Impacts of urea N addition on soil microbial community in a semi-arid temperate steppe in northern China

Abstract

Nitrogen (N) addition has been well documented to decrease plant biodiversity across various terrestrial ecosystems. However, such generalizations about the impacts of N addition on soil microbial communities are lacking. This study was conducted to examine the impacts of N addition (urea-N fertilizer) on soil microbial communities in a semi-arid temperate steppe in northern China. Soil microbial biomass carbon (C), biomass N (MBN), net N mineralization and nitrification, and bacterial and fungal community level physiological profiles (CLPP) along an N addition gradient (0-64 g N m −2 year −1 ) were measured. Three years of N addition caused gradual or step increases in soil NH 4 -N, NO 3 -N, net N mineralization and nitrification in the early growing season. The reductions in microbial biomass under high N addition levels (32 and 64 g N m −2 year −1 ) are partly attributed to the deleterious effects of soil pH. An N optimum between 16 and 32 g N m −2 year −1 in microbial biomass and functional diversity exists in the temperate steppe in northern China. Similar N loading thresholds may also occur in other ecosystems, which help to interpret the contrasting observations of microbial responses to N addition.

Effects of addition of nitrogen on soil fungal and bacterial biomass and carbon utilisation efficiency in a city lawn soil

“…Previous studies showed that N addition stimulated microbial biomass in grassland or pasture (Rousk and Bååth 2007;Hamer et al 2009). However, decreases in microbial biomass with increasing N application in steppe have also been reported (Zhang et al 2008;Bi et al 2012), which is consistent with our results. The soil acidification caused by N addition in this study was more severe than that experienced in other studies (Magill et al 1997;Lu et al 2009).…”

Effects of Cryo-Treatment on Corrosion Behavior and Mechanical Properties of Laser-Welded Commercial Pure Titanium

“…5. The data was statistically analyzed by One-way analysis of variance (ANOVA) and followed by Turkey's HSD test 26) at a 95% significance level. Statistical p-value was set to p < 0.05.…”

Response of fungal composition and diversity to simulated nitrogen deposition and manipulation of precipitation in soils of an Inner Mongolia desert steppe of Northern China

“…Increasing N deposition, precipitation changes, and associated ecological alterations influence the soil microbial communities in various ecosystems; hence, these phenomena will become important topics for future research (Zhang et al 2008;Zak et al 2011). …”