Bioassays were undertaken in a controlled environment to assess whether the potential for suppression of Rhizoctonia root rot of wheat, in a highly calcareous topsoil, was positively influenced by nutrient (nitrogen (N) or phosphorus (P)) addition and whether any disease suppression response to augmented nutrition was affected by the addition of carbon (C), either as a readily available C source (sucrose) or as wheat stubble. The soil was P deficient, which limited plant growth, populations of putatively beneficial soil microorganisms, and microbial activity and diversity. This ultimately reduced potential for suppression of Rhizoctonia solani AG8. Addition of fertiliser P to the soil increased R. solani AG8 DNA and percent root infection but not the effectiveness of the pathogen. A positive effect of P fertiliser on plant growth partially compensated for the negative effect of increased root infection. Addition of P increased DNA for Microbacterium spp. where labile C had been added and in the presence of plant roots. Stubble addition alone, after 6 weeks of incubation, increased DNA for Pantoea agglomerans, Trichoderma A and Microbacterium spp. although differences in microbial activity and diversity between stubble treatments were only detected after the bioassay had commenced and P was added. Fertiliser P addition to stubble-amended soil resulted in less Rhizoctonia infection compared with that in soil without P or stubble addition. Effectiveness of R. solani AG8 was decreased by 50% with stubble amendment. The application of N alone did not have a marked effect on plant growth or potential for suppression of Rhizoctonia root disease. Agronomic management practices that affect quantity and lability of C input to soil, when combined with strategic P fertiliser decisions, are likely to improve the potential for development of suppression of Rhizoctonia root rot disease in cereal crops on alkaline and highly calcareous soils.

在受控环境中进行了生物测定，以评估在高钙质表土中抑制小麦根瘤菌根腐病的潜力是否受到营养物（氮（N）或磷（P））的添加以及是否对任何疾病抑制反应有积极影响添加碳（C）既可以作为现成的C源（蔗糖），也可以作为麦茬来增加营养。土壤缺磷，限制了植物的生长，土壤中有益微生物的数量以及微生物活性和多样性。最终降低了抑制茄根枯菌AG8的潜力。向土壤中添加肥料P会增加茄茄AG8 DNA和根部感染百分数，但对病原体无效。磷肥对植物生长的积极影响部分抵消了根系感染增加的不利影响。P的增加使微细菌属spp的DNA增加。在其中添加了不稳定的C且存在植物根的地方。孵育6周后，仅添加茬就可以增加聚结泛菌，木霉A和微细菌的DNA。spp。尽管仅在生物测定开始并添加P后才检测出茬处理之间的微生物活性和多样性差异。与不添加磷或不留茬的土壤相比，向残茬改良的土壤中添加磷肥导致的根瘤菌感染较少。茬茬处理后，R。solani AG8的有效性降低了50％。单独施用氮对植物生长或抑制根瘤菌根病的潜力没有显着影响。当与战略性磷肥决策结合时，影响土壤碳输入量和土壤肥力的农艺管理措施可能会提高在碱性和高钙质土壤上抑制谷物作物根瘤菌根腐病的潜力。