The Mineralogy, Chemistry, and Physics of Tropical Soils with Variable Charge Clays

Uehara, G.; Gillman, G. P.

doi:10.1097/00010694-198504000-00019

Cited by 177 publications

(260 citation statements)

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“…Furthermore, hydrolysis of Al 3+ can result in release of H + to soil solution, constantly lowering its pH. 48 Our results confirm this suggestion, showing that exchangeable acid cations (H + and Al 3+ ) predominated soil cation pools, and both their concentrations were significantly higher than any base cation at the base of equivalent. These cation composition patterns also reflect that the soils are at the stage of Al buffering, 6 which is distinctly different from that of most temperate ecosystems, where exchangeable base cations generally dominate soil cation pools.…”

Section: Characteristics Of Soil Buffering Capacity In Tropicalsupporting

confidence: 84%

Divergent Responses of Soil Buffering Capacity to Long-Term N Deposition in Three Typical Tropical Forests with Different Land-Use History

Mao

et al. 2015

Environ. Sci. Technol.

112

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Elevated anthropogenic nitrogen (N) deposition has become an important driver of soil acidification at both regional and global scales. It remains unclear, however, how long-term N deposition affects soil buffering capacity in tropical forest ecosystems and in ecosystems of contrasting land-use history. Here, we expand on a long-term N deposition experiment in three tropical forests that vary in land-use history (primary, secondary, and planted forests) in Southern China, with N addition as NH 4 NO 3 of 0, 50, 100, and 150 kg N ha −1 yr −1 , respectively. Results showed that all three forests were acid-sensitive ecosystems with poor soil buffering capacity, while the primary forest had higher base saturation and cation exchange capacity than others. However, long-term N addition significantly accelerated soil acidification and decreased soil buffering capacity in the primary forest, but not in the degraded secondary and planted forests. We suggest that ecosystem N status, influenced by different land-use history, is primarily responsible for these divergent responses. N-rich primary forests may be more sensitive to external N inputs than others with low N status, and should be given more attention under global changes in the future, because lack of nutrient cations is irreversible.

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Section: Characteristics Of Soil Buffering Capacity In Tropicalsupporting

confidence: 84%

Divergent Responses of Soil Buffering Capacity to Long-Term N Deposition in Three Typical Tropical Forests with Different Land-Use History

Mao

et al. 2015

Environ. Sci. Technol.

112

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“…A second approach used resin bags as anion exchangers to quantify the amount of inorganic P in organic layers and mineral topsoil by applying a standardized procedure. Most likely, this technique measures soil solution P and part of the non-specifically adsorbed P, thereby approaching the plant-available fraction, while tightly bound P (precipitated and occluded fractions) will not be removed by the anion exchangers (Irion 1978;Uehara and Gillman 1981). Clearly, additional P fractions may be available to plants as well that are not measured by this technique, notably organic and inorganic P mobilized by external phosphatases and other rhizosphere processes.…”

Section: Elevational Change In P Availabilitymentioning

confidence: 99%

“…Inorganic P is supplied to the P a fraction by desorption processes, in acidic soils mostly from iron and aluminium oxide minerals, P release through organic matter mineralization, and mineral weathering (Walker and Syers 1976;Irion 1978;Uehara and Gillman 1981;Grierson et al 1999). Uptake by plants and microbes and, to a lesser extent, leaching with percolating water are processes which deplete the P a pool (Olander and Vitousek 2004).…”

Section: Elevational Change In P Availabilitymentioning

confidence: 99%

Variability of indices of macronutrient availability in soils at different spatial scales along an elevation transect in tropical moist forests (NE Ecuador)

2010

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The availability of key plant nutrients may change with elevation in tropical mountains due to altitudinal gradients in temperature and moisture which affect pedogenesis and nutrient cycling. In a transect from upper lowland to montane forests in NE Ecuador, we tested the hypotheses that (1) the availability of P is low in low-elevation forests but increases upslope, while the availability of N is relatively high at low elevations but decreases with elevation, and (2) increasing amounts of calcium, magnesium and potassium are stored on top of the soil with progressive humus accumulation toward higher elevations, likely to improve nutrient availability. In each 20 plots in undisturbed natural forest at 500, 1000, 1500 and 2000 ma.s.l., we measured in situ N net mineralization and nitrification rate (N NM and N NI , buried bag method), plant-available phosphorus (P a , resin-bag method), and salt-exchangeable calcium, potassium and magnesium concentrations (Ca ex , K ex , Mg ex ) in the organic and mineral topsoils. N NM and N NI , and the Ca ex , K ex and Mg ex concentrations were much more variable at the plot level than across the four elevations, while P a varied equally at small and large spatial scales. P a increased more than 10fold from 500 to 2000 m. The net release of nitrate dominated over ammonium at all elevations. While mass-related N NM and N NI rates and also organic matter C/N ratio in the topsoil remained invariant along the slope, N NM and N NI rates per ground area decreased by about 40% from 500 to 2000 m. Thus, the N NM /P a ratio decreased markedly with elevation proving our first hypothesis. In support of the second hypothesis, the pools of Ca ex , Mg ex and K ex in the organic layers increased with elevation, demonstrating the key role that organic topsoil horizons are playing for forest nutrition at high elevations. We suggest that the large difference in N versus P availability of tropical (upper) lowland and montane forests is likely to be a key factor influencing the species composition and productivity along tropical mountain slopes.

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“…Como a curva de pH em função da adição de ácidos e de bases tem um comportamento seno-hiperbólico, à medida que se afasta do PESN do solo (extremidades da curva), adições de quantidades iguais de ácido ou de base irão resultar em variações cada vez menores de pH do solo. O controle dessa variação, tanto na parte ácida como na básica, é definido pelo desmonte da rede cristalina, o que ocorre em torno de pH 2,5 a 3,0 e de 9,0 a 9,5 (Uehara & Gillman, 1981). A variação de pH obtida não extrapolou esses limites.…”

Section: Resultsunclassified

Adsorção de nitrato em solos com cargas variáveis

Alcântara¹,

Camargo

2005

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi avaliar o comportamento adsortivo do nitrato em relação às modificações da carga líquida do solo decorrentes da adição de ácidos, bases (carbonatos), fosfato e sulfato. Foram utilizadas amostras dos horizontes A e B de dois solos: Latossolo Vermelho acriférrico e Nitossolo Vermelho eutrófico. Para verificar o comportamento adsortivo do nitrato em relação aos tratamentos, ajustaram-se isotermas de adsorção de Freundlich (exponencial). O modelo de Freundlich descreve satisfatoriamente a adsorção do nitrato ao solo em todos os tratamentos. Existe correlação significativa entre o pH e a carga líquida dos solos, considerando-se os tratamentos aplicados ao horizonte B do Latossolo Vermelho. A adsorção do nitrato nos horizontes A e B comporta-se de maneira diferenciada nos dois solos utilizados. No Latossolo Vermelho, a adsorção é maior no horizonte subsuperficial em relação ao superficial. No Nitossolo Vermelho, a adsorção é maior no horizonte superficial em relação ao subsuperficial. As adições de sulfato e de fosfato ao solo resultam em pequena diminuição na adsorção de nitrato em relação ao observado no horizonte B do Latossolo Vermelho acriférrico.Termos para indexação: solos tropicais, nitrogênio, carga líquida. Nitrate adsorption in variable charged soilsAbstract -The objective of this work was to assess the adsorptive behavior of nitrate due to net charge (pH) modifications caused by the addition of acids, bases (carbonates), phosphate and sulfate. Samples of A and B horizons of two soils: an Ustox and an Ustalf . Freundlich isotherms were adjusted in order to verify the influence of the different treatments. The Freundlich model fits well to experimental data. There is significance correlation between pH and net charge for the soils, considering the treatments applied to the B horizon of the Ustox soil. Nitrate adsorption in the A and B horizons is different for the two soils. In Ustox soil, adsorption is greater in subsuperficial than in superficial horizon. In Ustalf soil, adsorption is greater in the superficial horizon than in the subsuperficial one. Sulfate and phosphate additions result in little reduction on the nitrate adsorption comparing to the Ustox B horizon.

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The Mineralogy, Chemistry, and Physics of Tropical Soils with Variable Charge Clays

Cited by 177 publications

References 0 publications

Divergent Responses of Soil Buffering Capacity to Long-Term N Deposition in Three Typical Tropical Forests with Different Land-Use History

Divergent Responses of Soil Buffering Capacity to Long-Term N Deposition in Three Typical Tropical Forests with Different Land-Use History

Variability of indices of macronutrient availability in soils at different spatial scales along an elevation transect in tropical moist forests (NE Ecuador)

Adsorção de nitrato em solos com cargas variáveis

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