High-yield cultivation techniques for no-till direct seeding in rapeseed-rice double cropping

Zhejiang Province is relatively economically developed, with high labor costs. At the same time, as diesel prices rise, the cost of mechanical plowing of farmland increases, and the production cost of grain and oil crops increases year by year. For this reason, Zhejiang Province carried out trials, demonstrations and extension of high-yield cultivation techniques for no-till direct seeding in rapeseed-rice double cropping, which reduced the production cost of grain and oil crops and improved planting efficiency. According to surveys, each mu of no-till direct-seeded rapeseed saves 62.5 yuan in costs and increases efficiency compared with transplanted rapeseed, and each mu of no-till direct-seeded late rice saves 70.24 yuan in costs and increases efficiency compared with plowed and transplanted late rice. The annual cumulative cost saving and efficiency increase of no-till direct seeding cultivation in rapeseed-rice double cropping is 132.74 yuan. The high-yield cultivation techniques for no-till direct seeding in rapeseed-rice double cropping are introduced as follows.

1 Key points of high-yield cultivation techniques for no-till direct-seeded rapeseed

No-till direct-seeded rapeseed refers to a rapeseed cultivation method in which, after the late rice harvest, the soil is not plowed, old weeds are killed off and the field is simply leveled, and then rapeseed seeds are sown directly.

1.1 Variety selection No-till direct-seeded rapeseed roots are relatively shallow, and lodging is likely to occur later, so in production, "double-low" rapeseed varieties with high yield, moderate plant height and good lodging resistance, such as Zheshuang 72 and Huyou 15, should be selected for no-till direct seeding cultivation.

1.2 Early sowing at the appropriate time After the late rice harvest, sowing should be done early as soon as possible, generally in mid-to-late October, and no later than the end of October. When the field soil is moist and sowing is done early at the appropriate time, the seeding rate per mu is 0.15-0.2 kg; when the field soil is dry or sowing is late, the seeding rate per mu is 0.2-0.3 kg. To ensure even sowing, 0.5-0.75 kg of roasted rapeseed can be mixed evenly with the seeds before sowing. The main sowing methods are direct drilling in rows and broadcasting, and mechanical direct drilling in rows is advocated to improve field operation efficiency.

1.3 Mechanical ditching After sowing, use a ditching machine promptly to open furrows and cover soil, with a furrow width of 20 cm and a furrow depth of 15 cm, a bed width of 120-140 cm, and a soil covering thickness on the bed surface of 2-3 cm. After mechanical ditching is completed, open drainage ditches at the corners of the field so that all ditches are connected. Spread 150-200 kg of rice straw evenly over each mu of bed surface, which both shades and preserves moisture to promote full emergence of seedlings and also fertilizes the soil.

1.4 Thinning and final singling Thin the seedlings when the seedlings have 2 leaves and 1 heart, thinning where dense and filling in where sparse. Final singling is done at the 3-4 leaf stage. For early-sown fields, leave 12,000-18,000 plants per mu; for late-sown fields, leave 18,000-25,000 plants per mu.

1.5 Chemical weed control

1.5.1 Pre-sowing treatment For fields with heavy weeds before sowing, 3-5 days before sowing, use 500 ml of 10% glyphosate per mu mixed with 40 kg of water and spray to kill old weeds in the no-till paddy field.

1.5.2 Treatment after sowing and before emergence After sowing and covering soil, use 50-75 ml of 50% acetochlor per mu, or 100 ml of 60% butachlor, mixed with 40 kg of water and spray as a soil treatment to prevent weed germination.

1.5.3 Foliar treatment For fields mainly infested with grass weeds, at the 3-4 leaf stage of the weeds, use 50 ml of 5% quizalofop-p-ethyl per mu or 20-25 ml of 10.8% haloxyfop-R-methyl, mixed with 40 kg of water and spray for control. For fields mainly infested with broadleaf weeds, at the 2-3 leaf stage of the weeds, use 30 ml of 50% benazolin per mu, mixed with 40 kg of water and spray for control.

1.6 Scientific fertilization In the fertilizer management of direct-seeded rapeseed, the early-promotion fertilization method is adopted, that is, sufficient base fertilizer, early seedling fertilizer, and steady stem-elongation fertilizer, to promote dual vigorous growth in winter and spring. Generally, the total fertilization amount per mu is controlled at 15-16 kg of pure nitrogen equivalent in nitrogen fertilizer, 25 kg of calcium superphosphate, 7.5 kg of potassium chloride, and 1 kg of boron fertilizer. Generally, phosphorus, potassium and boron fertilizers are applied all at once as base fertilizer, and the nitrogen fertilizer application ratio is 30% base fertilizer, 35% seedling fertilizer, 15% winter fertilizer, and 20% stem-elongation fertilizer.

1.7 Pest and disease control In the early and middle stages of direct-seeded rapeseed, aphids occur heavily; use 20 g of 10% imidacloprid per mu mixed with 40 kg of water and spray for control. At the early flowering and full flowering stages, use 100 g of 50% procymidone per mu or 20-40 ml of 25% iprodione, mixed with 40 kg of water and spray to control sclerotinia stem rot.

1.8 Timely harvest When the siliques are loquat-yellow, pull and harvest by hand promptly, pile for after-ripening, and thresh on sunny days. If mechanical harvesting is used, harvest on a sunny day when the rapeseed maturity rate reaches more than 90%.

2 Key points of high-yield cultivation techniques for no-till direct-seeded late rice

No-till direct-seeded late rice refers to a rice cultivation method in which, in a paddy field that has not been plowed or harrowed after the harvest of rapeseed and other crops, a non-selective herbicide is used to kill weeds, deep water is irrigated to soak the field, and after the water layer naturally drains away, germinated rice seeds with white sprouts are sown directly into the field to grow.

2.1 Variety selection Choose high-yield late rice varieties with short stems, thick and sturdy stalks, and moderate tillering, such as Jiahua 1, Xiushui 994, and Xiushui 09.

2.2 Ensure full seedling emergence After the rapeseed harvest, retain the original beds and furrows, first use a tooth rake to level the original bed surface to achieve fine soil and a level surface, then irrigate and soak for 1-2 days. Before sowing, select and sun-dry the seeds, then use 4.5 g of 18% rice seed disinfectant added to 10 kg of water to soak 7.5 kg of seeds for 48 hours. Before sowing, use 10 g of 18% pyraclostrobin-thiram per mu to dress the sprouted grain. The suitable sowing period is from May 20 to June 5. The seeding rate per mu is 2.0-3.0 kg for conventional late rice varieties and 1.0-1.2 kg for hybrid late rice varieties.

2.3 Weed control Three days before sowing, use 200 ml of 20% paraquat per mu or 500 ml of 10% glyphosate mixed with 40 kg of water and spray to control old weeds. Two to three days after sowing, use 60 g of 40% direct-seeding herbicide or 35% Xinhebao per mu mixed with 40 kg of water and spray evenly. When the seedlings have 2 leaves and 1 heart, under the condition of keeping the field moist, use 40 g of 53% Tiancaoling per mu mixed with 40 kg of water and spray, and re-water the next day after spraying. Manual weeding can also be carried out in combination with field management.

2.4 Reasonable fertilization Generally, the nitrogen fertilizer amount per mu is 13-15 kg of pure nitrogen equivalent, and the nitrogen fertilizer application ratio is 30% weaning fertilizer, 30% tillering fertilizer, 20% stem-thickening fertilizer, and 20% panicle fertilizer.

2.5 Water management One to two days before sowing, irrigate to soak the soil. After sowing and before emergence, keep the bed surface moist. After emergence, except when applying fertilizer and controlling pests, when water is irrigated onto the bed surface as required, and when draining the field, when ditch water is drained dry, keep water level with the furrows at all other times. Cut off water 5-7 days before harvest.

2.6 Lodging prevention When the number of seedlings per mu reaches 250,000-300,000, drain the field promptly to suppress ineffective tillering. At the early jointing stage, spray 100 ppm paclobutrazol solution per mu to control plant height. According to pest and disease forecast reports, control pests and diseases at the appropriate time.