Irrigation of previous crops alleviates the negative impact of replacing chemical fertilizers with organic fertilizers on foxtail millet yield

Switching from chemical to organic fertilizers is considered an ideal choice because it can yield numerous benefits for soil health, environmental sustainability, and crop production. However, it is still unclear how to effectively implement and maximize the advantages of replacing chemical fertilizers with organic fertilizers while ensuring crop yield. The main objectives of this study were to explore the impact of previous crops irrigation and replacing chemical fertilizers with organic fertilizers on millet yield in the semi-arid North China Plain. The results showed that the irrigation of previous crops and the replacement of chemical fertilizer by organic fertilizer could affect the yield of millet by different pathways in the North China Plain. Irrigation of previous crops significantly increased millet yield, spike weight, and 1000-grain weight by reducing blighted grain ratio. The influence of organic and nitrogen fertilizer applications on millet yield was significantly affected by the amount of irrigation of previous crops. Millet yield decreased with higher soil exchangeable potassium and increased with higher soil pH by affecting blighted grain ratio, and the changes of soil pH and exchangeable potassium caused by irrigation and fertilizer applications significantly affected the yield of foxtail millet. Moreover, irrigation of previous crops and replacement of chemical fertilizer by organic fertilizer could affect millet yield by altering soil fungal community structure and reducing soil pathogen abundance, rather than soil fungal community species diversity. These findings highlight that the irrigation of previous crops should be considered as an efficiency pathway to maintain crop yield by replacing chemical fertilizers with organic fertilizers because it reduces pathogen abundance and enhances soil nutrient utilization.