Effect Of Compounds Migrating From Agricultural UPVC Pipes On Soil Enzyme Activity

Since the birth of plastic pipe,due to its excellent performance and low price,the use of pipes in many fields remains high.In recent years,with the widespread promotion of drip irrigation,sprinkler irrigation and other irrigation technologies in the agricultural sector,the use of UPVC-based plastic pipe has been further improved.However,the plastic pipe may has impact on the quality of irrigation water when used as a water supply pipe,directly or indirectly destroy the soil environment.Therefore,UPVC agricultural pipe was selected as a subject in the research,static test method was used to prepare irrigation water to soak the soil sample,and the effect of pipe compounds migration on soil enzyme activity under different soil and irrigation time was studied.The early growth condition of the crops in the soil after irrigation were explored;the relationship between pipe migration compounds and changes in soil enzyme activity was discussed,and its role in soil-crop system was discussed initially.the recommendations for the evaluation of soil environmental safety of irrigation pipes were put forward.The following results were obtained.(1)Soil enzyme activities of pipe compounds migration under different soil conditions: From the changes of catalase,urease and sucrase activities in the soils tested after 21 days of irrigation,soil enzyme activity affected by the type of soil is greater under the interference of agricultural UPVC pipe compounds migration.From the perspective of interference with the activity of soil catalase and sucrase,for different brands of tested UPVC pipes,soils with high organic matter content were not easily disturbed by the migration of pipe compounds.Activity was easily activated,and soil enzyme activity with low organic content was more easily suppressed.At the same time,the catalase,urease and sucrase were disturbed by the migration of pipe compounds,and their activity changes were different.Under any soil condition,there were the following rules: The catalase activity was activated when the Ca and Zn was large([Ca]=12.46 mg/L,[Zn]=0.108 mg/L),while the urease and sucrase activities were activated when Ca and Zn was smaller([Ca]=8.71 mg/L,[Zn]=0.093 mg/L).In addition,the study also found that after the changes in the type of soil,changes in sucrase is more obvious than catalase and urease,indicating that it can express more information in the evaluation of soil environment.(2)Soil enzyme activity of pipe compounds migration under different irrigation time: After prolonging irrigation time,it was found that the changes of catalase,urease and sucrase activity after 63 d irrigation were not the same as those at 21 days:Compared with 21 d irrigation,the activity of urease and sucrase still showed a trend of inhibition,and the degree of inhibition increased,the activity decreased from 0.161mg/(g.d)and 4.68 mg/(g.d)to 0.138 mg/(g.d)and 1.82mg/(g.d),respectively;but the activity of catalase showed a different trend with 21 d,the enzyme activity showed a trend of activation.Before irrigating for 21 days,both urease and sucrase showed the trend to be inhibited and activated,but catalase showed a tendency to be activated and inhibited.All three enzyme activities were inhibited at 21 d.However,from the effects of irrigation time on the changes of soil enzyme activities,the changing trend of three soil enzyme activities were different with the irrigation time prolonged.Moreover,there are some relationship between brand of the pipe and soil enzyme activity with the irrigation time.The activity of urease was not significantly different from the control group.The activities of catalase and sucrase were more obvious.The activity of sucrase can be used as a useful indicator in evaluating the impact of UPVC agricultural pipe compounds on soil environmental quality.(3)From the germination of crops treated with different soils,the germination of the tested soils in different soils differed greatly under the same time,although they were also affected by the migration of pipe compounds.The crop germination was less effected by soils with high organic matter content.For the test greenhouse soil,the germination of crops with different types were different with the prolongation of irrigation time,The ryegrass seeds germinated best in the 21 d soil,and the carrot seeds germinated best in 63 d soil.For greening lawns that are irrigated with plastic water pipes,the early growth of the crop may deteriorate with the extension of irrigation.It is advisable to grow carrots in long-irrigated soils.It is not recommended to grow ryegrass.By analyzing the relationship between fresh weight and soil enzyme activity of the two crops,it was found that the fresh weight of the two crops was significantly correlated with the urease activity.The stem length of ryegrass was significantly associated with sucrase,and the stem length of carrots was significantly associated with urease.According to this,when assessing the migration of plastic pipe compounds through changes in soil enzyme activity,it is also possible to perform primary assessments of the effects of soil cultivation on the long-term irrigation of the pipe.