How to grow spring-planted soybeans in Northeast China? A detailed explanation of the technical guidance

In the autumn and winter of last year, precipitation in Northeast China was lower than normal, soil moisture was insufficient, and drought was relatively severe. This spring there has been more rain and snow, temperatures began to rise rapidly in early April, and temperature and precipitation are close to normal. The Soybean Expert Steering Group of the Ministry of Agriculture, together with the National Agricultural Technology Extension Service Center, based on full investigation, proposed the following technical guidance for spring soybean planting: 1. Strictly select excellent varieties

Because of the dry climate last autumn, soybeans may not have matured normally physiologically at harvest, and mechanical threshing increased the possibility of damage to the seed embryo; all of these can affect the germination rate of the seeds. Therefore, seed selection must be strict this spring; grain selection is best, removing injured seeds, and germination tests should be done well to ensure that purity and germination rate meet the standard, and to select varieties with excellent quality, high yield potential and wide adaptability. It is worth noting that due to the global greenhouse effect, the annual accumulated temperature has shown an increasing trend in recent years, but the maturity period of varieties must still be reasonably arranged according to local meteorological conditions, and planting beyond the suitable region must be eliminated, otherwise seed moisture content will be too high at autumn harvest and cause unnecessary losses.

2. Do a good job of seed treatment before sowing. First, sun the seeds before sowing. Sunning seeds generally can increase the germination rate by about 13% and advance emergence by 2-3 days. Second, chemical seed dressing or seed coating. When temperatures are low or drought occurs, seeds germinate for a long time in the soil and are prone to pests and diseases; soybean seed coating agent can be used at a drug-to-seed ratio of 1:75-1:100 for control. To control soybean root rot, 50% carbendazim-thiram mixture at 0.5% of seed weight or 50% carbendazim at 0.3% of seed weight can be used for seed dressing. In fields with severe insect pests, coated seeds containing both fungicides and insecticides should be selected; for uncoated seeds, 35% methyl thiocyclophosphorus emulsifiable concentrate should be used for seed dressing to control soil insects. Ammonium molybdate can be added to the seed dressing agent to increase soybean emergence rate and nitrogen fixation capacity.

3. Select suitable sowing methods. Before freezing last autumn, subsoil moisture was insufficient, and this spring there has been more snow than in previous years. It is recommended that soybean fields avoid measures to activate snow, so as to prevent water from evaporating too early and causing drought during the soybean sowing period. For plots without autumn plowing, use no-till sowing on the original ridges; for plots that were autumn-plowed and ridged, use flat sowing followed by ridging or flat cultivation with narrow-row dense planting; for plots with poor soil moisture, use deep furrow opening, shallow soil covering and heavy compaction; for plots with severe drought, use the sowing method of film mulching between rows, and carry out continuous operations to prevent soil moisture loss.

4. Sow at the right moisture and strive to secure full stands in one sowing. Although there has been more spring snow this year, because of last autumn's drought, subsoil moisture is still insufficient; we should seize the favorable opportunity of rising ground temperature and use the early spring "returning slurry water" to sow at the right moisture. Sowing can be carried out when the stable ground temperature in the plow layer passes 5°C, and continuous operations should prevent soil moisture loss. The sowing method of deep furrow opening, shallow soil covering and heavy compaction can be used. Deep furrow opening ensures that seeds are sown on moist soil, soil covering is uniform, and after compaction it reaches 2 cm, ensuring consistent sowing depth. Compact after sowing to preserve moisture. When soil moisture is suitable, compact 2-3 hours after sowing; when soil moisture is poor, compact as soon as sowing is done; for plots with high soil moisture (water content >25%) or that encounter rain after sowing, compact only after a 2 cm dry soil layer appears on the surface. After sowing, inspect the field regularly. Begin checking soil moisture 3-5 days after sowing, and take measures to supplement moisture in plots with severe moisture loss; before emergence, check bud condition, and for plots with dried buds or spoiled seeds, supplement sowing with water in time; after emergence, check seedling and insect conditions, and for plots with missing seedlings or broken rows or damaged by pests, replant with early-maturing varieties or apply chemical control.

5. Promote soil testing and formula fertilization. For a long time, many places have fertilized only based on experience, causing imbalance of soil nutrient elements and making potassium deficiency and trace element deficiency common in production. In conjunction with the soil testing and formula fertilization project implemented by the Ministry of Agriculture, we should adhere to scientific fertilization and, according to soil test results, apply nitrogen, phosphorus and potassium fertilizers in a certain ratio. Advocate returning straw to the field, split application or slow release of nitrogen fertilizer, increase potassium fertilizer according to soil potassium status, and appropriately supplement magnesium fertilizer. Encourage more application of farmyard manure, applied together with land preparation. When chemical fertilizer is used as seed fertilizer, it should be applied deeply 4-5 cm below the seed to avoid burning the seed. Based on the above fertilization principles, it is recommended that the fertilization amounts for different yield targets are as follows: (1) Yield level 250 kg/mu: nitrogen fertilizer (N) 2.7-4 kg/mu, phosphate fertilizer (P2O5) 2.3-5 kg/mu, potassium fertilizer (K2O) 2.3-5 kg/mu. (2) Yield level 200 kg/mu: nitrogen fertilizer (N) 2.3-3.7 kg/mu, phosphate fertilizer (P2O5) 1.5-4.3 kg/mu, potassium fertilizer (K2O) 1.5-4 kg/mu. (3) Yield level 150 kg/mu: nitrogen fertilizer (N) 3 kg/mu, phosphate fertilizer (P2O5) 3.7 kg/mu, potassium fertilizer (K2O) 3.3 kg/mu. 6. Use herbicides safely and efficiently. Adapt to local conditions, and according to different weed spectra, scientifically and reasonably choose safe and efficient chemical weed control methods and herbicides. In the central and western drought-prone areas, post-emergence stem and leaf weed control is advocated. To prevent herbicide damage, in white pulp soil, saline-alkali soil, sandy loam soil and soybean fields with relatively high soil moisture, it is not suitable to use metribuzin, 2,4-D butyl ester or formulas containing such agents for pre-emergence closed weed control. In view of the large winter snow and early warming this year, which favors the early germination of perennial weeds, glyphosate can be used for non-selective weed control during the visible weed period after soybean sowing and before soil cracking, which can effectively improve control of perennial rhizomatous weeds such as "field sowthistle" and "creeping thistle." For pre-emergence closed weed control, if soil moisture is good, use normal herbicide rates according to the herbicide instruction manual; in soybean fields, agents such as acetochlor, propisochlor, metolachlor, clomazone and flumioxazin (Sumisoya) can be used. If soil moisture is relatively poor, closed weed control is not recommended. For post-emergence stem and leaf weed control, agents such as quizalofop-p-ethyl, haloxyfop-p-methyl (Gallant Super), fluazifop-p-butyl (Fusilade Super), fomesafen, sethoxydim and bentazone can be used. The stem and leaf control period for "field sowthistle" and "creeping thistle" is when the first trifoliolate leaf of soybean is fully expanded, which can both improve efficacy and reduce herbicide damage. For stem and leaf control of crabgrass, the herbicide must be applied when the weeds have just germinated. It is best not to use long-residual herbicides such as imazethapyr, chlorimuron-ethyl, thifensulfuron, cloransulam and clomazone.

7. Scientifically control pests and diseases. The continuous warm winter this year is extremely favorable for the safe overwintering of soybean pathogens and pest eggs, and soybean pests and diseases may occur more heavily. According to local pest and disease damage conditions and the main targets of control, seed coating agents should be selected in a targeted way, and soybean seed coating should be fully implemented. In areas where two-striped leaf beetle and bean root maggot occur relatively heavily, use 35% carbofuran-carbendazim-thiram seed coating agent (carbofuran content must reach 10%) to control root rot caused by insect injury. In areas with light soil insect occurrence, 2.5% fludioxonil can be used for coating to control soybean root rot. In areas with severe soybean cyst nematode occurrence, rotation with non-legume crops for more than five years or planting resistant lines should be implemented. To control soybean root mealybug, seize the young nymph stage before they become fixed and cause damage; use 75% imidacloprid 3 g plus 48% chlorpyrifos 60 ml per mu, applying twice before soybean cotyledons emerge and after cotyledons unfold. In plots with severe white grub occurrence, granular formulations such as phoxim and chlorpyrifos should be applied into the field with seed fertilizer for prevention. This spring, prevention should be strengthened against pests such as two-striped leaf beetle, Mongolian gray weevil, sand, and sloe bug. Use 3% acetamiprid 50 ml per mu diluted with 30-50 L water for spray control. Cutworms can be trapped and killed with green grass in the early seedling stage, cutting green grass and piling it every 5 m, spraying 80% dichlorvos 300-fold solution at the bottom of the piles, or manual killing can also be carried out. In addition, for continuous cropping plots, attention should be paid to using poison bait to control rodent damage after emergence.