Does liming improve microbial carbon use efficiency after maize litter addition in a tropical acidic soil?

Abstract

Soil pH is one of the main drivers of soil microbial functions, including carbon use efficiency (CUE), the efficiency of microorganisms in converting substrate C into biomass, a key parameter for C sequestration. We evaluated liming effects after maize-litter addition on total CUE (including microbial residues), CUE of microbial biomass (CUEMB), and fungal biomass on an acidic Acrisol with a low C. We established a 6-week incubation experiment to compare limed and unlimed Acrisol treatments and a reference soil, a neighboring Nitisol with optimal pH. Fungal biomass (ergosterol) increased ~ 10 times after litter addition compared with soils without litter, and the final amount was greater in the limed Acrisol than the Nitisol. Litter addition induced a positive priming effect that increased with increasing pH. The increases in soil pH also led to increases in litter-derived CO2C and decreases in particulate organic matter (POM)C. Thus, in spite of increasing microbial biomass C, CUE decreased with increasing pH and CUEMB was similar across the three soils. CUEMB was positively associated with saprotrophic fungi, implying that fungi are more efficient in incorporating litter-derived C into microbial, especially fungal biomass after 42 days. By including undecomposed maize litter and microbial residues, CUE provided a more comprehensive interpretation of pH and liming effects than CUEMB. Nevertheless, longer-term studies may provide further information on substrate-C turnover and the persistence of liming and pH effects.

The Effects of Exogenous Benzoic Acid on the Physicochemical Properties, Enzyme Activities and Microbial Community Structures of Perilla frutescens Inter-Root Soil

“…Rousk et al proposed that low pH values can reduce microbial indicators of soil quality, such as fungi, bacteria, and microbial biomass and, to a lesser extent, reduce microbial activity without affecting metabolism [ 52 ]. Fungi in soil have a strong tolerance for acidification, and Moran et al’s research has shown that fungal biomass is not affected by pH values [ 53 ]. Therefore, the changes in fungal biomass are not as significant as those in bacteria, and the abundance of some acidophilic microbial populations changes significantly, disrupting the distribution balance between bacterial and fungal communities.…”

Microbial Mechanisms of the Priming Effect over 12 Years of Different Amounts of Nitrogen Management

“…For example, Marie et al [11] suggested that soil amended with N benefited from both an increase in the residual C absorbed by the microbes and a reduction in the SOC loss triggered by the PE when compared with soil under conditions of limited N. Additionally, a significant negative relationship between CUE and the PE under low-N treatment conditions was recently reported [14,15]. N fertilizer can increase the CUE by decreasing the stoichiometric C-to-N imbalance [13][14][15][16]. Many researchers have noted that CUE not only represents residual C utilization, but it also is associated with SOC accumulation and long-term C stabilization [9,17], because a positive relationship between SOC sequestration and CUE has been found [13,18].…”

“…Soil N availability is a dominant factor driving microbial CUE. For example, Marie et al [11] suggested that soil amended with N benefited from both an increase in the residual C absorbed by the microbes and a reduction in the SOC loss triggered by the PE when compared with soil under conditions of limited N. Additionally, a significant negative relationship between CUE and the PE under low-N treatment conditions was recently reported [14,15]. N fertilizer can increase the CUE by decreasing the stoichiometric C-to-N imbalance [13][14][15][16].…”

“…Nitrogen (N) is one of the most important elements for crop growth in agroecosystems [13]. Many studies have shown that N addition can directly influence soil microbes [14][15][16]. Normally, it enhances the relative abundance of R strategists (which are mainly copiotrophs that prefer nutrient-rich environments and are likely to use labile C) but decreased the abundance of K strategists (which are mainly oligotrophs that prefer nutrient-limited conditions and are likely to consume refractory C in soil) [8,13,17].…”