Characteristics of No-Till Direct Seeding of Single-Season Late Rice and Supporting Cultivation Techniques

1. Application effects of no-till direct seeding:
1.1 High and stable yield. From sample surveys conducted from 2003-2005, no-till direct seeding increased yield by 40-50 kg per mu compared with tillage direct seeding, an increase of 7-10%. 1.2 Low cost, high benefit. According to the survey results, no-till direct seeding saved 38.5 yuan per mu in costs compared with tillage direct seeding, and saved 59.5 yuan compared with transplanting; adding the yield increase, the benefit per mu increased by 40-80 yuan.
2. Growth characteristics of no-till direct seeding:
2.1 Wide adaptability. According to demonstrations of no-till direct seeding across multiple types of preceding crops, whether wheat stubble, rapeseed fields, green manure stubble, or cash crop stubble, all showed good yield-increasing effects.
2.2 High emergence rate. No-till direct seeding only requires appropriate leveling of the field before broadcasting the seed, without destroying the plow layer; moreover, the surface soil has undergone a winter of sun-baking of clods, improving soil aeration, which is favorable for germination and root establishment, thus increasing the emergence rate. According to field trial surveys, with the variety Xiushui 110 and a seeding rate of 7 jin, no-till direct seeding produced 169 seedlings per square meter, 18 more than the control tillage direct seeding's 151, an increase of 12.16%.
2.3 Early tillering and rapid establishment. Because no-till direct seeding sows the seed directly onto the unplowed field, the seed enters the soil shallowly; combined with the fertile surface soil layer of the paddy field and its strong fertilizer supply capacity, seedlings emerge early, individuals are robust, tillering is early and abundant, and there are many low-node tillers. According to fixed-point field surveys of seedling conditions (variety Xiushui 110), 17 days after sowing, no-till direct seeding averaged 0.89 tillers per plant, 0.57 more than the control tillage direct seeding's 0.32; 25 days after sowing, it averaged 3.73 tillers per plant, 1.27 more than the control's 2.46; at 35 days, tillers per plant reached 5.9, only 0.3 more than the control's 5.6. The time of maximum seedling number occurred about 6 days earlier than with tillage direct seeding, indicating that no-till direct seeding has an obvious advantage in early development.
2.4 Well-developed root system. No-till direct seeding directly uses the previous crop's bed field for sowing; the seedling-stage growth environment is similar to dry-raised seedlings, with good soil aeration and a well-developed root system with many white roots. According to sampling during the tillering stage, no-till rice averaged 112.5 white roots per plant, 40 more than the tilled control; root fresh weight per plant reached 20.2 g, 5.2 g more than the control; root length was 26.5 cm, 6.5 cm more than the control.
2.5 Prone to premature senescence in the later stage. In the late growth stage, no-till direct-seeded rice is more prone to premature senescence than tillage direct-seeded rice. The reason is that no-till direct-seeded rice grows vigorously early and consumes much nutrition; in addition, the soil is compacted, its fertilizer and water retention capacity is poor, and its fertilizer supply capacity declines later, so the application rate of flower-preserving fertilizer should be appropriately increased.
3. Supporting cultivation techniques
3.1 Field preparation: For no-till direct seeding, select fields with sufficient water sources, convenient drainage and irrigation, level surface, and good water and fertilizer retention. Before sowing, irrigate to soak the field; after the water drains naturally, simply level the field and sow directly, ensuring no standing water on the field surface, otherwise it will cause seed rot or sprout burn.
3.2 Timely and appropriate sowing rate: Generally sow from late May to early June, no later than June 10. In southern Zhejiang, do not advance it before May 20; in northern Zhejiang, do not advance it before May 25. Generally, for high-quality conventional japonica rice varieties, the seeding rate is 3-3.5 kg per mu; for hybrid japonica rice, 1.0-1.5 kg is suitable; for hybrid indica rice, 0.75-1.0 kg; and it is required to carry a scale into the field and sow a fixed amount per bed.
3.3 Weed control
3.3.1 Kill old weeds before sowing. No-till direct seeding has more weed species and a larger weed population than tillage direct seeding. About 7 days before sowing, use 200 ml of 20% paraquat, diluted in 40 kg of water, and spray to kill weeds across the whole field and along surrounding roadsides. When spraying, note: first, drain the water layer from the field surface; second, be sure to dilute the chemical with clean water; third, spray evenly. Three days after spraying, irrigate to soak the field.
3.3.2 After sowing and before seedling establishment. Generally within 1-3 days after sowing, use 60 g/mu of 40% direct-seeding wettable powder or 100 ml/mu of 30% pretilachlor emulsifiable concentrate plus 40 kg of water and spray evenly; after application, keep the field surface moist without standing water for 3-5 days to seal and kill weeds on the bed surface.
3.3.3 From emergence to the three-leaf stage. Generally about 15 days after sowing, irrigate 1 cun of shallow water, and use 40 g/mu of 53% Tiancaoling powder or 100 ml/mu of 60% butachlor emulsifiable concentrate plus 15 g/mu of 10% bensulfuron-methyl wettable powder, and apply evenly together with the seedling fertilizer. After application, maintain water for 5-7 days to improve the weeding effect. During this period, if water leakage occurs, replenish water by slow irrigation in time; this is very critical.
3.3.4 After the three-leaf stage. For fields where earlier treatment failed or weed damage is especially severe, distinguish the weed situation and carry out timely supplementary treatment, with timing controlled at about 35 days of seedling age. Before applying chemicals, drain the field water; add water the next day and maintain water for more than 5 days to ensure the weeding effect.
3.3 Eliminate rodent and bird damage. Conduct unified rodent control once 5-7 days before sowing and once at the booting stage. At sowing, seeds can be dressed with imidacloprid or Haoniandong, which can both prevent rodent and bird damage and control rice thrips at the seedling stage.
3.4 Improve fertilizer application techniques and increase ear fertilizer. No-till direct seeding generally does not apply base fertilizer (referring to fields with relatively high soil fertility), and advocates small amounts applied multiple times. During the growth period of single-season late rice, it can be divided into 4 applications, with about 13 kg of pure nitrogen applied per mu; fields with good fertility can apply less. Apply phosphorus and potassium fertilizer in combination; if phosphorus fertilizer was used on the previous crop, it may be omitted, and apply 10-15 kg of potassium chloride per mu.
Seedling fertilizer: At the 2-leaf 1-heart stage, apply 5-6 kg of urea per mu to promote early growth and rapid development.
Tillering fertilizer: At the 4-leaf 1-heart stage, apply 8-9 kg of urea and 5-7.5 kg of potassium chloride per mu to promote tillering.
Stem-strengthening fertilizer: In early July, apply 5-6 kg of urea and 7.5 kg of potassium chloride per mu.
Ear-grain fertilizer: In early August, apply 8-9 kg of urea per mu.
No-till direct-seeded rice has shallow roots and is prone to premature senescence. To prevent premature senescence, foliar fertilizer can be sprayed in the later stage according to the rice growth condition.
3.5 Scientific water management. Before the 2-leaf 1-heart stage, irrigate to level with the furrow and keep the soil moist; after the 2-leaf 1-heart stage, add water and use moist irrigation; after the three-leaf stage, combine exposure and irrigation, alternating dry and wet; when the seedling number reaches 80% of the planned ear number, drain and lightly dry the field multiple times. Because no-till cultivation fields have relatively hard field bases and drain easily, field drying can be carried out in combination with moist intermittent irrigation, and it is not suitable to dry the field too hard all at once. In the later stage, keep it alternately dry and wet to prevent cutting off water too early and ensure green stems and yellow ripening.
3.6 Pest and disease control: Before sowing, seeds must be disinfected with chemicals to prevent seed-borne viruses. Chemicals such as 25% Shibaike emulsifiable concentrate, or 1.5% Difuling wettable powder, or 18% Daozhongqing wettable powder can be selected for seed soaking and disinfection, and according to pest and disease forecasts, timely control sheath blight, rice blast, rice planthopper, striped stem borer, rice leaf roller, and other pests and diseases.