Technical Guidance on Wheat Autumn and Winter Planting (2015/2016 Season)

Since July this year, rainfall has been relatively abundant in the main wheat-producing areas, soil subsoil moisture has generally been sufficient, and previous crops have grown and developed normally, ensuring timely sowing in most areas. However, rainfall has been relatively low in some parts of the northwest, and surface soil moisture is insufficient. At the same time, meteorological authorities predict that, under the influence of El Niño, precipitation in the northern winter wheat region during autumn and winter will be lower than usual, and temperatures will generally be higher than normal. Some areas may experience continuous autumn-winter drought, which is unfavorable for winter wheat sowing, seedling emergence and safe overwintering. In order to effectively improve winter wheat sowing quality, cultivate strong seedlings before winter, and consolidate the foundation for next year's summer grain harvest, technical guidance on wheat autumn and winter planting for the 2015/2016 season is hereby proposed by region for reference by all localities.

I. Huang-Huai and Northern Winter Wheat Region

This region includes Hebei, Shandong, Henan, northern Jiangsu, northern Anhui, central and southern Shanxi, and the Guanzhong area of Shaanxi, and is the largest winter wheat-producing region in China. This region has relatively good production conditions, abundant light and heat resources, annual precipitation of 400-900 mm, flat terrain and fertile soil. The cropping system is mainly a one-year two-crop rotation of wheat and maize, with wheat sown in early to mid-October and harvested from late May to early to mid-June. The main factors affecting wheat production are water resource shortage, frequent natural disasters such as drought, freezing injury and dry hot wind, and relatively severe damage from stripe rust, sheath blight, powdery mildew and fusarium head blight. The key aspects of wheat autumn sowing and pre-winter management in this region include the following:

(1) Pre-sowing Preparation

1. Variety selection. Select suitable varieties according to local climate, soil, soil fertility, cropping system, yield level and pests and diseases. First, select varieties according to weather conditions. Select winter or semi-winter varieties according to temperature conditions. Cross-region planting and the use of unapproved varieties are strictly prohibited. In the northern winter wheat region, winter varieties should be strictly selected; in the Huang-Huai winter wheat region, winter and semi-winter varieties should be selected. Second, select varieties according to soil conditions. For high-yield fields with good water and fertilizer conditions, select varieties with high yield potential, tolerance to fertilizer and resistance to lodging. For water-deficient areas, select drought-tolerant, water-saving and stable-yielding varieties. For dry and poor land, select drought-resistant and barren-tolerant varieties. For dry but fertile land with thicker soil layers and higher fertility, select drought-resistant and fertilizer-tolerant varieties. Third, select varieties according to the cropping system. Wheat-cotton intercropping requires wheat varieties suitable for late sowing and early maturity to shorten the symbiotic period of wheat and cotton, while also having shorter plants, compact plant type and strong border-row advantage to fully utilize light energy and improve photosynthetic efficiency. Fourth, select varieties according to disaster conditions. Areas with severe dry hot wind should select varieties that are appropriately early-maturing, resistant to premature senescence and resistant to premature wilting, so as to avoid or reduce the harm of dry hot wind. Fifth, select varieties according to disease conditions. Areas with severe rust infection should select rust-resistant (tolerant) varieties. Areas with excessive rainfall and severe waterlogging should select varieties that are moisture-tolerant, resistant (tolerant) to fusarium head blight and have a long seed dormancy period. Sixth, select varieties according to quality. Select high-quality varieties with good nutritional quality, processing quality meeting the requirements of finished products, plump grains and high test weight. Seventh, strictly manage variety introduction and replacement. Replace new varieties according to changes in production conditions and yield improvement, prevent large-scale introduction, seed transfer and frequent replacement of improved varieties without experimentation; while planting main promoted varieties, actively introduce new varieties for experimentation and demonstration, and do a good job in seed reproduction to determine "successor" varieties and maintain the quality of seeds used in production.

2. Seed treatment. Strengthen wheat seed treatment, effectively carry out seed coating or chemical seed dressing, reduce autumn seedling disease, lower overwintering inoculum sources, and control damage from underground pests at the seedling stage, which can delay the onset time of wheat stripe rust, powdery mildew, sheath blight and other diseases. Reasonably select chemicals according to the disease resistance of wheat varieties in different regions, disease incidence, climatic conditions and cultivation methods. Strictly control the amount of chemicals used for seed dressing, and prohibit excessive use; sow immediately after seed dressing, use freshly dressed seed, and finish sowing on the same day; appropriately increase the seeding rate after chemical seed dressing.

3. Straw return. For maize straw crushing and return to the field, the length is required to be ≤7 cm and evenly spread on the soil surface. Plow the crushed straw into the ground. If the subsoiling technique is used, rotary tillage must be carried out to cut the straw into the soil layer, with a rotary tillage depth of more than 15 cm. After straw return, irrigate and firm the soil. If moisture conditions are suitable, harrow and press in time.

4. Deep plowing (subsoiling) and harrowing. Deep plow 23-25 cm and then harrow and press, or subsoil 30-35 cm and then rotary till and harrow and press, in order to break clods, settle the soil, facilitate root penetration, prevent air leakage and moisture loss, and ensure safe overwintering of seedlings. The effect of deep plowing or subsoiling can last for 2 years. After 1 year of deep plowing or subsoiling, rotary tillage for seedbed preparation is sufficient for 2-3 years. For one-crop-per-year dryland fallow wheat fields, deep plowing and subsoiling should be carried out in early July to facilitate rain absorption and moisture storage, combined with harrowing before sowing to conserve moisture.

5. Irrigation to build soil moisture. Adhere to sowing with sufficient soil moisture to ensure full seedling emergence in one sowing. When the relative water content of the 0-40 cm soil layer is below 75%, irrigation should be carried out to build moisture before sowing. For wheat fields that cannot be irrigated in time to build moisture and are irrigated after sowing, timely hoeing should be carried out to prevent soil cracking and reduce soil moisture loss.

6. Application of base fertilizer. Soil testing and formula fertilization, combined application of nitrogen, phosphorus and potassium fertilizers, and supplementary application of trace element fertilizers. High-yield fields should adopt the technique of postponing nitrogen fertilizer, with 50% of nitrogen fertilizer applied as base and 50% as topdressing, and all other fertilizers applied as base. According to production experience, the reference values of suitable fertilization amounts for different fertility levels are as follows: for low-yield fields with a yield of 200-300 kg per mu, apply 6-10 kg of pure nitrogen (N), 3-5 kg of phosphorus (P2O5) and 2-4 kg of potassium (K2O) per mu, with all nitrogen, phosphorus and potassium fertilizers applied as base; for medium-yield fields with a yield of 300-400 kg per mu, apply 10-12 kg of pure nitrogen (N), 4-6 kg of phosphorus (P2O5) and 4-6 kg of potassium (K2O) per mu, with 70% of nitrogen fertilizer applied as base and 30% topdressed at the erect stage, and all phosphorus and potassium fertilizers applied as base; for high-yield fields with a yield of 400-500 kg per mu, apply 12-14 kg of pure nitrogen (N), 6-7 kg of phosphorus (P2O5) and 5-6 kg of potassium (K2O) per mu, with 60% of nitrogen fertilizer applied as base and 40% topdressed at the erect stage or jointing stage, and all phosphorus and potassium fertilizers applied as base; for super-high-yield fields with a yield of more than 500 kg per mu, apply 14-16 kg of pure nitrogen (N), 7-8 kg of phosphorus (P2O5) and 6-8 kg of potassium (K2O) per mu, with 50% of nitrogen fertilizer applied as base and 50% topdressed at the jointing stage, and all phosphorus and potassium fertilizers applied as base.

(2) Sowing

7. Suitable sowing period. Generally, the daily average temperature for suitable sowing of winter varieties is 16-18°C, and for semi-winter varieties is 14-16°C. To cultivate strong seedlings before winter, winter and semi-winter varieties must ensure an effective accumulated temperature of 550-600°C before winter, while also considering weather conditions, fertility level, pests and diseases and safe overwintering. Generally, the suitable sowing period is late September to early October in the northern winter wheat region, October 5-15 in the northern and central Huang-Huai winter wheat region, and October 10-20 in the southern Huang-Huai winter wheat region.

8. Reasonable seeding rate. A reasonable seeding rate and suitable basic seedling number are the starting point for establishing a high-quality population, and are also important measures for building a reasonable population structure and coordinating the relationship between population and individuals, and between wheat growth and development and environmental conditions. The principles to be mastered are: First, variety characteristics. For varieties with strong tillering ability and high spike-forming rate, appropriately reduce the seeding rate. Second, sowing time. For early sowing, the seeding rate should be appropriately reduced; for late sowing, the seeding rate should be appropriately increased. Third, soil fertility level. For soil with better water and fertilizer conditions, the basic seedling number should be sparse and the seeding rate should be small. Generally, the basic seedling number per mu is 200,000-300,000 in the northern winter wheat region, 150,000-250,000 in the northern and central Huang-Huai winter wheat region, and 150,000-180,000 in the southern Huang-Huai region. When the daily average temperature at sowing is below 15°C, for each day of delay in sowing, the basic seedling number should increase by about 10,000, but should not exceed 350,000 at most.

9. Fine sowing. Use wheat seeders that meet requirements and are of qualified quality, and determine suitable sowing row spacing according to local actual conditions, ensuring consistent row spacing, accurate seeding rate, consistent depth, sowing depth of 3-5 cm, and no missed sowing or double sowing.

10. Post-sowing compaction. Seeders with compacting devices should compact while sowing. Seeders without compacting devices should be compacted with a roller after sowing. Ensure compaction strength and quality, so as to firm the soil, reduce field moisture loss, promote wheat seedling growth, cultivate strong seedlings before winter, and increase the proportion of strong seedlings.

(3) Pre-winter Management

11. Irrigation for overwintering. For wheat fields lacking moisture and fields with straw return, rotary tillage sowing and hollow, uncompacted soil, timely irrigation for overwintering should be carried out to ensure safe overwintering of seedlings. Winter irrigation is generally carried out when the daily average temperature is stable at 3-4°C and water can infiltrate in time, and should be completed before heavy freezing. Water-saving irrigation is advocated, and flood irrigation is prohibited. After irrigation, timely hoeing should be carried out to loosen the soil and conserve moisture, prevent surface cracking, and avoid air leakage that damages roots and kills seedlings. For wheat fields with suitable soil moisture, high seedbed preparation quality, sufficient base fertilizer, normal growth and suitable population, overwintering irrigation may be omitted before winter. For wheat fields without irrigation conditions, timely hoeing should be carried out after each rainfall to conserve moisture.

12. Chemical weeding. In recent years, malignant grassy weeds have shown a gradual development trend, greatly affecting wheat yield. It is necessary to focus on autumn treatment of spring weeds and do a good job in autumn chemical weeding, generally from mid-November to early December, when wheat is at the 3-4 leaf stage and weeds are at the 2-leaf 1-heart to 3-leaf stage. To control grassy weeds such as wild oat, jointed goatgrass, shortawn foxtail and ryegrass, spray 40-60 ml of 6.9% fenoxaprop-p-ethyl emulsifiable concentrate per mu plus 30 kg of water on the leaves. To control jointed goatgrass and bromegrass, use 30 g of 3% mesosulfuron or 20 g of 3.6% mesosulfuron-iodosulfuron per mu, plus 30 kg of water for spraying. To control broadleaf weeds such as flixweed, shepherd's purse and cleavers, use 1.0-1.8 g of 75% tribenuron-methyl dry suspension concentrate per mu, or 10 g of 10% tribenuron-methyl wettable powder, or 50-60 ml of 20% fluroxypyr emulsifiable concentrate plus 30-40 kg of water for uniform spraying. To control alkaligrass and hard grass, after wheat emergence use 200-400 g of 25% isoproturon wettable powder per mu plus 20 kg of water for spraying.

13. Pest and disease control. For wheat fields with severe damage from underground pests such as white grubs and wireworms, use 500 ml of 40% isofenphos-methyl emulsifiable concentrate or 50% phoxim emulsifiable concentrate per mu plus 750 kg of water, and irrigate along the rows; or use 250-300 ml of 50% phoxim emulsifiable concentrate or 48% chlorpyrifos emulsifiable concentrate, diluted 10 times with water, mixed with 40-50 kg of fine soil, and apply into the soil together with hoeing. For wheat fields with severe occurrence of wheat leafminer, use 80 ml of 40% omethoate per mu plus 30 ml of 4.5% beta-cypermethrin, plus 40-50 kg of water for spraying; or spray with 1% abamectin at 3000-4000 times dilution, which also controls wheat aphids and red spiders. To control wheat sheath blight, use 20-30 g of 12.5% diniconazole wettable powder per mu, or 100 g of 15% triadimefon wettable powder, diluted with 50 kg of water for uniform spraying. For fields with severe occurrence of wheat cyst nematode, use 3.7 kg of 5% nematode-killing granules per mu, broadcast along the rows at the seedling stage, and irrigate in time to improve control efficacy.

14. Grazing on green seedlings is strictly prohibited. Strengthen the management and protection of wheat fields before winter, manage livestock and poultry well, eliminate grazing by livestock and poultry on green seedlings, and ensure normal growth and safe overwintering of wheat seedlings.

II. Middle and Lower Reaches of the Yangtze River Winter Wheat Region

This region includes the areas south of the Huai River in Jiangsu and Anhui provinces, Hubei, and Xinyang City in Henan, and is one of the main winter wheat-producing regions in China. This region has a humid climate, good heat conditions, and annual precipitation of 800-1400 mm; the terrain is low and flat, and the soil is mainly paddy soil with organic matter content of about 1%. The cropping system is mainly a one-year two-crop rotation of rice and wheat, with wheat sown from late October to mid-November and harvested from late May to early June. The main factors affecting wheat production are waterlogging damage and high-temperature forced ripening, with occasional pre-harvest sprouting, and relatively severe damage from fusarium head blight, powdery mildew, sheath blight and stripe rust. The key aspects of wheat autumn sowing and pre-winter management in this region include the following:

1. Variety selection. Select varieties with high yield, high quality and strong resistance to moisture, lodging and disease (mainly fusarium head blight, powdery mildew and sheath blight). In the southern part of the middle and lower reaches of the Yangtze River wheat region, spring varieties should be selected; in the northern part, semi-winter varieties should be selected.

2. Seed treatment. Use 2% tebuconazole suspension concentrate, 15-20 g of chemical per 10 kg of seed, plus 0.5 kg of water for seed dressing, which can also control soil-borne and seed-borne diseases such as sheath blight and take-all. For wheat sown early at the suitable time, paclobutrazol and other chemical control agents can be used for seed dressing or seed soaking, which can play a role in dwarfing and increasing tillers, controlling excessive growth and promoting strong growth. It is advisable to dress 1 kg of wheat seed with 1 g of 15% paclobutrazol powder or soak seeds with 100-150 mg/L paclobutrazol solution. When dressing seeds, pay attention to uniform mixing to prevent excessive local chemical concentration from affecting wheat seedling growth.

3. Straw return. For rice, control the last irrigation time well, cut off water 7-10 days before harvest to create good moisture conditions for wheat sowing, and harvest in time after maturity to prevent excessively "aging the rice". When harvesting rice, the stubble height should be below 10 cm, and the rice straw should be chopped to about 5 cm and evenly spread. For full straw return, first carry out deep rotary tillage (or deep plowing) to destroy stubble before mechanical drilling, and the depth of rotary tillage for burying straw should be at least 12 cm or more (preferably 15 cm) to prevent rice straw from accumulating in the sowing layer.

4. Application of base fertilizer. For weak-gluten wheat, generally apply 12-14 kg of pure nitrogen (N) per mu, with the ratio of base fertilizer : balanced fertilizer (applied at the 3-4 leaf stage of the main stem) : jointing fertilizer (applied at the inverted 3rd leaf) being 7:1:2. For medium-gluten wheat, generally apply 14-16 kg of pure nitrogen (N) per mu. In large-scale production, the ratio of base fertilizer : tillering fertilizer (or balanced fertilizer) : jointing fertilizer is 5:1:4. For high-yield fields, the ratio of base fertilizer : tillering fertilizer (or balanced fertilizer, applied at the 3-4 leaf stage of the main stem) : jointing fertilizer (applied at the inverted 3rd leaf) : booting fertilizer (applied when half of the flag leaf has emerged) is 5:1:2:2. According to the basic soil fertility level, the nitrogen, phosphorus and potassium ratio for medium-gluten and weak-gluten wheat is 1:(0.4-0.6):(0.4-0.6), and phosphorus and potassium are preferably applied as base fertilizer : jointing fertilizer at 5:5. Generally, base fertilizer can use 5-10 kg of urea (containing N 46%) and 15-25 kg of 45% compound fertilizer (N, P2O5 and K2O contents all 15%).

5. Suitable sowing period. To ensure that wheat seedlings form age-appropriate strong seedlings at the beginning of overwintering (main stem 5-6 leaves, 2-3 tillers per plant, 3-5 secondary roots), 500-550°C of accumulated temperature above 0°C is needed from sowing to the beginning of overwintering. The suitable sowing period in this region is from late October to early November.

6. Reasonable seeding rate. For wheat fields sown at the suitable time in this region, the basic seedling number per mu is 120,000-160,000. For those later than the suitable sowing period, appropriately increase the seeding rate, increasing the basic seedling number by 5,000 for each day of delayed sowing, not exceeding 80% of the expected spike number at most.

7. Fine sowing. For wheat fields with earlier rice harvest, timely field clearing, suitable moisture (soil water content below 80% of field capacity) and good soil workability, a 2BG-6A type and other reduced-tillage (no-tillage) drill can be used to complete shallow rotary tillage, furrow opening, sowing, soil covering and compaction in one operation. Sowing depth is 2-3 cm, row spacing 25 cm, drive at medium speed to ensure uniform seed distribution, ensure that the joints between the two passes match, avoid double sowing or widening row spacing, and avoid stopping in the field to form seed piles. Leave empty strips at both ends of the field first to facilitate turning of the machine body, and finally reseed the empty strips at both ends. For dead corners that the machine cannot reach, manually reseed or transplant dense seedlings to fill sparse areas after emergence. When soil water content is above 80% of field capacity, a newly improved band drill should be used for sowing to prevent blockage of seed outlets and missing seedlings or broken rows.

8. Post-sowing compaction. Seeders with compacting devices should compact while sowing. Seeders without compacting devices should be compacted with a roller after sowing to ensure compaction quality.

9. Mechanical ditching. Carry out mechanical ditching in time after sowing. Dig a vertical ditch every 2.5-3 m, with a ditch width of 20 cm and a depth of 25-30 cm. Dig a horizontal ditch 2-3 m from the horizontal ridge at both ends of the field. For longer fields, add a waist ditch every 50 m, with a ditch width of 20 cm and a depth of 35-40 cm. The outlet ditch at the field head should be 25 cm wide and 40-50 cm deep. Ensure that the internal and external three ditches are connected, and pay attention to evenly spreading ditch soil to cover wheat rows, reduce exposed seeds, and prevent freezing and protect seedlings.