自然生草对黄河三角洲梨园土壤物理性状及微生物多样性的影响

以山东省东营市济南军区黄河三角洲生产基地自然生草4a、6a和9a的黄金梨Pyrus pyrifolia(Burm.f.).cv.Nakai]梨园耕作层土壤为试材,以清耕为对照,探讨了多年自然生草对黄河三角洲梨园土壤物理性状及微生物多样性的影响。结果表明,自然生草能明显提高耕作层土壤孔隙度,降低土壤容重和电导率(可溶性含盐量),而对土壤含水量没有影响;自然生草增加了土壤微生物量C、N,通过PCR-DGGE及测序技术发现细菌主要增加的是未培养菌类;与清耕对照相比,多年自然生草梨园土壤微生物呼吸、活性、活跃微生物量、微生物磷酯脂肪酸总量提高效果明显,但对微生物磷酯脂肪酸种类影响较小,处理间差异均不显著;同时,自然生草提高了碳源利用能力,其中以生草4a最大,随着生草年限增加,6类碳源利用更加均衡。综上所述,自然生草优化了黄河三角洲梨园耕作层土壤物理性状,增加了微生物量C、N,其中细菌主要增加的是未培养菌类;同时,持续多年自然生草,有利于参试梨园土壤微生物呼吸、活性、活跃微生物量及磷酯脂肪酸总量的提高,并对微生物均衡利用6类碳源作用明显。

Effects of self-sown grass on soil physical properties and microbial diversity of pear orchards in yellow river delta

In this study, we investigated the effects of natural grass growth on the physical properties of soil and microbial diversity in a pear orchard located in the yellow river delta. The soil properties and microbe diversity in orchards containing grass grown for 4, 6, and 9 years respectively, was characterized and compared with those in soil from orchards that did not have grass growth, which served as the control in this experiment. The results showed that multiple years of grass growing significantly enhanced soil porosity and reduced soil bulk density and conductivity, suggesting that permitting growth of natural grass in the orchard could reduce soluble salts in soil, without an influence on water content in the soil. Grass growth also increased the microbial mass C and N. By employing PCR-DGGE and sequencing technology, we found that the majority of the increased bacteria were species that could not be cultured. In comparison with control, the microbial respiration and activity, and the global phospholipid fatty acid concentration was increased after several years of grass growth, although the phospholipid fatty acid varieties were not affected, and no significant differences were found among treatments. Meanwhile, grass growth also improved carbon utilization capacity, with the most significant effect being displayed after 4 years implementation, and the more balanced utilization of six carbons were simultaneously achieved during this process.In summary, our study shows that the culture of naturally grown grass in the orchard significantly increases microbial biomass C, N, and microbe diversity, and that uncultured species constitute the major part of the increased bacterial concentration. Moreover, sustained grass culture in the orchard benefits the up-regulation of soil microbial activity and respiration and the increasing amount of active microbes and total phospholipid fatty acids. It is also effective at stimulating the balanced utilization of six carbons by microbes.