Carbon use efficiency and microbial functional diversity in a temperate Luvisol and a tropical Nitisol after millet litter and N addition

Abstract

Tropical soils often contain less soil organic C (SOC) and microbial biomass C (MBC) than temperate soils and, thus, exhibit lower soil fertility. The addition of plant residues and N fertilizers can improve soil fertility, which might be reflected by microbial C use efficiency (CUE) and functional diversity. A 42-day incubation study was carried out, adding leaf litter of the C4 plant finger millet (Eleusine coracana Gaertn.) and inorganic 15N fertilizer. The aim was to investigate amendment effects on CUE and functional diversity in a tropical Nitisol and a temperate Luvisol. At day 42, 28% of the millet litter-derived C (C4) added was mineralised to CO2C4 in the temperate Luvisol and only 18% in the tropical Nitisol, averaging all N treatments. In contrast, none of the different fractions used for calculating CUE values, i.e. CO2C4, MBC4, microbial residue C4, and particulate organic matter C4, differed between the soils in the N0 (no N addition) treatment. CUE values considering microbial residues varied around 0.63, regardless of soil type and sampling day, which needs further evaluation. Millet litter increased autochthonous SOC-derived CO2C3 production, but N addition did not. This priming effect was apparently not caused by N mining. The respiratory response to most substrates added by multi-substrate-induced respiration (MSIR) and, thus, functional diversity was higher in the Luvisol than in the Nitisol. Millet litter had positive and N addition negative effects on the functional diversity of Nitisol, indicating that MSIR is a useful tool for evaluating soil fertility.

Effects of Litter and Root Manipulations on Soil Bacterial and Fungal Community Structure and Function in a Schrenk’s Spruce (Picea schrenkiana) Forest

“…Soil microbial diversity is closely related to microbial stability, soil quality, and nutrient cycles and is susceptible to the input of exogenous organic matter ( Schroeder et al, 2020 ; Xu et al, 2021 ). Generally, the increase in resource availability under litter addition treatments contributes to the growth of individual microorganisms ( Storch et al, 2018 ), thus increasing soil microbial diversity ( Dilly et al, 2004 ).…”

Microbial carbon use efficiency of litter with distinct C/N ratios in soil at different temperatures, including microbial necromass as growth component

“…litter, respectively, using the POM recovery approach (Joergensen and Wichern 2018). Schroeder et al (2020) also observed no effect of N fertilization on CUE, but a strong true priming effect on SOM (Kuzyakov et al 2000), apparently not caused by N mining, as N fertilization affected neither CUE nor SOM priming. This might be different for plant residues differing in their C/N ratio, especially at different temperatures, which has not been tested by the POM recovery approach (Joergensen and Wichern 2018) until now.…”

“…Positive (Oliver et al 2021;Soares and Rousk 2019) and negative relationships (Manzoni et al 2017;Xiao et al 2021) have been reported between the litter C/N ratio and CUE vales. However, Lukas et al (2019) and Schroeder et al (2020) did not find any effect of soil type on the CUE of maize (Zea mays L.) and finger millet (Eleusine coracana Gaertn.) litter, respectively, using the POM recovery approach (Joergensen and Wichern 2018).…”

“…(3) N-rich maize litter caused a smaller true priming effect than N-poor Rhodes grass litter. Schroeder et al (2020) also did not find any effect of incubation time, although the metabolization of added complex substrates is usually incomplete to different extents at specific sampling dates (Faust et al 2019). However, incubation times of 7 and 42 days used by Schroeder et al (2020) may still not be the optimum for estimating CUE values of plant residues, which requires additional experimental efforts.…”

Efeito Das Mudanças Do Uso Da Terra Nas Propriedades Dos Solos Temperados E Tropicais

“…Em ecossistemas temperados os solos contem mais carbono orgânico e nutrientes minerais do que os solos de clima tropical, e portanto, apresentam maior fertilidade (SCHROEDER et al, 2020). As vezes, um excesso de nutrientes é uma preocupação maior com muitos solos temperados sob agricultura, enquanto ao aumento da fertilidade do solo é um importante tópico de pesquisa atual em muitas regiões tropicais (LIZCANO et al, 2017).…”