Variation of nitrate and bacterial diversity along soil profiles in
manure-disposal maize field and adjacent woodland
Abstract
Intensified livestock system produced large amount of bio-waste, and
improper disposal of livestock manure has led to severe environmental
consequences. However, knowledge about the time-dependent changes of
manure-derived nitrate and soil bacterial diversity along the soil
profiles is limited. In this study, vertical variation of soil bacterial
diversity and composition in a manure-amended maize field and adjacent
non-manured woodland was investigated using high-throughput sequencing
technique in spring and autumn along a 1-meter profile depth. The
results showed that higher amount of nitrate was detected along the soil
profile loaded with cattle manure compared with the adjacent non-manured
woodland, and soil δ15N-NO3- composition further corroborated the
manure-derived nitrate in the maize field. No significant difference in
bacterial richness between the two land uses was found, while clear
separation of bacterial structure was detected even to the deep soil
layers. Canonical correspondence analysis showed that soil properties
were the major factors influencing the variance of bacterial community
composition. Bacterial network is more complex in the maize field than
in the adjacent woodland. Soil bacterial communities among the depth
profiles in the two land uses tended to be more phylogenetically
clustered than expected by chance, and were more likely to be clustered
along the depth. These findings suggested that bacterial β diversity was
strongly related to multi-nutrient properties with high livestock manure
load, and had important implications for assessing the environmental
impacts on below-ground biodiversity in sandy loam soils.