Effect Of Reducing Fertilizer Application On Spring Rapeseed(Brassica Napus L.)in Qinghai

Rapeseed is the largest crop in Qinghai Province,but the fertilization in the eastern region of Qinghai Province is uneven and unreasonable.In spring rapeseed,the application rate of nitrogen fertilizer is too high,and the application rate of phosphate fertilizer is too high,and the input of potassium fertilizer and organic fertilizer is less.Aiming at the production problems of low fertilization technology,excessive use of chemical fertilizers,and low technological integration in spring rape areas in Qinghai Province.In this study,the late rape variety Qingza No.12 and the early maturity variety Qingza No.7 were used as research objects.Field experiments were conducted in irrigated agricultural areas and high-altitude dry farming areas to investigate the agronomic characteristics,yield and nutrient utilization efficiency of spring rape.Refining the efficient use of nitrogen and phosphorus nutrients with the goal of reducing fertilizers,and integrating the establishment of fertilizer efficiency and reduction and special fertilizer replacement technology models based on the standard of fertilizer limit,which is important for achieving the target of fertilizer reduction at the target level of spring rapeseed significance.The test results are as follows:1.Techniques for reducing fertilizer application and increasing efficiency of late-ripening rapeseed in irrigated agricultural areas1.1 Nitrogen,Phosphorus,and Potassium Fertilizer Efficiency Test:(1)Combined application of nitrogen,phosphorus,and potassium fertilizers significantly increased spring rapeseed yield,with an increase of 29% to 153%,an average increase of 107%,and an average increase of 1365kg/hm2,of which the NPK treatment yield was the highest up to 3230kg/hm2.(2)The effects of nitrogen,phosphorus,and potassium fertilizer on rapeseed production were specifically expressed as nitrogen fertilizer> phosphorus fertilizer> potassium fertilizer,indicating that nitrogen is the main nutrient factor affecting rapeseed yield.(3)In the same yield range,in this experiment,the amount of nitrogen fertilizer was reduced by 25%,the amount of phosphate fertilizer was reduced by 55.8%;the agronomic efficiency and partial productivity of fertilizers were improved.1.2 Nitrogen gradient test:(1)Increased application of nitrogen fertilizer can promote the growth and development of spring rape,increase grain yield and nutrient accumulation.(2)The grain yield of the late-maturing varieties in this test can reach 3230kg/hm2 when the nitrogen application rate is 150kg/hm2.Therefore,it is necessary to pay attention to the rational application of nitrogenous fertilizer in the promotion of spring rapeseed production in Chuanshui agro-ecological zone,so as to achieve the purpose of reducing fertilizer application and increasing efficiency.1.3 Water-fertilizer integration test:(1)The growth traits index values were all treated with a chemical fertilizer reduction of 12.5% T1,which indicates that the application of water-soluble fertilizer in the later stage of spring rape growth can promote the growth of spring rape.(2)The yield of late-maturing varieties under the condition of water and fertilizer integration in spring rape is 2846?4204kg/hm2.With a 25% reduction in chemical fertilizers,the yield reached 3823kg/hm2,which is equivalent to the output of conventional planting rapeseed,and the input cost of chemical fertilizers was reduced by 37%.2.Techniques for reducing fertilizer application and increasing efficiency of early maturing rapeseed rape in high-altitude dry farming areas2.1 Fertilizer effect test of spring rape special fertilizer based on different fertility levels:(1)Slow release special fertilizer can increase spring rape yield and nutrient accumulation,indicating that rape special slow release fertilizer has the characteristics of long-lasting fertilizer effect.(2)30kg of special fertilizer per acre is the best recommended amount.Compared with conventional fertilizing FP,the yield is increased by 32kg/hm2,the amount of fertilizer is reduced by 6.5%,the input cost is reduced by 33%,and the economic benefit is increased by 1.5%.2.2 Organic fertilizer replacement test:(1)Under the treatment of 40% organic fertilizer instead of chemical fertilizer,the early agronomic traits of rapeseed were at a high level,and the grain yield was the highest,reaching 4024kg/hm2.(2)Compared with conventional fertilizing FP,40% organic fertilizer replacement yields 17% increase,that is,it can be used as the recommended amount of organic fertilizer replacement chemical fertilizer for early-ripening cabbage spring rape in high-altitude dry farming areas.