When is winter rapeseed sown for the 2018-2019 season and how much is sown per mu?
The national autumn and winter rapeseed planting is about to begin. Based on this year's climate characteristics and actual production conditions, the Oil Crops Expert Steering Group of the Ministry of Agriculture and Rural Affairs, together with the National Agricultural Technology Extension Service Center, has studied and put forward the 2018-2019 Technical Guidance Opinions on Winter Rapeseed Production.
I. Which rapeseed varieties are good to plant in winter?
(1) Adapt to local conditions and select high-yield, high-quality, highly resistant varieties. According to the climate, soil and other natural conditions of different regions, as well as the cropping system and the patterns of disease and pest occurrence, select locally dominant rapeseed varieties with high yield, good quality, disease resistance, lodging resistance and high oil content, adapting to local conditions. For direct-seeded rapeseed in paddy fields, pay attention to selecting rapeseed varieties that are tolerant of waterlogging and suitable for dense planting; in areas with a rice-rice-rapeseed triple cropping system, varieties with a short growth period and early or very early maturity should also be considered; for direct-seeded rapeseed on dry land, select medium (late) maturing varieties with tolerance to dense planting, lodging resistance and good yielding ability.
(2) Seed dressing before sowing to improve sowing quality and efficiency. Drought or excessive rain during the autumn sowing season in the Yangtze River Basin can affect rapeseed emergence. To ensure the quality of sowing and emergence, seeds can be sun-dried for 2-3 days before sowing, which can both kill pathogens on the seed surface and improve seed germination vigor and germination rate. Seed coating or chemical seed dressing is advocated; pay attention to strictly controlling the amount of dressing agent used, use it immediately after mixing or spread the seeds out in the sun immediately after dressing, and appropriately increase the seeding rate after dressing.
(3) Supporting machinery and strengthening the integration of agricultural machinery and agronomy. According to agronomic measures, tillage patterns, operation techniques and machinery selection and matching, and in combination with related operation links and the matching of preceding and following crops, reasonably select green, high-quality and high-efficiency rapeseed production technologies such as suitable soil moisture management, high-density planting, one-time fertilization with slow and controlled release full nutrition, combined mechanical sowing and drone aerial spraying for prevention and control. At the sowing stage, the use of combined seeders is advocated to complete ditching, stubble removal, soil loosening, fertilization, sowing and weed control in one pass, improving sowing efficiency. At the field management stage, mechanical or drone chemical spraying should be used on contiguous rapeseed plots to improve control efficiency. At the harvest stage, mechanical combine harvesting should be carried out as much as possible to reduce harvest costs.
II. How to plant winter rapeseed for high yield? What is the sowing rate per mu?
(1) Sow while there is still soil moisture to ensure full stands and strong seedlings. To reduce the impact of autumn drought or autumn waterlogging, all regions should sow as early as possible while there is soil moisture to ensure full emergence in one sowing. For fields with excessive humidity or areas with frequent rainy weather, mechanical ridge-raising and direct seeding can be adopted. When direct-seeded rapeseed on dry land encounters drought, post-sowing compaction can be carried out to bring seeds into close contact with the soil and promote emergence. The suitable sowing period for direct-seeded rapeseed is generally from late September to early to mid-October, with a sowing rate of 200-300 grams per mu and a seedling stand of 20,000-30,000 plants per mu. For late-sown fields or fields with poor soil fertility, the sowing rate per mu can be increased to 300-400 grams, with a seedling stand of 30,000-40,000 plants per mu. In areas promoting rice straw return, attention should be paid to even straw return, and the sowing rate of direct-seeded rapeseed should be increased by 15%-20% compared with no straw return to ensure the basic seedling number. Rapeseed seedling raising and transplanting is generally carried out around mid to late October when soil moisture is suitable, with a transplanting density of 6,000-8,000 plants per mu; the transplanting period should not be too late, and late-transplanted rapeseed should appropriately increase transplanting density to compensate for the delay with density.
(2) Scientific fertilization to promote fertilizer reduction. Fertilize scientifically according to soil fertility and expected yield. It is recommended to use rapeseed-specific slow-release formula fertilizer to reduce the topdressing steps and improve fertilizer use efficiency, applying 40-50 kg per mu as base fertilizer; generally no topdressing is needed, and high yield requirements can basically be met. If traditional fertilization methods are adopted, generally apply 10-12 kg of pure nitrogen, 3-4 kg of phosphorus pentoxide, 3-5 kg of potassium oxide and 0.75 kg of borax per mu. Among these, 60% of the total nitrogen fertilizer and potassium fertilizer and all of the phosphorus fertilizer and boron fertilizer are applied as base fertilizer, 20%-30% of the nitrogen fertilizer is used for seedling promotion before winter, and 10%-20% of the nitrogen fertilizer and 40% of the potassium fertilizer are used as bolting fertilizer. During topdressing, the side-deep placement fertilizer technique can be used, that is, the fertilization position is 3-5 cm from the side of the seedling and the fertilization depth is 5-8 cm, improving fertilizer use efficiency.
(3) Prevent waterlogging and drain excess water to reduce diseases, pests and weeds. Rapeseed in paddy fields in the Yangtze River Basin is prone to waterlogging damage, which aggravates the occurrence of diseases and pests, so field management should be strengthened to reduce disease and pest damage. First, do a good job of “one promotion and four preventions”. The early flowering stage is the best period for controlling rapeseed sclerotinia and flower sterility; a mixed solution of appropriate chemicals, phosphate fertilizer and boron fertilizer can be sprayed on the leaves to both prevent and control diseases and promote rapeseed growth and development. Second, prevent autumn and winter pests. Promote seed coating technology to control seedling-stage diseases and pests. For rapeseed not treated with coating, use appropriate chemicals to focus on controlling pests such as aphids and cabbage caterpillars. At the same time, pay attention to timely weed control in direct-seeded rapeseed. Third, prevent freezing injury. Spray a plant growth regulator once before the Winter Solstice to enhance plant cold resistance. For fields with excessively vigorous seedlings before the Winter Solstice, appropriate chemicals should be used to control excessive growth, prevent early bolting and early flowering, and avoid damage from late spring cold. Fourth, strengthen integrated control of clubroot. Focus on areas where clubroot occurs; in addition to selecting disease-resistant varieties, transplanted rapeseed can use sterile seedbeds for seedling raising and delay transplanting by about 5 days, while direct-seeded rapeseed can be sown late at the appropriate time after October 10 after seed coating, which can greatly reduce the incidence rate.
III. What uses does rapeseed have?
Rapeseed has multiple uses such as for oil, vegetables, flowers, honey, green manure and feed. The multifunctional development and utilization of rapeseed should be strengthened to achieve “one crop, multiple uses”, improving planting benefits and farmers' income.
(1) Dual use for vegetables and oil. It is advisable to select high-quality, high-yield, early-maturing varieties that are easy to promote early growth and have strong regeneration ability, sow and transplant early, and plant at a reasonable density. Generally, apply 30-50 kg of rapeseed-specific compound fertilizer and 0.25-0.5 kg of borax per mu as base fertilizer; where conditions permit, a certain amount of organic fertilizer can also be added. The best harvesting period is when the bolt is 25-35 cm high; pick about 15 cm of the top of the main stem as a vegetable. Apply 3-5 kg of urea per mu 2-3 days before picking the bolt to promote branch growth. After picking the bolt, depending on the growth of the rapeseed, apply 3-5 kg of urea and 2 kg of potassium fertilizer per mu to promote recovery growth.
(2) Rapeseed as green manure. Using rapeseed as green manure can increase soil organic matter, promote the release of insoluble phosphorus in the soil, reduce the base number of diseases and pests, improve soil physical and chemical properties, and benefit the growth and development of the following crop. In double-cropping rice and ratoon rice production areas, select varieties with good disease resistance and relatively high stem and leaf yield, with a sowing rate of 0.5-1 kg per mu as appropriate. According to soil temperature and humidity and climatic conditions, promptly crush and turn the rapeseed into the field for return 10-15 days before sowing or planting the following crop, and no later than before the final flowering stage of rapeseed.
(3) Rapeseed as feed. It is advisable to select double-low feed rapeseed varieties with high protein content and high green fodder yield. According to feeding methods and processing requirements, harvest from the bud-bolting stage to the early stage of pod formation.
In addition, in areas rich in tourism resources, the multiple functions of rapeseed can be fully utilized to vigorously develop the comprehensive utilization of flowers and honey. On the one hand, develop sightseeing tourism and leisure agriculture by planting varieties with different flower colors, designing landscape patterns and extending the flowering period. On the other hand, by developing the beekeeping industry, develop a series of bee products such as honey, pollen, royal jelly and propolis, and deeply tap the income-increasing potential of rapeseed.