How can winter rapeseed be planted across China to achieve high yields? The Ministry of Agriculture and Rural Affairs issues the 2018-2019 production technical guidance recommendations
The nationwide autumn and winter rapeseed planting is about to begin. Based on this year's climate characteristics and production realities, 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 winter rapeseed production technical guidance recommendations.
1. Integrated promotion of green, high-quality and high-efficiency technologies
(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, high quality, disease resistance, lodging resistance and high oil content according to local conditions. For direct-seeded rapeseed in paddy fields, pay attention to selecting rapeseed varieties that are tolerant to waterlogging and suitable for close planting; in areas with a rice-rice-rapeseed triple cropping system, consideration should also be given to varieties with a short growth period and early or very early maturity; for dryland direct-seeded rapeseed, select medium (late) maturing varieties that tolerate close planting, resist lodging and have good yield potential.
(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; attention should be paid to strictly controlling the amount of chemical used for seed dressing, using it immediately after mixing or spreading it out to dry immediately after dressing, and appropriately increasing the seeding rate after seed dressing.
(3) Support with machinery and strengthen the integration of agricultural machinery and agronomy. According to agronomic measures, tillage patterns, operation techniques, machinery selection and matching, and in combination with the relevant operation links and the matching of preceding and following crops, rationally select green, high-quality and high-efficiency rapeseed production technologies such as soil moisture suitability management, high-density planting, one-time fertilization with slow and controlled release full nutrition, combined mechanical sowing and drone aerial control. In the sowing link, the use of combined seeders is advocated to complete furrowing, stubble removal, soil loosening, fertilization, sowing and weeding in one pass, improving sowing efficiency. In the field management link, for contiguous rapeseed plots, machinery or drones should be used for chemical spraying to improve control efficiency. In the harvest link, mechanical combine harvesting should be carried out as much as possible to reduce harvest costs.
2. Comprehensive supporting field sowing and transplanting management measures
(1) Sow when there is sufficient soil moisture to ensure full stands and strong seedlings. To reduce the impact of autumn drought or autumn waterlogging, all localities should sow as early as possible while there is sufficient soil moisture to ensure a full stand in one sowing. For fields with excessive moisture or areas with frequent rainy weather, mechanical ridge-forming direct seeding can be adopted. For dryland direct-seeded rapeseed encountering 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 seeding rate of 200—300 grams per mu and 20,000—30,000 plants retained per mu. For late-sown fields or fields with poor soil fertility, the seeding rate per mu can be increased to 300—400 grams, with 30,000—40,000 plants retained per mu. In areas where rice straw return is promoted, attention should be paid to uniform straw return, and the seeding rate for direct-seeded rapeseed should be increased by 15%—20% compared with no return to ensure the basic seedling number. Rapeseed seedling 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, using density to compensate for lateness.
(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 link and improve fertilizer use efficiency, applying 40—50 kg per mu as base fertilizer, generally without the need for topdressing, which can basically meet high-yield requirements. 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 stem fertilizer. During topdressing, the fertilizer side-deep placement 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, to improve 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 preventing and controlling rapeseed sclerotinia and flower sterility; a mixed solution of suitable chemicals, phosphate fertilizer and boron fertilizer can be used for foliar spraying, which both prevents and controls diseases and promotes rapeseed growth and development. Second, prevent autumn and winter pests. Promote seed coating technology to prevent and control seedling-stage diseases and pests. For rapeseed not treated with coating, select suitable 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 damage. Spray a plant growth regulator once before the Winter Solstice to enhance plant cold resistance. For fields with overly vigorous seedlings before the Winter Solstice, suitable chemicals should be selected to control excessive growth, prevent early bolting and early flowering, and avoid damage from late spring cold. Fourth, strengthen comprehensive 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, after seed coating, should be sown late at the appropriate time after October 10, which can greatly reduce the incidence rate.
3. Actively expand the multiple functions of rapeseed
Rapeseed has multiple uses including for oil, vegetables, flowers, honey, fertilizer and feed. The multi-functional development and utilization of rapeseed should be strengthened to achieve “one rapeseed 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. When the stems are 25—35 cm high, this is the best harvesting period; pick about 15 cm of tender stems from the top of the main stem for use as a vegetable. Apply 3—5 kg of urea per mu 2—3 days before picking the stems to promote branch growth. After picking the stems, depending on the growth of the rapeseed, apply 3—5 kg of urea and 2 kg of potassium fertilizer per mu as topdressing 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-season rice and ratoon rice production areas, select varieties with good disease resistance and relatively high stem and leaf yield, with a seeding rate of 0.5—1 kg per mu as appropriate. According to soil temperature and moisture and climatic conditions, promptly crush and turn the rapeseed into the field 10—15 days before sowing or transplanting 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 and stem stage to the early pod formation stage.
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, through planting varieties with different flower colors, designing landscape patterns and extending the flowering period, develop sightseeing tourism and leisure agriculture. On the other hand, through 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.