Selection And Evaluation Of The Formula Of Pesticide-fertilizer Mixture For Spring Rapeseed In Qinghai Province

As one of the main economic crops in Qinghai Province,spring rapeseed has an important position in the local agricultural production.At present,the phenomenon of excessive application of fertilizers and pesticides by farmers is serious,which could result in lower fertilizer use efficiency and a series of environmental problems such as pesticide residues.Pesticides-fertilizer mixtures are prepared by thoroughly mixing fertilizers and pesticides according to a given ratio.Pesticide-fertilizer mixture provides comprehensive nutrients,and pesticides and fertilizers can work together to increase efficiency,save labor and so on.In this study,a spring rapeseed variety Qingza No.6 was used,and a field experiment was conducted in the Huzhu Tuzu Autonomous County of Qinghai Province.Seven treatments were set up in the trial,non-pesticide application treatment,conventional treatment,two treatments of biological pesticides-fertilizer mixture(Bacillus thuringiensis treatment and Beauveria bassiana treatment)and three chemical pesticide-fertilizer mixture treatments(thiamethoxam treatment,chlorpyrifos treatment,and carbosulfan treatment).The incidence of pests in spring rapeseed was investigated,and biomass,nitrogen,phosphorus and potassium nutrient uptake,yield,yield components,agronomic traits and pesticide residues at the seedling,flowering and harvesting stages were analyzed.The main results are as follows:1)At 21 days after sowing,the incidence of pests of carbosulfan treatment was not significantly different from that in non-pesticide application treatment and thiamethoxam treatment,but was significantly lower than that in other treatments.Compared with the conventional treatment,the incidence of pests of carbosulfan treatment was reduced by44.9%.At 38 days and 57 days after sowing,there was no significant difference in the incidence of pests of the three chemical pesticide-fertilizer mixture treatments.The two biological pesticides fertilizer mixture treatments had little effect on pest control.2)The yield of thiamethoxam treatment(Pesticide-fertilizer mixture were applied twice)was not significantly different from the conventional treatment(Conventional pesticides were applied three times).Compared with the non-pesticide application treatment,yield in the thiamethoxam treatment increased by 20.2%.3)Compared with the conventional treatment,the accumulation of potassium at the seedling stage and the accumulation of nitrogen and potassium at the harvesting stage in the thiamethoxam treatment increased by 86.9%,35.4%,and 34%,respectively.Biomass and nutrient accumulation in the thiamethoxam treatment were significantly higher than the non-pesticide application treatment at either seedling or harvesting stages.At the flowering stage,biomass in the carbosulfan treatment was significantly higher than that in the non-pesticide application treatment.Biomass,nitrogen and potassium content in the Beauveria bassiana treatment were higher than that in the non-pesticide application treatment at the flowering stage.Nutrients accumulation in stem and silique walls in the Beauveria bassiana treatment was also higher than that in the non-pesticide application treatment at the harvesting stage.Biomass or nutrients accumulation in the chlorpyrifos treatment were significantly higher than that in the non-pesticide application treatment at either flowering or harvesting stages.4)The residue of thiamethoxam in spring rapeseed was too low to be detected,and the residue in the soil is also low enough.In the five pesticides-fertilizer mixtures,the thiamethoxam pesticide-fertilizer mixture not only reduced the damage caused by pests of spring rapeseed at the seedling stage,but also improved the growth of rapeseed as well as increased rapeseed yield.The application of the thiamethoxam pesticide-fertilizer mixture can reduce the application of pesticide,and thus was safe for rapeseed production ecosystem.We concluded that the thiamethoxam pesticide-fertilizer mixture is worth to be widely used in spring rapeseed planting area in Qinghai.