Effects of long-term application of chemical fertilizers on soil phosphorus forms,phosphatase activity and bacterial phoD gene abundance and diversity in red soil
This study was conducted at the national long-term experimental site of red soil fertility and fertilizer benefit in the Qiyang Red Soil Experimental Station,Hunan Province.There were four fertilization treatments:nitrogen fertilizer(N),NK fertilizer(NK),NP fertilizer(NP),NPK fertilizer(NPK).The effects of long-term applications of chemical fertilizers on soil P forms,phosphatase activity,and bacterial phoD gene abundance and diversity in red soils were examined using real-time quantitative PCR and high-throughput sequencing.Results showed that compared with N fertilizer only,N combined with P or K could retard soil acidification,and N com-bined with P could significantly increase the contents of all soil P forms.Furthermore,NP and NK treatments sig-nificantly increased soil alkaline phosphatase activity and the abundance of soil total bacteria and phoD gene com-pared with N treatment.Similarly,NPK treatment significantly increased soil alkaline phosphatase activity and soil total bacterial abundance,but decreased soil phoD gene abundance.However,both α-and β-diversity of phoD gene communities was similar across all the treatments.More than 45%of phoD gene originated from Pseudomonas and Janthinobacterium in all the treatments,respectively.Furthermore,there were significantly positive correlations between the relative abundance of Streptomyces,Massilia,Brevundimonas and the contents of soil P forms.Our findings indicated that the critical factors regulating functional bacterial abundance and phosphatase activity were distinct under different nutrient input conditions.Rational fertilization of NPK could increase soil P content and phosphatase activity and change phoD gene abundance and community structure,which could improve soil P sup-ply.However,long-term application of chemical fertilizers caused simplification of soil microbial community.
chemical fertilizerhigh-throughput sequencingphosphorusphosphatasephoD gene abundance and diversity