三种种植方式对土壤微生物群落组成的影响

 土壤微生物是表征土壤质量变化的敏感指标之一。借助长期定位试验, 采用磷脂脂肪酸分析方法研究了3种种植方式(玉米(Zea mays)连作、玉米非连作和撂荒)对土壤微生物群落组成的影响。结果表明, 在不同的种植方式下, 土壤微生物群落组成有明显的差异。玉米连作的土壤中总磷脂脂肪酸和细菌磷脂脂肪酸含量最低, 分别为33.12 nmol·g^–1和18.09 nmol·g^–1。非连作的土壤真菌磷脂脂肪酸和真菌/细菌分别为0.61 nmol·g^–1和3.06%, 显著低于撂荒和连作(p < 0.05), 非连作方式下, 革
兰氏阳性细菌/革兰氏阴性细菌增大。撂荒土壤的总磷脂脂肪酸和细菌磷脂脂肪酸分别为42.98和24.68 nmol·g^–1, 高于耕作处理。 同时, 在撂荒方式下, 革兰氏阳性细菌和革兰氏阴性细菌的含量增加, 革兰氏阳性细菌/革兰氏阴性细菌降低。主成分分析结果表明: 耕作处理(玉米连作和非连作)分布第一主成分负方向上, 第一主成分得分系数分别为–2.48和–1.84; 撂荒分布第一主成分正方向上, 第一主成分得分系数为2.31, 与连作和非连作差异显著(p < 0.05)。冗余分析(RDA)表明: 土壤pH、总氮、有效磷和土壤>0.25 mm水稳性团聚体含量与磷脂脂肪酸呈正相关, 并且土壤pH和土壤>0.25 mm水稳性团聚体含量对土壤微生物群落的影响最大。

Effects of three planting patterns on soil microbial community composition

Aims Planting patterns have direct effects on soil microorganisms. Because of different plants and human activities, planting patterns change soil fertility. Our objective is to understand the effects of different planting patterns on soil microbial community structure.
Methods We carried out a long-term field experiment at Jilin Agriculture University that used phospholipid fatty acid analysis method to study the effects of three planting patterns of corn: continuous cropping, non-continuous cropping and uncultivated.
Important findings Different planting patterns affected soil microbial community structure. Continuous cropping of corn had the lowest total phospholipid fatty acids and bacterial phospholipid fatty acids (33.12 nmol·g^–1 and 18.09 nmol·g^–1, respectively). Fungal phospholipid fatty acids and fungi/bacteria with non-continuous cropping were 0.61 nmol.g^–1 and 3.06%, respectively, and were significantly lower than with uncultivated and continuous cropping (p < 0.05). But the ratio of gram positive phospholipid fatty acids/gram negative phospholipid fatty acids was greater with non-continuous cropping. The uncultivated treatment had greater total and bacterial phospholipid fatty acids (42.98 nmol·g^–1 and 24.68 nmol·g^–1, respectively), higher contents of gram positive phospholipid fatty acids and gram negative phospholipid fatty acids, and a lower ratio of gram positive phospholipid fatty acids/gram negative phospholipid fatty acids. Principal component analysis showed that soil microbial community structure with cropping was significant different (p < 0.05) with that of uncultured in first principal component. Non-continuous cropping and continuous cropping were negatively positioned in first principal component with principal component scores of –2.48 and –1.84, respectively. Uncultivated was in a positive position in first principal component with a principal component score of 2.31. Redundancy analysis of soil microbial community structure and environmental variables showed that soil pH and soil-water stable aggragates had the strongest positive correlation with phospholipid fatty acids and that total nitrogen and available phosphorus were also positively correlated with phospholipid fatty acids.