The Effect Of Straw Returning On The Soil Structure Of Black Carp And Springtail In Black Soil Farmland

On-site recycling of straw is an important method of soil fertility management in farmland.Straw is not only habitat for soil fauna,but also as a main source of litter.However,little is known about the effect of straw recycling on the community structure of soil fauna.In order to better understand the influence of straw recycling on community structure of soil Oribatida and Collembola in black soil,an experiment was conducted in black soil farmland in Northeast China.Soil samples were collected from 0~20 cm soil layer under straw recycling for 4 years(SR4),10 years(SR10)and conventional tillage(CK)in June and October of 2014 and 2015 and a modified Tullgren method was used to extract soil mites from the soil samples.And a modified Tullgren method was used to extract soil collembola from the soil samples in July and October of 2014 and May of2015.The results of Oribatida showed that a total of 11,366 soil mites were captured on four sampling dates,of which 8,373(74%)were Oribatida.The density of soil Oribatida was SR4: 13774/m2,15 families SR10: 11946/m2,12 families and CK:5871/m2,7 families.Straw recycling,season,and the interaction between straw recycling and season all had significant(P<0.001)effects on individual density of soil Oribatida,but not on the number of families of Oribatida.Straw recycling also significantly affected the richness index,the evenness index,the diversity index,the dominance index and the density-groups index of Oribatida.The density of the dominant species of soil Oribatida in autumn were generally higher than those in summer.Cluster analysis also showed that the Oribatida communities in SR4 and SR10 were significantly different from CK,but not from each other.The results of Collembola showed that a total of 6935 soil Collembola were captured on three sampling dates.The density of soil Collembola was SR4: 10807/m2,20 families SR10: 16673/m2,20 families and CK: 9256/m2,17 families.Straw recycling(P<0.001),season(P<0.001),and the interaction between straw recycling and season(P<0.05)all had significant effects on individual density of soil Collembola,and the number of families of Collembola was effected by straw recycling(P<0.001)and season(P=0.001).Species indicator values(Ind Val)analysis suggested SR10(Ceratophysella sp.1、Pseudachorutes sp.1、Anurida sp.1、Thalassaphorura encarpata、Mesaphorura sp.1),SR4(Hemisotoma sp.1、Folsomides parvulus),CK(Sminthurinus sp.2)had its own unique indicators.Straw returning also significantly affected the richness index,theevenness index and the density-groups index of Collembola groups.In a word,our results indicated that straw recycling is conducive to maintaining the diversity and density of soil Oribatida and Collembola communities,and to the protection of ecological environment and fertility of the soils.