Microbial biomass C and N, and mineralizable-N, in litter and mineral soil under Pinus radiata on a coastal sand: Influence of stand age and harvest management

1995 ◽  
Vol 175 (2) ◽  
pp. 167-177 ◽  
Author(s):  
D. J. Ross ◽  
G. P. Sparling ◽  
C. M. Burke ◽  
C. T. Smith
Keyword(s):  
Microbial Biomass ◽  
Pinus Radiata ◽  
Mineral Soil ◽  
Stand Age ◽  
Microbial Biomass C ◽  
Harvest Management ◽  
Mineralizable N ◽  
C And N ◽  
Coastal Sand

Root effects on soil carbon and nitrogen cycling in a Pinus radiata D. Don plantation on a coastal sand

Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 1027 ◽  
Author(s):  
Des J. Ross ◽  
Neal A. Scott ◽  
Kevin R. Tate ◽  
Natasha J. Rodda ◽  
Jackie A. Townsend
Keyword(s):  
Soil Carbon ◽  
Pinus Radiata ◽  
Mineral Soil ◽  
Mineral N ◽  
Organic C ◽  
Production Values ◽  
C And N ◽  
Microbial C ◽  
Coastal Sand ◽  
Root Effects

Although the contribution of roots to soil carbon (C) fluxes and biochemical processes is recognised, it is difficult to quantify. One approach to assess their importance is the use of trenched plots, in which C inputs to the soil and respiration by living roots has ceased. We give here an account of C and nitrogen (N) pools and mineralisation in samples taken 27 months after trenching in a 26-year-old Pinus radiata D. Don plantation on a coastal sand (an Aquic Udipsamment); above-ground litter inputs continued throughout the 27-month period.Moisture contents were higher in FH material and mineral soil from the trenched than from the control plots. Trenching had no effect on total organic C and N concentrations, but led to decreases in extractable C, microbial C and N, and CO2-C production values at some depths in the soil profile. Mineral-N concentrations and gross nitrification rates were, in contrast, initially higher in the trenched-plot samples, but were similar in both treatments after incubation of the samples at 25°C for 57 days. Mineral-N concentrations were also higher in the trenched than control mineral soil after in situ incubation. On an area basis (to 20 cm depth of mineral soil), inputs from roots were estimated to account for about 40% of the extractable C pool, 28% of microbial C, 26% of microbial N, and 23% of heterotrophic CO2-C production (0–7 days at 25°C) in the control soil. Overall, our results suggest a tight connection between N cycling rates and the labile C pools derived from below-ground inputs, with nitrification in particular increasing as C availability declined as a result of trenching.

scholarly journals Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland .VII. Dynamics of nitrogen mineralization potentials and microbial biomass

Soil Research ◽  
1987 ◽  
Vol 25 (4) ◽  
pp. 461 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer
Keyword(s):  
Microbial Biomass ◽  
Nitrogen Mineralization ◽  
Continuous Cultivation ◽  
Microbial Biomass C ◽  
Total N ◽  
Organic C ◽  
Mineralizable N ◽  
Biomass N ◽  
Potentially Mineralizable N ◽  
C And N

The dynamics of nitrogen mineralization potential (N0) and mineralization rate constant (k) were studied in six major soils which had been used for cereal cropping for up to 20-70 years. In the top 0.1 m layer of virgin soils, N0 varied from 110 � 22 mg kg-1 soil (Riverview) to 217 � 55 mg kg-1 soil (Langlands-Logie), representing about 13% and 11%, respectively, of total N in these soils. Upon cultivation and cropping, N0 declined by 1 7 � 0.5 mg kg-1 yr-1 (Riverview) to 4.8 � 2.0 mg kg -1 yr -1 (Billa Billa). This represented < 20% of total N lost annually from the top layer (0-0.1 m depth) of these soils. The k values varied less than the N0 values, both within and among soils, and were also less affected by cultivation than N0. The mineralizable N in cultivated soil during cropping for periods up to 70 years can be estimated from N0 and k values, taking No as 5% of total N for soils of <40% clay and 15% of total N for soils of >40% clay and k as 0.066 week-1 at 40�C (0.027 week-1 and 0.054 week-1 at 25�C and 35�C, respectively). Organic C and N contained in the 'stabilized' microbial biomass (determined after 30 weeks' pre-incubation) accounted for 1.7-38% of total organic C and 2.0-5.1% of total N in the six soils studied. The microbial biomass C and N declined with cultivation in most soils, biomass N representing 10-23% of the total annual loss of N0. The microbial biomass, urease activity and total N, in addition to a number of other soil properties [e.g. light-fraction (<2 Mg m-3) C, sand-size C, CEC and ESP], were significantly correlated with N0 and k, thus indicating the existence of a myriad of environments for the activity, association and stability of microbial biomass and potentially mineralizable N in soil.

EFFECT OF CROP ROTATION AND FERTILIZATION ON SOME BIOLOGICAL PROPERTIES OF A LOAM IN SOUTHWESTERN SASKATCHEWAN

1984 ◽  
Vol 64 (3) ◽  
pp. 355-367 ◽  
Author(s):  
V. O. BIEDERBECK ◽  
C. A. CAMPBELL ◽  
R. P. ZENTNER
Keyword(s):  
Microbial Biomass ◽  
Crop Residues ◽  
Biological Properties ◽  
Organic N ◽  
Microbial Biomass C ◽  
Rotation Length ◽  
Continuous Type ◽  
Mineralizable N ◽  
P Fertilizer ◽  
Potentially Mineralizable N

Effects of rotation length, fallow-substitute crops, and N and P fertilizer on some physical and biological properties of a Brown Chernozemic loam in southwestern Saskatchewan were determined over a period of 16 yr. After 12 yr, the erodible fraction in the top 15 cm of soil (i.e., < 0.84 mm) was inversely related to trash conserved and thus rotation length. Soil organic N (in the top 15 cm) increased from 0.18 to 0.20% in continuous-type rotations receiving an average 32 kg N∙ha−1∙yr−1 and adequate P, but it did not increase in continuous wheat receiving P only, nor in fallow rotations, except the one that included fall rye (Secale cereale L.). This N increase was credited partly to fertilizer and partly to more efficient use and cycling of subsoil NO3-N via plant roots and crop residues. After 10 yr, well-fertilized continuous-type rotations had a 13% greater C content than fallow rotations and continuous wheat receiving only P. In the top 7.5 cm of soil under the four rotations examined in detail, bacterial numbers were lowest in fallow-wheat, intermediate in fallow-wheat-wheat, higher in continuous wheat receiving N and P, and highest in continuous wheat receiving only P. Similarly, microbial biomass C in these four rotations was 180, 226, 217 and 357 kg∙ha−1; biomass N was 52, 65, 54 and 72 kg∙ha−1; and biomass C/N ratios were 3.4, 3.5, 4.1 and 5.1, respectively. Differences in biomass C/N, respiration rates and numbers of bacteria, actinomycetes and yeasts indicated both quantitative and qualitative microbial changes and reflected increasing rotation length and differences in fertility. Potentially mineralizable N (No) was 192 kg∙ha−1 for adequately fertilized continuous wheat, and exceeded No in fallow-wheat by 45%, in fallow-wheat-wheat by 17% and in continuous wheat receiving only P by 25%. The latter rotation contained a large but fairly inactive microbial population. We concluded that land degradation caused by frequent summerfallowing can be arrested and the decline in amount and quality of organic matter reversed by use of available agronomic technology. Key words: Microbial biomass, microbial activity, potentially mineralizable N, respiration, soil erodibility

Microbial biomass and activity in the humus layer following burning: short-term effects of two different fires

1993 ◽  
Vol 23 (7) ◽  
pp. 1275-1285 ◽  
Author(s):  
Janna Pietikäinen ◽  
Hannu Fritze
Keyword(s):  
Microbial Community ◽  
Microbial Biomass ◽  
Soil Respiration ◽  
Mass Loss ◽  
Forest Fire ◽  
Prescribed Burning ◽  
Microbial Biomass C ◽  
Soil Microbial ◽  
Fungal Hyphae ◽  
C And N

During a 3-year study, soil microbial biomass C and N, length of the fungal hyphae, soil respiration, and the percent mass loss of needle litter were recorded in coniferous forest soil humus layers following a prescribed burning (PB) treatment or a forest fire simulation (FF) treatment (five plots per treatment). Unburned humus from adjacent plots served as controls (PC and FC, respectively). Prescribed burning was more intensive than the forest fire, and this was reflected in all the measurements taken. The amounts of microbial biomass C and N, length of fungal hyphae, and soil respiration in the PB area did not recover to their controls levels, whereas unchanged microbial biomass N and recovery of the length of the fungal hyphae to control levels were observed in the FF area. The mean microbial C/N ratio was approximately 7 in all the areas, which reflected the C/N ratio of the soil microbial community. Deviation from this mean value, as observed during the first three samplings from the PB area (3, 18, and 35 days after fire treatment), suggested a change in the composition of the microbial community. Of the two treated areas, the decrease in soil respiration (laboratory measurements) was much more pronounced in the PB area. However, when the humus samples from both areas were adjusted to 60% water holding capacity, no differences in respiration capacity were observed. The drier humus, due to higher soil temperatures, of the PB area is a likely explanation for the low soil respiration. Lower soil respiration was not reflected in lower litter decomposition rates of the PB area, since there was a significantly higher needle litter mass loss during the first year in the PB area followed by a decline to the control level during the second year. Consistently higher mass losses were recorded in the FC area than in the FF area.

Carbon and nitrogen mineralization in cultivated and grassland soils in subtropical Queensland

Soil Research ◽  
1993 ◽  
Vol 31 (5) ◽  
pp. 611 ◽  
Author(s):  
FA Robertson ◽  
RJK Myers ◽  
PG Saffigna
Keyword(s):  
Microbial Biomass ◽  
Specific Activity ◽  
Continuous Cultivation ◽  
Microbial Biomass C ◽  
N Availability ◽  
Grassland Soils ◽  
Prolonged Incubation ◽  
Cultivated Soil ◽  
C And N ◽  
Cultivated Soils

Availability of N in the clay soils of the brigalow region of Queensland declines rapidly under sown pasture, but under continuous cultivation and cropping, it remains high enough to supply the needs of cereal crops for at least 20 years. The aim of this work was to determine whether the low availability of N under pasture was due to low microbial activity or to rapid re-immobilization of mineralized N. Microbial biomass C and N (0-28 cm) were 420 and 68 �g g-1 respectively in pasture soil but only 214 and 41 �g g-1 respectively in cultivated soil. Pasture soils respired more CO2 (Cresp) and mineralized less N (Nmin) than cultivated soils (219 and 93 �g C g-1 and 3.1 and 5.9 �g N g-1 respectively) during 10-day incubations over 2 years. Increased Crop under pasture was due to an increase in the amount rather than the specific activity of the microbial biomass. The smaller Nmin in grassland soils was due to more rapid immobilization rather than reduced gross mineralization of N, as the ratio Cresp : Nmin was larger and the ratio Nmin :biomass N was smaller in the grassland than in the cultivated soil. On prolonged incubation. with progressive loss of CO2 through respiration, Nmin increased and N immobilization decreased in the grassland soils. Prolonged incubation of the cultivated soils reduced Nmin because of C limitation. The above patterns of C and N mineralization in the grassland and cultivated soils helped to explain the differences in N availability in the two systems.

Seasonal trends in selected soil biochemical attributes: Effects of crop rotation in the semiarid prairie

1999 ◽  
Vol 79 (1) ◽  
pp. 73-84 ◽  
Author(s):  
C. A. Campbell ◽  
V. O. Biederbeck ◽  
G. Wen ◽  
R. P. Zentner ◽  
J. Schoenau ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Microbial Biomass ◽  
Microbial Biomass Carbon ◽  
Light Fraction ◽  
Water Soluble ◽  
Microbial Biomass C ◽  
Weather Variables ◽  
Total N ◽  
Organic C ◽  
C And N

Measurements of seasonal changes in soil biochemical attributes can provide valuable information on how crop management and weather variables influence soil quality. We sampled soil from the 0- to 7.5-cm depth of two long-term crop rotations [continuous wheat (Cont W) and both phases of fallow-wheat (F–W)] at Swift Current, Saskatchewan, from early May to mid-October, 11 times in 1995 and 9 times in 1996. The soil is a silt loam, Orthic Brown Chernozem with pH 6.0, in dilute CaCl2. We monitored changes in organic C (OC) and total N (TN), microbial biomass C (MBC), light fraction C and N (LFC and LFN), mineralizable C (Cmin) and N (Nmin), and water-soluble organic C (WSOC). All biochemical attributes, except MBC, showed higher values for Cont W than for F–W, reflecting the historically higher crop residue inputs, less frequent tillage, and drier conditions of Cont W. Based on the seasonal mean values for 1996, we concluded that, after 29 yr, F–W has degraded soil organic C and total N by about 15% compared to Cont W. In the same period it has degraded the labile attributes, except MBC, much more. For example, WSOC is degraded by 22%, Cmin and Nmin by 45% and LFC and LFN by 60–75%. Organic C and TN were constant during the season because one year's C and N inputs are small compared to the total soil C or N. All the labile attributes varied markedly throughout the seasons. We explained most of the seasonal variability in soil biochemical attributes in terms of C and N inputs from crop residues and rhizodeposition, and the influences of soil moisture, precipitation and temperature. Using multiple regression, we related the biochemical attributes to soil moisture and the weather variables, accounting for 20% of the variability in MBC, 27% of that of Nmin, 29% for LFC, 52% for Cmin, and 66% for WSOC. In all cases the biochemical attributes were negatively related to precipitation, soil moisture, temperature and their interactions. We interpreted this to mean that conditions favouring decomposition of organic matter in situ result in decreases in these attributes when they are measured subsequently under laboratory conditions. We concluded that when assessing changes in OC or TN over years, measurements can be made at any time during a year. However, if assessing changes in the labile soil attributes, several measurements should be made during a season or, measurements be made near the same time each year. Key words: Microbial biomass, carbon, nitrogen, mineralization, water-soluble-C, light fraction, weather variables

Seasonal dynamics of soil microbial biomass C and N in different habitats in Zhalong Wetland

2014 ◽  
Vol 34 (13) ◽  
Author(s):  
张静 ZHANG Jing ◽  
马玲 MA Ling ◽  
丁新华 DING Xinhua ◽  
陈旭日 CHEN Xuri ◽  
马伟 MA Wei
Keyword(s):  
Microbial Biomass ◽  
Seasonal Dynamics ◽  
Soil Microbial Biomass ◽  
Microbial Biomass C ◽  
Soil Microbial Biomass C ◽  
Soil Microbial ◽  
Zhalong Wetland ◽  
C And N

What controls microbial growth in tropical soils? The role of carbon and phosphorus.

2020 ◽  
Author(s):  
Christian Ranits ◽  
Lucia Fuchslueger ◽  
Leandro Van Langenhove ◽  
Ivan Janssens ◽  
Josep Peñuelas ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Microbial Communities ◽  
Microbial Growth ◽  
Microbial Respiration ◽  
Tropical Soils ◽  
Microbial Biomass C ◽  
P Availability ◽  
Respiration Activity ◽  
Respiration Rates ◽  
C And N

&lt;p&gt;Tropical forest ecosystems are important components of global biogeochemical cycling. Many tropical rainforests grow in old and highly weathered soils, depleted in phosphorus (P) and net primary productivity in tropical forests is often limited by P availability. It is unclear, however, if heterotrophic microbial communities in tropical soils are also limited by P or rather by carbon (C). Elemental limitations of microorganisms in soil have often been approached by measurements of respiration rates in response to additions of nutrients or carbon. However, it has been argued lately, that microbial growth rather than respiration should be used to assess limitations.&lt;/p&gt;&lt;p&gt;In this study we therefore ask the question whether the growth of heterotrophic microbial communities in tropical soil is limited by available phosphorus or by carbon. We collected soils from three sites along a topographic gradient (plateau, slope, bottom) differing in soil texture, total and available P concentrations from a well-studied, P-poor region in Nouragues, French Guiana. We incubated these soils in the laboratory with C in the form of cellulose, inorganic phosphorus and with a combination of both, and studied microbial growth by measuring the &lt;sup&gt;18&lt;/sup&gt;O incorporation from labelled water into microbial DNA. Moreover, we measured microbial respiration and determined microbial biomass C, N (nitrogen) and P.&lt;/p&gt;&lt;p&gt;Our results demonstrate that, although microbial biomass C and N was similar in soil collected from all three topographic sites, soil respiration rates were significantly higher in soils from the plateau indicating a more active microbial community. Microbial C and N did not respond to cellulose and inorganic P additions, only microbial P increased significantly when P was added in all soils. Although microbial biomass C was not increased, C and P additions stimulated microbial respiration in clay rich plateau soils. In slope soils microbial communities initially only increased respiration activity in response to P additions, however at the end of the incubation also C showed significant differences in respiration activity, with strongest increases when C and P were added in combination. In sandier bottom soils microorganisms responded with increased activity to C addition, but also here respiration showed strongest increases in response to combined carbon and phosphorus additions. We will discuss these findings in relation to the pattern of gross growth rates in these soils and evaluate the stoichiometric limitations of microbial activity and turnover.&lt;/p&gt;

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