Composition and stability of soil aggregates in Fluvisols under forest, meadows, and 100 years of conventional tillage (original) (raw)
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Effects of land use conversion on soil aggregate stability and organic carbon in different soils
Agrociencia, 2013
Aggregate stability is an important factor of the soil functioning. Greater aggregate stability leads to greater soil organic carbon (SOC) preservation, while SOC acts as a key cementing agent in aggregation processes. The objective of this study was to investigate the effects of native vegetation conversion in soil aggregate stability and SOC concentration. The investigation was conducted in the Vojvodina Province, Serbia, in July 2009. Undisturbed soil samples were taken from Haplic Chernozem, Haplic Fluvisol and Gleyic Vertisol, at a depth ranging from 0 to 20 cm. A completely randomized experimental design was used with three replicates. Each soil type was considered under treatments 1) cropland >100 years, 2) native meadow and 3) native deciduous forest. The means were compared by the Tukey test (p£0.05). The sampling distance between different land use areas was less than 200 m. Wet sieving was performed in order to obtain four size classes of stable aggregates (8000-2000, 2000-250, 250-53 and <53 mm). The soil organic carbon concentration in aggregate classes was determined by the dichromate wet oxidation method. The conversion of native vegetation to cropland caused the MWD reduction of 78 % in Haplic Chernozem, 55 % in Haplic Fluvisol and 50 % in Gleyic Vertisol, and the largest decrease was recorded in the content of aggregates 2000-8000 mm. The reduction of the SOC concentration in sand-free aggregates occurred mainly in the aggregates 53-2000 mm amounting to 48 % in Gleyic Vertisol and 52 % in Haplic Chernozem, whereas in Haplic Fluvisol was 52 % in the aggregates 8000-2000. The silt and clay fraction (<53 mm) showed the highest level of SOC preservation. Due to the high concentration of SOC and clay, Gleyic Vertisol showed lower susceptibility to aggregate stability deterioration and greater ability for SOC preservation than Haplic Chernozem * Author for correspondence v Autor responsable.
Properties of soil aggregates as influenced by tillage practices
Soil Use and Management, 1989
Changes in aggregate stability, density, and porosity as well as the water retention and nutrient contents of different aggregate size fractions due to intensive tillage were investigated. Three soils from Vicarello, Fagna and Gambassi in North Central Italy which had been under permanent Vegetation, minimum or conventional tillage for more than seven years were studied. 'l'he aggregates on conventionally tilled plots were slightly denser and less porous than those on the untilled or minirnum-tilled plots. 'rhe aggregates Here less stable under conventional tillage on all soils. Conventional tillage reduced the proportion or macro-aggregates by 22% at Vicarello and 35% at Garnbassi. 'I'here were no differences in macroaggregate proportions between minimum-and conventionally tilled plots at Fagna. The potential of the d p aggregates to distintegrate upon contact with water was greatest in the conventionally tilled and least in the untilled treatments. The proportions of dry macro-aggregates (> 0.25 rnm) in the untilled and tilled plots were YO and 71%, respectively. The soil ofthe tilled plots contained less carbon and nitrogen than that of the untilled plots in all aggregate size fractions. The silt-plus-clay contents of the aggregates accounted for between 65 and 93% ofvariability in the water they retained at small potentials while organic carbon contents accounted for between 7 1 and 90% ofvariability in the stability ofthe aggregates irrespective of the tillage treatments.
2011
Dlapa P., Chrenková K., Hrabovský A., Mataix-Solera J., Kollár J., Šimkovic I., Juráni B.: The effect of land use on the soil aggregate stability in the viticulture district of Modra (SW Slovakia). Ekológia (Bratislava), Vol. 30, No. 4, p. 397-404, 2011. Lack of information still exists on relationships between the land use and various soil management practices on soil aggregate stability. This work focuses on the effect of soil management on soil properties and aggregate stability in the viticulture region where the soils are influenced by management practices such as deep ploughing before vineyard establishment and the long-term cultivation of grapevines and forestry. The obtained results showed marked differences in physical and chemical soil properties between the four study sites. In particular, the soil pH values and the contents of organic carbon and clay-fraction differed significantly. The comparison of the aggregate stability values determined for the various soil management systems indicated differences between the vineyard and forest sites. Soil aggregate stability decreases approximately according to the order where comparable original forest soil and afforested vineyard soil have greater stability than vineyard soil which is more stable than deeply ploughed vineyard soil. From all the soil properties studied, the soil organic matter content appears to be the main determining factor controlling aggregate stability.
Soil dry aggregate size distribution: effects of soil type and land use
Journal of soil science and plant nutrition, 2012
Soil structure is an important physical property of soil and has a great impact on the environment and agriculture. Dry aggregate size distribution and related soil structure indices are essential parameters in understanding the structural state of the soil. This study was conducted to determine the effects of different soil types and land uses on structure parameters and to relate them to selected soil properties. The investigation was performed on five soil types (Arenosols, Fluvisols, Chernozems, Gleysols and Solonetz), each from three different locations and under three different land uses (cropland, meadow and forest), so that a total of 135 undisturbed soil samples were collected. Dry sieving analysis was performed to obtain eight aggregate size classes (ASCs) (>10, 10-5, 5-3, 3-2, 2-1, 1-0.5, 0.5-0.25 and <0.25mm). The results suggest a highly significant impact of soil type on all ASCs and structure indices. Land use has a highly significant impact on the >10, 5-3 and 3-2 mm ASCs. Chernozems and Gleysols have more favorable structure than Arenosols, Fluvisols and Solonetz. Long term cultivation leads to the deterioration of soil structure and the formation of clods. Forest soils have a significantly better structure than soils under meadows and croplands. The application of principal component analysis and regression models identifies water retention at-33 kPa, bulk density and pH value as for the most important factors in predicting dMWD and dGMD.
2014
The present study was carried out to clarify the effects of some soil physical and chemical specifications on soil aggregates size distribution and stability under different tillage methods. Conventional tillage cause to break soil aggregates especially in loamy soils consequently increase soil sensitivity to water and winderosion. On the other hand, soil aggregate size distribution and aggregate stability are the two important physical properties of the soil with profound effects on soil health. Thus, soil sensitivity to destruction might be a criterion for evaluating soil agronomic capacity that may be defined by its stability i.e. physical structure. In an experiment carried out in 2011-12 crop season at agricultural education and research farm of Tehran University, Karaj. Iran (35048'N, 510'E, and 1321m above sea level) using randomized complete block design in split-plot arrangement with three replications physical soil parameters of aggregates size distribution and sta...
Soil and Tillage Research, 1982
The effects of direct drilling, shallow and deep tine cultivation, ploughing, and of growing and permanent grass sward on the stability and organic matter content of surface soil aggregates were studied on a range of soils in Southern England. Cultivation treatments were applied continuously for 4 to 6 years. Generally, relative aggregate stability, assessed by turbidimetric and wet-sieving techniques, was enhanced by direct drilling and other forms of simplified cultivation compared with ploughing. Increased stability was associated with increased organic matter status and was most pronounced under grass. In the case of a soil which was previously under permanent grass stability and organic matter content declined after direct drilling but significantly less so than after mouldboard ploughing. Differences in aggregate stability were detected in some soils only after modifying the test procedure and it appeared likely that the magnitude of differences were variable within a season and were related possibly to the tilth forming properties of the soils.
Soil Structure and Soil Organic Matter of Selected Soil Types in Different Ecosystems
Agriculture, 2013
In this study, differences in soil structure in different ecosystems (forest, meadow, urban, and agro-ecosystem) and soil types (Haplic Chernozem, Haplic Luvisol, Haplic Stagnosol) with a dependence on the influence of quantity and quality of soil organic matter and the particle size distribution on fraction composition of soil aggregates were compared. Soils had different productive capacity and particle size distribution. The most favourable soil structure was in the agro-ecosystem, then in forest, meadow, and urban ecosystem. The worst soil structure was in Haplic Stagnosol. An important indicator in assessing of ecosystem influence, water-resistant macro-aggregates of the 0.5-1 mm size fraction seems to be. This fraction was the only one which was statistically significantly influenced by the ecosystem, and also the only one which was not statistically significantly influenced by the soil type. This fraction also was not influenced either with the quantity and quality of soil or...
Land Use Policy, 2009
Forest and pastureland soils in highland of northern Iran are being seriously degraded and destructed due to extensive agricultural activities. These land use changes are usually accompanied by decreasing in concentrations of soil organic carbon and nutrients and also deterioration of soil structure in these regions. However, studies on concentration of nutrients and carbohydrates in soils suggest that the location of nutrients within aggregates of each size should be determined. This study was to evaluate the nutrient elements and carbohydrate distributions within water-stable aggregates (WSA) of virgin forest and pasture lands under different land uses in Alborz maintain range, northern Iran. In September 2006, soil samples were collected from depths of 0-20 cm in Typic Haploxerolls soils. The overall pattern indicated that the mean weight diameter (MWD) and WSA were greater in the virgin pasture and forest soils compared with the adjacent cultivated (ex-forest and ex-pasture) soils and aggregates of >1.0 mm size were dominant in the virgin soils, whereas the cultivated soils comprised aggregates of the size ≤0.5 mm. Distribution of organic carbon, nitrogen, phosphorus and carbohydrates within the WSA showed preferential enrichment of these parameters in the macroaggregate fraction (4.75-1.0 mm) for the virgin soils and microaggregate fraction (>0.25 mm) for the exposed soils. Cultivation decreased the concentration of carbohydrates by 23.6% and 20.6% in ex-forest and ex-pasture lands, respectively. Average distribution of total exchangeable bases within WSA showed that the cultivation of forest and pasture soils significantly led to reduce in these nutrient in the 4.75-2.0 mm fraction and increase in concentration of these exchangeable cations in <0.25 mm fractions. In general, results indicated that cultivation significantly led to 71% and 6% reductions in total exchangeable bases within the 4.75-2.0 and <0.25 mm aggregate fraction, respectively, for virgin soil. Since smaller aggregates are preferentially removed by erosion, this study emphasizes the need for sustainable soil management practices that they will minimize nutrient loss when forest or pastures lands are converted to croplands.