scholarly journals Land-Use Change Depletes Quantity and Quality of Soil Organic Matter Fractions in Ethiopian Highlands

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 69
Author(s):  
Iftekhar U. Ahmed ◽  
Dessie Assefa ◽  
Douglas L. Godbold
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Natural Forest ◽  
Grazing Land ◽  
Eucalyptus Plantation ◽  
C And N ◽  
C And N Pools ◽  
Recalcitrant C

The depletion of soil organic matter (SOM) reserve after deforestation and subsequent management practices are well documented, but the impacts of land-use change on the persistence and vulnerability of storage C and N remain uncertain. We investigated soil organic C (SOC) and N stocks in a landscape of chrono-sequence natural forest, grazing/crop lands and plantation forest in the highlands of North-West Ethiopia. We hypothesized that in addition to depleting total C and N pools, multiple conversions of natural forest significantly change the relative proportion of labile and recalcitrant C and N fractions in soils, and thus affect SOM quality. To examine this hypothesis, we estimated depletion of SOC and N stocks and labile (1 & 2) and recalcitrant (fraction 3) C and N pools in soil organic matter following the acid hydrolysis technique. Our studies showed the highest loss of C stock was in grazing land (58%) followed by cropland (50%) and eucalyptus plantation (47%), while on average ca. 57% N stock was depleted. Eucalyptus plantation exhibited potential for soil C recovery, although not for N, after 30 years. The fractionation of SOM revealed that depletions of labile 1 C stocks were similar in grazing and crop lands (36%), and loss of recalcitrant C was highest in grazing soil (56%). However, increases in relative concentrations of labile fraction 1 in grazing land and recalcitrant C and N in cropland suggest the quality of these pools might be influenced by management activities. Also, the C:N ratio of C fractions and recalcitrant indices (RIC and RIN) clearly demonstrated that land conversion from natural forest to managed systems changes the inherent quality of the fractions, which was obscured in whole soil analysis. These findings underscore the importance of considering the quality of SOM when evaluating disturbance impacts on SOC and N stocks.

scholarly journals Modeling rhizosphere carbon and nitrogen cycling in <i>Eucalyptus</i> plantation soil

2018 ◽  
Vol 15 (16) ◽  
pp. 4943-4954 ◽  
Author(s):  
Rafael Vasconcelos Valadares ◽  
Júlio César Lima Neves ◽  
Maurício Dutra Costa ◽  
Philip James Smethurst ◽  
Luiz Alexandre Peternelli ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Root Growth ◽  
Priming Effect ◽  
Model Performance ◽  
N Cycling ◽  
Eucalyptus Plantation ◽  
Eucalyptus Plantations ◽  
C And N ◽  
C And N Cycling

Abstract. Vigorous Eucalyptus plantations produce 105 to 106 km ha−1 of fine roots that probably increase carbon (C) and nitrogen (N) cycling in rhizosphere soil. However, the quantitative importance of rhizosphere priming is still unknown for most ecosystems, including these plantations. Therefore, the objective of this work was to propose and evaluate a mechanistic model for the prediction of rhizosphere C and N cycling in Eucalyptus plantations. The potential importance of the priming effect was estimated for a typical Eucalyptus plantation in Brazil. The process-based model (ForPRAN – Forest Plantation Rhizosphere Available Nitrogen) predicts the change in rhizosphere C and N cycling resulting from root growth and consists of two modules: (1) fine-root growth and (2) C and N rhizosphere cycling. The model describes a series of soil biological processes: root growth, rhizodeposition, microbial uptake, enzymatic synthesis, depolymerization of soil organic matter, microbial respiration, N mineralization, N immobilization, microbial death, microbial emigration and immigration, and soil organic matter (SOM) formation. Model performance was quantitatively and qualitatively satisfactory when compared to observed data in the literature. Input variables with the most influence on rhizosphere N mineralization were (in order of decreasing importance) root diameter > rhizosphere thickness > soil temperature > clay concentration. The priming effect in a typical Eucalyptus plantation producing 42 m3 ha−1 yr−1 of shoot biomass, with assumed losses of 40 % of total N mineralized, was estimated to be 24.6 % of plantation N demand (shoot + roots + litter). The rhizosphere cycling model should be considered for adaptation to other forestry and agricultural production models where the inclusion of such processes offers the potential for improved model performance.

scholarly journals Microbial Respiration as Indicator of Soil Quality of Different Land Uses in Cienda, Gabas, Baybay City, Leyte

2017 ◽  
pp. 55-66
Author(s):  
Jessa May Malanguis ◽  
Cheryl Batistel ◽  
Marlito Jose Bande
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Moisture Content ◽  
Soil Quality ◽  
Total Nitrogen ◽  
Agricultural Land ◽  
Microbial Respiration ◽  
Land Uses

Land use conversion affects soil ecosystem quality and balance, which can be reflected by microbial activities. This study was conducted to assess the effectiveness of microbial respiration as indicator of soil quality of different land uses, reforestation site, agricultural land and grassland, in Cienda, Gabas, Baybay City, Leyte. The amount of CO2 evolved after one, three and seven days of incubation was used to determine microbial respiration rate of different land uses and across relief. Relationship between microbial respiration on pH, organic matter, total nitrogen, and moisture content at field capacity were also examined. Results revealed that microbial respiration varies significantly among land uses with the highest rate observed in grassland while the lowest was in the reforestation site. Across relief, amount of CO2 released was significantly higher in the lower slope compared to the upper and the middle. The process tends to be significantly influenced by soil organic matter and moisture content. Results suggest that there is an inverse relationship between microbial respiration and organic matter, and a direct relationship with moisture content. High soil respiration in the grassland and in the lower topographic relief implies that the soil organic matter is converted into inorganic forms which are available for uptake by plants. A significant interaction between land use types and relief was also observed in both organic matter and moisture content leading enhanced microbial respiration. Land use and relief showed no significant effect on total nitrogen and soil pH.

scholarly journals Effect of agricultural lands afforestation and tree species composition on the soil reaction, total organic carbon and nitrogen content in the uppermost mineral soil profile

2014 ◽  
Vol 9 (No. 4) ◽  
pp. 192-200 ◽  
Author(s):  
O. Holubík ◽  
V. Podrázský ◽  
J. Vopravil ◽  
T. Khel ◽  
J. Remeš
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Czech Republic ◽  
Soil Organic Matter ◽  
Agricultural Land ◽  
Mineral Soil ◽  
Stand Age ◽  
Soil Reaction ◽  
The Czech Republic ◽  
C And N

Forests occupy one third of the world&rsquo;s land area and govern carbon (C) transfers and influence nitrogen (N) content in the biosphere. Afforestation leads to soil changes of specific dynamics, often accompanied by acidification. Especially at higher altitudes this effect is accelerated and increased with the stand age since forestation. The change in soil C and N content following afforestation is controlled by a number of factors, including: previous land use (grasslands, cropland, etc.), tree species, soil cultivation method, soil properties (clay content, pH), stand age, site management, topography, and climate. In the Czech Republic, large area changes in land use took place in the last centuries &ndash; forests covering roughly 20% in the 18<sup>th</sup> century currently occupy almost 34%, with still increasing tendencies. This paper compares basic soil properties (soil reaction, total soil organic carbon as well as total nitrogen contents) of the agricultural land and land afforested 40&ndash;60 years ago. The results confirmed the key role of afforestation in the change of soil organic matter dynamics after establishing new forests on the former agricultural lands in the uppermost mineral soil part of the Orlick&eacute; hory Mts. region in the Czech Republic. During that time, comparatively substantial changes in soil organic matter and nitrogen were registered. Afforestation considerably increased organic matter content in the studied A-horizons of different land use types. Soil development resulted in a high production of C and N pools under the forest stands, contrary to agricultural land. In general, afforestation caused significant soil acidification. The common tendency of higher acidity of forest soils compared to agricultural ones was documented in the studied case as well. The general tendencies of soil reaction and soil organic matter dynamics at the studied sites are comparable to those in other regions of the Czech Republic.

scholarly journals Soil carbon and nitrogen under different land-use and landscape loca-tions in central Brazil

2021 ◽  
Vol 9 (2) ◽  
pp. 178-186
Author(s):  
Fábio Luís de Souza Santos ◽  
Antônio Felipe Couto Júnior ◽  
Adriana Reatto ◽  
Éder de Souza Martins ◽  
Arminda Moreira de Carvalho ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Stable Isotope ◽  
Isotope Ratios ◽  
Native Vegetation ◽  
Stable Isotope Ratios ◽  
Δ13c And Δ15n ◽  
Central Brazil ◽  
C And N

In Central Brazil, plateaus, the most common geomorphologic form, have been undergoing intense conversion from native vegetation to pasture and agriculture in recent decades. We used carbon stable isotope ratios (δ13C) and nitrogen stable isotope ratios (δ15N) to assess possible changes in soil organic matter dynamics under such land use modifications. This study aimed to evaluate the differences in soil δ13C and δ15N and C and N stocks between native vegetation and agricultural or pasture areas in different locations of a plateau in the savannas of Central Brazil. We sampled soil up to 100 cm depth in pasture areas in the summit of the plateau and no-tillage and conventional tillage on the border of a plateau, as well as soils under native vegetation in both landscape locations. Both soil δ13C and δ15N, and C and N stocks showed no differences between land uses. The different relationships between δ15N and C/N ratio at different locations indicated distinct behavior of the soil organic matter between the summit and border of the plateau. Therefore, in addition to land-use, landscape location contributes to both δ13C and δ15N, and C and N stocks in the soil of the plateau.

Post-thinning soil organic matter evolution and soil CO2 effluxes in temperate radiata pine plantations: impacts of moderate thinning regimes on the forest C cycle

2012 ◽  
Vol 42 (11) ◽  
pp. 1953-1964 ◽  
Author(s):  
Irene Fernandez ◽  
Juan Gabriel Álvarez-González ◽  
Beatríz Carrasco ◽  
Ana Daría Ruíz-González ◽  
Ana Cabaneiro
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Radiata Pine ◽  
Soil Samples ◽  
Mitigation Strategies ◽  
Change Scenario ◽  
Soil C ◽  
C Storage ◽  
C Cycle ◽  
C And N

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.

Accumulation patterns of soil organic matter in forests as a legacy of historical charcoal burning

2021 ◽  
Author(s):  
Anna Schneider ◽  
Alexander Bonhage ◽  
Florian Hirsch ◽  
Alexandra Raab ◽  
Thomas Raab
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Large Scale ◽  
Soil Surface ◽  
Landscape Scale ◽  
Legacy Effects ◽  
Charcoal Production ◽  
Study Region ◽  
Land Use Legacies

&lt;p&gt;Human land use and occupation often lead to a high heterogeneity of soil stratigraphy and properties in landscapes within small, clearly delimited areas. Legacy effects of past land use also are also abundant in recent forest areas. Although such land use legacies can occur on considerable fractions of the soil surface, they are hardly considered in soil mapping and inventories. The heterogenous spatial distribution of land use legacy soils challenges the quantification of their impacts on the landscape scale. Relict charcoal hearths (RCH) are a widespread example for the long-lasting effect of historical land use on soil landscapes in forests of many European countries and also northeastern USA. Soils on RCH clearly differ from surrounding forest soils in their stratigraphy and properties, and are most prominently characterized by a technogenic substrate layer with high contents of charcoal. The properties of RCH soils have recently been studied for several regions, but their relevance on the landscape scale has hardly been quantified.&lt;/p&gt;&lt;p&gt;We analyse and discuss the distribution and ecological relevance of land use legacy soils across scales for RCH in the state of Brandenburg, Germany, with a focus on soil organic matter (SOM) stocks. Our analysis is based on a large-scale mapping of RCH from digital elevation models (DEM), combined with modelled SOM stocks in RCH soils.&amp;#160;The distribution of RCH soils in the study region shows heterogeneity at different scales. The large-scale variation is related to the concentration of charcoal production to specific forest areas and the small-scale accumulation pattern is related to the irregular distribution of single RCH within the charcoal production fields. Considerable fractions of the surface area are covered by RCH soils in the major charcoal production areas within the study region. The results also show that RCH can significantly contribute to the soil organic matter stocks of forests, even for areas where they cover only a small fraction of the soil surface. The study highlights that considering land use legacy effects can be relevant for the results of soil mapping and inventories; and that prospecting and mapping land use legacies from DEM can contribute to improving such approaches.&lt;/p&gt;

Effects of climate change on soil organic matter chemical composition and carbon content in different physical fractions

2021 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Alberto Canarini ◽  
Wolfgang Wanek ◽  
Michael Bahn ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Soil C ◽  
Size Classes ◽  
Soil Fractions ◽  
Total Soil ◽  
C And N ◽  
Amp Clay

&lt;p&gt;Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3&amp;#176;C), atmospheric CO&lt;sub&gt;2&lt;/sub&gt;-concentration (eCO&lt;sub&gt;2&lt;/sub&gt;: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO&lt;sub&gt;2&lt;/sub&gt;: +3&amp;#176;C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, &gt; 250 &amp;#181;m), micro-aggregates (miA, 63 &amp;#181;m &amp;#8211; 250 &amp;#181;m) and free silt &amp; clay (sc, &lt; 63 &amp;#181;m). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of &amp;#961; = 1.6 g*cm&lt;sup&gt;-3&lt;/sup&gt;, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt &amp; clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO&lt;sub&gt;2&lt;/sub&gt; and eT x eCO&lt;sub&gt;2 &lt;/sub&gt;plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO&lt;sub&gt;2 &lt;/sub&gt;treatment. Total soil C and N did not significantly change with treatments.&amp;#160; eCO&lt;sub&gt;2&lt;/sub&gt; decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO&lt;sub&gt;2&lt;/sub&gt; fumigation treatment. This significantly differed between size classes and density fractions (p &lt; 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;

Conversion of Brazilian savannah to agricultural land affects quantity and quality of labile soil organic matter

Geoderma ◽  
2022 ◽  
Vol 406 ◽  
pp. 115509
Author(s):  
Rafael S. Santos ◽  
Martin Wiesmeier ◽  
Dener M.S. Oliveira ◽  
Jorge L. Locatelli ◽  
Matheus S.C. Barreto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Agricultural Land ◽  
Brazilian Savannah ◽  
Labile Soil Organic Matter
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