Study On Nutrients Requirement And Fertilizer Rate Reduction Effects On Spring Oilseed Rape

Spring rapeseed has a short growth period and a fast development process.It is a crop that requires a lot of fertilizer.Meeting the demand for nutrients of rapeseed is the basis for achieving high yield and quality of rapeseed.It has a long history of cultivation in Qinghai Province,which is a dominant production area for high oil content rapeseed in China However,excessive fertilization is common in the production of spring rapeseed in Qinghai.Excessive fertilization not only decreased the yield and quality of rapeseed,but also increased the cost of planting,reduced the utilization of fertilizer and caused serious environmental pollution.Therefore,it is important to reduce the amount of fertilizer for the efficient and high-quality production of Qinghai spring rapeseed.This study used the local promotion variety Qingza 6 and the three nitrogen-efficient varieties?Qingza 11,Qingza7and Qinyou 558?which were selected in our previous research as the experiment material,arranged a two-year field experiment to study the fertilizer requirement and the effect of nitrogen and phosphorus fertilizer reduction in spring rapeseed.The study obtained the following main results:?1?The bolting stages was the main stages of nitrogen uptake in 2017 and the mature stages was the main stages of nitrogen uptake in 2018.The difference in precipitation and its distribution may be the main reasons for changing the law of nitrogen accumulation in each growth period.The main absorption period of phosphorus were the bolting and mature stage while the main absorption period of potassium was the bolting stage.?2?There was a significant difference in fertilizer requirement of 100 kg grain among different varieties.For every 100 kg of grain produced by Qingza 6,the fertilizers requirement were N 6.61⁷.39 kg,P₂O₅ 1.70¹.80 kg,K₂O 4.37⁴.96 kg,and the rate among them was 1:?0.31⁰.41?:?0.84¹.15?.The fertilizers requirement of 100 kg grain for Qingza 7 were N 5.8⁷.8 kg,P₂O₅ 2.0².8 kg,K₂O 6⁷.5 kg,and the rate among them was1:?0.30⁰.32?:?0.93¹.05?.To get 100 kg seeds of Qingza 11 needed to absorb N 6.24⁶.34kg,P₂O₅ 1.63¹.83 kg,K₂O 3.65⁴.29 kg,and the rate among them was 1:?0.26⁰.29?:?0.59⁰.68?.The N?P₂O₅ and K₂O requirements of 100 kg grain for Qinyou 558 were6.43⁶.72 kg,1.78¹.84 kg,and 4.04⁴.47 kg,and the rate among them was 1:?0.27⁰.28?:?0.63⁰.67?.The nitrogen requirement of 100 kg grain for Qinyou 558 was significantly higher than those for Qingza 7 and Qingza 11,respectively while the phosphorus requirement of 100 kg grain for Qingza 11 was significantly lower than those for Qingza 7and Qinyou 558,and the potassium requirement of 100 kg of Qingza 7 was significantly higher than that for Qingza 11 and Qinyou 558.Fertilizer reduction treatment reduced the amount of fertilizer needed of 100 kg for rapeseed.?3?When the amount of phosphorus applied was 120 kg/ha,the amount of nitrogen can be reduced by 50%.Compared with the local recommended nitrogen application rate of 160kg/ha,the yield and oil yield of Qingza 6 was not decreased,and the soil mineral nitrogen residue was reduced during the harvest period.When the amount of nitrogen applied was160 kg/ha,the amount of phosphate can be reduced by 50%.Compared with the local recommended phosphorus application rate of 120 kg/ha,the yield and oil yield was not reduced and the phosphate use efficiency was not decreased.?4?When the application amount of phosphate fertilizer was 120 kg/ha,the nitrogen-efficient variety Qingza 11 with high nitrogen application has the highest yield when the nitrogen application rate was reduced from 160 kg/ha to 80 kg/ha;The nitrogen-efficient variety Qingza 7 under low nitrogen conditions has a tendency to increase production when the nitrogen application rate droped to zero.The yield of Qinyou 558,a nitrogen-efficient variety under high nitrogen and low nitrogen conditions,showed little change when the nitrogen application rate decreased from 160 kg/ha to 0.Nitrogen-efficient varieties under high nitrogen conditions have a small amount of nitrogen reduction,and nitrogen-efficient varieties with low nitrogen have the largest reduction of nitrogen fertilizer.Combining the average yield and oil yield of the three varieties,we recommend Qingza 7,a nitrogen-efficient variety under low nitrogen conditions,and Qinyou 558,a nitrogen-efficient variety under high nitrogen and low nitrogen,as the first choice for nitrogen fertilizer reduction in spring rapeseed.In summary,the accumulation of nutrients in spring rapeseed is affected by precipitation.There is a significant difference in fertilizer requirement for 100 kg of grain among different varieties.The reduction of chemical fertilizer reduces the amount of fertilizer required for 100 kg grain.The synergistic effect of nitrogen and phosphorus fertilizer is beneficial to the reduction of spring rapeseed fertilizer.Qingza 7 and Qinyou 558can be used as the choice for the reduction of nitrogen fertilizer in spring rapeseed.