| This experiment was based on the long-term research and monitoring station of national fluvo-aquic soil fertility and fertilizer efficiency under the jurisdiction of the Henan Academy of Agricultural Sciences.The soil-forming parent material was the Yellow River sediment,and the soil type is light fluvo-aquic soil.The fluvo-aquic soil has low organic matter content,poor soil fertility and strong dependence on fertilizers.Different long-term fertilization treatments changed soil physicochemical indexes and animal community structure.This study selected three different long-term fertilization treatments,they were single fertilizer application(N2PK),fertilizer application with organic(N2PKM),fertilizer application with straw(N2PKS),use non-fertilizer treatment(CK)and land reclamation treatment(LH)for comparison,sampling at the critical period of crop growth,through field experiments combined with indoor analysis,the effects of long-term fertilization on the community structure and diversity of soil nematodes were studied,to provided a theoretical basis for the evaluation of long-term fertilization soil properties used soil nematode indicators.The main findings were follows:(1)Compared with N2 PK,N2PKM and N2 PKS significantly increased the contents of ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium and organic matter in soil(p < 0.05),this improved soil fertility.There were significant difference in soil p H between fertilization and no fertilization(p <0.05),p H was significantly higher than fertilization in non-fertilizer treatment(p <0.05),in the N2 PK,p H was significantly higher than in N2 PKM and N2PKS(p <0.05),organic fertilizer and straw could reduce the p H of alkaline soil.(2)The interaction between the time and the period in maize season had significant effects on the total number of nematodes(p < 0.05),and different fertilization treatments had extremely significant effects on the total number of nematodes(p < 0.01).Except for the sowing in maize season,N2 PKM and N2 PKS increased the total number of nematodes,bacterivores,and plant parasitic nematodes.The number of omnivorous-predatory nematodes was significantly higher in LH than in cultivated land(p < 0.05),this indicated that fertilization and farming hadinhibitory effects on omnivorous-predator nematodes.A total of 46 nematodes genera were identified in the sample,including 12 genera of plant parasitic nematodes,17 genera of bacterivorous nematodes,6 genera of phytophagous nematodes,and 11 genera of omnivorous-predatory nematodes.The proportion of bacterial nematodes and plant parasitic nematodes were relatively large,Dolichodoridae,Pratylenchus,Acrobeles were advantage nematode in the treatment of cultivated land,in addition to the CK treatment in the corn season,its abundance >5%.The omnivorous-predator nematodes mainly existed in LH and CK,indicated that the fertilization had a significant inhibitory effect on omnivorous-predatory nematodes.(3)Different fertilization treatments in wheat season and corn season had extremely significant effects on NCR(p < 0.01),except the heading period of the wheat season and the jointing period of the maize season,compared with CK,N2 PKM significantly increased the value of NCR,organic fertilizer could increase the proportion of bacteria-eating nematodes in microworms;In the wheat season and the corn season,the WI value was less than 1,so there was higher chance of emerging nematode disease.In the heading and maturing stages of the maize season,N2 PKM and N2 PKS significantly reduced Hg values compared with CK.The organic fertilizer and straw could inhibit the diversity of soil nematode.In the wheat season,the comparison between EI and SI shows that portion treatments of the N2 PKM,N2PKS,and N2 PK in the fourth quadrant,but in the corn season all the treatments were in the third quadrant.It showed that the application of organic and straw in wheat season to the field had greater disturbance to the food network,but from the wheat season to the corn season,obviously reduced disturbances.In addition to the sowing and ripening of the wheat and maize seasons,the BI of N2 PKS was significantly higher than that of CK and LH,explain that organic and straw increased the food network resistance.(4)In the corn season,ammonium nitrogen and quick-acting potassium has significant effects on plant parasitic nematodes(p < 0.05),ammonium nitrogen,available phosphorus and available potassium had extremely significant effect on the number of bacterial nematodes(p < 0.01),ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium and organic carbon had extremely significant inhibitory effects on omnivorous-predator nematodes(p < 0.01),there was significant negative correlation between the organic carbon and the total number of nematodes(p < 0.05),organic matter carbon significantly inhibited the growth of plant-parasitic nematodes and omnivorous-predator nematodes(p < 0.05),There was significant negative correlation between p H and the total number of nematodes(p <0.01),p H has significant inhibitory effect on plant parasitic nematodes and bacterivores,at the same time it also has significant inhibitory effect on NCR(p <0.01).That was,p H could promote food web connectivity and the length of the food chain,but it reduced the food network resistance.From the above series of analysis could be drawn: The application of organic fertilizer and straw could improve soil fertility,and could promote the number of plant parasitic nematodes and bacterivores,promoted the stability of the food network. |
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