Technical Guidance on Wheat Autumn and Winter Planting (2015-2016 Season)
Since July this year, the main wheat-producing areas have received relatively abundant rainfall, and the subsoil moisture is generally sufficient. The previous crops have grown and developed normally, and timely sowing is guaranteed in most areas. However, some areas in the northwest have received less rainfall, and the surface soil moisture is insufficient. At the same time, the meteorological department predicts that, under the influence of El Niño, precipitation in the northern winter wheat region during autumn and winter will be lower than normal, and temperatures will generally be higher than normal. Some areas may experience continuous autumn-winter drought, which is unfavorable for the sowing, emergence, and safe overwintering of winter wheat. In order to effectively improve the sowing quality of winter wheat, cultivate strong seedlings before winter, and consolidate the foundation for next year's summer grain harvest, the 2015-2016 technical guidance on wheat autumn and winter planting 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. It 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. Wheat is 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 shortages, frequent natural disasters such as drought, freezing damage, and dry hot winds, and relatively severe damage from stripe rust, sharp eyespot, powdery mildew, and Fusarium head blight. The key aspects of autumn sowing and pre-winter management for wheat in this region include the following:
(1) Pre-sowing preparation
1. Variety selection. Suitable varieties should be selected according to local climate, soil, soil fertility, cropping system, yield level, and diseases and insect pests. First, select varieties according to weather. Choose winter or semi-winter varieties according to temperature conditions. Cross-regional planting and the use of unapproved varieties are strictly prohibited. In the northern winter wheat region, winter varieties must be strictly used; in the Huang-Huai winter wheat region, winter and semi-winter varieties should be used. Second, select varieties according to soil. For high-yield fields with good water and fertilizer conditions, choose fertilizer-tolerant and lodging-resistant varieties with high yield potential. For water-deficient areas, choose drought-tolerant, water-saving, and stable-yield varieties. For dry and poor soils, choose drought-tolerant and barren-tolerant varieties. For dry fertile land with thicker soil layers and higher fertility, choose drought-tolerant 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, and also requires shorter plants, compact plant type, and strong edge-row advantage to fully utilize light energy and improve photosynthetic efficiency. Fourth, select varieties according to disaster risk. Areas with severe dry hot winds should choose 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 winds. Fifth, select varieties according to disease. Areas with severe rust infection should choose rust-resistant (tolerant) varieties. Areas with relatively high precipitation and severe waterlogging should choose varieties that are moisture-tolerant, resistant (tolerant) to Fusarium head blight, and have a long seed dormancy period. Sixth, select varieties according to quality. Choose high-quality varieties with good nutritional quality, processing quality that meets the requirements of finished products, full grains, and high test weight. Seventh, strictly manage variety introduction and replacement. Replace new varieties according to changes in production conditions and yield improvement, and prevent large-scale introduction, seed transfer, and frequent replacement of improved varieties without testing. While planting main promoted varieties, actively introduce new varieties for testing and demonstration, do a good job in seed reproduction, 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 underground pest damage at the seedling stage. This can delay the onset time of diseases such as wheat stripe rust, powdery mildew, and sharp eyespot. Reasonably select chemicals according to the disease resistance of wheat varieties in each locality, disease incidence, climatic conditions, and cultivation methods. Strictly control the amount of seed-dressing chemicals, and prohibit excessive use. Sow immediately after seed dressing, use while freshly mixed, 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 it should be evenly spread on the soil surface. Plow the crushed straw into the ground. If subsoiling technology 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 compact the soil. If moisture is suitable, harrow and press in time.
4. Deep plowing (subsoiling) and harrowing-pressing. Deep plow 23-25 cm and then harrow and press, or subsoil 30-35 cm and then rotary till and harrow-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. With 1 year of deep plowing or subsoiling, rotary tillage and land preparation will be 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 rainwater absorption and moisture storage, combined with pre-sowing harrowing to conserve moisture.
5. Irrigation to create moisture. Adhere to sowing with sufficient moisture to ensure full seedling emergence in one sowing. When the relative water content of the 0-40 cm soil layer is below 75%, create moisture first and then sow. For wheat fields that cannot be irrigated in time to create moisture and are irrigated after sowing with a light surface watering, loosen the soil in time to prevent soil cracking, reduce soil moisture loss.
6. Application of base fertilizer. Soil testing and formula fertilization, combined application of nitrogen, phosphorus, and potassium fertilizers, and supplemental application of trace element fertilizers. High-yield fields adopt the technique of delaying nitrogen fertilizer, with 50% of nitrogen fertilizer applied as base fertilizer and 50% as topdressing, while all other fertilizers are applied as base fertilizer. According to production experience, the reference suitable fertilization rates for different fertility levels are as follows: 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 fertilizer; 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 fertilizer and 30% as topdressing at the green-up stage, and all phosphorus and potassium fertilizers applied as base fertilizer; 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 fertilizer and 40% as topdressing at the green-up or jointing stage, and all phosphorus and potassium fertilizers applied as base fertilizer; 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 fertilizer and 50% as topdressing at the jointing stage, and all phosphorus and potassium fertilizers applied as base fertilizer.
(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, diseases and insect pests, 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 number of basic seedlings are the starting point for establishing a high-quality population, and are also important measures for constructing a reasonable population structure, coordinating the relationship between population and individuals, and between wheat growth and development and environmental conditions. Principles to grasp: First, variety characteristics. For varieties with strong tillering ability and high ear-bearing rate, appropriately reduce the seeding rate. Second, sowing time. For early sowing, appropriately reduce the seeding rate; for late sowing, appropriately increase the seeding rate. Third, soil fertility level. For soils with better water and fertilizer conditions, basic seedlings should be sparser and the seeding rate should be lower. Generally, the number of basic seedlings 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 delayed sowing, increase basic seedlings by about 10,000, but it should not exceed 350,000 at most.
9. Fine sowing. Use wheat seeders that meet requirements and are of qualified quality, and determine the suitable row spacing according to local actual conditions, ensuring consistent row spacing, accurate seeding rate, and consistent depth. The sowing depth is 3-5 cm, with no missed sowing or repeated sowing.
10. Post-sowing compaction. Seeders equipped with compacting devices should compact while sowing. Seeders without compacting devices should be compacted with a compactor 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 wheat fields with straw return, rotary tillage sowing, and loose, unsettled soil, irrigate overwintering water in time 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. Advocate water-saving irrigation, prohibit flood irrigation, and loosen the soil in time after irrigation to preserve moisture, prevent surface cracking, and avoid air leakage that damages roots and kills seedlings. For wheat fields with suitable soil moisture, high land preparation quality, sufficient base fertilizer, normal growth, and suitable population, overwintering irrigation may be omitted before winter. For wheat fields without irrigation conditions, loosen the soil in time after each rainfall to preserve moisture.
12. Chemical weed control. In recent years, malignant grass weeds have gradually increased and have a great impact on wheat yield. It is necessary to focus on treating spring weeds in autumn and do a good job in autumn chemical weed control, 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 grass weeds such as wild oat, jointed goatgrass, shortawn foxtail, and ryegrass, use 40-60 ml of 6.9% fenoxaprop-P-ethyl emulsifiable concentrate per mu plus 30 kg of water for foliar spraying. To control jointed goatgrass and brome, 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, and spray evenly. 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, dilute with 10 times water, mix with 40-50 kg of fine soil, and apply into the soil while 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% avermectin 3000-4000 times solution, which also controls wheat aphids and red spiders. To control wheat sharp eyespot, use 20-30 g of 12.5% diniconazole wettable powder per mu, or 100 g of 15% triadimefon wettable powder, dilute with 50 kg of water and spray evenly. For fields with severe occurrence of wheat cyst nematode, use 3.7 kg of 5% Xiandi granules per mu, broadcast along the rows at the seedling stage, and irrigate in time to improve control efficacy.
14. Strictly prohibit grazing on green seedlings. 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 Yangtze Winter Wheat Region
This region includes the area south of the Huai River in Jiangsu and Anhui provinces, Hubei, and Xinyang City in Henan. It is one of the major winter wheat-producing regions in China. This region has a humid climate and good heat conditions, with 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. Wheat is sown from late October to mid-November and harvested from late May to early June. The main factors affecting wheat production are waterlogging and high-temperature forced ripening, occasional pre-harvest sprouting, and relatively severe damage from Fusarium head blight, powdery mildew, sharp eyespot, and stripe rust. The key aspects of autumn sowing and pre-winter management for wheat in this region include the following:
(1) Pre-sowing preparation
1. Variety selection. Choose varieties with high yield, good quality, and strong resistance to moisture, lodging, and disease (mainly Fusarium head blight, powdery mildew, and sharp eyespot). In the southern part of the middle and lower Yangtze wheat region, spring varieties should be used; in the northern part, semi-winter varieties should be used.
2. Seed treatment. Use 2% tebuconazole suspension concentrate, 15-20 g of chemical per 10 kg of seed, add 0.5 kg of water for seed dressing, which can also control soil-borne and seed-borne diseases such as sharp eyespot and take-all. For wheat sown early in the suitable period, paclobutrazol and other chemical control agents can be used for seed dressing or seed soaking, which can dwarf plants, increase tillering, control excessive growth, and promote 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, mix evenly to prevent excessive local chemical concentration from affecting wheat seedling growth.
3. Straw return. For rice, control the final 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 excessive “nursing of old rice.” When harvesting rice, keep stubble height below 10 cm, chop rice straw to about 5 cm, and spread evenly. For full straw return, first perform deep rotary tillage (or deep plowing) to eliminate stubble before mechanical drilling. The depth of rotary tillage for burying straw should be at least 12 cm or more (preferably reaching 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 3rd leaf from the top) 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 3rd leaf from the top) : 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 46% N) and 15-25 kg of 45% compound fertilizer (with N, P2O5, and K2O contents all at 15%).
(2) Sowing
5. Suitable sowing period. In order 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, and 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 late October to early November.
6. Reasonable seeding rate. For wheat fields sown at the suitable time in this region, the number of basic seedlings per mu is 120,000-160,000. For fields sown later than the suitable sowing period, appropriately increase the seeding rate, increasing basic seedlings by 5,000 for each day of delayed sowing, and not exceeding 80% of the expected number of ears at most.
7. Fine sowing. For wheat fields where rice is harvested earlier, stubble is cleared in time, moisture is suitable (soil water content below 80% of field capacity), and soil tillage condition is good, a 2BG-6A type and other reduced-tillage (no-tillage) drill can be used to complete shallow rotary tillage, trenching, sowing, soil covering, and compaction in one operation. The sowing depth is 2-3 cm, row spacing is 25 cm, and the machine should be driven at medium speed to ensure uniform seed distribution. The joints between the two passes should match to avoid repeated sowing or widened row spacing, and avoid stopping in the field to form seed piles. Leave empty widths at both ends of the field first to facilitate turning of the machine body, then replant the empty widths at both ends last. For dead corners and other places that the machine cannot reach, manually replant or thin and fill gaps after emergence. When soil water content reaches more than 80% of field capacity, a newly improved band drill should be used for sowing to prevent blockage of the seed outlet and missing seedlings or broken rows.
8. Post-sowing compaction. Seeders equipped with compacting devices should compact while sowing. Seeders without compacting devices should be compacted with a compactor after sowing to ensure compaction quality.
9. Mechanical ditching. Mechanically ditch in time after sowing. Dig one vertical ditch every 2.5-3 m, with a ditch width of 20 cm and a depth of 25-30 cm. Dig one horizontal ditch 2-3 m from the horizontal ridges at both ends of the field. For longer fields, add one 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. Note to evenly spread ditch soil to cover wheat rows, reduce exposed seeds, and prevent freezing and protect seedlings.
(3) Pre-winter management
10. Early supplementary seedling fertilizer. For fields with relatively few basic seedlings and insufficient base fertilizer application, apply seedling fertilizer in time at the 2-leaf stage. For wheat fields where the total number of leaves on the main stem is 11 or fewer, if both base seed fertilizer and seedling fertilizer are insufficient, apply tillering fertilizer at the 3-4 leaf stage of the main stem. Before winter and during overwintering, apply mud and miscellaneous ash fertilizers to earth up around the roots, keep warm and prevent freezing, and enrich the soil. For wheat fields with a large amount of straw return, if wheat seedlings are severely yellowing, apply quick-acting compound fertilizer or nitrogen fertilizer as soon as possible to transform the seedling condition.
11. Timely chemical weed control. Chemicals should be used at the appropriate time according to weed species, weed age, and moisture conditions, with emphasis on pre-winter chemical weed control. Before overwintering, when the daily average temperature is above 5°C, take advantage of sunny days to apply chemicals, ensuring that no frost or low temperature below 0°C is encountered within 7 days after application, so as to improve the effect of chemical weed control and avoid phytotoxicity. For monocotyledonous weeds in wheat fields, chemicals such as fenoxaprop-P-ethyl or pinoxaden can be selected; for dicotyledonous weeds, fluroxypyr can be selected; for wheat fields with mixed monocotyledonous and dicotyledonous weeds, relevant chemicals can be compounded for use.
12. Prevent waterlogging and resist drought. Clear ditches and manage moisture in time, dredge drainage and irrigation systems, and prevent waterlogging damage. If moisture is unsuitable after sowing, irrigate for full seedling emergence to promote timely emergence. Note that flood irrigation should not be used, to prevent bud rot and stifled buds. If drought occurs before overwintering, irrigate overwintering water in time. Winter irrigation should be flexibly controlled according to climatic conditions and soil moisture status. Irrigate in winter when base moisture is insufficient or autumn-winter drought occurs, and when the water content of the cultivated layer is below 60% of field capacity. Note that lean land and weak seedlings should be irrigated early, while fertile land and vigorous seedlings should be irrigated later. Winter irrigation is generally carried out when the daily average temperature is 3-4°C. If irrigation is too early, with high temperatures and large surface evaporation, the moisture storage and insulation effects of winter irrigation are reduced, and wheat seedlings are prone to excessive growth and freezing damage. If winter irrigation is too late, the soil freezes, infiltration is difficult, the surface freezes, and seedlings are prone to death. Winter irrigation should preferably adopt methods such as furrow irrigation and seepage irrigation, ensuring no water accumulation in the field to avoid soil compaction. Flood irrigation is strictly prohibited to avoid scouring the topsoil.
13. Control excessive growth and promote strong growth. For wheat fields sown too early, with too large a population and excessive growth, intertillage or compaction can be adopted, and growth inhibitors can also be sprayed to control excessive growth and promote strong growth, ensuring safe overwintering of seedlings.