Influence of soil mineral nitrogen content on soil respiratory activity and measurements of microbial carbon and nitrogen by fumigation-incubation procedures

Soil Research ◽  
1990 ◽  
Vol 28 (2) ◽  
pp. 311 ◽  
Author(s):  
DJ Ross
Keyword(s):  
Microbial Biomass ◽  
Respiratory Activity ◽  
Microbial Biomass Carbon ◽  
Low Fertility ◽  
Co2 Production ◽  
Soil Mineral ◽  
Grassland Soils ◽  
Mineral N ◽  
N Content ◽  
Carbon And Nitrogen

The influence of soil mineral-N (min-N) content on rates of respiratory activity (CO2 production), and measurements of microbial biomass carbon and nitrogen by fumigation-incubation procedures, was investigated with three fertile soils and one low-fertility soil. These soils were sampled at each of the four seasons from pastures in which intensive grazing can result in high levels of min-N. Values of CO2-C flush and thin-N flush [the difference between CO2-C and min-N produced by fumigated samples and an unfumigated contl ol (or, for CO2-C only, fumigated control)] were used as indices of biomass C and N. Soil min-N content was adjusted by the addition of ammonium sulfate (approx. 50 �g NH4+-Ng-1 soil). In the low fertility soil and two of the fertile soils, added min-N had no significant effect on CO2 production or CO2-C flush values. In the other soil (Castlepoint), the added min-N usually lowered CO2 production in unfumigated samples, and increased CO2-C flush values when an unfumigated control was used; CO2-C flush values were not affected when a fumigated control was used. Use of a fumigated control for estimating biomass C in these grassland soils is recommended. Added min-N had few significant effects on the min-N flush values of the three fertile soils. In the low-fertility soil (Pomare), the min-N flush values of summer and autumn samples were appreciably higher in the presence of added min-N, with the results suggesting that the min-N flush values of the samples without added min-N were erroneously low because of N immobilization. Overall, min-N flush measurements appear to provide a satisfactory index of microbial biomass in fertile soils under pasture, but care in the interpretation of min-N flush values from low-fertility grassland soils seems advisable.

Effects of sieving on estimations of microbial biomass, and carbon and nitrogen mineralization, in soil under pasture

Soil Research ◽  
1985 ◽  
Vol 23 (2) ◽  
pp. 319 ◽  
Author(s):  
DJ Ross ◽  
TW Speir ◽  
KR Tate ◽  
VA Orchard
Keyword(s):  
Microbial Biomass ◽  
Biochemical Properties ◽  
Co2 Production ◽  
Soil Co2 ◽  
Mineral N ◽  
Carbon And Nitrogen ◽  
Four Seasons ◽  
Net Mineralization ◽  
Biochemical Indices ◽  
Soil Co2 Production

Biochemical indices of microbial biomass and other biochemical properties of a Typic Haplaquoll, sampled under pasture over four seasons, were compared in intact cores and soil sieved through a 6 mm and a 2 mm mesh. Sieving had an inconsistent influence on biomass C estimates, which tended, however, to be higher in <2 mm-mesh than in <6 mm-mesh soil. Sieving had no deleterious effect on mineral-N flush values, and no significant effect on biomass P, and generally adenosine 5'-triphosphate (ATP), contents. Judged by the values of biomass C/ATP and biomass C/mineral-N flush ratios, the biomass C estimates of winter samples, collected under water-logged conditions, were unrealistically low, particularly in sieved soil. CO2 production by soil at a standardized water potential tended to be lowest in <2 mm-mesh samples. In contrast, net mineralization of N, in all except the winter <2 mm-mesh soil, was highest in sieved soil, as generally were extractable inorganic and organic P contents. Overall, sieving is considered preferable to the use of intact cores for measurements of these biochemical properties in soil under pasture.

scholarly journals Reviews and syntheses: Soil resources and climate jointly drive variations in microbial biomass carbon and nitrogen in China's forest ecosystems

2015 ◽  
Vol 12 (22) ◽  
pp. 6751-6760 ◽  
Author(s):  
Z. H. Zhou ◽  
C. K. Wang
Keyword(s):  
Microbial Biomass ◽  
Forest Ecosystems ◽  
Microbial Biomass Carbon ◽  
Mean Annual Temperature ◽  
Biomass Carbon ◽  
Large Variability ◽  
Soil Resources ◽  
Carbon And Nitrogen ◽  
Soil Microbial ◽  
Microbial Quotient

Abstract. Microbial metabolism plays a key role in regulating the biogeochemical cycle of forest ecosystems, but the mechanisms driving microbial growth are not well understood. Here, we synthesized 689 measurements on soil microbial biomass carbon (Cmic) and nitrogen (Nmic) and related parameters from 207 independent studies published up to November 2014 across China's forest ecosystems. Our objectives were to (1) examine patterns in Cmic, Nmic, and microbial quotient (i.e., Cmic / Csoil and Nmic / Nsoil rates) by climate zones and management regimes for these forests; and (2) identify the factors driving the variability in the Cmic, Nmic, and microbial quotient. There was a large variability in Cmic (390.2 mg kg−1), Nmic (60.1 mg kg−1, Cmic : Nmic ratio (8.25), Cmic / Csoil rate (1.92 %), and Nmic / Nsoil rate (3.43 %) across China's forests. The natural forests had significantly greater Cmic (514.1 mg kg−1 vs. 281.8 mg kg−1) and Nmic (82.6 mg kg−1 vs. 39.0 mg kg−1) than the planted forests, but had less Cmic : Nmic ratio (7.3 vs. 9.2) and Cmic / Csoil rate (1.7 % vs. 2.1 %). Soil resources and climate together explained 24.4–40.7 % of these variations. The Cmic : Nmic ratio declined slightly with Csoil : Nsoil ratio, and changed with latitude, mean annual temperature and precipitation, suggesting a plasticity of microbial carbon-nitrogen stoichiometry. The Cmic / Csoil rate decreased with Csoil : Nsoil ratio, whereas the Nmic / Nsoil rate increased with Csoil : Nsoil ratio; the former was influenced more by soil resources than by climate, whereas the latter was influenced more by climate. These results suggest that soil microbial assimilation of carbon and nitrogen are jointly driven by soil resources and climate, but may be regulated by different mechanisms.

scholarly journals Soil resources and climate jointly drive variations in microbial biomass carbon and nitrogen in China's forest ecosystems

2015 ◽  
Vol 12 (14) ◽  
pp. 11191-11216 ◽  
Author(s):  
Z. H. Zhou ◽  
C. K. Wang
Keyword(s):  
Microbial Biomass ◽  
Microbial Growth ◽  
Forest Ecosystems ◽  
Microbial Biomass Carbon ◽  
Biomass Carbon ◽  
Large Variability ◽  
Soil Resources ◽  
Carbon And Nitrogen ◽  
Soil Microbial ◽  
Microbial Quotient

Abstract. Microbial metabolism plays a key role in regulating the biogeochemical cycle of forest ecosystems, but the mechanisms driving microbial growth are not well understood. Here, we synthesized 689 measurements on soil microbial biomass carbon (Cmic) and nitrogen (Nmic) and related parameters from 207 independent studies published during the past 15 years across China's forest ecosystems. Our objectives were to (1) examine patterns in Cmic, Nmic, and microbial quotient (i.e., Cmic / Csoil and Nmic / Nsoil rates) by climate zones and management regimes for these forests; and (2) identify the factors driving the variability in the Cmic, Nmic, and microbial quotient. There was a large variability in Cmic (390.2 mg kg−1), Nmic (60.1 mg kg−1), Cmic : Nmic ratio (8.25), Cmic / Csoil rate (1.92 %), and Nmic / Nsoil rate (3.43 %) across China's forests, with coefficients of variation varying from 61.2 to 95.6 %. The natural forests had significantly greater Cmic and Nmic than the planted forests, but had less Cmic : Nmic ratio and Cmic / Csoil rate. Soil resources and climate together explained 24.4–40.7 % of these variations. The Cmic : Nmic ratio declined slightly with the Csoil : Nsoil ratio, and changed with latitude, mean annual temperature and precipitation, suggesting a plastic homeostasis of microbial carbon-nitrogen stoichiometry. The Cmic / Csoil and Nmic / Nsoil rates were responsive to soil resources and climate differently, suggesting that soil microbial assimilation of carbon and nitrogen be regulated by different mechanisms. We conclude that soil resources and climate jointly drive microbial growth and metabolism, and also emphasize the necessity of appropriate procedures for data compilation and standardization in cross-study syntheses.

scholarly journals Split nitrogen application in potato: effects on accumulation of nitrogen and dry matter in the crop and on the soil nitrogen budget

1999 ◽  
Vol 133 (3) ◽  
pp. 263-274 ◽  
Author(s):  
J. VOS
Keyword(s):  
Dry Matter ◽  
N Recovery ◽  
Separate Analysis ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
N Application ◽  
N Content ◽  
Total N ◽  
N Utilization

In four field experiments, the effects of single nitrogen (N) applications at planting on yield and nitrogen uptake of potato (Solanum tuberosum L.) was compared with two or three split applications. The total amount of N applied was an experimental factor in three of the experiments. In two experiments, sequential observations were made during the growing season. Generally, splitting applications (up to 58 days after emergence) did not affect dry matter (DM) yield at maturity and tended to result in slightly lower DM concentration of tubers, whereas it slightly improved the utilization of nitrogen. Maximum haulm dry weight and N content were lower when less nitrogen was applied during the first 50 days after emergence (DAE). The crops absorbed little extra nitrogen after 60 DAE (except when three applications were given). Soil mineral N (0–60 cm) during the first month reflected the pattern of N application with values up to 27 g/m2 N. After 60 DAE, soil mineral N was always around 2–5 g/m2. The efficiency of N utilization, i.e. the ratio of the N content of the crop to total N available (initial soil mineral N+deposition+net mineralization) was 0·45 for unfertilized controls. The utilization of fertilizer N (i.e. the apparent N recovery) was generally somewhat improved by split applications, but declined with the total amount of N applied (range 0·48–0·72). N utilization and its complement, possible N loss, were similar for both experiments with sequential observations. Separate analysis of the movement of Br− indicated that some nitrate can be washed below 60 cm soil depth due to dispersion during rainfall. The current study showed that the time when N application can be adjusted to meet estimated requirements extends to (at least) 60 days after emergence. That period of time can be exploited to match the N application to the actual crop requirement as it changes during that period.

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