农田土壤有效态中量微量元素的时空变化特征研究OACSTPCD

The contents and spatial distribution of available medium and trace elements in farmland soil were analyzed based on the monitoring points of Cultivated Land Fertility Evaluation in 2019.Combined with the grading standard and the critical value,the abundance and deficiency degree of available medium and trace elements in soil were revealed,and they were compared with the sampling data in 1983 and 2004.The results showed that available S was concentrated in the level of 20-30 mg/kg,available Si of＞300 mg/kg,available Cu of 4-6 mg/kg,available Zn of 2-3 mg/kg,available Fe of 100-150 mg/kg,available Mn of 30-40 mg/kg,available B of 0.75-1 mg/kg and available Mo of 0.1-0.15 mg/kg in farmland soil of Fengxian District.The average contents of these medium and trace elements was 20.04 mg/kg,390.92 mg/kg,4.31 mg/kg,2.42 mg/kg,131.08 mg/kg,34.74 mg/kg,0.95 mg/kg and 0.13 mg/kg,which was in the 3rd,1st,3rd,2nd,2nd,2nd,2nd and 3rd of the grading standard.Accorded to the coefficient of variation,they belonged to medium variation intensity with the largest value of available Fe.In the periods of 1983,2004 and 2019,the available medium and trace elements were increased or decreased in varying degrees,and the area of their critical value was decreased or non-existent except for available Mo.It was relatively stable and its area was increased rapidly(the area of its critical value=73.68％).During the past 15 years,the content of available S was decreased and available Si was increased,both of which in orchard were higher than other land use patterns.The content of available Cu,available Fe and available Mn were relatively rich and no field was below the critical value.But they were lower than vegetable field and paddy field.In spatial distribution,they were gradual decreased from west to east occur as strip distribution or patch distribution.The content of available Zn and available B were increased year by year,and they were generally high in vegetable field.The regional distribution showed that their trend was different.Available Zn was high in the middle and low in the east and west,but available B was opposite.At the same time,many trace elements had a high correlation in soil.There was positive correlation between available Cu,available Zn,available Fe and available Mn.They were also greatly affected by soil organic matter and pH,among which soil organic matter was the major factor on available Cu and pH was affected on available Mn.These results could provide a theoretical reference for soil nutrients management and reasonable combination of medium and trace fertilizers in different land use patterns and regional distribution.