Responses of absolute and specific enzyme activity to consecutive application of composted sewage sludge in a Fluventic Ustochrept

Abstract

Composted sewage sludge (CS) is considered a rich source of soil nutrients and significantly affects the physical, chemical, and biological characteristics of soil, but its effect on specific enzyme activity in soil is disregarded. The present experiment examined the absolute and specific enzyme activity of the enzymes involved in carbon, nitrogen, and phosphorus cycles, the diversity of soil microbial functions, and soil community composition in a Fluventic Ustochrept under a maize—wheat rotation system in North China during 2012–2015. Application of CS led to increase in MBC and in its ratio to both total organic carbon (TOC) and microbial biomass nitrogen (MBN). Absolute enzyme activity, except that of phosphatase, increased in CS-treated soils, whereas specific activity of all the enzymes declined, especially at the highest dose of CS (45 t ha−1). The diversity of soil microbial community also increased in CS-treated soils, whereas its functional diversity declined at higher doses of CS owing to the lowered specific enzyme activity. These changes indicate that CS application induced the domination of microorganisms that are not metabolically active and those that use resources more efficiently, namely fungi. Redundancy analysis showed that fundamental alterations in soil enzyme activity depend on soil pH. Soil specific enzyme activity is affected more than absolute enzyme activity by changes in soil properties, especially soil microbial activity and composition of soil microflora (as judged by the following ratios: MBC/TOC, MBC/MBN, and TOC/LOC, that is labile organic carbon) through the Pearson Correlation Coefficient. Specific enzyme activity is thus a more accurate parameter than absolute enzyme activity for monitoring the effect of adding CS on the activities and structure of soil microbial community.

Relationships between Cement Dust Emissions and Soil Properties

“…Similarly, the maximum DH activity is reported at soil pH of 6.6-7.2 [44]. Since both urease and DH activity had been greatly influenced by substrate availability, low amounts of labile organic C and N in high pH soil close to cement plant correspondingly resulted in low levels of urease and DH activity [45]. Likewise, a difference in microbial Table 3.…”

Synthesis of Novel Core-Shell Magnetic Fe₃O₄@C Nanoparticles with Carboxyl Function for Use as an Immobilisation Agent to Remediate Lead-Contaminated Soils

“…The pH was determined by potentiometry FE20 (METTLER-TOLEDO CO., Ltd, ZURICH, CH) [28]. Briefly summarized here are the following: step 1 (acid soluble state) -the WC was determined by drying method [29]. The EC was determined by the 5:1 extraction method [28].…”

Soil Phosphatase Activities across a Liming Gradient under Long‐Term Managements in Kenya

“…(3) Phosphate activities normalized to microbial biomass P (i.e., µmol pNP µg -1 P mic h -1 ), in order to account for the potential influence of microbial biomass changes on measured response of phosphatase activities (Waldrop, 2000;Turner and Haygarth, 2005;Liu, 2017).…”