Effects of Replanting Summer Broad Bean after Spring Potatoe Harvest on Soil Nutrients and Bacterial Community Structure under Rainwater Harvesting and Supplementary Irrigation

PurposeTo study the effects of spring potato-summer broad bean multiple cropping (potato-bean multiple cropping) + bean stalk returning to the field on the changes of soil nutrient and the structure of bacterial community under rainwater harvesting and supplementary irrigation.

MethodsAfter potato-bean multiple cropping + bean stalk return to field, fallow after potato planting, and potato continuous cropping treatments, taking the soil of three different treatments to measure the soil physical and chemical properties on agrochemical analysis method, and the Illumina NovaSeq PE250 was used to perform high-throughput sequencing of the soil bacteria 16S V3-V4 region.

ResultsOn the conditions of rainwater harvesting and supplemental irrigation, spring-cropped potatoes emerged 75-76 days earlier and harvested 43-74 days earlier than conventional cultivation mode, avoiding late blight, and the yields of Dianshu23, Dianshu47, and Qingshu No.9 increased 28 953.0, 8 571.0, 28 570.5 kg/hm², respectively. To compare with continuous potato cropping, the soil pH of potato-bean multiple cropping + bean stalk return to the field increased by 0.17, organic matter content increased by 0.35%, total nitrogen content increased by 0.02%, available nitrogen content increased by 43.6 mg/kg, and available potassium content increased by 51.5 mg/kg. To compare with fallow after potato planting, the soil pH of potato-bean multiple cropping + bean stalk return to the field increased by 0.14, organic matter content increased by 0.33%, total nitrogen content increased by 0.02%, total phosphorus content increased by 0.02%, and available nitrogen content increased by 39.8 mg/kg. The relative abundance of Actinobacteria, Gemmatimonadetes, and Sphingomonas in the soil under the potato-bean multiple cropping + bean stalk return mode was higher than that in the fallow and continuous cropping mode of potato, but the abundance of Acidobacteria in continuous cropping mode was higher. Correlation analysis showed that the soil pH, total phosphorus and total potassium content were the main environmental factors that drive changes in bacterial phyla abundance.

ConclusionPotato-bean multiple cropping + returning bean stalks to the field can improve soil fertility, slowing down soil acidification, and increasing the relative abundance of soil beneficial bacteria phyla and genera, while continuous potato cropping will reduce soil pH and decrease the abundant of beneficial bacteria; supplemental irrigation with rainwater harvesting of spring potatoes can increase the multiple cropping index, improve land used efficiency, improve soil nutrition and bacterial community structure, and reduce the obstacles to continuous potato cropping.