| Corn is an important food crop in China,and its yield directly affects national food security.Phosphorus plays an important role in agricultural production and environmental safety.A large amount of phosphorus is needed in corn production,and sufficient phosphorus can promote growth,maturity and increase yield.Phosphate fertilizer is mostly used as base fertilizer,but because of its weak mobility in the soil,it is easy to be adsorbed and fixed by the soil,which leads to low availability,affecting the utilization rate of phosphate fertilizer in the season,and then affecting the yield.It is of great significance for agriculture and maize production to reduce soil phosphorus fixation,improve soil phosphorus environment and increase the utilization rate of phosphorus fertilizer.The experiment was carried out by continuous positioning and continuous cropping of maize from 2016 to 2020.In this experiment,300kg/hm~2(PH),150kg/hm~2(PC)and no phosphate fertilizer(PN)were applied for 5 consecutive years.In 2016 and 2017,high phosphorus fertilizer was applied,and in 2018,2019 and 2020,no phosphorus fertilizer(PH-N)was applied.In 2016and 2017,P fertilizer was applied,and in 2018,2019 and 2020,P fertilizer(PC-N)was not applied.In 2016 and 2017,no phosphate fertilizer was applied,and in 2018,2019 and 2020,PN-C fertilizer was applied.In 2016 and 2017,no phosphate fertilizer was applied,and in 2018,2019 and 2020,high amount phosphate fertilizer(PN-H)was applied,with a total of 7 treatments.The effects of phosphorus application rate on plant phosphorus content,soil phosphatase activity,soil available phosphorus content,phosphorus utilization and yield of maize were systematically studied.The test results show that:(1)The yield of maize under high phosphorus(PH)and constant phosphorus(PC)treatments was 9.04%and 13.07%higher than that under no phosphorus(PN)treatments,respectively.When the amount of phosphorus application was changed from the third year,the average yield of each treatment in 2018-2020 was as follows:no phosphorus application changed to high phosphorus level(PN-H)>no phosphorus application changed to constant phosphorus level(PN-C)>constant changed to no phosphorus application(PC-N)>high phosphorus level changed to no phosphorus application(PH-N).In addition,the yield of the treatment without P application to high P was2.84%,3.41%and 6.14%higher than that of the treatment without P application to constant P level,constant P to no P level and high P to no P level,respectively.(2)The phosphorus content of each part of the maize plant was in the order of seeds>stalks>roots>ears.Phosphorus application could increase the phosphorus content in maize plants at harvest stage,but it did not change the phosphorus content in different parts,and too high phosphorus application was not conducive to the increase of phosphorus content in maize plants.(3)The activity of soil acid phosphatase was similar to that of soil neutral phosphatase,and was much higher than that of soil alkaline phosphatase.The activities of soil acid phosphatase and neutral phosphatase reached the highest when the application rate of 150kg/hm~2(PC)was 9.19%、4.05%、7.90%and 3.70%higher than those in the treatment of high phosphorus and no phosphorus application,respectively.The more phosphate fertilizer was applied,the less alkaline phosphatase activity was.(4)The contents of soil total phosphorus and soil available phosphorus were directly proportional to the amount and years of phosphorus application.Soil total P content under high P and constant P treatments was 23.30%and 19.43%higher than that under no P treatments,and soil available P was 79.18%and 64.68%higher than that under no P treatments,respectively.After changing the amount of P application,the soil total P content in the treatment from no P application to high P application level was the highest,and the soil available P content in the treatment from high P application to no P application level was the lowest,with a difference of25.85%from the highest to the lowest,and the soil available P content showed the same performance,the content of available P in the soil changed from high P level to high P level without P application,which changed to 68.02%.(5)The agronomic efficiency,physiological utilization efficiency,partial productivity and use efficiency of phosphorus fertilizer under 5 consecutive years of constant P treatment were141.34%,47.08%,107.39%and 113.70%higher,respectively.After changing the amount of P application,the physiological utilization rate,partial productivity and use efficiency of P fertilizer without P application to normal P level were 87.42%,94.45%and 107.11%higher than those of the treatment without P application to high P level.The agronomic efficiency of P fertilizer without P application to high P level was 42.93%higher than that without P application to normal P level. |
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