Optimized fertilization for effective suppression of soil-borne disease: Differential effects on bulk and rhizosphere soils

Abstract

Continuous cropping is widely practiced to maximize economic benefits and land utilization, but it often leads to outbreaks of soil-borne diseases, posing significant challenges to crop production and sustainable use of farmland soil. To sustain soil fertility and productivity in continuous cropping system, various fertilization strategies have been explored. However, the relationship between fertilization and soil microbial communities, particularly concerning soil-borne diseases, remains poorly understood. This study aims to investigate the mechanism of optimized fertilization in mitigating soil-borne diseases by comparing the responses of bulk and rhizosphere soils to different fertilizer applications. We investigated the effects of fertilization methods on soil chemical properties, microbial communities, early blight and yields through a six-year continuous potato cropping experiment, including optimized fertilization (NPK), farmer fertilization practice (FP), nutrient omissions, and application of agricultural organic materials. NPK alleviated early blight in potatoes and slowed down yield reduction by 33.9 %. NPK with corn straw or sheep manure increased particulate organic matter (POM), reduced the disease index (2.25 % and 3.80 %, respectively), and had more significant effect on fungal community in bulk soil ( R 2 = 0.45, P = 0.002) than rhizosphere soil. The results demonstrated that optimized fertilization facilitated carbon accumulation in bulk soil and nitrogen fixation in rhizosphere soil. Moreover, the impacts of nitrogen, phosphorus, or potassium on microbial communities differed between bulk and rhizosphere soils, largely due to the responses of POM. We identified POM as a key factor influencing soil-borne diseases and demonstrated its relationship with disease suppression. Optimized fertilization was found to mitigate early blight and reduce yield loss by increasing POM, a key factor influencing soil-borne diseases and balancing fungal communities in continuous cropping soils. Our research sheds light on the mechanism of optimized fertilization in abating soil-borne diseases, which remained elusive in prior studies. For the first time, we identified and demonstrated the strong association between POM and soil-borne disease. These findings highlight the crucial, yet often overlooked, role of bulk soil quality in suppressing soil-borne disease and provide valuable insights into cultivating disease-suppressing soils. • Relationship between particulate organic matter (POM) and soil-borne disease is demonstrated. • Optimized fertilization enhances carbon/nitrogen sequestration by increasing POM. • Optimized fertilization alleviates fungal community deterioration in bulk soil. • A promising perspective for broad-spectrum control of diseases is provided.