Abstract
Fertilization plays important roles in improving soil fertility and in increasing crop yield. Soil microbial communities are sensitive indicators of soil quality and health, which could be affected by fertilization strategy. However, our knowledge on how organic–inorganic fertilizers application affects soil bacterial communities remains largely poorly understood. In this study, we investigated the long-term effects of different organic–inorganic fertilization strategies: without fertilizer (CK), fertilizers NPK (CF), fertilizers NPK, plus 30% organic manure (CFM1), and fertilizers NPK plus 60% organic manure (CFM2) on soil bacterial communities in paddy fields. Results showed that the bacterial 16S ribosomal DNA (rDNA) gene abundances in treatments CF, CFM1, and CFM2 were 1.44, 1.54, and 1.28 times higher than that in CK and the ACE index in treatment CFM1 was 9.0% greater than that in treatment CFM2, respectively. Fertilization strategy significantly changed the relative abundance of Nitrospirae, Gemmatimonadetes, and unclassified bacteria at the phylum level and bacteria belonging to order Nitrospira, candidate bacterium SBR2076, unclassified bacteria, Syntrophobacterales, and Solibacterales at the order level, respectively. High organic–inorganic fertilizer application rates inhibited the growth of Nitrospirae by 20–35%, and stimulated the growth of Gemmatimonadetes by 14–77%, relative to the rest of the treatments, respectively. Hierarchical cluster and principal coordinate analysis (PCoA) showed that the fertilization strategy affected the bacterial community structures, and the organic–inorganic fertilized treatments possessed similar bacterial community structures. Furthermore, soil pH, total nitrogen (TN), and soil organic carbon (SOC) were the main driving factors altering the bacterial communities. Our results suggested that combined organic–inorganic fertilizers application increased soil nutrient contents and bacterial abundances, and this could be an optimized fertilization strategy in regulating soil bacterial communities for rice production.
Highlights
Fertilization is the most commonly used agricultural practice worldwide for improving soil fertility and increasing grain yield in crop production [1,2]
Our results suggested that combined organic–inorganic fertilizers application increased soil nutrient contents and bacterial abundances, and this could be an optimized fertilization strategy in regulating soil bacterial communities for rice production
Our results demonstrated that long-term fertilization significantly increased the bacterial 16S ribosomal DNA (rDNA) gene abundances by 1.28–1.54 fold, and rarely affected the bacterial alpha diversity, with the exception of the abundance-based coverage estimator (ACE) index
Summary
Fertilization is the most commonly used agricultural practice worldwide for improving soil fertility and increasing grain yield in crop production [1,2]. Farmers normally apply high amounts of fertilizers into agricultural fields, in order to obtain high crop grain yield, and to maintain soil productivity. Agronomy 2019, 9, 14 has been supposed to be an effective way to increase soil organic matter and to improve soil fertility [6], and which has been wildly recommended by the Chinese government since the 1980s [7]. Soil microbial communities can supply some essential nutrients for crop growth [12] and their biomasses, diversities, and activities are sensitive indicators of soil quality, productivity, and sustainability in terrestrial ecosystems [5,13,14]. The growth, activity, and functional diversity of soil bacterial communities can be affected by various factors, including climatic, vegetation, soil type, land use strategy, and fertilization practices [10,11,15]
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