Long-term nitrogen fertilization and sweetpotato cultivation in the wheat-sweetpotato rotation system decrease...

Area of Science:

• Soil microbiology
• Biogeochemical cycles
• Agricultural science

Background:

• Alkaline phosphomonoesterase (ALP)-harboring bacteria (phoD-harboring communities) are vital for converting organic phosphorus to available phosphorus.
• Understanding how fertilization and crop type affect these communities in crop rotations is crucial but poorly understood.
• A nine-year field experiment under a wheat-sweetpotato rotation investigated these impacts.

Purpose of the Study:

• To analyze the response of phoD-harboring bacterial communities to different fertilization strategies and crop types.
• To investigate the correlation between these communities, their functional activity (ALP), and soil physicochemical properties.
• To elucidate the interactions within a wheat-sweetpotato rotation system.

Main Methods:

• Field experiment with four fertilization strategies: no fertilization (CK), inorganic NK, inorganic NPK, and NPK + organic fertilizer (NPKM).
• Soil sampling after crop harvest for analysis.
• High-throughput sequencing for bacterial community composition and enzymology for ALP activity.
• Structural equation modeling to assess relationships between variables.

Main Results:

• Long-term nitrogen (N) fertilization, particularly inorganic N, decreased soil pH and ALP activity, while increasing available phosphorus (AP).
• Available phosphorus (AP) levels were higher in the sweetpotato season than in the wheat season.
• Inorganic N fertilization significantly altered phoD-harboring bacterial communities, reducing diversity and the abundance of key genera like Acuticoccus, Methylibium, Rhizobacter, and Roseivivax.
• Soil pH and AP were identified as key regulators of phoD-harboring bacteria communities and ALP activity.

Conclusions:

• Fertilization strategies and crop types significantly impact phoD-harboring bacterial communities and their phosphorus-cycling functions.
• Soil acidification from inorganic N fertilization has detrimental effects on these crucial bacterial communities.
• Combined application of inorganic and organic fertilizers can effectively mitigate the adverse effects of N fertilization on soil P-cycling bacteria.