Soil bacterial communities exhibit systematic spatial variation with landform across a commercial potato field

Large numbers of bacterial species inhabit soils of agricultural fields. The number and abundance of bacterial species (i.e. bacterial community diversity) is influenced by soil properties (e.g., organic matter, soil pH, clay content). It is widely accepted that soil properties in agricultural fields change along slopes, however it was unclear how slopes and soil properties would influence the bacterial community diversity. This study examined the influence of soil properties and slope characteristics on bacterial community diversity in a commercial potato field with rolling landscape. Eighty-three soil samples were collected over a distance of 1100 m. Soil pH (the acidity of the soil) was strongly correlated with slope (i.e. soils at the top of the slope were more acidic compared to soils at the foot of the slope). Analysis of the bacterial community diversity showed that soil pH, slope steepness and organic carbon were the major factors influencing the diversity of the bacterial community across the field. The study brought new insight into how bacterial communities develop in agricultural soils, and what factors may be important in maintaining soil essential functions which support crop productivity, such as nitrogen cycling and carbon matter decomposition. The two major factors influencing bacterial communities, soil pH and organic carbon, are ones that can be managed within agricultural fields through application of lime and application of organic amendments (manure, compost), respectively. Thus it may be possible to influence diversity of bacterial communities in agricultural fields.