Detailed Explanation of Key Techniques for High-Yield Semi-Dry Rice Cultivation

① Land preparation and ridging: For winter-flooded fields, plow promptly after rice harvest, level the field surface, build high field bunds, and store water for the winter. After spring begins, generally no further plowing or harrowing is needed, but for fields with compacted soil and abundant weeds, plow and harrow once half a month before transplanting. Ridging is done in two stages. The first stage is carried out 5-7 days before transplanting, using ropes stretched to specification to open furrows and form rough ridges (for deep-footed and muddy fields, this can be moved earlier to 7-10 days before transplanting); it should not be done too early, to avoid prolonged exposure of the ridge surface, which tends to breed weeds. The second stage is carried out 2-3 days before transplanting, further raising the ridge (bed) surface according to quality requirements, clearing the furrows, and shaping them. For winter-cropped fields, after the small spring harvest, dry-plow and sun the clods for several days, then 3-4 days before transplanting let water into the field to soak it, prepare the field surface, and after the soil has settled, ridge and form beds in one operation.

Ridge specifications are divided into bed type and bund type, depending on the variety, field type, and utilization method. Bed type: generally bed width 60-80 cm, furrow width 33-40 cm, furrow depth 27-33 cm. Bund type: generally ridge width 27-40 cm, furrow width 33-44 cm, furrow depth 27-33 cm. For highly fertile fields and @#@233@#@ fields, appropriately enlarge the ridge and furrow surface widths. When ridging, maintain a 6-8 cm water layer in the field. The dug-up mud should be placed down gently in sequence, without disturbing the soil layers, without pressing, and without smoothing the ridge surface. The ridge top may be slightly tile-backed or flat-topped. After transplanting, clear the furrows and tidy the ridges 1-2 times; after rice harvest, do not level the ridges. Lightly clear the furrows and tidy the ridges, and continue to use them through winter to achieve continuous no-till.

② Fertilization: The fertilizer rate for semi-dry cultivation is the same as for flat cultivation. The fertilization method generally adopts heavy application of base fertilizer and early application of topdressing (nitrogen fertilizer applied all at once; base fertilizer accounts for 70-80% of the total fertilizer amount, topdressing 20-30%). Before the first ridging, evenly broadcast decomposed manure, ammonium bicarbonate, and ammonia water over the whole field; urea and quick-acting phosphorus and potassium fertilizers are broadcast on the first-level flat surface before the second ridging. Topdressing is applied within 7-10 days after transplanting. For varieties with a long growth period and for fields directly transplanted with medium or small seedlings, an additional topdressing should be applied around 20 days after transplanting as appropriate, depending on seedling condition.

③ Transplanting: Determine the type of seedlings to transplant according to different field types. In cold, shaded, muddy, and rusty fields, where "seedling stagnation" is common, it is best to transplant large seedlings at the 7-9 leaf stage (multi-tiller strong seedlings). In general winter-flooded fields, it is suitable to transplant medium seedlings at the 3.5-5 leaf stage or small seedlings at the 2-leaf stage. For bed type, plant 4-6 rows on each bed. For bund type, seedlings must be planted on both sides of the ridge crest slightly below the water line, 1 row on each side. Row spacing is generally 16-20 cm, hill spacing 10-13 cm. For small seedlings, transplant double plants per hill; for multi-tiller strong hybrid rice and conventional medium rice, 6-8 stems and tillers per hill, 16,000-30,000 hills per mu (depending on soil type and regional ecological characteristics; more in Yunnan, fewer in Sichuan), and 120,000-180,000 basic seedlings (stems and tillers).