Microbial nutrient limitation and catalytic adjustments revealed from a long‐term nutrient restriction experiment. Issue 2 (11th April 2022)

• Record Type: Journal Article
• Authors: Kumar, Amit; Pausch, Johanna
• Is Part Of: Journal of sustainable agriculture and environment. Volume 1:Issue 2(2022)
• Page Start: 142
• Page End: 148
• Publication Date: 2022-04-11
• Subjects: catalytic efficiency -- enzyme activity -- kinetic parameters -- microbial biomass -- phosphorus fertilisation; Sustainable agriculture -- Periodicals; Agriculture -- Environmental aspects -- Periodicals; Agriculture -- Environmental aspects; Alternative agriculture; Sustainable agriculture; Periodicals; 630.2086
• DOI: 10.1002/sae2.12015
• Languages: English
• ISSNs: 2767-035X

Abstract

Abstract: Introduction: Microbial abundance and activities in soils are predominantly determined by soil carbon (C), nitrogen (N) and phosphorus (P) availability. Much research has focused on the effects of soil N than P availability on soil microbial biomass and enzyme activities as sensitive proxies of microbial ecophysiology highlighting the need to investigate how microbes will respond to P availability in soil, especially in cropping systems. Materials and Methods: The effect of P fertilisation on microbial biomass‐C, ‐N and ‐P, and the kinetic parameters (maximal velocity [ V max ], Michaelis constant [ K m ] and catalytic efficiency [ K a ]) of β‐1, 4‐glucosidase (BG; C‐acquiring), leucine‐aminopeptidase (LAP; predominantly N‐acquiring) and acid phosphomonoesterase (PHO; P‐acquiring) were measured in a nutrient‐poor agricultural soil (devoid of fertiliser application since 1942). Results: This study showed that P fertilisation led to a 65% and 56% increase in microbial biomass‐N and ‐P, respectively, indicating severe P limitation and inefficient N acquisition by microbes without P availability. Increased K a values of LAP with P fertilisation further hint toward the production of efficient isoenzymes to avoid resource tradeoffs for nutrient acquisition. Conclusions: Overall, these results decipher microbial metabolic and catalytic adjustments mediated by soil P availability. Increased microbial biomass‐N and ‐P with P fertilisation indicated microbial N and P colimitation that was partly overcome by the production of efficient enzymes for N acquisition with P fertilisation. We argue to incorporate microbial enzyme activities as a response to different management strategies to better inform us about soil biogeochemical cycles in cropping systems.