Mechanisms of macroaggregate stabilisation by carbonates: implications for organic matter protection in semi-arid calcareous soils

Soil Research ◽  
2014 ◽  
Vol 52 (2) ◽  
pp. 180 ◽  
Author(s):  
Oihane Fernández-Ugalde ◽  
Iñigo Virto ◽  
Pierre Barré ◽  
Marcos Apesteguía ◽  
Alberto Enrique ◽  
...  
Keyword(s):  
Organic Matter ◽  
Calcareous Soils ◽  
Clay Mineralogy ◽  
Exchange Capacity ◽  
Agricultural Field ◽  
Thin Sections ◽  
Organic C ◽  
Precipitation Phenomena ◽  
Different Response ◽  
Semi Arid

Carbonates interfere with soil aggregation in semi-arid calcareous soils, promoting the stability of macroaggregates and decelerating the decomposition of the organic matter within them. Our aim was to determine the process through which carbonates participate in aggregation. We hypothesised (i) a tendency to accumulate reactive clay minerals via Ca2+ bridging, and (ii) a precipitation of carbonates within aggregates due to dissolution/re-precipitation phenomena. The <250-µm fractions of a Typic Calcixerept (CALC) and a decarbonated Calcic Haploxerept (DECALC) were incubated from the same agricultural field in semi-arid Spain with added maize straw during 28 days. A size-based fractionation was used to separate different aggregates in incubated and field-moist samples, and aggregates were analysed for organic C and maize-derived C, clay mineralogy by X-ray diffraction, and micromorphology in digital images of thin sections. Contrary to the first hypothesis, the two soils showed a similar tendency to accumulate smectite in aggregates, probably because the cation exchange capacity was saturated by Ca2+ in both CALC and DECALC. Macroaggregates showed a less porous structure in CALC than in DECALC due to the accumulation of calcite microcrystals, as formulated in the second hypothesis. We propose that low porosity of macroaggregates is mainly responsible for the slower turnover of organic matter observed in CALC than in DECALC. These results explain the greater concentration of organic C in microaggregates within macroaggregates in field-moist samples in CALC than in DECALC. The different porosity of macroaggregates may also result in differences in physical properties between CALC and DECALC. These observations suggest a different response of calcareous soils in terms of organic matter protection, resistance to erosion, and water storage compared with other soil types in semi-arid lands.

scholarly journals Micromorphological analysis on the influence of the soil mineral composition on short-term aggregation in semi-arid Mediterranean soils .

2014 ◽  
Vol 3 ◽  
Author(s):  
Inigo Virto ◽  
Pierre Barré ◽  
Alberto Enrique ◽  
Rosa María Poch ◽  
Oihane Fernández-Ugalde ◽  
...  
Keyword(s):  
Organic Matter ◽  
Physical Characteristics ◽  
Organic Matter Decomposition ◽  
Equivalent Diameter ◽  
Mineral Phase ◽  
Thin Sections ◽  
Fresh Organic Matter ◽  
Mediterranean Soils ◽  
Semi Arid ◽  
Micromorphological Analysis

Aggregation in soils is the result of the interaction of the soil organic components and soil minerals. The reactivity of the mineral phase is acknowledged to interfere with aggregates formation and stabilization, but its influence on aggregation in semi-arid Mediterranean soils remains mostly unknown. In this study, we used micromorphological analysis of aggregates formed in a 28-d incubation in two agricultural soils differing only in the composition of the mineral phase in the upper Ap horizon (a carbonate-depleted Palexeralf with 21.5% clay, and a contiguous carbonate-rich Typic Calcixerept with 20.9% clay before decarbonation which was reduced to 10.4% upon decarbonation). The two soils belong to the same agricultural field and have had similar management for decades. Soil samples were completely disaggregated into their fractions &lt; 250 μm, and incubated with fresh organic matter to stimulate re-aggregation. Macroaggregates (&gt; 2 mm) formed during the incubation were separated at days 3, 7, 14, 21 and 28 and used to prepare thin sections. Macroaggregates were more abundant at day 3, and then decreased in number in the two soils, which indicates a dependency between organic matter decomposition and stable macroaggregates formation. They contained a greater proportion of smaller aggregates in the decarbonated soil. Micromorphological analysis revealed significant differences in the fabric and physical characteristics of these macroaggregates, in which bonds among primary particles were observed to be led by clays in the Palexeralf while the coarse fraction appeared embedded in a micromass with crystallitic b-fabric corresponding to carbonates in the Calcixerept. This resulted in a more compact fabric and less porosity in macroaggregates in the Calcixerept. Image analysis of thin sections was used to quantify and characterize the pore system of macroaggregates. Porosity (pores &gt; 20 μm) was more than double (36.9% for 15.6%) within macroaggregates in the decarbonated soil, with more elongated pores. Although in both soils most pores were 20 to 150-μm in equivalent diameter, some porosity &gt; 150 μm was observed only in macroaggregates from the decarbonated soil. These observations allow hypothesizing that the mechanisms responsible for aggregates stabilization and/or formation are different in the two soils, and that they result in different physical characteristics of soil aggregates. The implications of such differences on air and water flow rates within aggregates, and thus on the soil microbial activity and organic matter decomposition, as well as on soil erodibility, need to be studied and accounted for when evaluating the effect of soil management and other practices on soil quality in semi-arid Mediterranean agrosystems.

Burning crop residues under no-till in semi-arid land, Northern Spain—effects on soil organic matter, aggregation, and earthworm populations

Soil Research ◽  
2007 ◽  
Vol 45 (6) ◽  
pp. 414 ◽  
Author(s):  
Iñigo Virto ◽  
Maria José Imaz ◽  
Alberto Enrique ◽  
Willem Hoogmoed ◽  
Paloma Bescansa
Keyword(s):  
Organic Matter ◽  
Crop Residues ◽  
Penetration Resistance ◽  
No Tillage ◽  
Organic C ◽  
No Till ◽  
Mineralisation Potential ◽  
Earthworm Populations ◽  
Semi Arid ◽  
Stubble Burning

Stubble burning has traditionally been used in semi-arid land for pest and weed control, and to remove the excess of crop residues before seeding in no-tillage systems. We compared differences in soil properties in a long-term (10 years) tillage trial on a carbonated soil in semi-arid north-east Spain under no-tillage with stubble returned and stubble burnt, with the conventional tillage system (mouldboard plough, stubble returned) as a reference. Differences in total soil organic C and C in particulate organic matter, mineralisation potential, soil physical properties (bulk density, penetration resistance, and aggregate size distribution and stability), and earthworm populations were quantified. The effect of stubble burning was absent or insignificant compared with that of tillage in most of the parameters studied. The most significant effect of stubble burning was the change in soil organic matter quality in the topsoil and penetration resistance. No-till plus stubble burning stocked an amount of organic C in the soil similar to no-till without burning, but the particulate organic matter content and mineralisation potential were smaller. Earthworm activity was similar under the 2 no-till systems, although a trend towards bigger earthworms with increasing penetration resistance was observed under the system with burning. Our results indicate that the role of burnt plant residues and earthworms in organic matter accumulation and soil aggregation in Mediterranean carbonated soils under no tillage is of major importance, meriting further attention and research.

scholarly journals A Comparison of Methods for the Determination of Cation Exchange Capacity of Soils/Porównanie Metod Oznaczania Pojemności Wymiany Kationów I Sumy Kationów Wymiennych W Glebach

2014 ◽  
Vol 21 (3) ◽  
pp. 487-498 ◽  
Author(s):  
Dawid Jaremko ◽  
Dorota Kalembasa
Keyword(s):  
Organic Matter ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Sodium Acetate ◽  
Calcareous Soils ◽  
Acid Soils ◽  
Barium Chloride ◽  
Exchange Capacity ◽  
Organic Carbon Content

Abstract The object of this study was to compare the results obtained with four methods of determination of cation exchange capacity (CEC) and sum of exchangeable cations (Ca, Mg, K) in soils. One of these methods is Kappen’s method and the others methods are based on different extracting reagents: sodium acetate (pH = 8.2), barium chloride and hexaamminecobalt(III) chloride. Values measured with barium ions and hexaamminecobalt(III) ions as index cations are very comparable and these two methods can be considered as equivalent. Kappen’s method gives overestimated results, especially for acid soils reach in organic matter and very calcareous soils. Sodium acetate, buffering the pH of the extracting solution, causes increase of numbers of negatively charged sites and particularly those bonded to organic matter and for this reason values obtained with this method are overestimated. Nevertheless, it is possible to correct this error for a given soil sample by regression equation considering pH of soil, clay and organic carbon content.

scholarly journals Carbon input control over soil organic matter dynamics in a temperate grassland exposed to elevated CO<sub>2</sub> and warming

2010 ◽  
Vol 7 (2) ◽  
pp. 1575-1602 ◽  
Author(s):  
Y. Carrillo ◽  
E. Pendall ◽  
F. A. Dijkstra ◽  
J. A. Morgan ◽  
J. M. Newcomb
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Elevated Co2 ◽  
Combined Effects ◽  
Organic C ◽  
Soil C ◽  
C Storage ◽  
C Pools ◽  
Labile C ◽  
Semi Arid

Abstract. Elevated CO2 generally increases soil C pools. However, greater available C concentrations can potentially stimulate soil organic matter (SOM) decomposition. The effects of climate warming on C storage can also be positive or negative. There is a high degree of uncertainty on the combined effects of climate warming and atmospheric CO2 increase on SOM dynamics and its potential feedbacks to climate change. Semi-arid systems are predicted to show strong ecosystem responses to both factors. Global change factors can have contrasting effects for different SOM pools, thus, to understand the mechanisms underlying the combined effects of multiple factors on soil C storage, effects on individual C pools and their kinetics should be evaluated. We assessed SOM dynamics by conducting long-term laboratory incubations of soils from PHACE (Prairie Heating and CO2 Enrichment experiment), an elevated CO2 and warming field experiment in semi-arid, native northern mixed grass prairie, Wyoming, USA. We measured total C mineralization and estimated the size of the labile pool and the decomposition rates of the labile and resistant SOM pools. To examine the role of plant inputs on SOM dynamics we measured aboveground biomass, root biomass, and soil dissolved organic C (DOC). Greater aboveground productivity under elevated CO2 translated into enlarged pools of readily available C (measured as total mineralized C, labile C pool and DOC). The effects of warming on the labile C only occurred in the first year of warming suggesting a transient effect of the microbial response to increased temperature. Experimental climate change affected the intrinsic decomposability of both the labile and resistant C pools. Positive relationships of the rate of decomposition of the resistant C with aboveground and belowground biomass and dissolved organic C suggested that plant inputs mediated the response by enhancing the degradability of the resistant C. Our results contribute to a growing body of literature suggesting that priming is a ubiquitous phenomenon that should be included in C cycle models.

The role of active fractions of soil organic matter in physical and chemical fertility of Ferrosols

Soil Research ◽  
1998 ◽  
Vol 36 (5) ◽  
pp. 809 ◽  
Author(s):  
M. J. Bell ◽  
P. W. Moody ◽  
R. D. Connolly ◽  
B. J. Bridge
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Management Practices ◽  
Chemical Properties ◽  
Aggregate Stability ◽  
Infiltration Rate ◽  
Exchange Capacity ◽  
Organic C ◽  
Wide Range ◽  
Physical And Chemical

The relationships between fractions of soil organic carbon (C) oxidised by varying strengths of potassium permanganate (KMnO4) and important soil physical and chemical properties were investigated for Queensland Ferrosols. These soils spanned a wide range of clay contents (31-83%), pH values (4·4-7·9; 1 : 5 water), and total C contents (12· 1-111 g/kg). Carbon fractions were derived by oxidation with 33 mM (C1), 167 mM (C2), and 333 mM (C3) KMnO4, while organic C and total C were determined by Heanes wet oxidation and combustion, respectively. Aggregate stability was determined by wet sieving soil from the surface crust after 30 min of high intensity (100 mm/h), simulated rainfall on disturbed samples in the laboratory. The proportion of aggregates <0·125 mm (P125) was used as the stability indicator because of the high correlation between this size class and the final rainfall infiltration rate (r2 = 0qa86, n = 42). The soil organic C fraction most closely correlated with P125 was C1 (r2 = 0·79, n = 42). This fraction was also highly correlated with final, steady-state infiltration rates in field situations where there were no subsurface constraints to infiltration (r2 = 0·74, n = 30). Multiple linear regression techniques were used to identify the soil properties determining effective cation exchange capacity (ECEC, n = 89). Most variation in ECEC (R2 = 0 ·72) was accounted for by a combination of C1 (P < 0·0001) and pH (P < 0·0001). These results confirm the very important role played by the most labile (easily oxidised) fraction of soil organic matter (C1) in key components of the chemical and physical fertility of Ferrosols. Management practices which maintain adequate C1 concentrations are essential for sustainable cropping on these soils.

Zinc Adsorption in Different Calcareous Soils

2020 ◽  
Vol 23 (2) ◽  
pp. 118-130
Author(s):  
Payizan Ihsan Ramadhan ◽  
Lazkeen Ahmed Merween Mehmedany
Keyword(s):  
Organic Matter ◽  
Calcium Carbonate ◽  
Calcareous Soils ◽  
Clay Content ◽  
Exchange Capacity ◽  
Ion Concentration ◽  
Available Phosphorus ◽  
The Difference ◽  
Physical And Chemical ◽  
Zinc Adsorption

Zinc adsorption was studied for ten selective representative soils according the difference amount of clay content, calcium carbonate and organic matter in Duhok governorate, Iraqi-Kurdistan region included (Kanimasi-1&2, Batofa, Zakho, Assih, Semeel, Khanke, Faydi, Zawita and Bamarny locations). Samples were air dried and sieved through a 2-mm sieve to study the physical and chemical characteristics of the soils, forms of zinc and it’s adsorption. Results showed the soluble, DTPA extractable zinc (available), CaCl2 extractable zinc (exchangeable) and total zinc ranged between (0.29 – 0.94), (0.88 – 1.64), (1.71 – 2.05), and (12.25 – 56.15) mg kg-1 respectively. Negative significant correlation found between soluble zinc with pH, also negative significant correlation found between DTPA extractable zinc with exchangeable potassium, bicarbonate and available phosphorus but positive significant correlation found between CaCl2 extractable zinc with pH, total–Zn negatively affected with pH and positively with HCO3 and sand. Results demonstrated that by increasing added zinc concentration to studied soil zinc will be adsorbed zinc adsorbed greatly at temperature 25°C and 48°C. In general total zinc adsorbed at 25C° in six concentrations was less than zinc adsorbed at 48C°. At temperatures 25°C and 48°C the high total amount of zinc adsorbed found in the soil of Zawita and Zakho respectively, but the lower total zinc adsorbed observed in soil of Batofa and Kani masi-2. The quantity of adsorption affected positively by presence of clay, calcium carbonate, active calcium carbonate and cation exchange capacity and negatively affected by the ion concentration of bicarbonate, calcium, potassium, organic matter and sand content.

CATION EXCHANGE CAPACITIES AND SURFACE AREAS OF HUMIC GLEYSOLIC Ap HORIZONS FROM SOUTHWESTERN ONTARIO

1982 ◽  
Vol 62 (2) ◽  
pp. 291-296 ◽  
Author(s):  
L. J. EVANS
Keyword(s):  
Organic Matter ◽  
Regression Analysis ◽  
Cation Exchange ◽  
Multiple Regression Analysis ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Organic C ◽  
Surface Areas ◽  
A Value

Thirty-four samples from the Ap horizons of heavy-textured Orthic Humic Gleysols (Typic Haplaquolls) were sampled in southwestern Ontario. Surface areas of the soils ranged from 79–223 m2/g and multiple regression analysis indicated that the surface area of the clay fractions was 207 m2/g and that of the organic matter 805 m2/g. Approximately 74% of the variability in cation exchange capacity could be attributed to their clay and organic C contents at pH 4 and about 86% at pH 8. A value of 181 meq/100 g was calculated as the cation exchange capacity of organic matter at pH 4 and of 316 meq/100 g at pH 8. Mean cation exchange capacities at pH 4 were 20.3 meq/100 g and 31.6 meq/100 g at pH 8.

Physical quality of a Luvisol under agroforestry systems in a semi-arid region, Brazil

Soil Research ◽  
2016 ◽  
Vol 54 (4) ◽  
pp. 430 ◽  
Author(s):  
Rafaela Watanabe ◽  
Getulio Coutinho Figueiredo ◽  
Alvaro Pires da Silva ◽  
Júlio César Lima Neves ◽  
Teógenes Senna de Oliveira
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Bulk Density ◽  
Agroforestry Systems ◽  
Organic C ◽  
Physical Quality ◽  
Consolidation Pressure ◽  
Critical Water Content ◽  
Semi Arid

Agroforestry systems provide many environmental benefits in semi-arid regions; however, trampling by cattle, and agricultural practices, can degrade physical quality of the soil. The aim of this study was to evaluate the degree of compaction and the compression behaviour of a Luvisol after 14 years under agro-silvopastoral (ASP) and silvopastoral systems (SILV), compared with a soil under natural vegetation (NV). We evaluated the degree of soil compactness, compaction index, pre-consolidation pressure, maximum bulk density, critical water content and the stocks of total organic carbon (C), organic matter (OM), C in light organic matter (LOM), and nitrogen (N) in LOM. The results indicated that agroforestry systems change the compressive behaviour of the soil, increasing maximum bulk density (P < 0.05) and reducing critical water content (P < 0.05). Despite the increases in maximum bulk density, changes induced by agroforestry system did not affect the pore space, as shown by similar values for degree of compactness (P > 0.05) under ASP, SILV and NV. This suggests a change in the quality of OM, as evidenced by the lower values for stocks of N in LOM (P < 0.10) and total organic C (P < 0.05) under ASP and SILV, whereas pre-consolidation pressure was unaffected (P > 0.05). After 14 years, the degree of compactness and load-bearing capacity of the soils under ASP and SILV had not increased, being suitable for plant growth.

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