Vital roles of soil microbes in driving terrestrial nitrogen immobilization

Abstract

Nitrogen immobilization usually leads to nitrogen retention in soil and, thus, influences soil nitrogen supply for plant growth. Understanding soil nitrogen immobilization is important for predicting soil nitrogen cycling under anthropogenic activities and climate changes. However, the global patterns and drivers of soil nitrogen immobilization remain unclear. We synthesized 1350 observations of gross soil nitrogen immobilization rate (NIR) from 97 articles to identify patterns and drivers of NIR. The global mean NIR was 8.77 ± 1.01 mg N kg−1 soil day−1. It was 5.55 ± 0.41 mg N kg−1 soil day−1 in croplands, 15.74 ± 3.02 mg N kg−1 soil day−1 in wetlands, and 15.26 ± 2.98 mg N kg−1 soil day−1 in forests. The NIR increased with mean annual temperature, precipitation, soil moisture, soil organic carbon, total nitrogen, dissolved organic nitrogen, ammonium, nitrate, phosphorus, and microbial biomass carbon. But it decreased with soil pH. The results of structural equation models showed that soil microbial biomass carbon was a pivotal driver of NIR, because temperature, total soil nitrogen, and soil pH mostly indirectly influenced NIR via changing soil microbial biomass. Moreover, microbial biomass carbon accounted for most of the variations in NIR among all direct relationships. Furthermore, the efficiency of transforming the immobilized nitrogen to microbial biomass nitrogen was lower in croplands than in natural ecosystems (i.e., forests, grasslands, and wetlands). These findings suggested that soil nitrogen retention may decrease under the land use change from forests or wetlands to croplands, but NIR was expected to increase due to increased microbial biomass under global warming. The identified patterns and drivers of soil nitrogen immobilization in this study are crucial to project the changes in soil nitrogen retention.

Plant‐available soil nitrogen fluxes and turfgrass quality of Kentucky bluegrass fertilized with humic substances

“…The PCHCU had the longest N release period, allowing for the longest duration of plant‐available N to be captured on the IEM. Microbial growth and activity can affect the turnover and organic matter mineralization, which can regulate the inorganic N pool (Chen et al., 2018; Li et al., 2021). Furthermore, PCHCU was found to increase microbial activity by 30% and 68% and the amount of potential N mineralization by 5% and 59% compared with urea and the nontreated control, respectively (Lindsey et al., 2021).…”

“…The PCHCU had the longest N release period, allowing for the longest duration of plant-available N to be captured on the IEM. Microbial growth and activity can affect the turnover and organic matter mineralization, which can regulate the inorganic N pool (Chen et al, 2018;Li et al,…”

Effects of arbuscular mycorrhizal fungi on improvement of degraded landscape soil in an ionized rare earth mining area, subtropical China

“…Soil microbes are very sensitive to environmental changes and can be used as an indicator of soil quality (Z. Li et al., 2021); their community composition and activity could indicate the element cycles of natural ecosystems, which play important roles in improving soil fertility and restoring the positive succession of ecosystems (L. Zhou et al., 2015). A previous study showed that biochar addition has positive effects on soil microbes (Prayogo et al., 2013).…”

Enriching organic carbon bioavailability can mitigate soil acidification induced by nitrogen fertilization in croplands through microbial nitrogen immobilization

“…Strong nitrification may result in surplus NO 3 − in soil, which is susceptible to loss by leaching or denitrification and causes both economic and environmental problems (Subbarao et al, 2006). However, microbial N immobilization is of great importance because it incorporates N into microbial biomass and reduces the risk of reactive N being lost to the environment (Nascente et al, 2021;Z. L. Li et al, 2021).…”