Soybean Narrow-Row Dense Planting Cultivation Methods and Technical Key Points

Soybean narrow-row dense planting cultivation is currently an advanced cultivation technique with a relatively large application area and rapid development rate in soybean cultivation internationally. Since the early 1990s, our province, on the basis of absorbing and digesting foreign techniques and in combination with the province's natural characteristics and production conditions, has explored a soybean narrow-row dense planting cultivation technique suitable for the province's production conditions.

Soybean narrow-row dense planting is divided into two modes: flat-planting narrow-row dense planting and ridge-planting narrow-row dense planting. The former high-yield cultivation technique is flat sowing, flat management, a narrow-row dense planting cultivation that stays flat throughout, and the latter refers to narrow-row dense planting cultivation based on ridge planting, which is further divided into large-ridge narrow-row dense planting and small-ridge narrow-row dense planting.

I. Select suitable varieties and carry out seed treatment well

Increasing yield through narrow-row dense planting must be premised on "not producing severe lodging"; otherwise, not only will yield not increase, but it will instead decrease. Therefore, narrow-row dense planting must select dwarf and semi-dwarf varieties with lodging resistance and large yield-increasing potential. At present, the more suitable varieties applied in production include Hefeng 25, Hefeng 35, Suinong 14, Beifeng 14, Beifeng 11, Hongfeng 11, Heihe 22, etc. In addition, selecting varieties or lines with a maturity period earlier than the local one mostly shows increased yield. For example, Heijiao 99-1372 selected in Bayan, and Baofeng 9 and Beifeng 11 selected in Huachuan County, are all types with earlier maturity periods locally. This point can serve as a reference basis for variety selection, but the maturity period should not be too early, otherwise accumulated temperature will be wasted and yield will be affected.

Seeds must be carefully selected before sowing, using a soybean seed selecting machine or manual grain selection, removing diseased-spot grains, insect-eaten grains and impurities, to reach grade II improved seed or above in the seed grading standard. Purity not less than 98%, germination rate not less than 85% (seedling formation rate), moisture content not higher than 13%. According to the types of diseases and insect pests and soil conditions, carry out chemical seed dressing. The main underground diseases and insect pests affecting soybean yield are mainly cyst nematode, root rot and root maggot, which can be controlled by selecting 35% Keduofu seed coating agent and other soybean seed coating agents according to the coating method of pesticide-to-seed ratio 1:75-100, or by using 35% ethion or 35% methyl ethion at 0.5% of seed amount with 50% Duofu mixture or 0.3% of seed amount with 50% carbendazim for seed dressing. To control soybean cyst nematode, use 2% of seed amount of soybean root-protecting microbial agent for seed dressing, while also controlling root rot.

II. Fine land preparation

Rational ploughing and turning and fine land preparation can mature the soil, store water and preserve moisture, and can eliminate weeds and reduce diseases, insect pests and damage. It is the foundation for full stands and strong soybean seedlings, and one of the fundamental measures for increasing soybean yield. Narrow-row dense planting has stricter requirements for the soil plough layer. Flat-planting narrow-row dense planting does not carry out hoeing and ridging during the growth period, and its abilities to increase temperature, prevent drought and resist waterlogging are weakened. It requires good soil plough layer conditions, achieving a deep plough layer, level surface and fine, crumbly soil. Adopting large-ridge narrow-row dense planting increases the number of rows on the ridge, which increases the difficulty of mechanical sowing, so the land preparation requirements are higher than conventional ridge planting. It not only requires a deep plough layer, but the surface soil on the ridge must also be level, the land clean, and the soil fine and crumbly. For flat-sowing narrow-row dense planting, plots without a foundation of deep ploughing and deep loosening should carry out summer-autumn ploughing or stubble harrowing and deep loosening land preparation to reach a ready-to-sow state. Deep ploughing, deep leveling and fine harrowing are required.

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

III. Increase fertilizer input

To achieve high yield in narrow-row dense planting, fertilizer input must be increased and applied rationally. First is increasing the application of farmyard manure; for medium-fertility plots, the application rate is more than 22.5 tons per hectare. Chemical fertilizers must be matched with nitrogen, phosphorus and potassium, and the application rate must be increased by more than 15% compared with conventional ridge planting. Where conditions permit, carry out soil testing and formula fertilization. Generally, for medium-fertility plots, apply 150-225 kg of diammonium phosphate per hectare, 60-75 kg of potassium sulfate or potassium chloride; where biological potassium fertilizer is used for seed dressing, potassium fertilizer may not be applied. Also apply trace element fertilizers according to the land. Farmyard manure and chemical fertilizers must be applied deeply or in layers.

When the early growth of soybean is poor, at the early flowering stage use 10 kg of urea plus 1.5 kg of potassium dihydrogen phosphate per hectare, dissolved in 500 kg of water for spraying. For plots where trace fertilizer was not applied as seed fertilizer or where seeds were not dressed with trace fertilizer, trace fertilizer can be added for spraying.

IV. Sowing

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

2. Sowing period: sow at the right time; begin sowing when the ground temperature stably passes 7-8°C. In the central and southern regions, April 25 to May 10; in the northern and eastern regions, May 5 to May 15.

3. Sowing method: for flat-row narrow-row dense planting sowing, a 24-row seeder can be used, blocking every other sowing opening; a combined seeder produced by John Deere Company can also be used. For 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 mechanically on the ridge at equal row spacing. For large ridges of 90-105 cm formed by changing three ridges into two ridges, use a four-row-on-ridge seeder produced by the 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 type special large-ridge narrow-row 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 to sow 2 rows on the ridge.

4. Density: in the central and southern regions, keep 330,000-380,000 seedlings per hectare; in the northern region, keep 360,000-460,000 seedlings per hectare.