Key Technical Points for Field-Stage Management of Machine-Transplanted Rice
Machine-transplanted rice, due to constraints such as seedling age, nursery age, sowing date and plant traits, has relatively high requirements for the tillage and preparation quality of the transplanting field. At the same time, machine transplanting achieves wide-row, fixed-hole, fixed-seedling and fixed-depth planting, satisfying the population basis for high-yield rice population-quality cultivation. Therefore, only by grasping field-stage management of machine-transplanted rice without letting up can we ensure early tillering and steady growth after transplanting, strive for sufficient panicles, promote large panicles and achieve high yields.
I. Field preparation:
1. Fine land preparation: Field tillage and preparation should adopt rotary tillage for stubble removal, with a rotary tillage depth of about 12-15 cm. After introducing water, wait until the water is fully absorbed before harrowing and leveling, achieving a level field surface with a height difference across the whole field of no more than 3 cm, a clean field surface free of debris and floating matter, fine on top and coarse below, muddy on top and firm below, so that during transplanting operations the machine does not sink or clog with mud. At the same time, clear weeds from field ridges and repair ditches and field ridges.
2. Appropriate basal fertilizer application: On the basis of applying decomposed organic fertilizer or returning wheat straw to the field as a base, apply 30 kg of 45% compound fertilizer per mu. Where conditions permit, an additional 10 kg of silicon fertilizer and 2 kg of zinc fertilizer may be applied as basal fertilizer.
3. Settling floating mud: To avoid transplanting too deep or floating and falling seedlings, after puddling the field it must be left to settle for 2-3 days. If the season and seedling age are particularly tight, the settling time should be at least 24 hours. Achieve clear separation of mud and water, with sediment that is not hardened, and transplant in clear water.
II. Fine machine transplanting
1. Transplanting at the appropriate age: Adhere to the principle of "rather have the field wait for the seedlings than have the seedlings wait for the field," and strictly control the leaf age at about 3.5 leaves, not exceeding 4 leaves, and the seedling age at 15-18 days, not exceeding 20 days. If transplanting is delayed due to rainy weather or mechanical reasons, drain the water promptly and take measures to shield from rain, and seize the gaps between rains for machine transplanting.
2. Transplanting in shallow water: During machine transplanting, maintain a thin film of water of 1-2 cm in the field. If the water is too deep, seedlings tend to float; if the water is too shallow, it is not conducive to machine movement.
3. Machine adjustment: Machine adjustment should be subordinate to the requirements of agronomic cultivation. Generally, the transplanting depth should be controlled at about 1-1.5 cm. The hill spacing is 11.7 cm (with the hill-spacing adjustment handle at position 90), the density is about 18,000 hills per mu, with 4 seedlings per hill, and about 70,000 basic seedlings per mu.
III. Field management
1. Timely replanting: Due to uneven seedlings, poor field tillage and preparation quality, short settling time, excessively deep water layers, and difficulty of machine operation near field edges, missing hills and floating seedlings easily occur. After machine transplanting is completed, manual replanting should be carried out promptly to reduce the rate of empty hills and ensure the number of basic seedlings.
2. Water and slurry regulation: After machine transplanting is completed, irrigate promptly to protect the seedlings, with the water depth preferably not submerging the seedling heart. Enter thin-water-layer management 3-4 days after transplanting, interspersed with short periods of drainage and field exposure for aeration; avoid prolonged deep water. During the tillering stage, implement frequent shallow irrigation, with a water depth of about 3 cm, allowing it to dry naturally, exposing the field at the appropriate time, then adding new water, and repeating this cycle. When each plant has an average of 12-13 tillers, drain and dry the field, from light to heavy. The standard for "light drying" is when fine cracks begin to appear at the field edges, at which point water should be reintroduced. Through multiple light dryings, the soil is made to settle, achieving the requirement of clear water over a firm surface after rewatering. From the booting stage to the heading and flowering stage, a shallow water layer should be established to meet the water requirements for spikelet differentiation and heading and flowering. During the grain-filling and maturity period, irrigate intermittently, alternating dry and wet, to benefit root maintenance and leaf preservation, ensuring ripening until full maturity; avoid cutting off water too early.
3. Precise fertilization: Combine organic and inorganic fertilizers rationally, save nitrogen, increase phosphorus, supplement potassium, add silicon and micro-fertilizers. The total amount per mu of field is about 20 kg pure nitrogen, 5 kg phosphorus pentoxide, and 10-12 kg potassium oxide, with the ratio of basal (tillering) fertilizer to panicle fertilizer being 6:4.
Tillering fertilizer. The first application at about 5 days after transplanting, applying 5-6 kg urea per mu; the second application at about 12 days after transplanting, applying 10-12.5 kg urea; at about 18 days after transplanting, apply an appropriate amount of supplementary fertilizer according to seedling condition to promote balance.
Stem-thickening fertilizer. Generally in mid-July, apply about 10 kg potassium chloride per mu.
Panicle fertilizer. Determine application time by checking leaf age and determine fertilizer amount by observing leaf color. When the remaining leaf age of the main stem is 4.0-3.5 leaves, apply flower-promoting fertilizer (late July to early August), using 12.5-15 kg urea per mu; when the remaining leaf age of the main stem is 2.0 leaves, apply flower-preserving fertilizer, using about 5 kg urea per mu. In the later period, combine with pest and disease control and carry out mixed spraying of pesticide and fertilizer.
4. Integrated control of diseases, insects, weeds and pests. The general principle is "prevention first, integrated control." For chemical weeding, combine with the first application of tillering fertilizer by using 75 g of 37.5% Yinshou herbicide per mu for small seedlings, mix with urea and broadcast, and maintain the water layer for 5-7 days. On the basis of cultivation-based insect avoidance, with the rice growth period as the main axis and based on the severity and urgency of disease and insect occurrence, at different growth stages, consider both preceding and following factors, and adopt methods of one pesticide controlling multiple pests, mixing multiple pesticides, and mixed spraying of pesticide and fertilizer, to fight 3-4 general battles in rice disease and insect control.