Legacies of organic matter removal: decreased microbial biomass nitrogen and net N mineralization in New Zealand Pinus radiata plantations

2009 ◽  
Vol 46 (4) ◽  
pp. 309-316 ◽  
Author(s):  
Simeon John Smaill ◽  
Peter W. Clinton ◽  
Laurie G. Greenfield
Keyword(s):  
Organic Matter ◽  
New Zealand ◽  
Microbial Biomass ◽  
Pinus Radiata ◽  
N Mineralization ◽  
Net N Mineralization ◽  
Microbial Biomass Nitrogen ◽  
Organic Matter Removal

Nitrogen mineralization dynamics following the establishment of a loblolly pine plantation

2003 ◽  
Vol 33 (2) ◽  
pp. 364-374 ◽  
Author(s):  
Qingchao Li ◽  
H Lee Allen ◽  
Carlos A Wilson
Keyword(s):  
Organic Matter ◽  
Loblolly Pine ◽  
Soil Type ◽  
N Mineralization ◽  
The United States ◽  
Net N Mineralization ◽  
Soil Core ◽  
Organic C ◽  
Organic Matter Removal ◽  
Vegetation Control

The USDA Forest Service initiated a national study in the early 1990s to examine the effects of organic matter removal, compaction, and vegetation control on tree growth and soil processes at several locations across the United States and Canada. Our study was undertaken on the Lower Coastal Plain of North Carolina installation during the second and the fifth growing seasons following loblolly pine (Pinus taeda L.) plantation establishment. We used the in situ soil core incubation method to assess net N mineralization, and collections were conducted monthly from March to December in 1993 and 1996. The largest differences in N mineralization resulted from soil type differences between blocks. Organic matter removal did not affect N mineralization in either year; however, compaction reduced N mineralization during both years. Vegetation control had a pronounced positive effect on N mineralization and was only slightly less important as compared with soil type. Mineralization rates in year 5 were 80% less than in year 2. We hypothesized that the high N mineralization rates in year 2 may be related to a decrease in the input of soluble organic C following harvest (reducing immobilization), a quick mineralization of microbial N, fluctuating soil temperature and water conditions, and fine roots and litter biomass input following harvest.

Short-term net N mineralization from plant residues and gross and net N mineralization From soil organic-matter after rewetting of a seasonally dry soil

Soil Research ◽  
1995 ◽  
Vol 33 (6) ◽  
pp. 961 ◽  
Author(s):  
GP Sparling ◽  
DV Murphy ◽  
RB Thompson ◽  
IRP Fillery
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
N Mineralization ◽  
Rainfall Event ◽  
Isotopic Dilution ◽  
Plant Residues ◽  
Net N Mineralization ◽  
Soil Cores ◽  
Gross N Mineralization ◽  
Net Mineralization

The mineralization of N from shoot residues of two legume species and a common weed component of Western Australian pastures was measured after a simulated 'summer rainfall' in a laboratory experiment using undisturbed soil cores of a loamy sand. Water was added to the surface of the cores equivalent to a single rainfall event of 10 mm water (treatment 1); or followed 48 h later by a further application of 10 mol water (treatment 2). Net mineralization and microbial biomass N were measured over 144 h following the initial rewetting of the soil cores. Three types of 15N-labelled plant residue, namely (i) lupin leaf (Lupinus angustifolium), (ii) clover (Trifolium subterraneum) shoot, burr and petiole, and (iii) capeweed (Arctotheca calendula) shoots and leaves were placed on the soil surface as large fragments and examined to assess their mineralization and incorporation into microbial biomass. The soils dried rapidly after rewetting and net mineralization of N was very low. The proportion of N as nitrate was increased in the rewetted soils with the major changes occurring in the top 5 cm of soil. However, there was very little mineralization of the surface-applied plant residues, with more than 90% of the mineral N being derived from the native organic matter. Microbial biomass showed fluctuations in both the rewetted treatments, but no consistent increase or decrease and no significant immobilization of 15N. Gross N mineralization was measured using an isotopic dilution technique involving the injection of 15N-labelled solutions into the soil. Estimates of gross N mineralization after a single rainfall event of 10 mm water were, on average, four times greater than measures of net N mineralization. Gross N mineralization rates declined as the soil dried, with three times more mineralization occurring in the 0-5 cm depth (4.73-8.93 �g g-1 day-1), compared with the 5-10 cm depth (0.86-2.38 �g g-1 day-1). A major disadvantage with the isotopic dilution method was that injection of the solutions into soil greatly increased the soil moisture content. Gross mineralization in the injected cores is likely to have been overestimated because of N movement below the sampling zone and increased microbial activity relative to non-injected cores.

Influence of sampling date and substrate on nitrogen mineralization: comparison of laboratory-incubation and buried-bag methods for two Massachusetts forest soils

1992 ◽  
Vol 22 (12) ◽  
pp. 1895-1900 ◽  
Author(s):  
Richard D. Boone
Keyword(s):  
Organic Matter ◽  
N Mineralization ◽  
Unit Area ◽  
Seasonal Pattern ◽  
Mineral Soil ◽  
Net N Mineralization ◽  
Laboratory Incubation ◽  
Mineralization Potential ◽  
Organic Horizons ◽  
N Mineralization Potential

Nitrogen (N) mineralization potential and net N mineralization insitu were measured monthly over 7 months for the forest floor horizons (Oi, Oe, Oa) and mineral soil (0–15 cm) of a pine stand and the mineral soil (0–15 cm) of a maple stand in Massachusetts, United States. In all cases, N mineralization potential per unit organic matter (anaerobic laboratory incubation) varied significantly by sampling month but was unrelated to the seasonal pattern for net N mineralization (buried-bag method). The organic horizons in the pine stand exhibited the most variable N mineralization potential, with the Oe horizon having more than a fourfold seasonal range. For the pine stand the Oe horizon also had the highest N mineralization potential (per unit organic matter) and the highest net N mineralization insitu (per unit area). In general, temporal and depth-wise variability should be considered when sites are assessed with respect to the pool of mineralizable N.

Microbial Activity in Soils of Vegetation-Growing Concrete Slopes

2012 ◽  
Vol 599 ◽  
pp. 124-127
Author(s):  
Cheng Hu Zhang ◽  
Ting Ting Song ◽  
Ju Liu ◽  
Hui Juan Xia ◽  
Jian Zhu Wang
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Negative Correlation ◽  
Microbial Biomass Carbon ◽  
Significant Negative Correlation ◽  
Concrete Technology ◽  
Microbial Biomass Nitrogen ◽  
Natural Restoration ◽  
Microbial Quotient

Natural restoration slope and vegetation-growing concrete slope were selected as plots. Soil water content (SWC), pH, and soil organic matter, total nitrogen content (TN), total organic carbon (TOC), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal respiration, microbial quotient and metabolic quotient (qCO2) were analyzed. The main results show that: Soil organic matter, TN and MBC of 0-10 cm soil in the natural restoration slope are significantly lower than that in the vegetation-growing concrete slopes at 0.05 level. Both MBC and MBN show a highly significant positive correlation with soil organic matter and TN. Microbial quotient shows a highly significant negative correlation with TOC and MBN, and shows a significant negative correlation with MBC. The qCO2 shows a highly significant negative correlation with pH, and a significant negative correlation with MBC. The vegetation-growing concrete technology can improve the soil ecosystem in the impaired slope.

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