Ying-Chun Qi

SUMMARY: Two long-term field experiments, each consisting of three treatments (organic compost treatment, chemical fertilizer treatment and an untreated control) were established in 1993 and 1997, respectively. Soil samples were collected from each plot in June 2004 and 2005 after crop harvest and were used to determine soil physical-chemical properties, biological and biochemical activity, and the nematode community. Soil physicochemical parameters, microbial biomass, biological activities and nematode communities were significantly influenced by long-term application of organic compost. In general, soil total organic carbon, dissolved organic carbon, total nitrogen, alkaline-hydrolysable nitrogen, available phosphorus, and available potassium, microbial biomass, basal respiration, urease activities, total number of nematodes and bacterial-feeding nematodes were significantly higher in the compost plots than in the chemical fertilizer and control plots at two experimental sites and two sampling dates. Soil bulk density and pH values were significantly lower in the compost plots. We conclude that soil physical-chemical properties, size and activity of soil microbial biomass, metabolic quotient (qCO₂), urease activity, total number of nematodes and bacteria-feeding nematodes could be used as indicators of soil quality.

Nematode abundance and diversity from different types of organic manure soil treatments were investigated in a longterm field experiment carried out in Qu-Zhou experimental station, China Agricultural University. The composts used in the experiment were a traditional compost (C) (60 % straw, 30 % livestock dung, 5 % cottonseed-pressed trash and 5 % brans), traditional compost and chicken dung compost (60 % straw, 30 % chiken dung, 5 % cottonseedpressed trash and 5 % brans) added with effective microorganisms, EMC and EMCDC respectively. Six treatments were arranged according to a randomized block design with three replicates per treatment. Treatments were incorporation into the soil of compost EMC, EMCDC, and C each at the rates of 7.5 and 15 t/ha. Plots were sown with winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) every year from 1997 to 2004. Overall, 28 nematode genera were found. Seven genera were bacterivores, 3 genera were fungivores, 13 genera were plantparasites and 5 genera were omnivores-predators. The Rhabditis, Cephalobus, Helicotylenchus were dominant genera in the present study. The bacterivores and plantparasitic nematodes were the dominant trophic groups except in C treatment. Nematode abundance per 100 g dried soil ranged from 372 to 553. Addition of effective microorganism increased the number and proportion of bacterivorous nematodes and decreased the number and proportion of plant-parasitic nematodes compared to traditional compost C. Total number of nematode was significantly influenced by compost amount, but didn’t significantly influence by EM agent. Total abundance of nematode was positively correlated with the content of soil organic matter, total N, available P and K. The long-term addition of EM agent hasn’t adverse effect on soil nematode community.