber is equipped with an exhaust hole connected to the exhaust pipe, which is controlled by a three-way valve. A sampling base is fixed in the rice planting area of ​​each experimental plot. The upper part of the base has a 4 cm deep groove, which is sealed with water during measurement.

[0180] During the rice growing season, samples were collected every 6–10 days from 9:00 AM to 11:00 AM. Gas was extracted from the chamber using a 50-ml syringe at intervals of 0, 10, 20, and 30 minutes. The syringe was pumped back and forth 5–10 times to thoroughly mix the gas. After extracting 50 ml of gas, the syringe was quickly brought back to the laboratory for analysis.

[0181] (2) Gas emission flux measurement

[0182] An Agilent 7890B gas chromatograph was used to measure the gas emission fluxes of N2O, CH4, and CO2. The detectors for measuring CH4 and CO2 were FID, with a detector temperature of 300°C, a separation column temperature of 60°C, and a carrier gas of 99.99% high-purity nitrogen at a flow rate of 500 mL / min. The detector for measuring N2O was ECD, with a detector temperature of 300°C, a separation column temperature of 60°C, and a carrier gas of 99.99% high-purity nitrogen at a flow rate of 500 mL / min. The gas emission flux was calculated according to formula (1):

[0183] Formula (1): F = ρ × h × dc / dt × 273 / (273 + T);

[0184] Where F represents the gas emission flux, mg / (m 2 ·h 1 ); ρ represents the density of the gas under standard conditions, in kg / m 3 ; h represents the net height of the sampling box, in m; dc / dt represents the rate of change of gas concentration in the sampling box per unit time; T represents the average temperature in the sampling box during the sampling process, in ℃; 273 represents the gas equation constant.

[0185] Calculate the cumulative gas emissions according to formula (2):

[0186] Formula (2): CE=Σ[(F i +F i+1 ) / 2×10 -3 ×d×24×10]

[0187] Where CE represents the cumulative gas emissions, kg / hm 2 , F i With F i+1 Gas emission flux during two consecutive sampling periods, mg / (m 2 h 1 )), d is the number of days between two consecutive adjacent sampling times.

[0188] (3) Greenhouse gas emission value

[0189] Calculate the greenhouse gas emission value according to formula (3) to formula (6).

[0190] Formula (3):

[0191] Among them, 24.5 represents the coefficient of converting CH4 into CO2, that is, the greenhouse effect generated by 1 kg of CH4 is equivalent to the greenhouse effect generated by 24.5 kg of CO2; 320 represents the coefficient of converting N2O into CO2, that is, the greenhouse effect generated by 1 kg of N2O is equivalent to the greenhouse effect generated by 320 kg of CO2.

[0192] Formula (4):

[0193] Among them, V 1TS It represents the negative economic value of greenhouse gas emissions from rice paddy ecosystems in one year calculated using the Swedish carbon tax method, in yuan; NC represents the C content in CO2 as 27.27%; CTS represents the Swedish carbon tax price of US$130 / tCO2 in 2022, which is converted into RMB 0.95 / kg according to the exchange rate in December 2022.

[0194] Formula (5):

[0195] Among them, V2ZL represents the negative economic value of greenhouse gas emissions from rice field ecosystems estimated using the afforestation cost method, in yuan; CZL represents China's afforestation cost, in 0.26 yuan / kg.

[0196] Formula (6): V = (V 1TS +V 2ZL )÷2;

[0197] Where V represents the negative economic value of greenhouse gas emissions from rice field ecosystems, with the unit being yuan / hm2. 2 (Liu Lihua et al., 2015).

[0198] 2. Experimental results

[0199] Table 1 Greenhouse gas emissions from different farming models Note: In Table 1, DZ represents rice monoculture, CK represents rice-fish integrated farming, LJ represents rice-fish-water chestnut integrated farming, and WC represents rice-fish-water spinach integrated farming. The percentage change (%) represents the increase (+) or decrease (-) in greenhouse gas emissions from each farming system compared to CK. Values ​​followed by the same letter indicate no significant difference (p>0.05); values ​​followed by different letters indicate significant difference (p<0.05).

[0200] As shown in Table 1, among all the greenhouse gas emissions under all farming modes, CO2 emissions are the highest and N2O emissions are the lowest.

[0201] In terms of CH4 emissions, compared with rice-fish farming, rice-fish-water spinach farming significantly reduced CH4 emissions from early and late rice, while rice-fish-water caltrop farming did not reduce CH4 emissions from early and late rice.

[0202] In terms of CO2 emissions, compared with rice-fish farming, rice-fish-water spinach farming significantly reduced CO2 emissions from late rice, while rice-fish-water caltrop farming did not significantly reduce CO2 emissions.

[0203] In terms of N2O emissions, compared with rice-fish farming, rice-fish-water spinach farming significantly reduced N2O emissions from early and late rice, while rice-fish-water caltrop farming had no significant effect on N2O emissions.

[0204] The above results show that rice-fish-water spinach farming significantly reduces the greenhouse gas CH4, CO2 and N2O emissions under rice-fish farming, especially the emission reduction effect of CH4 and N2O is better.

[0205] Table 2 Negative economic value (V) of greenhouse gas emissions from rice field ecosystems under different planting and breeding patterns Note: In Table 2, the change rate (%) refers to the increase (+) or decrease (-) in the negative economic value of greenhouse gas emissions from rice field ecosystems under various farming models compared to the rice-fish integrated farming model.

[0206] Table 2 shows that the negative economic value of greenhouse gas emissions from rice-fish farming is significantly higher than that from rice monoculture throughout the year. For early rice, both rice-fish-water spinach and rice-fish-water caltrop farming reduced the negative economic value of greenhouse gas emissions from rice paddy ecosystems compared to rice-fish farming, with the reduction being greater for rice-fish-water caltrop farming. For late rice, rice-fish-water caltrop farming significantly reduced the negative economic value of greenhouse gas emissions from rice paddy ecosystems compared to rice-fish farming, while rice-fish-water caltrop farming increased the negative economic value.

[0207] The above results show that compared with the rice-fish farming model, the rice-fish-water spinach farming model can reduce greenhouse gas emissions and reduce the negative economic value of greenhouse gas emissions from rice field ecosystems during the early rice and late rice planting periods.

[0208] Based on the above results, the rice-fish-water spinach model can effectively improve the greenhouse gas emission problem of the rice-fish farming model, reduce greenhouse gas emissions, and reduce the negative economic value of greenhouse gas emissions from rice field ecosystems.

[0209] Application Example 3: Impact of different planting and breeding models on farmland water environment

[0210] 1. Experimental methods

[0211] (1) Sampling

[0212] For the experimental plot of Application Example 1, 50 ml of water samples were collected at a depth of 30 cm to 40 cm from the water surface using a water sampler during the heading, tillering, and maturity stages of early rice and late rice, with each fish pond sampling three times. In addition, 50 ml of water samples were collected from the rice-growing area using a water sampler, and this was repeated six times. The water samples from the same experimental plot were mixed and placed in a black plastic bottle, which was placed in an insulated box with a -55°C ice box and brought back to the laboratory for subsequent analysis.

[0213] (2) Water quality measurement

[0214] Total nitrogen content was determined using the "Water quality—Determination of total nitrogen—Alkaline potassium persulfate digestion—UV spectrophotometry" (GB 11894-89). Dissolved oxygen was determined using a Hach HQ4300 (Hach, USA).

[0215] 2. Experimental results

[0216] As shown in Figure 3, different planting and breeding patterns affect the dissolved oxygen content in paddy field water, and there are significant differences during the early rice heading stage and the late rice maturity stage. Among them, the dissolved oxygen content in the water of rice-fish-water spinach co-cultivation is the highest during the early rice tillering stage, early rice heading stage, late rice tillering stage and late rice heading stage; during the early rice maturity stage and late rice maturity stage, the dissolved oxygen content in the water of rice monoculture is the highest, followed by the rice-fish-water spinach co-cultivation.

[0217] As shown in Figure 4, different planting and breeding patterns affect the total nitrogen content in paddy field water, and there are significant differences in the early rice tillering stage, early rice heading stage, late rice tillering stage and late rice heading stage. Among them, during the early rice heading stage, the total nitrogen content in the water of rice-fish-water chestnut farming is the lowest, followed by rice-fish-water spinach farming. Except for the early rice heading stage, the total nitrogen content in the water of rice-fish-water spinach farming is the lowest in other periods.

[0218] The above results show that compared with the rice-fish farming model, the rice-fish-water spinach farming model effectively increases the dissolved oxygen content in the water, enhances the self-purification ability of the water, and provides more oxygen for the survival of fish; on the other hand, it reduces the total nitrogen content in the water, reduces the loss of nitrogen resources in the rice field ecosystem, and significantly reduces the risk of agricultural non-point source pollution of water bodies faced by the rice-fish farming model.

[0219] Application Example 4: Impact of different planting and breeding models on farmland soil environment

[0220] 1. Experimental methods

[0221] (1) Sampling

[0222] Soil samples were collected from the paddy fields of each experimental plot in Application Example 1 during the maturity stage of early and late rice. Random sampling (three sampling points were selected on each side of the fish pit) was used to collect soil samples. A soil drill was used to extract the 0-20 cm topsoil layer, which was mixed and air-dried at room temperature. After air-drying, a portion was passed through a 0.15 mm mesh sieve to determine the total nitrogen, total phosphorus, and total potassium content.

[0223] (2) Determination of soil chemical properties

[0224] Soil total nitrogen content was determined by the Kjeldahl method using sulfuric acid-accelerator digestion (HJ717-2014 Determination of Total Nitrogen in Soil). Soil total phosphorus content was determined by the molybdenum antimony spectrophotometric method using NaOH alkali fusion (HJ 632-2011 Determination of Total Phosphorus in Soil). Soil total potassium content was determined by the flame photometric method using NaOH alkali fusion (GB 9836-1988 Determination of Total Potassium in Soil).

[0225] 2. Experimental results

[0226] Table 3 Soil nutrient increase under different planting and breeding modes (unit: g / kg) Note: In Table 3, DZ represents rice monoculture, CK represents rice-fish integrated farming, LJ represents rice-fish-water chestnut integrated farming, and WC represents rice-fish-water spinach integrated farming. Values ​​followed by the same letters indicate no significant difference (p>0.05), while values ​​followed by different letters indicate significant difference (p<0.05).

[0227] Table 3 shows that the increases in total nitrogen, total phosphorus, and total potassium in the soil of early and late rice differed significantly under different cultivation systems. The increase in total nitrogen ranged from 14.37 mg / kg to 37.98 mg / kg, the increase in total phosphorus ranged from 33.63 mg / kg to 147.12 mg / kg, and the increase in total potassium ranged from 10.63 mg / kg to 20.37 mg / kg. Among early rice, the increase in total nitrogen and total phosphorus in the soil of the rice-fish-water spinach system was the highest, and the increase in total potassium in the soil of the rice-fish-water spinach system was the highest. Among late rice, the increase in total phosphorus in the soil of the rice-fish-water spinach system was the highest, the increase in total nitrogen in the soil of the rice-fish-water chestnut system was the highest, and the increase in total potassium in the soil of the rice-fish-water chestnut system was the highest.

[0228] Overall, compared with other farming models, the rice-fish-water spinach farming model effectively increases the nitrogen and phosphorus content in farmland soil, especially phosphorus.

[0229] Application Example 5: The impact of different planting and breeding models on agricultural product yields

[0230] 1. Experimental methods

[0231] (1) Determination of yield indicators

[0232] Rice yield: For the experimental plot of application example 1, when the rice is mature, two 1m 2 The yield of the (1m×1m) sample plot was harvested and measured. After removing impurities and drying, the rice grain yield and straw yield were weighed and measured respectively. The actual yield was converted according to the rice harvest area of ​​the experimental plot (10% of the fish pond area was removed in the experimental plot for fish farming).

[0233] Water spinach yield: For the rice-fish-water spinach co-cultivation (WC) experimental plot of Application Example 1, water spinach was harvested once every three weeks during the rice planting process, that is, when the plant height was 25 cm to 30 cm. The water spinach yield of each harvest was recorded and converted into actual yield based on the vegetable harvest area of ​​the experimental plot.

[0234] Water chestnut yield: For the rice-fish-water chestnut (LJ) experimental plot in Application Example 1, water chestnuts were picked every 7 days after maturity, and the entire harvesting period was divided into 6 times. The water chestnut yield of each harvest was recorded and the actual yield was converted according to the vegetable harvesting area of ​​the experimental plot.

[0235] Fish yield: For the rice-fish farming (CK), rice-fish-water caltrop farming (LJ) and rice-fish-water spinach farming (WC) experimental plots of Application Example 1, after rice harvest, the grass carp in the experimental plots were harvested, counted and weighed, and the fish yield was converted according to the area of ​​the rice field fish pond.

[0236] 2. Experimental results

[0237] Table 4 Agricultural product yields of different planting and breeding models (unit: t / hm2) 2 )

[0238] The results in Table 4 show that in terms of rice production, the rice monoculture model has the highest yield, followed by the rice-fish-water spinach farming model, the rice-fish farming model and the rice-fish-water caltrop farming model; in terms of fish product production, the rice-fish-water caltrop farming model has the highest yield, followed by the rice-fish-water caltrop farming model and the rice-fish farming model; in terms of vegetable production, the rice-fish-water caltrop farming model has the highest yield, followed by the rice-fish-water caltrop farming model.

[0239] The above results show that the rice-fish-water spinach farming model not only increases the yield of vegetables, but also further improves the rice yield and fish yield under the rice-fish farming model, and the yield of all agricultural products in the entire system is the highest.

[0240] In summary, the rice-fish-water spinach farming model not only reduces greenhouse gas emissions (CH4, N2O, and CO2) from rice paddy ecosystems, but also enhances the utilization of nutrients in water, reducing water pollution, increasing soil carbon and nitrogen sequestration, and increasing soil nutrient content, particularly phosphorus. By increasing overall rice paddy agricultural output through strategies that enhance efficiency and reduce emissions, the rice-fish-water spinach farming model represents an efficient, green, and ecological agricultural production model.

[0241] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that other variations or modifications may be made based on the above descriptions and concepts. It is not necessary and impossible to provide an exhaustive list of all possible implementations. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A rice-fish-water spinach co-cultivation system, wherein a plurality of fish pits are provided in the rice field, characterized in that: Rice is planted in the rice fields, and fish and water spinach are grown in the fish ponds, forming a rice-fish-water spinach co-cultivation system in which rice and water spinach are intercropped in a horizontal structure and rice, water spinach and fish are cultivated and raised in a vertical structure.

2. The rice-fish-water spinach co-cultivation system according to claim 1, characterized in that: The fish pit is a strip-shaped fish pit.

3. The rice-fish-water spinach co-cultivation system according to claim 1, characterized in that: The species of fish is grass carp.

4. The rice-fish-water spinach co-cultivation system according to claim 1, characterized in that: The ratio of the number of rice plants, the number of water spinach plants and the number of fish released is (905-985) plants: 60 plants: (26-38) fish.

5. The rice-fish-water spinach co-cultivation system according to claim 1, characterized in that: The rice is early rice and / or late rice.

6. Use of the rice-fish-water spinach system according to any one of claims 1 to 5 in controlling agricultural non-point source pollution in the rice-fish system.

7. The use according to claim 6, characterized in that The controlling of agricultural non-point source pollution in the rice-fish farming system includes reducing greenhouse gas emissions and / or improving water quality.

8. Use of the rice-fish-water spinach integrated farming system according to any one of claims 1 to 5 for reducing soil nutrient loss and / or increasing soil nutrient content in the rice-fish integrated farming system.

9. The use according to claim 8, characterized in that The rice-fish integrated farming system is a rice-fish integrated farming system in which only base fertilizer is applied, no topdressing is performed, no pesticides are applied, and no feed is fed.

10. The field management method of the rice-fish-water spinach cooperative farming system according to any one of claims 1 to 5, characterized in that: The following steps are involved: The method comprises applying base fertilizer to the rice field 2 to 4 days before transplanting rice seedlings; planting water spinach in the fish pit 1 to 2 days before transplanting rice seedlings; putting fish into the fish pit in the late tillering stage of rice; cultivating rice, fish and water spinach together; and harvesting them separately.

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