Key Technical Points for Direct-Seeding Rapeseed in Rice Paddies

Direct seeding of rapeseed in rice paddies is a relatively new cultivation technique proposed in recent years. It not only reduces labor input, but also allows rapeseed to achieve increased and stable yields with high efficiency. The reasons why the use of this technique previously affected high rapeseed yields are: 1. Sowing was delayed after rice harvest; 2. Seedlings emerged unevenly; 3. Improper fertilizer application left rapeseed seedlings thin and weak; 4. Chemical weed control was inadequate, leading to rampant weeds. The direct-seeding method for rapeseed in rice paddies is briefly introduced below for reference:

I. Preparation Before Sowing

1. Choose rice paddies with relatively high terrain and a relatively low groundwater level.

2. Drain and dry the field 10 days before rice harvest, when the rice heads are bending down and the grains are filling.

3. Keep the rice stubble height below 10 cm.

4. After rice harvest, dig furrows and level the bed surface, keeping the "three furrows" unobstructed.

II. Chemical Weed Control

Immediately after rice harvest, spray acetochlor evenly on the soil surface; then, when rapeseed has 4 to 5 leaves, spray with haloxyfop, which gives good control results.

III. Sowing

1. Sowing rapeseed before early October allows safe and complete seedling emergence. Sowing while the rice paddy is still moist is beneficial for germination and rapid emergence. Therefore, chemical weed control should be carried out immediately after rice harvest, and sowing can be done the next day.

2. Choose varieties with high purity and a large number of siliques on the main inflorescence.

3. At sowing, mix dry fine soil with borax and then sow in rows, in holes, or by broadcasting. Sow immediately after rice harvest to promote rapeseed emergence.

4. The sowing rate per mu should be 200 to 250 grams, with a density of about 20,000 plants. However, as the sowing date is delayed, the sowing rate may be increased as appropriate.

IV. Fertilization

Apply fertilizer in 3 applications: seed fertilizer, seedling fertilizer, and winter fertilizer, with organic fertilizer and phosphorus and potassium fertilizers as the main types, while also paying attention to the application of boron fertilizer.

V. Field Management

1. Check seedlings and fill gaps: thin out clustered seedlings during the 3-leaf stage of rapeseed, and check seedlings and fill gaps at the 5-leaf stage.

2. Irrigate to prevent drought: if autumn drought occurs before or after sowing, promptly irrigate with temporary flowing water to combat drought and promote full stands.

3. Clear furrows in spring: after the beginning of spring there is more rain, so furrows should be cleared promptly to drain water, ensuring the "three furrows" remain unobstructed and the field dries after the rain stops.

4. Control pests and diseases: generally, direct-seeded rapeseed is sown later than transplanted rapeseed, so pest damage is not serious. The control of sclerotinia stem rot at full bloom is basically the same as for transplanted rapeseed.