| As a large agricultural country,agricultural irrigation is essential in the agricultural production.As an important source of water and fertilizer,Sewage is an important source of water and fertilizer,irrigating with suitable sewage can save fertilizer,improve soil fertility and reduce agricultural production cost.Based on the investigation of the current situation of soil quality in typical farmland in Liugou watershed of Yingshang county,Fuyang city,this study explored the effects of rural mixed wastewater irrigation on wheat growth,soil nutrient,soil enzyme activity and soil microbial diversity through indoor soil column simulation experiment.The main research results are as follows:1.Soil quality evaluation of typical farmland in Liugou watershed of Yingshang County,Fuyang City(1)The contents of Cu,Zn,Cr,Ni,Pb,Cd,As and Hg in the farmland soil of the study area did not exceed the screening values of Soil Environmental Quality Standards-Soil Pollution Risk Control Standards for Agricultural Lands(GB15618-2018),but the contents of Cd,Ni,As and Zn exceeded the soil background value of Anhui Province to varying degrees;(2)The single factor pollution index of each heavy metal elements in farmland soil of the study area was less than 1,and there was no heavy metal pollution in soil,and the pollution indexes of Ni and Cd were the highest,with a variation range of0.27-0.47 and 0.40-0.57,respectively.At the same time,the comprehensive pollution index of soil in the study area was less than 0.7,and the soil belongs to safety grade.(3)Heavy metals Cd and Hg were the most important potential ecological risk factors,and the total potential ecological risk value(RI)in the study area was83.93-118.86,the degree of potential ecological risk was mild;(4)The comprehensive fertility index of soil in the study area was in the range of0.98-1.07,the soil fertility was at general level,and organic matter and alkali-hydrolyzable nitrogen were the main limiting factors of soil fertility.2.Effects of rural mixed wastewater irrigation on soil nutrient content,enzyme activity and microbial diversityCompared with clean water irrigation(CK),after rural mixed wastewater irrigation(WG):(1)The contents of soil total potassium,total phosphorus,available potassium and alkali-hydrolyzable nitrogen increased(4.54-46.84%),while the contents of soil organic matter,total nitrogen and available phosphorus decreased(2.02-32.61%),and the pH of soil decreased highly significantly(P<0.01),the content of available potassium increased significantly(P<0.05).Rural mixed wastewater irrigation can improve the integrated soil fertility.(2)The activities of soil catalase and soil acid phosphatase of WG treatment were highly significantly lower than the ones of CK treatment(P<0.01),while the activities of soil urease and soil invertase were significantly higher(P<0.05);(3)The microbial activity indexes(Shannon,Ace,Chao and Coverage)of bacteria and fungi increased in soil,but the Simpson index decreased,indicating that WG increased the diversity of soil bacteria and fungi.At the same time,the results of microbial community structure analysis showed that the relative abundances of each dominant species of bacteria and fungi at the genus level were changed by WG.3.Effects of rural mixed wastewater irrigation on growth and rhizosphere Micro-environment of wheatCompared with clean water irrigation(CK),after rural mixed wastewater irrigation(WG):(1)The plant height,diameter,fresh weight and dry weight of wheat treated with WG were significantly higher than those in CK treatment(P<0.05),and the contents of chlorophyll a,chlorophyll b and total chlorophyll in wheat leaves increased significantly(P<0.05);(2)In the WG treatment,the organic matter content in wheat rhizosphere soil increased by 16.42%,while soil pH,the contents of total nitrogen,total potassium,total phosphorus,available phosphorus,available potassium and alkali-hydrolyzable nitrogen as well as comprehensive fertility decreased(0.95%-16.79%),and available potassium content decreased significantly(P<0.05);(3)The activities of acid phosphatase,urease and invertase in wheat rhizosphere soil in WG treatment were significantly higher than those in CK treatment(P<0.05),but catalase activity significantly decreased(P<0.05);(4)According to Shannon,ace,Chao,coverage,Simpson index and microbial community structure distribution map of bacteria and fungi at genus level,the diversity of bacteria in wheat rhizosphere soil decreased in WG treatment,while the diversity of fungi increased.At the same time,WG changed the relative abundance of dominant species of bacteria and fungi at genus level in wheat rhizosphere soil,but the dominant species of bacteria did not change,and the fungi dominant species changed. |
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