| Phosphorus is one of the necessary nutrients for tobacco and plays an important role in the normal growth of tobacco.Phosphorus fertilizer is often used in tobacco production to provide phosphorus nutrients,while the transformation process of phosphorus fertilizer in soil is complex and affects the availability of phosphorus.At present,the transformation of different phosphorus fertilizers in tobacco-planting soil and its effect on tobacco growth are not clear.In this study,tobacco varieties‘Yunyan87’and tobacco-planting soils in northern Guangdong were used as experimental materials to study the effects of different phosphate fertilizers（Calcium superphosphate,Calcium magnesium phosphate,Ammonium polyphosphate,Monoammonium phosphate,and Diammonium phosphate）on changes of phosphorus forms in soil,tobacco growth and phosphorus uptake and accumulation through pot experiments.The main research results were as follows:1.The results of soil cultivation test show that:within 90 days,with the extension of soil culture time,the available phosphorus content of each phosphorus application treatment increased gradually,and the effects on the changes of soil inorganic phosphorus components were different.Among them,for Ca2-P with the highest activity,the Calcium superphosphate treatment showed a gradual increase trend within 90 days,while the other treatments showed a gradual decrease trend within 30 days,and then stabilized;For Ca8-P,all treatments increased within 90 days except for Ammonium polyphosphate treatment;As for Ca10-P with low activity,each phosphate fertilizer treatment showed a trend of increasing gradually and the decreasing in the first 30 days,and the content of Ca10-P in Calcium magnesium phosphate treatment was higher than that in other treatments at different times;For Al-P and Fe-P,each treatment showed a trend of increasing first and then decreasing;The content of Fe-P in different forms of inorganic phosphorus components in soil treated with different phosphate fertilizers was higher than that of other components.2.The path analysis of the effect of inorganic phosphorus forms on available phosphorus showed that the main decisive variables of the change of available phosphorus were different in different types of phosphorus fertilizer treatments.The decision coefficient of Ca2-P was the highest in Monoammonium phosphate treatment,which was the main decisive variable for the change of available phosphorus.Fe-P was used in Calcium superphosphate treatment and Diammonium phosphate treatment,O-P was used in calcium magnesium phosphate fertilizer treatment,and Ca10-P and O-P were used in ammonium polyphosphate treatment.3.Under the condition of tobacco planting,the soil available phosphorus content of Calcium magnesium phosphate and Diammonium phosphate treatment was significantly higher than that of other treatments,which were 42.46%and 25.18%higher than Calcium superphosphate,respectively.The phosphorus activation coefficient of Calcium magnesium phosphate treatment was the largest,which was 51.84%higher than that of Calcium superphosphate treatment.The results of path analysis of the effects of different phosphorus forms on available phosphorus showed that the decision coefficients of Resin-P and Ca2-P were the highest,and they were the main decisive variables of soil available phosphorus in Hedley and inorganic phosphorus graded phosphorus components,respectively.4.The results of pot experiment showed that the fresh weight of leaves in diammonium phosphate treatment was the largest,which was 24.28%higher than that in monoammonium phosphate treatment,and there was no significant difference among the other phosphate fertilizer treatments;The phosphorus accumulation of calcium magnesium phosphate and diammonium phosphate was significantly higher than that of other treatments.Path analysis of the effects of different phosphorus component on phosphorus accumulation in tobacco shoot showed that Resin-P and Ca8-P were the main decisive variables for phosphorus accumulation in shoot.5.The results showed that the fresh leaf weight of Calcium superphosphate and Diammonium phosphate treatments increased by 43.4%and 11.62%respectively with 0.5‰soil humic acid compared with the control;while the fresh weight of leaves increased by45.61%and 13.79%respectively when Calcium superphosphate and Diammonium phosphate were combined with 0.5‰soil biochar.In conclusion,the application of different phosphate fertilizers increased the content of available phosphorus in soil,and the application of Calcium magnesium phosphate and Diammonium phosphate treatment was relatively higher.The yield of tobacco leaf under Diammonium phosphate treatment was the largest.Combined application of biochar and humic acid could improve the availability of phosphorus of Calcium superphosphate and Diammonium phosphate in soil,which was conducive to promoting the growth of tobacco and improving the absorption and utilization of phosphorus by tobacco. |
