Investigation And Assessment Of Soil Fauna Diversity In Organic Farming

Conventional agriculture has caused serious environmental problems with the extensive use of chemical fertilizers and pesticides,which has restricted the sustainable development of agriculture.Organic agriculture can improve soil structure and soil fertility,which is conducive to environmental protection and the balance and stability of ecosystem,and also of great value to preserve the biodiversity of soil animals.Our study aims to compare the difference of soil fauna community between organic agriculture and conventional agriculture,and evaluate the effect of organic farming on soil fauna community.Nine organic farming and conventional farming soils from East,Central and West China were compared during 2013-2014.The main findings were addressed as follows:A total of 102 families were found in all the organic farming and conventional farming soil samples,falling into 30 orders.Among them,a total of 63 families macrofauna were observed falling into 20 orders,in which 56 families falling into 19 orders were observed in the aboveground whereas 37 families falling into 16 orders were observed in the belowground.The macrofauna belongs to 57 families,18 orders were found in the organic farming,whereas 47 families,19 orders were found in the conventional fanning.Coleoptera,Araneae.Stylommatophra were the dominant groups in the aboveground of organic fanning and conventional farming,with the relative abundance of 12.9%,21.4%,and 10.4%respectively in the organic fanning,and 11.9%,33.9%and 19.1%respectively in the conventional farming.Oligochaeta was the dominant groups of the belowground,with the relative abundance of 43.3%in the organic farming and 37.8%in the conventional farming.In addition,dominant groups differ with crops:Isopoda was the dominant group only in the vegetables soils,Stylommatophra was the dominant group in the paddy rice soils,and Blattoptera and Hemiptera were the dominant groups in the soils planted with tea and orange.T-test showed that the total abundance(0.59 million individuals per square meter)and density-groups index(DG)of soil animals were significantly higher(P<0.05)in the organic farming compared with conventional farming,with a higher(P<0.05)abundance(203 individuals per square meter),Shannon-Wiener diversity index(H')and density-groups index(DG)of macrofauna in the organic farming compared with the conventional farming.The higher value of soil biological quality index(FAI)in organic farming than conventional farming indicated that organic farming could improve the soil quality.For the soil nematode,a total of 57 genera belonging to 27 families were found.Among them,21 genera were bacterivores,9 genera were fungivores,10 genera were herbivores and 17 genera were omnivores/carnivores.A total of 57 genera were observed in organic farming and 51 genera nematodes were observed in conventional farming.Caenorhabditis,Diplogaster,Cervidellus,Wilsonema and Thorneellalronus were only found in organic farming.Cephalobus,Eucephalobus,Aphelenchoides and Filenchus were dominant genera in both organic and conventional farming systems.The results of ANOVA showed that management measurement,sampling site and their interaction had significant effect on soil nematode abundance.Compared with conventional farming(748 individuals per 100 g dry soils),organic cultivation greatly enhanced the number of soil nematode(1037 individuals per 100 g dry soils),especially the number of bacterivores in c-p 1 and omnivores/carnivores in c-p 4.There was no significant difference in the number of fungivores between organic and conventional farming.The number of herbivores in the organic farming was higher than the conventional farming when the cultivation was more than 10-year,but lower than the conventional farming when the cultivation was less than 3-4 years.Redundancy analysis(RDA)revealed that soil nutrients had significant correlations with soil fauna community,especially the dominant groups.The correlation analysis also found that soil nutrients correlated significantly with the nematode community,with a positive correlation with bacterivores and negative correlation with herbivores.In summary,organic farming can increase soil organic matter,improve soil nutrient level and preserve soil fauna abundance and diversity.The diversity of macrofauna was better indicating the difference between organic farming and conventional farming,whereas soil nematode was better indicating soil fertility.We concluded that soil fauna community is good indicator of soil ecosystem function.