Relationship between extractable Al and organic C in volcanic soils of Chile

Geoderma ◽  
2008 ◽  
Vol 148 (2) ◽  
pp. 180-188 ◽  
Author(s):  
Francisco Matus ◽  
Estrella Garrido ◽  
Noelia Sepúlveda ◽  
Iris Cárcamo ◽  
Marcelo Panichini ◽  
...  
1989 ◽  
Vol 69 (1) ◽  
pp. 17-23 ◽  
Author(s):  
DALE E. MARTIN ◽  
L. E. LOWE

Podzols formed in high-rainfall areas of south coastal B.C. often have layers of highly organic material at depth in the profile, and in many cases, “pipes” of similar material angling down through the profile. These materials have a greasy feel, few discernible mineral grains, occasional remnants of wood structure and a cellular nature. The horizontal layers, termed "root mats", range in thickness from 1 cm to > 30 cm, and are overlain by coarse-textured material of low organic matter content. Chemically this material is similar to surficial H horizons with respect to C:N and N:S ratios, but closely resembles Podzolic B horizons with respect to Fe content and humus fraction ratios. In contrast oxalate-extractable Al values are remarkably high, sometimes exceeding 10%. The majority of the root mats can be classified as organic (> 17% organic C), either as H or O horizons. Those containing < 17% C meet the criteria for Bhf horizons. Key words: Root mat, root channel, oxalate-extractable Al, organic horizons


1985 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
R. W. HOWITT ◽  
S. PAWLUK

An undisturbed site under forest cover near Breton, Alberta was chosen to study the characteristics of a typical Gray Luvisol. Smectite and to a lesser extent mica were dominant in the clay fraction of the Bt. This horizon contained higher levels of organic C, pyrophosphate-extractable Fe and Al and dithionite-citrate-bicarbonate-extractable Al than adjacent horizons. Lime carbonate was not found to a depth of 2.25 m. Argillans occupied more than 1% of the area of thin sections from Bt and BC horizons but were better developed and more numerous at depths of 1.5–2.25 m. Pedoturbation appears to have caused the disruption and incorporation of argillans into the soil matrix. Argillans in the upper Bt horizon were optically similar to mica and contained more K than argillans from the BC horizons. Silt grains imbedded in argillans were common throughout the solum. Key words: Genesis, Gray Luvisol, pedogenesis, static pedology, clay migration, lessivage


2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Edgardo Auxtero ◽  
Manuel Madeira ◽  
David Parker

Strongly leached soils occurring in Northwest Iberia contain high concentration of Al which may affect crop growth. Information regarding the extractability of Al and lime required to eliminate toxic Al species in the soil solution is scarce. In this context, the extractability of Al on these soils was determined using 1 M KCl, 0.33 M LaCl3 and 0.5 M CuCl2. The effects of lime on the concentration and activity of Al species in soil solution, using the GEOCHEM program was also evaluated. Extractability of Al was in the order: 1 M KCl < 0.33 M LaCl3 < 0.5 M CuCl2, with ranges from 0.7–3.3, 1.3–4.4, and 1.8–13.5 cmolc kg-1, respectively. These values were positively correlated with cation exchange capacity and organic C, clay, Alo and Feo contents. Application of 6 t CaCO3 ha-1 increased the total concentrations of Ca+2, Mg+2, K+, and Na+ ions in soil solution, whereas, application of 2 t CaCO3 ha-1 reduced the concentration and activity of Fe+3, Al+3, Mn+2, Zn+2, Cu+2, SO4-2, and PO4-3 ions,and eliminated toxicity threshold of free Al+3 and Al soluble complexes in the soil solution. Application of low amounts of lime may prevent the negative effects of soluble Al on crops.


1974 ◽  
Vol 54 (4) ◽  
pp. 379-385 ◽  
Author(s):  
T. G. ALEXANDER ◽  
J. A. ROBERTSON

Soil samples from virgin profiles of Solonetzic and geographically associated Chernozemic series along with Ap horizons of Solonetzic and Chernozemic soils were taken. Soil pH, organic C, oxalate-extractable Al and Fe, inorganic P forms, organic and total P, and extractable P by NH4F + H3SO4 and NaHCO3 methods were determined. On the average, Solonetzic sola had higher contents of oxalate-extractable Al and Fe, Fe-P, and lower levels of Ca-P than do their associated Chernozemic sola. There was not a clear difference in Al-P contents between the sola of the two Orders. Ap samples from Solonetzic soils had twice the amount of NH4F + H2SO4- and NaHCO3-extractable P found in the Chernozemic ones. The higher levels of extractable P in the Solonetzic than in the Chernozemic Ap samples could be explained by the higher contents of Al-P and Fe-P in the former. The high acidity in the upper sola of Solonetzic soils, indicative of intense weathering conditions, apparently has resulted in relatively high contents of oxalate-extractable Al and Fe, and these probably account for the higher levels of Al-P and Fe-P and lower levels of Ca-P in the Solonetzic than in the Chernozemic soils.


CATENA ◽  
2015 ◽  
Vol 127 ◽  
pp. 17-25 ◽  
Author(s):  
Susana R. Valle ◽  
Jermán Carrasco ◽  
Dante Pinochet ◽  
Paz Soto ◽  
R. Mac Donald

1990 ◽  
Vol 62 (1) ◽  
pp. 9-15
Author(s):  
Raina Niskanen

The dependence of the indicator of phosphate sorption capacity on extractable Al and Fe and other soil properties was studied in a material consisting of 102 mineral soil samples. The sum of P adsorbed on soil during two days from a solution containing P 5 mmol/l and P extracted by 0.02 M EDTA (pH 5.3) as an estimate of the initial P content in the soil was used as the indicator of P sorption capacity. In clay and silt soils (n = 51), the Al and Fe extracted by 0.05 M oxalate (pH 2.9) together with the organic C content explained 85 %, the Al and Fe extracted by 0.05 M K4P2O7 (pH 10) together with the clay content 87 %, the Al and Fe extracted by 0.02 M EDTA (pH 5.3) 91 %, and the Al extracted by 1 M CH3COONH4 (pH 4.8) together with the organic C and clay contents 78 % of the variation of the indicator of phosphate sorption capacity. In coarse soils (n = 51), the variation of the indicator was explained well only by oxalate-extractable metals, which together with soil pH and clay content explained 80 % of the variation. Extractable Al was generally the most important explainer of variation. The results suggest that forms of extractable Al and Fe explaining the variation of the indicator of P sorption capacity in clay and silt soils are partially different from those in coarse soils.


2017 ◽  
Vol 5 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Kewat Sanjay Kumar ◽  

Mechanisms governing carbon stabilization in soils have received a great deal of attention in recent years due to their relevance in the global carbon cycle. Two thirds of the global terrestrial organic C stocks in ecosystems are stored in below ground components as terrestrial carbon pools in soils. Furthermore, mean residence time of soil organic carbon pools have slowest turnover rates in terrestrial ecosystems and thus there is vast potential to sequester atmospheric CO2 in soil ecosystems. Depending upon soil management practices it can be served as source or sink for atmospheric CO2. Sustainable management systems and practices such as conservation agriculture, agroforestry and application of biochar are emerging and promising tools for soil carbon sequestration. Increasing soil carbon storage in a system simultaneously improves the soil health by increase in infiltration rate, soil biota and fertility, nutrient cycling and decrease in soil erosion process, soil compaction and C emissions. Henceforth, it is vital to scientifically explore the mechanisms governing C flux in soils which is poorly understood in different ecosystems under anthropogenic interventions making soil as a potential sink for atmospheric CO2 to mitigate climate change. Henceforth, present paper aims to review basic mechanism governing carbon stabilization in soils and new practices and technological developments in agricultural and forest sciences for C sequestration in terrestrial soil ecosystems.


Author(s):  
Brian J. Wilsey

Net primary productivity (NPP) is the amount of C or biomass that accumulates over time and is photosynthesis—autotroph respiration. Annual NPP is estimated by summing positive biomass increments across time periods during the growing season, including offtake to herbivores, which can be high in grasslands. Remote sensing techniques that are used to assess NPP are discussed by the author. Belowground productivity can be high in grasslands, and it is important to carbon storage. Across grasslands on a geographic scale, NPP, N mineralization, and soil organic C all increase with annual precipitation. Within regions, NPP can be strongly affected by the proportion of C4 plant species and animal species composition and diversity. Humans are adding more N to the environment than all the natural forms of addition (fixation and lightning) combined. Animals, especially herbivores, can have strong effects on how plants respond to changes in changes in resource availability.


Soil Research ◽  
2019 ◽  
Vol 57 (2) ◽  
pp. 200 ◽  
Author(s):  
J. Somasundaram ◽  
M. Salikram ◽  
N. K. Sinha ◽  
M. Mohanty ◽  
R. S. Chaudhary ◽  
...  

Conservation agriculture (CA) including reduced or no-tillage and crop residue retention, is known to be a self–sustainable system as well as an alternative to residue burning. The present study evaluated the effect of reduced tillage coupled with residue retention under different cropping systems on soil properties and crop yields in a Vertisol of a semiarid region of central India. Two tillage systems – conventional tillage (CT) with residue removed, and reduced tillage (RT) with residue retained – and six major cropping systems of this region were examined after 3 years of experimentation. Results demonstrated that soil moisture content, mean weight diameter, percent water stable aggregates (&gt;0.25mm) for the 0–15cm soil layer were significantly (Pmoderately labile&gt;less labile. At the 0–15cm depth, the contributions of moderately labile, less labile and non-labile C fractions to total organic C were 39.3%, 10.3% and 50.4% respectively in RT and corresponding values for CT were 38.9%, 11.7% and 49.4%. Significant differences in different C fractions were observed between RT and CT. Soil microbial biomass C concentration was significantly higher in RT than CT at 0–15cm depth. The maize–chickpea cropping system had significantly (P–1 followed by soybean+pigeon pea (2:1) intercropping (3.50 t ha–1) and soybean–wheat cropping systems (2.97 t ha–1). Thus, CA practices could be sustainable management practices for improving soil health and crop yields of rainfed Vertisols in these semiarid regions.


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