Response of potato yield, soil chemical and microbial properties to different rotation sequences of green manure-potato cropping in North China

Continuous cropping of potato (Solanum tuberosum L.) can result in soil degradation and yield decline. These negative effects could be alleviated by crop rotation. Green manure-potato rotation is being proposed as an alternative that can sustain high yield and soil quality in potato production system. However, the mechanisms by which biotic and abiotic factors are affected by different cropping sequences remain unclear. A 12-year green manure (G)-potato (P) rotation experiment was conducted to explore the response of potato yield, soil chemistry properties, and microbial community composition to different rotation sequences in North China, the cropping sequence treatment included 2-year of green manure and 1-year of potato (P1G2), 1-year of green manure and 2-year of potato (P2G1), and continuous cropping potato (P3), with a rotation period of 3-year. The content of NH4+-N (AN), organic matter (OM), available potassium (AK), total phospholipid fatty acids (PLFAs), and bacterial PLFAs in soil, and potato yield were higher in P1G2 compared with those in P2G1 and P3, while the ratio of fungal to bacterial biomarkers was decreased significantly than that in P3. Soil dominant bacterial phyla Bacteroidetes, Gemmatimonas, Proteobacteria, and Nitrospirae presented higher abundance in P1G2 relative to those in P2G1 and P3; however, phyla Actinobacteria decreased significantly in P1G2 than other two treatments. The beneficial microflora Sphingomonas, Haliangium, Gemmatimonas, and Pseudogymnoascus increased significantly in P1G2 over P2G1 and P3, and the pathogenic fungal Fusarium, Stagonosporopsis, Alternaria, and Lectera showed higher abundance in P3 than P1G2 and P2G1. The redundant analysis showed that soil AN, OM, AP, and AK were positively correlated with dominant flora of bacteria and fungi in P1G2, and were negatively correlated with dominant flora of bacteria and fungi in P3. Partial least squares path modeling revealed that the conversion of cropping sequences had a direct positive effect on the fungal community rather than the bacterial community. Overall, the rotation cropping combined green manure and potato attained higher potato yield by maintaining higher soil fertility and healthy ecosystem, we also gave a suggestion on rotation sequences combined yield and economic benefits of potato.