沼液施用对海岸带围垦麦田土壤中小型节肢动物群落的影响

土壤节肢动物群落结构是反映土壤动物多样性及土壤质量的重要指标。沼液施用对土壤结构与肥力的改变,可能对土壤节肢动物群落的特征产生显著影响。以江苏东台海岸带连续施用沼液5年的围垦麦田为例,研究沼液不同用量(0、100、200、300 m~3/hm~2)及沼液替代(0%、33%、66%、100%)化肥对土壤中小型节肢动物群落结构的影响。结果表明:各施肥管理下麦田土壤中小型节肢动物的优势类群均为前气门亚目、甲螨亚目和弹尾目,平均分别占总捕获量的52.09%—53.33%、22.42%—23.86%和13.14%—16.51%。当沼液用量从0增加到300 m~3/hm~2时,土壤动物密度增加了94%,类群数增加约2个,优势度指数增加9.4%(P<0.05)。沼液66%替代化肥时,土壤动物密度、类群数和优势度指数最高。因此,施用沼液显著增加了土壤中小型节肢动物的密度、类群数与优势度指数。当沼液替代化肥的比例为66%时,促进效应最佳。主成分分析表明,无论单施沼液还是沼液替代化肥,弹尾目、前气门亚目与甲螨亚目的响应最为敏感,可将其作为土壤中小型节肢动物对施肥响应的指示指标。

Effect of biogas slurry application on small- and medium-sized arthropods communities in coastal reclaimed wheat fields

The high dependence on chemical fertilizers driven by crop yields has posed huge risks and challenges to soil quality and ecosystem balance for decades. The reduction and substitution of chemical fertilizers has now become a national strategy for high-quality agricultural development. The organic matter of livestock and poultry manure is converted into methane under highly anaerobic conditions, and the liquid by-products (biogas slurry) and solid residues (biogas residue) are also produced. The biogas slurry is rich in nitrogen, amino acids, and various mineral nutrient elements, being an efficient alternative to chemical fertilizers. Previous studies on the application of biogas slurry mainly focused on the effects of dosage and usage on crop yield and soil properties. The impact on soil fauna communities was insufficient yet. Soil arthropods participate in soil biochemical cycles, stimulating the metabolism of fungi and bacteria and maintaining the balance of the soil ecosystem. Due to their sensitive response to habitat changes, soil arthropods are used as important indicators to reflect soil health and stability. However, there is no investigation on the changes of soil arthropod communities under the condition of biogas slurry instead of chemical fertilizers. In the present study, the effects of different dosage of biogas slurry (0, 100, 200, and 300 m³/hm²) and substitution of biogas slurry (0%, 33%, 66%, and 100%) to chemical fertilizers on soil small- and medium-sized arthropod communities were investigated in coastal reclaimed wheat fields with repeated application of biogas slurry for 5 years in Dongtai city, Jiangsu, China. The results showed that the predominant soil fauna groups in wheat field were Prostigmata, Oribatida and Collembola, accounting for 52.09%-53.33%, 22.42%-23.86% and 13.14%-16.51% of the total catches, respectively. When the amount of biogas slurry increased from 0 to 300 m³/hm², the density of soil fauna increased by 94%, the number of groups increased by about 2, and the dominance index increased by 9.4% (P < 0.05). The density of soil fauna, number of groups and dominance index arrived the highest when using 66% of biogas slurry to replace chemical fertilizers. Therefore, the application of biogas slurry could significantly increase the density, group number, and dominance index of small- and medium-sized arthropods in the soil. When the ratio of biogas slurry to replace chemical fertilizer was 66%, the promotion effect was the best. In addition, principal component analysis showed that Collembola, Prostigmata and Oribatida were much sensitive to biogas slurry application alone or biogas slurry in place of chemical fertilizers. They could be used as indicators of the response of soil small- and medium-sized arthropods to fertilization.