Detailed Explanation of Key Points for Soybean Narrow-Row Dense Planting Cultivation Technology

Soybean narrow-row dense planting cultivation is currently an advanced cultivation technology with a relatively large application area and rapid development speed in international soybean cultivation. Heilongjiang Province began this practice in the early 1990s and designated it as a key research project of the Provincial Party Committee in 1995.

1. Select suitable varieties and carry out proper seed treatment

Narrow-row dense planting must select short-stalked or semi-short-stalked varieties with lodging resistance and high yield potential. Currently, the more suitable varieties applied in production include Hefeng 25, Hefeng 35, Suinong 14, Beifeng 14, Beifeng 11, Hongfeng 11, Heihe 22, etc.

Before sowing, seeds must be carefully selected. Use a soybean seed selecting machine or manual grain selection to remove diseased-spot seeds, insect-damaged seeds and impurities, reaching grade-two improved seed or above in the seed grading standard. Purity must not be lower than 98%, germination rate must not be lower than 85% (seedling establishment rate), and moisture content must not be higher than 13%. According to the types of pests and diseases and soil conditions, carry out chemical seed dressing. The main underground pests and diseases affecting soybean yield are mainly cyst nematode, root rot and root maggot. A soybean seed coating agent such as 35% Keduofu seed coating agent can be selected and applied by coating at a medicine-to-seed ratio of 1:75-100 for control. It can also be controlled by seed dressing with 35% ethylic thiocyclophosphamide or 35% methyl thiocyclophosphamide at 0.59 of the seed amount. At present, there are many types of seed coating agents on the market, with large differences in effect, so attention must be paid to selection when using them. To control soybean root rot, seed dressing can be done with 50% Duofu mixture at 0.5% of the seed amount or 50% carbendazim at 0.3% of the seed amount. To control soybean cyst nematode, seed dressing can be done with soybean root-protecting bacterial agent at 2% of the seed amount, which also controls root rot at the same time.

2. Fine land preparation

For flat-planting narrow-row dense planting, for plots without a foundation of deep plowing and deep loosening, carry out summer-autumn plowing or stubble-harrowing deep loosening land preparation. The plowing depth is 18-20 cm, the stubble-harrowing depth is 12-15 cm, and the deep loosening depth is more than 25 cm. Summer plowing, autumn plowing or stubble-harrowing deep loosening land preparation must reach a ready-to-sow state. For plots with a foundation of deep plowing and deep loosening, autumn stubble harrowing can be carried out, with a harrowing depth of 12-15 cm, harrowing level and fine.

For large-ridge narrow-row dense planting and small-ridge narrow-row dense planting, ridges should be formed on the basis of summer-autumn land preparation, carrying out summer and autumn plowing for ridge formation or stubble-harrowing deep loosening for ridge formation. For large-ridge narrow-row dense planting, a ridging machine can be used to form large ridges of 90-140 cm, with a ridge height of 15-18 cm. After the ridge body is compacted, the height from the furrow to the ridge top is 18 cm. For small-ridge narrow-row dense planting, an ordinary ridging plow can be used to form small ridges of 45-50 cm. After ridging, compact the soil to reach a ready-to-sow state.

3. Increase fertilizer input

First, increase the application of farmyard manure. For plots of medium fertility, the application rate is more than 22.5 t per hectare. Chemical fertilizers must be combined with nitrogen, phosphorus and potassium, and the application amount must be increased by more than 159 compared with conventional ridge cultivation. Where conditions permit, soil testing and formula fertilization should be carried out. Generally, for plots of medium fertility, apply 150-225 kg of diammonium phosphate, 60-75 kg of potassium sulfate or potassium chloride per hectare. If biological potassium fertilizer is used for seed dressing, potassium fertilizer may not be applied. Trace element fertilizers should also be applied according to the soil. Second, farmyard manure and chemical fertilizers must be applied deeply or in layers. At the early flowering stage of soybean, apply 10 kg of urea plus 1.5 kg of monopotassium phosphate per hectare, dissolved in 500 kg of water for spraying. For plots where micro-fertilizer was not applied as seed fertilizer or where seeds were not dressed with micro-fertilizer, micro-fertilizer can be added for spraying.

4. Sowing

1. Planting method: use pure sowing or interplanting with a large proportion.

2. Sowing time: sow at the proper time. Begin sowing when the ground temperature stably passes 7-8°C. In the central and southern regions of Heilongjiang Province, it is April 25 to May 10; in the northern and eastern regions, it is May 5 to May 15.

3. Sowing method: For flat-cropping narrow-row dense planting, a 24-row seeder can be used, blocking one sowing opening every other opening, or a combine seeder produced by JohnDeer Company can also be used. For a 30 cm row spacing, in addition to the above models, a 1.4 m precision hill-drop seeder developed by Dongnong and driven by a small four-wheel tractor can also be used.

For large-ridge narrow-row dense planting, precision sowing is carried out at equal row spacing on mechanical ridges. For large ridges of 90-105 cm formed by changing three ridges into two ridges, use a four-row-on-ridge seeder produced by Hailun Agricultural Machinery Repair and Manufacturing Factory and others for sowing. For large ridges of 120-140 cm formed by changing two ridges into one ridge, use the Huafeng 2BKM-IB large-ridge narrow-row special seeder from Huachuan to sow 6 rows on the ridge. For small ridges of 45-50 cm, appropriate adjustments can be made on the original model, planting 2 rows on the ridge.

4. Density: In the central and southern regions of Heilongjiang Province, maintain 330,000-380,000 plants per hectare; in the northern region, maintain 360,000-460,000 plants per hectare.

5. Field management

1. Chemical weed control

First, apply pre-emergence herbicide after sowing and before seedling emergence. Per hectare, use 2500-3000 ml of 50% acetochlor emulsifiable concentrate (or 1560-2200 ml of 90% Harness) plus 300-600 g of 70% metribuzin wettable powder, or plus 800-1000 ml of 40% clomazone emulsifiable concentrate, or plus 15-25 g of 75% clomazone powder, or use 1500-3000 mg of 72% Dual emulsifiable concentrate per hectare in 200 kg of water for soil spraying.

Second, post-emergence stem and leaf treatment is carried out after soybean emergence, at the 2-4 leaf stage of weeds. Per hectare, use 900-1500 ml of 5% quizalofop-p-ethyl emulsifiable concentrate, or 750-100 ml of 15% fluazifop-p-butyl emulsifiable concentrate, or 450 ml of 10.89% haloxyfop emulsifiable concentrate, or 750-900 ml of 6.9% Weiba concentrated emulsion, or 1250-1500 ml of 12.59% sethoxydim emulsifiable concentrate, mixed with 200 kg of water for spraying. To control broadleaf weeds, use 1000-1500 ml of 25% fomesafen per hectare, or 1000-1500 ml of 24% lactofen aqueous solution, mixed with 200 kg of water for spraying.

Third, autumn application: apply the herbicide in autumn when the temperature stably falls below 10°C and soil moisture is suitable (based on the criterion that plowed soil does not clod). First plow, harrow and level the land, then while spraying, use a machine-drawn disc harrow to harrow once, with a harrowing depth of 10-15 cm. After the whole field has been treated, harrow once more in a direction at right angles to the first, with the second harrowing depth the same as the first, and then form ridges. Autumn application can effectively control weeds in the following spring, and the dosage should be 10-20% more than spring application. Per hectare, use 2500-3500 ml of 70% Dual emulsifiable concentrate plus 800-1000 ml of 48% clomazone emulsifiable concentrate, or plus 120-180 g of 50% Suxiu powder, or use 2200-2500 ml of 90% Harness plus 120-180 g of 50% Suxiu.