旱地麦田蓄水保墒技术下土壤线虫群落的时空分布特征

Soil water conservation plays an important role in high and stable yields of dryland crops, soil nematode is a vital biological indicator of soil heathy. Therefore, clarifing the ecological distribution of nematode communities is of great significance to soil quality improvement and the sustainable production of dryland wheat. Our team has been working on the water conservation technology of dryland wheat for many years and already got a lot progress in water accumulation and nutrient cycling. However, the spatial distribution pattern and mechanism of soil nematode community are still unclear. This study is based on the “Three in advanced technology” which refers to soil deep tillage, organic fertilizer application and residue management in advance during summer fallow season in dryland wheat fields. We analyzed the spatial and temporal distribution of nematode communities, especially in soil aggregates. By combining with the variation of soil microbial communities, the interaction mechanism between nematode and microorganisms is explored. The changes of soil aggregate stability, enzyme activity, soil moisture, other physi-chemical properties and the growth of wheat were analyzed to reveal the effects of long-term water conservation on soil quality. Additionally, we will explore the correlation between soil nematode community, microbial community, soil structure, and wheat production. This will help to improve the dryland wheat cultivation technology, provide theoretical support for promoting soil capacity of water storage and wheat productivity in dry farmland.

土壤蓄水保墒措施是保障旱作作物丰产稳产的关键，线虫是衡量土壤生态健康的重要生物学属性，明确线虫群落的生态分布，对于改善土壤质量，实现旱地小麦可持续生产有重要意义。本团队长期从事旱作小麦蓄水保墒技术研究，对其水分积耗和养分循环等方面做了深入探索，但土壤线虫群落空间分布格局和分布机制尚不清晰。本项目基于旱地麦田夏闲期提前深翻或深松、提前深施有机肥、提前秸秆还田或覆盖的“三提前”蓄水保墒技术，研究线虫群落的时空分布规律，尤其在土壤团聚体中的分布特征；结合土壤微生物群落的动态变化，探索土壤线虫和微生物的互作机制；分析土壤团聚体稳定性、酶活力、土壤水分等理化性状的变化规律和小麦生长状况，揭示长期蓄水保墒措施对旱地麦田土壤质量的影响，探明旱地土壤线虫群落-微生物群落-土壤结构-小麦生产之间的相关关系，为完善旱地小麦耕作栽培技术体系，提高旱地土壤蓄水保墒能力和小麦生产力提供一定的理论依据。

土壤蓄水保墒措施是保障旱作作物丰产稳产的关键，线虫是衡量土壤生态健康的重要生物学属性，明确线虫群落的生态分布，对于改善土壤质量，实现旱地小麦可持续生产有重要意义。本项目基于旱地麦田夏闲期提前深翻或深松、提前深施有机肥、提前秸秆还田或覆盖的蓄水保墒技术，研究线虫群落的时空分布规律，探明旱地土壤线虫群落-微生物群落-土壤结构-小麦生产之间的相关关系，为完善旱地小麦耕作栽培技术体系，提高旱地土壤蓄水保墒能力和小麦生产力提供一定的理论依据。 研究结果发现：土壤线虫群落对耕作措施及小麦生育期变化均有显著响应。免耕处理下线虫数量及丰富度均显著高于深松和深翻，但免耕处理下的植物寄生性线虫占比较高，不利于作物根系健康。随着小麦生育期的进行，土壤线虫群落由胁迫状态发展为结构化状态，线虫优势类群也由c-p 2和c-p 3变为c-p 4，线虫群落结构较为稳定。深松和深翻降低了土壤团聚体稳定性，使得团聚体线虫数量减少，但大团聚体（＞2mm）受干扰程度相对较小，团聚体线虫也多分布于此，且大团聚体内线虫群落普遍达到结构化状态，较为稳定。深松和深翻显著降低了土壤容重并提高了土壤含水量，起到了疏松土壤，蓄水保墒的作用。免耕能够积累铵态氮，而深松处理下有机质含量较多，深翻则有利于有效磷和硝态氮积累。深松和深翻处理后较免耕分别增产65.24%和25.20%。土壤微生物对线虫的影响要大于土壤养分对线虫的影响。其中土壤细菌是线虫数量的决定性因素，而线虫丰富度，富集指数，线虫成熟度则均受土壤氮素影响。本项目立足旱地蓄水保墒技术，着力研究土壤耕作、有机肥和秸秆还田配套实施的蓄水保墒技术下，旱地小麦土壤线虫群落的时空分布特征，线虫和微生物的互作机制，土壤结构与线虫群落分布的相关关系。这一工作不仅有助于我们系统认识蓄水保墒技术对旱地小麦土壤微生态环境的影响，明确其改善土壤质量，提高土壤蓄水保墒能力和小麦生产力的机制，同时对于完善旱地耕作栽培技术有重要的启示。