Abstract. Conservation tillage has attracted increasing attention
over recent decades, mainly due to its benefits for improving soil organic
matter content and reducing soil erosion. However, the effects of long-term
straw mulching under a no-till system on soil physicochemical properties and
bacterial communities at different soil depths are still unclear. In this
12-year experiment of straw removal (CK) and straw mulching (SM) treatments,
soil samples were collected at 0–5, 5–10, 10–20, and 20–30 cm soil
depths. The results showed that the contents of organic carbon (C), nitrogen
(N), and phosphorus (P) fractions, and bacterial abundance significantly
decreased, whereas pH significantly increased with soil depth. Compared with
CK, SM significantly increased total N, inorganic N, available P, available
potassium, and soil water content at 0–5 cm, total organic C content at
0–10 cm, and dissolved organic C and N contents at 0–20 cm. Regarding
bacterial communities, SM increased the relative abundances of
Proteobacteria, Bacteroidetes, and Acidobacteria but reduced those of
Actinobacteria, Chloroflexi, and Cyanobacteria. Bacterial Shannon diversity
and Shannon's evenness at 0–5 cm were reduced by SM treatment compared to
CK treatment. Furthermore, SM increased the relative abundances of some
C-cycling genera (such as Terracidiphilus and Acidibacter) and N-cycling genera (such as
Rhodanobacter, Rhizomicrobium, Dokdonella, Reyranella, and Luteimonas) at 0–5 cm. Principal coordinate analysis showed that the
largest difference in the composition of soil bacterial communities between
CK and SM occurred at 0–5 cm. Soil pH and N and organic C fractions were
the major drivers shaping soil bacterial communities. Overall, SM treatment
is highly recommended under a no-till system because of its benefits to soil
fertility and bacterial abundance.
Effects of soil physicochemical properties and stand age on fine root biomass and vertical distribution of plantation forests in the Loess Plateau of China
