Arbuscular mycorrhizal (AM) fungi are very abundant in many agricultural soils and are important in increasing and maintaining the sustainability of agricultural systems. However, high soil fertility, especially high available soil phosphorus (P) status, often limits AM fungal development in intensively managed agricultural systems and results in the C-costs to the host plant outweighing any benefits from AM colonization. Some promising approaches can minimize negative effects on soil biota while providing the desired agricultural benefits (e.g. reduced soil tillage and organic amendments). However, the influence of these agricultural practices on the benefits of root mutualistic associations remains poorly understood. Here, we collected indigenous AM fungi from a long-term field experiment with different application rates of cow manure and conducted a pot experiment with different soil P levels. Using high throughput sequencing we demonstrate that increasing cow manure application changed the community composition of AM fungi and reduced community diversity in the field. Phosphorus addition in a bioassay experiment produced a mycorrhizal growth response (MGR) and the mycorrhizal P response (MPR) shifted from positive to negative, regardless of the origin of the inoculum. An increase in intraradical and extraradical AM fungal structures enhanced maize shoot biomass and P uptake under low (no P added) and moderate (20 mg P added kg⁻¹ soil) P levels but the opposite occurred at a high P level (250 mg P added kg⁻¹ soil). The MGR was higher in the treatment with higher community diversity at the moderate P level but there was no significant correlation at the other two P levels examined. We conclude that available soil P may regulate the abundance and diversity of AM fungi and their symbiotic function in intensive cropping systems. Our results indicate that managing the soil phosphorus level to favor a rich and diverse AM fungal community can enhance crop production and result in a more sustainable agricultural system.

丛枝菌根真菌（AM）真菌在许多农业土壤中非常丰富，对于增加和维持农业系统的可持续性具有重要意义。但是，高土壤肥力，尤其是高可用土壤磷（P）的状态，通常会限制集约化管理农业系统中AM真菌的生长，并导致宿主植物的C成本超过AM殖民化带来的任何好处。一些有希望的方法可以最大程度地减少对土壤生物的不利影响，同时提供所需的农业效益（例如减少土壤耕作和有机改良剂）。但是，这些农业实践对根源互惠协会的好处的影响仍然知之甚少。这里，我们从长期的田间试验中收集了不同施用牛粪肥的本地AM真菌，并进行了不同土壤P水平的盆栽试验。使用高通量测序，我们证明了增加牛粪肥施用量会改变AM真菌的群落组成，并减少田间的群落多样性。在生物测定实验中添加磷会产生菌根生长反应（MGR），而菌根P反应（MPR）从阳性变为阴性，无论接种物的来源如何。在低（不添加磷）和中度（添加20 mg P公斤）下，自由基内和自由基外AM真菌结构的增加增强了玉米苗的生物量和磷的吸收 使用高通量测序，我们证明了增加牛粪肥施用量会改变AM真菌的群落组成，并减少田间的群落多样性。在生物测定实验中添加磷会产生菌根生长反应（MGR），而菌根P反应（MPR）从阳性变为阴性，无论接种物的来源如何。在低（不添加磷）和中度（添加20 mg P千克）下，自由基内和自由基外AM真菌结构的增加增强了玉米苗的生物量和磷的吸收 使用高通量测序，我们证明了增加牛粪肥施用量会改变AM真菌的群落组成，并减少田间的群落多样性。在生物测定实验中添加磷会产生菌根生长反应（MGR），而菌根P反应（MPR）从阳性变为阴性，无论接种物的来源如何。在低（不添加磷）和中度（添加20 mg P公斤）下，自由基内和自由基外AM真菌结构的增加增强了玉米苗的生物量和磷的吸收^-1土壤）的磷水平，而高磷水平则相反（添加250 mg P kg kg ^-1土壤）。在中等磷水平上，MGR在具有较高群落多样性的治疗中较高，但在其他两个磷水平上没有显着相关性。我们得出的结论是，在集约化耕作系统中，可用土壤P可能会调节AM真菌的丰度和多样性及其共生功能。我们的结果表明，控制土壤磷水平以有利于丰富多样的AM真菌群落可以提高作物产量并导致更可持续的农业体系。