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.

scholarly journals Effect of compaction on microbial activity and carbon and nitrogen transformations in two oxisols with different mineralogy

2011 ◽  
Vol 35 (4) ◽  
pp. 1141-1149 ◽  
Author(s):  
Sérgio Ricardo Silva ◽  
Ivo Ribeiro da Silva ◽  
Nairam Félix de Barros ◽  
Eduardo de Sá Mendonça
Keyword(s):  
Organic Matter ◽  
Microbial Activity ◽  
Soil Compaction ◽  
N Mineralization ◽  
Organic N ◽  
Net N Mineralization ◽  
Mineral N ◽  
Organic C ◽  
Soil Microbial ◽  
Controlled Conditions

The use of machinery in agricultural and forest management activities frequently increases soil compaction, resulting in greater soil density and microporosity, which in turn reduces hydraulic conductivity and O2 and CO2 diffusion rates, among other negative effects. Thus, soil compaction has the potential to affect soil microbial activity and the processes involved in organic matter decomposition and nutrient cycling. This study was carried out under controlled conditions to evaluate the effect of soil compaction on microbial activity and carbon (C) and nitrogen (N) mineralization. Two Oxisols with different mineralogy were utilized: a clayey oxidic-gibbsitic Typic Acrustox and a clayey kaolinitic Xantic Haplustox (Latossolo Vermelho-Amarelo ácrico - LVA, and Latossolo Amarelo distrófico - LA, respectively, in the Brazil Soil Classification System). Eight treatments (compaction levels) were assessed for each soil type in a complete block design, with six repetitions. The experimental unit consisted of PVC rings (height 6 cm, internal diameter 4.55 cm, volume 97.6 cm³). The PVC rings were filled with enough soil mass to reach a final density of 1.05 and 1.10 kg dm-3, respectively, in the LVA and LA. Then the soil samples were wetted (0.20 kg kg-1 = 80 % of field capacity) and compacted by a hydraulic press at pressures of 0, 60, 120, 240, 360, 540, 720 and 900 kPa. After soil compression the new bulk density was calculated according to the new volume occupied by the soil. Subsequently each PVC ring was placed within a 1 L plastic pot which was then tightly closed. The soils were incubated under aerobic conditions for 35 days and the basal respiration rate (CO2-C production) was estimated in the last two weeks. After the incubation period, the following soil chemical and microbiological properties were detremined: soil microbial biomass C (C MIC), total soil organic C (TOC), total N, and mineral N (NH4+-N and NO3--N). After that, mineral N, organic N and the rate of net N mineralization was calculated. Soil compaction increased NH4+-N and net N mineralization in both, LVA and LA, and NO3--N in the LVA; diminished the rate of TOC loss in both soils and the concentration of NO3--N in the LA and CO2-C in the LVA. It also decreased the C MIC at higher compaction levels in the LA. Thus, soil compaction decreases the TOC turnover probably due to increased physical protection of soil organic matter and lower aerobic microbial activity. Therefore, it is possible to conclude that under controlled conditions, the oxidic-gibbsitic Oxisol (LVA) was more susceptible to the effects of high compaction than the kaolinitic (LA) as far as organic matter cycling is concerned; and compaction pressures above 540 kPa reduced the total and organic nitrogen in the kaolinitic soil (LA), which was attributed to gaseous N losses.

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.

Effects of organic matter removal, soil compaction, and vegetation control on Collembolan populations

Pedobiologia ◽  
2004 ◽  
Vol 48 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Robert J Eaton ◽  
Mary Barbercheck ◽  
Marilyn Buford ◽  
William Smith
Keyword(s):  
Organic Matter ◽  
Soil Compaction ◽  
Organic Matter Removal ◽  
Vegetation Control

scholarly journals Nitrogen transformations in the rhizosphere of different tree types in a seasonally flooded soil

2014 ◽  
Vol 60 (No. 6) ◽  
pp. 249-254 ◽  
Author(s):  
D. Liu ◽  
S. Fang ◽  
Y. Tian ◽  
Chang SX
Keyword(s):  
Tree Species ◽  
N Mineralization ◽  
Rhizosphere Soil ◽  
Net N Mineralization ◽  
Flooded Soil ◽  
N Transformations ◽  
Total N ◽  
Organic C ◽  
Rhizosphere Effects ◽  
Seasonally Flooded

Plant roots strongly influence C and N availability in the rhizosphere via rhizodeposition and uptake of nutrients. An in situ rhizobox approach was used to compare rhizosphere effects of different tree species and clones on N cycling under seasonally flooded soil. We examined N mineralization and nitrification rates, inorganic N, and microbial biomass C (MBC) and N (MBN) in rhizosphere and bulk soils of three poplar clones, alder, and willow plantations in southeast China. Significant differences in soil pH, total N, soil organic C, MBC, MBN, and MBC/MBN were found between bulk and rhizosphere soils except alder. Compared to bulk soil, the net N mineralization and nitrification rates in rhizosphere soil across all tree species and clones increased by 124&ndash;228% and 108&ndash;216%, respectively. However, NO<sub>3</sub><sup>&ndash;</sup>-N was depleted in the rhizosphere soil mainly owing to the root uptake and rhizosphere microbial immobilization. The magnitude of rhizosphere effects on N transformations was considerably different among the tree species studied. Of the tested ones, alder had the greatest rhizosphere effect on N transformation, indicating different capacities of tree species to facilitate N turnover in the rhizosphere.

scholarly journals Effects of long-term mowing on the fractions and chemical composition of soil organic matter in a semiarid grassland

2016 ◽  
Author(s):  
Jiang-Ye Li ◽  
Qi-Chun Zhang ◽  
Yong Li ◽  
Hong-Jie Di
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Functional Groups ◽  
Soil Microbial Activity ◽  
Net N Mineralization ◽  
Organic C ◽  
Semiarid Grassland ◽  
Soil Microbial ◽  
The Stability

Abstract. Grassland is the second largest carbon pool following forest. Intensive mowing is common to meet the need of increased livestock. However, little information on the quality and quantity of soil organic matter (SOM) under different mowing managements was documented. In this work, the fractions and chemical composition of SOM under different mowing managements were studied using traditional fractionation method and spectroscopy technology (13C-NMR and FTIR) based on a 13-year mowing trial with four treatments: control (CK, unmown), mowing once every second year (M1/2), mowing once a year (M1) and mowing twice a year (M2). The results showed that M1/2 and M1 significantly enhanced the SOM accumulation while M2 did not significantly impacted SOM content but it significantly limited the SOM humification and degradation. Substituted alkyl carbon (C) was the major organic C type as it made up over 40 % of the total C. M1/2 and M1 significantly increased stable C functional groups (alkyl C and aromatic C) by degrading labile C functional group (O-alkyl C) and forming calcium humic acid while M2 had opposite effects. The increase of NMR indices (HB/HI, Al/Ar, A/OA and CC/MC) in M1/2 and M1 further suggested that M1/2 and M1 increased the stability of SOM. Significant correlations between net N mineralization or MBC and C functional groups indicated that the shifts of SOM fractions and chemical composition were closely related to soil microbial activity. Meanwhile, M1 significantly increased soil MBC while M2 worked oppositely. Therefore, M1 are the most recommended mowing management while M2 should be avoided in the semiarid grassland.

Effects of organic matter removal, soil compaction, and vegetation control on 5-year seedling performance: a regional comparison of Long-Term Soil Productivity sites

2006 ◽  
Vol 36 (3) ◽  
pp. 529-550 ◽  
Author(s):  
Robert L Fleming ◽  
Robert F Powers ◽  
Neil W Foster ◽  
J Marty Kranabetter ◽  
D Andrew Scott ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Compaction ◽  
Forest Floor ◽  
Soil Productivity ◽  
Individual Tree ◽  
Seedling Performance ◽  
Organic Matter Removal ◽  
Vegetation Control ◽  
Wide Range

We examined fifth-year seedling response to soil disturbance and vegetation control at 42 experimental locations representing 25 replicated studies within the North American Long-Term Soil Productivity (LTSP) program. These studies share a common experimental design while encompassing a wide range of climate, site conditions, and forest types. Whole-tree harvest had limited effects on planted seedling performance compared with the effects of stem-only harvest (the control); slight increases in survival were usually offset by decreases in growth. Forest-floor removal improved seedling survival and increased growth in Mediterranean climates, but reduced growth on productive, nutrient-limited, warm–humid sites. Soil compaction with intact forest floors usually benefited conifer survival and growth, regardless of climate or species. Compaction combined with forest-floor removal generally increased survival, had limited effects on individual tree growth, and increased stand growth in Mediterranean climates. Vegetation control benefited seedling growth in all treatments, particularly on more productive sites, but did not affect survival or alter the relative impact of organic matter removal and compaction on growth. Organic matter removal increased aspen coppice densities and, as with compaction, reduced aspen growth.

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