Abstract
The influence of water and nitrogen (N) management on wheat have been investigated, but studies on the impact of long-term interactive water and N management on microbial structure and function are limited. Soil chemical properties and plants determine the soil microbial communities whose functions involved in nutrient cycling may affect plant productivity. There is an urgent need to elucidate the underlying mechanisms to optimize these microbial communities for agricultural sustainability in the winter wheat production area of the North China Plain. We performed high-throughput sequencing and quantitative PCR of the 16S rRNA gene on soil from a 7-year-old stationary field experiment to investigate the response of bacterial communities and function to water and N management. It was observed that water and N management significantly influenced wheat growth, soil properties and bacterial diversity. N application caused a significant decrease in the number of operational taxonomic units (OTUs), and both Richness and Shannon diversity indices, in the absence of irrigation. Irrigation led to an increase in the relative abundance of Planctomycetes, Latescibacteria, Anaerolineae, and Chloroflexia. In addition, most bacterial taxa were correlated with soil and plant properties. Some functions related to carbohydrate transport, transcription, inorganic ion transport and lipid transport were enriched in irrigation treatment, while N enriched predicted functions related to amino acid transport and metabolism, signal transduction, and cell wall/membrane/envelope biogenesis. Understanding the impact of N application and irrigation on the structure and function of soil bacteria is important for developing strategies for sustainable wheat production. Therefore, concurrent irrigation and N application may improve wheat yield and help to maintain those ecosystem functions that are driven by the soil microbial community.
Highlights
Water and nitrogen (N) are the two main factors limiting crop productivity worldwide (Sinclair and Rufty, 2012)
Significant interactions were obtained between water and N; this indicates that both wheat yield and root growth in the 0–20 cm are influenced by water, N application, and the combination of the two treatments
We found that irrigation significantly increased both root length density (RLD) and root weight density (RWD) (47.4% average increase)
Summary
Water and nitrogen (N) are the two main factors limiting crop productivity worldwide (Sinclair and Rufty, 2012). Most previous studies have focused on the influence of this pair of factors on ecosystem functions and higher level organisms (Qi et al, 2010; Lenka et al, 2013; Liu et al, 2018) These studies explored in-season effects of optimal water and N fertilizer management on crops, but not the sustainability of soil production capacity. Soil microbial biomass are the most abundant and ecologically important groups of organisms, and impact crop yield, soil productivity, and key ecosystem processes (Fierer et al, 2009; Marinari et al, 2010; Zhou et al, 2012; Agegnehu et al, 2016) Their response to water and N, in wheat field experiments, has not been examined
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