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General Crop Farming (Soil Preparation, Fertilizers, and Cultivation Management)

Agriculture · 農業 · Written by Tokutei Pass based on the official study texts; not copied verbatim.

Soil Properties, Soil Preparation, and Continuous Cropping Injury

Good soil for crop growth has a well-developed "crumb (aggregate) structure" that balances aeration, water retention, drainage of excess water, and nutrient-holding capacity.

Because abundant rainfall makes Japanese soils naturally acidic, lime materials such as magnesium lime and fully matured compost are plowed in to adjust soil pH to slightly acidic or neutral (around pH 6.0–6.5).

Growing crops of the same plant family (such as nightshades: tomatoes, eggplants, bell peppers, and potatoes) repeatedly in the same field causes "continuous cropping injury" due to soil-borne pests and diseases. Prevent this by practicing "crop rotation" with different plant families.

Key points


  • Soil with a crumb structure excels in aeration, water retention, drainage, and nutrient retention.

  • Use lime materials (like magnesium lime) to correct acidic soil and apply fully matured compost to build soil health.

  • Crop rotation across different plant families is effective in preventing continuous cropping injury.
WordMeaning
crumb (aggregate) soil structure
magnesium lime (dolomitic lime)
fully matured compost
continuous cropping injury / crop rotation

The Three Major Fertilizer Nutrients, Basal Application, and Topdressing

The "three major fertilizer elements" needed in the largest amounts by plants are Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen promotes leaf and stem growth ("leaf fertilizer"), Phosphorus aids flowering and fruiting ("fruit/flower fertilizer"), and Potassium strengthens roots ("root fertilizer").

Fertilizer incorporated into the soil before sowing or transplanting is called "basal fertilizer (motogoe)", whereas fertilizer added during growth to replenish nutrients is called "topdressing (tsuihi)".

Applying excessive nitrogen causes overly lush, weak foliage growth ("vine overgrowth"), resulting in poor fruit set and higher susceptibility to pests and diseases, so always apply proper amounts.

The Three Major Fertilizer Nutrients, Basal Application, and Topdressing

Key points


  • The three major fertilizer elements are Nitrogen (leaves/stems), Phosphorus (flowers/fruits), and Potassium (roots).

  • Fertilizer applied before planting is "basal fertilizer (motogoe)"; fertilizer added during growth is "topdressing (tsuihi)".

  • Excessive nitrogen leads to vegetative overgrowth and increased pest and disease problems.
WordMeaning
three major fertilizer elements
Nitrogen, Phosphorus, and Potassium
basal fertilizer (pre-plant application)
topdressing (additional fertilizer)

Sowing, Raising Seedlings, and Transplanting

The three essential conditions for seed germination are "water (moisture), temperature, and oxygen (air)". Light-favored seeds (photoblastic) like lettuce and carrots require only a thin soil cover, whereas dark-favored seeds like daikon and green onions need adequate soil coverage.

Field sowing methods include line sowing in furrows (sujimaki), spot sowing several seeds at fixed intervals (tenmaki), and broadcast sowing (baramaki). After emergence, perform "thinning (mabiki)" to remove crowded or weak seedlings.

Healthy seedlings have compact internodes, thick stems, vibrant leaves, and dense roots. During transplanting (teishoku), avoid planting too deep or too shallow, and water thoroughly right after planting so the roots establish quickly.

Sowing, Raising Seedlings, and Transplanting

Key points


  • The three germination conditions are water, temperature, and oxygen; cover light-favored seeds lightly.

  • Sowing methods include line, spot, and broadcast sowing, followed by thinning to proper spacing.

  • Good seedlings have short internodes and strong roots; water thoroughly after transplanting for root establishment.
WordMeaning
three conditions for germination
light-favored (photoblastic) seed
line sowing / spot sowing
thinning / transplanting

Ridging, Mulching, Staking, and Training/Pruning

Forming raised beds in rows, called "ridging (unetate)", improves drainage and soil aeration, creating a favorable environment for root growth. High ridges are used in poorly drained fields.

Covering the ridge surface with plastic film or straw, known as "mulching", regulates soil temperature, suppresses weeds, retains soil moisture, prevents fertilizer leaching, and stops rain splash from spreading soil-borne diseases.

Tall or vining crops require "staking" and "training/tying (yuuin)" to prevent lodging and improve sunlight exposure. Pinching the growing tip ("topping/tekishin") and removing lateral shoots ("desuckering/wakimekaki") direct nutrients to the fruit.

Key points


  • Ridging improves drainage and aeration; mulching regulates soil temperature, suppresses weeds, retains moisture, and prevents mud splash.

  • Black mulch excels at weed control, clear mulch raises soil temperature most, and silver mulch repels flying pests like aphids.

  • Pinching growing tips and removing side shoots improve airflow and concentrate nutrients into developing fruit.
WordMeaning
ridging (making raised beds)
mulching
pinching tips (topping) / removing side shoots
training and tying stems

Pest, Disease & Weed Control, Harvesting, and Pre-cooling

Major pests include sap-sucking and virus-transmitting aphids, thrips, and whiteflies; spider mites that thrive in hot, dry conditions; and leaf-chewing armyworms and cabbage worms. Major diseases include powdery mildew, gray mold, downy mildew, and bacterial wilt.

Rather than relying solely on chemical pesticides, practice Integrated Pest Management (IPM) by combining insect nets, yellow sticky traps, and solarization (physical control), crop rotation and resistant varieties (cultural control), and natural enemies (biological control).

Vegetables are generally harvested in the early morning when produce temperature is low and turgidity is high. After harvest, perform "pre-cooling (yorei)" to lower respiration and preserve freshness before shipping.

Key points


  • Aphids, thrips, and whiteflies not only suck plant sap but also transmit viral diseases.

  • IPM combines physical, cultural, and biological controls to reduce reliance on chemical pesticides.

  • Harvest vegetables in the cool early morning and pre-cool them to suppress respiration heat and quality loss.
WordMeaning
aphids / spider mites
powdery mildew / gray mold
Integrated Pest Management (IPM)
pre-cooling

General Crop Cultivation

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