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Cultivation Management of Rice, Upland Crops, and Open-Field Vegetables

Agriculture (SSW 2) · 農業(2号) · Written by Tokutei Pass based on the official study texts; not copied verbatim.

Rice Seed Preparation, Raising Seedlings, and Puddling

To select plump seed rice, perform saltwater selection at a specific gravity of 1.13 (for non-glutinous rice) to remove floating seeds, disinfect the seeds, and soak them until cumulative water temperature reaches ~100°C-days.

During pre-germination (saiga), keep seeds in 30–32°C warm water until buds swell uniformly to ~1 mm ('pigeon-breast stage') before sowing into nursery trays. Avoid sudden chilling or overwatering to prevent seedling damping-off.

Before transplanting, after dry plowing (kouki), flood the paddy and perform puddling (shirokaki) to pulverize clods and level the field surface, preventing water leakage and suppressing weeds.

Key points


  • Use specific gravity 1.13 for non-glutinous rice saltwater selection, soak for 100°C-days, and sprout at 30–32°C to the pigeon-breast stage.

  • Prevent seedling damping-off during nursery raising by avoiding low temperatures and excessive moisture.

  • Puddling (shirokaki) levels the flooded paddy soil, reduces water percolation, and promotes uniform transplanting.
WordMeaning
saltwater seed selection (specific gravity 1.13)
seed soaking and pre-germination
pigeon-breast sprouting stage (~1 mm)
puddling

Rice Water Management, Panicle Topdressing, and Harvesting

At the end of effective tillering, drain the paddy until light surface cracks appear ('mid-season drainage / nakaboshi') to suppress non-productive tillers, vent toxic gases, supply oxygen to roots, and prevent lodging.

During the young panicle formation (meiotic) stage before heading, if temperatures below 17°C are forecast, maintain 15–20 cm deep water to insulate the developing panicles against cool-weather sterility. Topdressing applied at this stage is called panicle fertilizer (hogoe).

Harvest when cumulative temperature after heading reaches ~950–1,050°C (85–90% yellow grains) and dry promptly to a brown-rice moisture content of 14.5–15.0%. Stink bugs feeding during grain filling cause pecky rice (hantenmai), lowering grade.

Rice Water Management, Panicle Topdressing, and Harvesting

Key points


  • Mid-season drainage (nakaboshi) suppresses unproductive tillers, oxygenates roots, and prevents lodging.

  • Use deep-water management (15–20 cm) to protect young panicles from cold damage, and apply panicle fertilizer 15–25 days before heading.

  • Dry harvested paddy to 14.5–15.0% brown-rice moisture and control rice stink bugs to prevent pecky rice.
WordMeaning
mid-season drainage
deep-water irrigation management
panicle fertilizer (topdressing)
pecky rice (stink bug-damaged rice)

Key Management for Upland Crops (Soybeans, Wheat, and Tubers)

Intertillage and hilling (earthing up) in soybeans and potatoes control weeds, improve soil aeration, encourage adventitious root growth against lodging, and prevent potato tubers from turning green (producing toxic solanine) in sunlight.

Wheat treading (mugifumi) in winter and early spring prevents frost heaving of roots, restrains spindly overgrowth, and promotes tillering and sturdy stems.

Cut seed potatoes several days before planting so cut surfaces suberize (heal) against rot. After harvesting sweet potatoes, apply curing treatment at 30–33°C and 90–95% humidity to heal skin wounds before storing at 13–15°C.

Key points


  • Intertillage and hilling control weeds, prevent lodging, and keep potato tubers covered to prevent greening (solanine formation).

  • Wheat treading prevents root lifting from frost pillars, suppresses overgrowth, and increases tiller numbers.

  • Cure sweet potatoes at 30–33°C and 90–95% RH to suberize wounds before storing them at 13–15°C.
WordMeaning
intertillage and hilling (earthing up)
wheat treading / rolling
greening and solanine toxin
curing treatment (wound healing)

Preventing Continuous Cropping Injury, Mulching, Grafting, and Bolting

Repeatedly growing vegetables of the same botanical family (Solanaceae: tomato, eggplant, pepper, potato; Cucurbitaceae: cucumber, watermelon; Brassicaceae: cabbage, radish, Chinese cabbage) causes continuous cropping injury from soilborne pathogens and nematodes.

Prevent this through crop rotation across different families and by planting grafted seedlings (joining a scion onto a disease-resistant rootstock). Always plant grafted seedlings shallowly so the graft union stays above the soil line.

Exposure of young radish, cabbage, Chinese cabbage, or onion plants to low temperatures induces vernalization and premature flower stalk elongation ('bolting / chuudai'), ruining market quality; prevent bolting with row covers, mulch, or slow-bolting cultivars.

Key points


  • Tomato, eggplant, bell pepper, and potato all belong to Solanaceae; rotating among them does not prevent continuous cropping injury.

  • Keep the graft union above the soil surface when transplanting so the susceptible scion does not root into infested soil.

  • Low-temperature vernalization triggers bolting (premature flowering), which destroys the market value of root and leafy vegetables.
WordMeaning
continuous cropping injury and crop rotation
grafting (rootstock and scion)
vernalization
bolting (premature flower stalk elongation)

Rice, Field Crop and Vegetable Management

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Official references