Key Technical Points for 45 cm Narrow-Row Dense Planting of Soybean

The 45 cm narrow-row dense planting cultivation technique for soybean is a new technique we selected in Dunhua City in 2004 on the basis of introducing the soybean narrow-row dense planting cultivation technique from Heilongjiang, adapted to the climate, soil and cultivation characteristics of our region, and it is a new breakthrough in the reform of the farming system in Dunhua City. In 2005, trials were conducted at the farms of Guandi, Heishi and Shaheyan; the average yield of soybean in the trial area was 202.9 kg per mu, 24.9% higher than the control. In 2006, 1500 mu were promoted citywide, with an average yield of 203.52 kg per mu and a maximum yield of 247.78 kg per mu, 34.9% higher than the control. This has explored a new technical approach for raising soybean yield to a new level.

I. Yield-increasing principles of narrow-row dense planting of soybean

Because narrow-row dense planting reduces row spacing and enlarges plant spacing, the plants are distributed more evenly and rationally, the green area is increased, and the light-receiving conditions are improved, especially the light-receiving conditions of the middle and lower layers. Because the plant distribution is rational, the leaf area receiving light is increased and the utilization rate of light is raised, thereby increasing dry matter weight and ensuring the realization of high yield.

II. Technical measures for narrow-row dense planting of soybean

1. Select suitable varieties: choose varieties that are short-stalked or semi-short-stalked, determinate or sub-determinate, with strong stems that do not lodge. Choose varieties with a maturity period earlier than that of local varieties. But they should not be too early, otherwise accumulated temperature will be wasted and yield will be affected. In Dunhua City, the varieties more suitable for narrow-row dense planting cultivation include: Kenjian 23, Hefeng 35, Heinong 35, Beifeng 11, Heihe 27, Hongfeng 11, etc.

2. Seed treatment: to control the two-striped leaf beetle and root rot and to control the damage of pests and diseases under continuous and alternating cropping, and to ensure full and strong seedlings, carry out seed coating 5-7 days before sowing. Mix 40 g of 35% Apron plus 300 g of 70% Raxil, add 1.3 L of water, then add 200 mL of 2.5% Maxim suspension seed coating agent and dress 100 kg of seeds; or use 1 kg of Zhongli (35% Duokefu) or Weid Douke (35% Duofuke suspension emulsion) to dress 70-100 kg of seeds.

3. Deep soil loosening: narrow-row dense planting must have good soil tilth conditions, achieving a deep plow layer, level surface and finely crushed soil. Narrow-row dense planting requires that the soil must have a deep-loosening foundation, otherwise yield cannot be increased. The rotary tillage depth is 15-20 cm; farmers with large machinery should preferably reach more than 25 cm.

4. Select sowing and fertilizing machinery: choose the GTX-2 (3) A2 general-purpose tillage machine to complete ridging, fertilizing, sowing, covering soil, compacting and later intertillage operations. The characteristic of this machinery is that it can carry out narrow-row dense planting and can also be used for soybean planting at ordinary row spacing.

5. Determine suitable density and specifications to ensure sowing quality: each locality should adjust measures to local conditions and determine them according to the actual local situation. Plant two rows on the ridge, with a row spacing of 8 cm and a single-row seed spacing of 10-12 cm. Generally, 23,200-26,600 seedlings per mu are retained. If the number of harvested plants is determined as 26,600, sow 30,000 seeds per mu, and the sowing rate is 6 kg/mu. The sowing depth is 3-5 cm below the compacted soil surface. Chemical fertilizer is applied 5-8 cm below the seed. Fertilizer input should be increased; on the basis of applying farmyard manure, apply 20 kg/mu of ternary compound fertilizer. Compacting width and strength: the seedling-band compacting width is 24-26 cm, and the compacting strength is 650 g per sq cm.

6. Do a good job of chemical weed control: narrow-row dense planting limits mechanical and manual weeding, so doing a good job of chemical weed control is extremely important. After soybean sowing and before emergence, use per hectare 0.75-1 L of 48% Command plus 30 g of 80% Broadstrike or 15-20 g of 75% Classic plus 1.35 L of Dual Gold (2.3 L of 72% Dual or 1.5 L of 90% acetochlor).

7. Apply chemical regulation technology and spray foliar fertilizer, combining promotion and control: for soybean under narrow-row dense planting, if the early growth is relatively vigorous, excessive growth after entering the flowering stage will make it a leggy field, causing lodging, flower and pod shedding, and yield reduction. Therefore, when field plants grow excessively and there is a risk of lodging, spray agents such as triiodobenzoic acid, paclobutrazol and Fengshoubao to prevent lodging, increase flowers and preserve pods, and raise yield. When soybean is short in the early stage and ridge closure is late due to drought and other reasons, carry out foliar topdressing. Apply foliar fertilizer once each at the early flowering stage and early podding stage of soybean; use 5-10 kg of urea plus 3 kg of monopotassium phosphate, and spray after mixing with 400-500 kg of water.

III. Precautions

1. There must be a foundation of deep loosening.

2. According to the actual local situation and adjusting measures to local conditions, different row spacings may be adopted; generally, single-row drilling can average about 15-20 cm.

3. There must be relatively good herbicide application technology. This technique should not be adopted in plots with many weeds.

4. Under different soil conditions, the density should differ; the number of harvested plants per hectare should be kept at 400,000-450,000.

5. In the later stage, foliar fertilizer must be sprayed twice.