Interannual variability of soil microbial biomass and respiration in responses to topography, annual burning and N addition in a semiarid temperate steppe

Geoderma ◽  
2010 ◽  
Vol 158 (3-4) ◽  
pp. 259-267 ◽  
Author(s):  
Weixing Liu ◽  
Wenhua Xu ◽  
Jianping Hong ◽  
Shiqiang Wan
Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2057
Author(s):  
Sehrish Ali ◽  
Kailou Liu ◽  
Waqas Ahmed ◽  
Huang Jing ◽  
Muhammad Qaswar ◽  
...  

A long-term experiment (38 years) was conducted to elucidate the effects of long-term N addition on the net N mineralization in both paddy and upland soils, based on their initial soil N status, with and in connection with soil microbial biomass and N cycling extracellular enzyme activities. Two treatments without N addition CK (No fertilizer) and K (inorganic potassium fertilizer) and two treatments with N addition N (inorganic nitrogen fertilizer) and NK (inorganic nitrogen and potassium fertilizer) were placed in incubation for 90 days. Results showed that the total N and soil organic carbon (SOC) contents were higher in the treatments with N application compared to the treatments without N in both paddy and upland soils. The SOC content of paddy soil was increased relative to upland soil by 56.2%, 45.7%, 61.1% and 62.2% without N (CK, K) and with N (N and NK) treatments, respectively. Site-wise, total N concentration in paddy soil was higher by 0.06, 0.10, 0.57 and 0.60 times under the CK, K, N and NK treatments, respectively, compared with upland soil. In paddy soil, soil microbial biomass nitrogen (SMBN) was higher by 39.6%, 2.77%, 29.5% and 31.4%, and microbial biomass carbon (SMBC) was higher by 11.8%, 11.9%, 10.1% and 12.3%, respectively, in CK, K, N and NK treatment, compared with upland soil. Overall, compared to upland soil, the activities of leucine-aminopeptidase (LAP) were increased by 31%, 18%, 20% and 11%, and those of N-acetyl-b-D-glucosaminidase (NAG) were increased by 70%, 21%, 13% and 18% by CK, K, N and NK treatments, respectively, in paddy soil. A significantly linear increase was found in the NO3−-N and NH4+-N concentrations during the 90 days of the incubation period in both soils. NK treatment showed the highest N mineralization potential (No) along with mineralization rate constant, k (NMR) at the end of the incubation. SMBC, SMBN, enzyme activities, NO3−-N and NH4+-N concentrations and the No showed a highly significant (p ≤ 0.05) positive correlation. We concluded that long-term N addition accelerated the net mineralization by increasing soil microbial activities under both soils.


Author(s):  
Gong ◽  
Zhang ◽  
Guo

: Soil and soil microbial biomass (SMB) carbon: nitrogen: phosphorus (C:N:P) stoichiometry are important parameters to determine soil balance of nutrients and circulation of materials, but how soil and SMB C:N:P stoichiometry is affected by climate change remains unclear. Field experiments with warming and N addition had been implemented since April 2007. Infrared radiators were used to manipulate temperature, and aqueous ammonium nitrate (10 g m-2 yr-1) was added to simulate nitrogen deposition. We found that molar nutrient ratios in the soil averaged 60:11:1, warming and warming plus N addition reduced soil C:N by 14.1% and 20% (P < 0.01), and reduced soil C:P ratios by 14.5% and 14.8% (P < 0.01). N addition reduced soil C:N significantly by 17.6% (P < 0.001) (Figs. 2B, 2D). N addition and warming plus N addition increased soil N:P significantly by 24.6% and 7.7% (P < 0.01). The SMB C:N, C:P and N:P ratios increased significantly with warming, N addition and warming plus N addition. Warming and N addition increased the correlations between SOC and soil microbial biomass C (SMBC), soil total P and soil microbial biomass P (SMBP), warming increased the correlation between the soil total N and soil microbial biomass N (SMBN). After four years’ treatment, our results demonstrated that the combined effects of warming and N fertilization could change the C, N, P cycling by affecting soil and SMB C:N:P ratios significantly and differently. At the same time, our results suggested SMB might have weak homeostasis in Sonnen Grassland and warming and N addition would ease N-limitation but aggravate P-limitation in northeastern China. Furthermore, these results further the current demonstration of the relationships between the soil and SMB C:N:P stoichiometry in response to global change in temperate grassland ecosystems.


2019 ◽  
Vol 28 (3) ◽  
pp. e018
Author(s):  
Jingjing Wang ◽  
Jun Cui ◽  
Zhen Teng ◽  
Wei Fan ◽  
Mengran Guan ◽  
...  

Aim of the study: The aim of this study was to examine the effects of a 5-year simulated nitrogen (N) deposition on soil microbial biomass carbon (MBC), nitrogen (MBN), microbial community activity and diversity in subtropical old-growth forest ecosystems.Area of study: The study was conducted in forest located at subtropical forest in Anhui, east China.Material and methods: Three blocks with three fully randomized plots of 20 m × 20 m with similar forest community and soil conditions were established. The site applied ammonium nitrate (NH4NO3) to simulate N deposition (50 and 100 kg N ha−1 year −1). From three depths (0–10, 10–20 and 20–30 cm), were collected over four seasons (December, March, June and September), and then measured by community-level physiological profiles (CLPPs).Main results: N addition had no significant effect on MBC and MBN. The spatiotemporal variations in MBC and MBN were controlled by seasonality and soil depth. Soil microbial activities and diversity in the growing season (June and September) were apparently higher than the dormant season (March and December), there were significantly lower diversity indices found following N addition in September. However, N addition enhanced microbial activities and increased diversity indices in the dormant season. Redundancy analysis showed that pH, soil moisture, NO3--N and total phosphorus were the most important factors controlling the spatial pattern of microbial metabolic activity.Research highlights: These results suggest that soil microbial community function is more easily influenced than microbial biomass. The site has a trend of P-limited or near-N saturation, and will threaten the whole forest ecosystem with the increasing duration of N addition.Keywords: Nitrogen deposition; Seasonality; Soil microbial biomass; Microbial community; Subtropical old-growth forest.


2008 ◽  
Vol 311 (1-2) ◽  
pp. 19-28 ◽  
Author(s):  
Naili Zhang ◽  
Shiqiang Wan ◽  
Linghao Li ◽  
Jie Bi ◽  
Mingming Zhao ◽  
...  

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