scholarly journals Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

2016 ◽  
Vol 64 (2) ◽  
pp. 111-120 ◽  
Author(s):  
Miroslav Fér ◽  
Martin Leue ◽  
Radka Kodešová ◽  
Horst H. Gerke ◽  
Ruth H. Ellerbrock
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Preferential Flow ◽  
Water Drop ◽  
Soil Aggregates ◽  
High Water ◽  
Contact Angles ◽  
Surface Wettability ◽  
Mineral Coatings ◽  
Droplet Infiltration

Abstract The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i) coated, (ii) not coated (both intact), and (iii) aggregates from which coatings were removed (cut). The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT). A potential wettability index (PWI) was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT) and contact angles (CA) during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA(t) = at−b). For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value (R2 = 0.75). The a parameter was significantly related to the WDPT (R2 = 0.84) and to the PWI (R2 = 0.64). The relations between the b parameter and the WDPT (R2 = 0.61) and the PWI (R2 = 0.53) were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM (R2 = 0.64). In contrast to dry samples, no significant relationships were found between parameters a or b of CA(t) and WDPT or PWI for wet aggregate surfaces. The results suggest that the effect of the SOM composition of coatings on surface wettability decreases with increasing soil moisture. In addition to the dominant impact of SOM, the wettability of aggregate surfaces could be affected by different mineralogical compositions of clay in coatings and interiors of aggregates. Particularly, wettability of coatings could be decreased by illite which was the dominant clay type in coatings. However, the influence of different clay mineral fractions on surface wettability was not due to small number of measurements (2 and 1 samples from coatings and interiors, respectively) quantified.

Effect of Soil Organic Matter on the Phytotoxicity of Thirteens-Triazine Herbicides

Weed Science ◽  
1979 ◽  
Vol 27 (2) ◽  
pp. 158-161 ◽  
Author(s):  
A. Rahman ◽  
L. J. Matthews
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Avena Sativa ◽  
Water Solubility ◽  
Sandy Loam ◽  
High Water ◽  
Triazine Herbicides ◽  
Greenhouse Experiments ◽  
High Water Solubility

The influence of soil organic matter on the initial and residual phytotoxicity of thirteens-triazine herbicides was investigated in greenhouse experiments using three Horotiu sandy loam soils with organic matter levels of 9.8, 15.5, and 20.6%. The amount of herbicide required to reduce the growth of oats (Avena sativaL. ‘Mapua’) by 50% (GR50) when compared with the control was determined for each herbicide and each organic matter level. Results showed that the GR50values for all herbicides were highly and positively correlated with the soil organic matter. In general, the phytotoxicity of compounds of high water solubility was less influenced by soil organic matter than those having low water solubility. The chloro-triazines persisted longer in soil than did the methoxy- or methylthio-triazines. Simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] and atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] were the most persistent of the chloro-triazines.

Wettability of soil aggregates from cultivated and uncultivated Ustolls and Usterts

Soil Research ◽  
2004 ◽  
Vol 42 (2) ◽  
pp. 163 ◽  
Author(s):  
Anna Eynard ◽  
Thomas E. Schumacher ◽  
Michael J. Lindstrom ◽  
Douglas D. Malo ◽  
Robert A. Kohl
Keyword(s):  
Organic Matter ◽  
Great Plains ◽  
Water Intake ◽  
Agricultural Soils ◽  
Water Drop ◽  
Soil Aggregates ◽  
Management Systems ◽  
Northern Great Plains ◽  
Organic C ◽  
Cultivated Soils

Soil organic matter can modify the interaction of clay minerals with water, limiting the rate of water intake of swelling clays and stabilising soil aggregates. Soil structural stability and organic C content usually decrease with cultivation. Faster wetting increases stresses on aggregates and decreases stability. Aggregate wettabilities of prairie soils under 3 different management systems (grassland, no-till, and conventional-till) were compared in the Northern Great Plains of the USA. Six Ustolls and 2 Usterts were selected as replications along the Missouri River. Wettability was measured as water drop penetration time (WDPT) and as rate of water intake under 30 and 300 mm tension. At low tension, aggregates from both cultivated fields and uncultivated grasslands showed similar wettability. Water intake in grass aggregates was attributed to a greater amount of stable pores relative to cultivated aggregates. In cultivated aggregates, slaking created planes of failure that allowed rapid water entry. Differences of wettability between management systems at 300 mm tension (in Ustolls, grasslands had greater wettability than cultivated soils, 0.24 v. 0.17 g water/h.g dry soil) and between soil orders (Usterts had longer WDPT than Ustolls, 2.9 v. 1.7 s) were explained by both clay and organic C contents. Simple measurements of aggregate wettability may be effectively used for soil quality characterisation. Aggregate wettability is a desirable property for agricultural soils when it is related to stable porosity, as may be found in high organic matter soils (e.g. grasslands). Wettability is excessive when fast aggregate wetting results in aggregate destruction as observed in low organic matter cultivated soils.

scholarly journals Ecohydrological effectiveness of litter crusts in sandy ecosystem

2018 ◽  
Author(s):  
Yu Liu ◽  
Zeng Cui ◽  
Ze Huang ◽  
Hai-Tao Miao ◽  
Gao-Lin Wu
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Matter Content ◽  
Terrestrial Ecosystems ◽  
Infiltration Rate ◽  
High Water ◽  
Matter Content ◽  
Water Infiltration ◽  
Desert Ecosystems ◽  
Positive Effects

Abstract. Litter crusts are integral components of the water budget in terrestrial ecosystems, especially in arid areas. This innovative study is to quantify the ecohydrological effectiveness of litter crusts in desert ecosystems. We focus on the positive effects of litter crusts on soil water holding capacity and water interception capacity compared with biocrusts. Litter crusts significantly increased soil organic matter, which was 2.4 times the content in biocrusts and 3.84 times the content in bare sandy lands. Higher organic matter content resulted in increased soil porosity and decreased soil bulk density. Meanwhile, soil organic matter can help to maintain maximum infiltration rates. Litter crusts significantly increased the water infiltration rate under high water supply. Our results suggested that litter crusts significantly improve soil properties, thereby influencing hydrological processes. Litter crusts play an important role in improving hydrological effectiveness and provide a microhabitat conducive to vegetation restoration in dry sandy ecosystem.

scholarly journals Determining the influencing factors of preferential flow in ground fissures for coal mine dump eco-engineering

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10547
Author(s):  
Yexin Li ◽  
Gang Lv ◽  
Hongbo Shao ◽  
Quanhou Dai ◽  
Xinpeng Du ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Hydraulic Conductivity ◽  
Preferential Flow ◽  
Soil Depth ◽  
Ground Fissure ◽  
Ground Fissures ◽  
Depth Ratio ◽  
Three Fissures ◽  
Path Number

Ground fissures (GF), appearing in front of dumps, are one of the most obvious and harmful geological hazards in coal mining areas. Studying preferential flow and its influencing factors in the ground fissures of dumps may provide basic scientific support for understanding the rapid movement of water and vegetation restoration and reconstruction in mining areas. Based on field surveys of ground fissures, three typical ground fissures were selected in the studied dump. The morphological characteristics of preferential flow for ground fissures were determined through field dye tracing, laboratory experiments, and image processing technology. The results indicated that the lengths of the three ground fissures ranged from 104.84 cm to 120.83 cm, and the widths ranged from 2.86 cm to 9.85 cm. All of the ground fissure area densities were less than 10%, and the proportion of ground fissure surface area was small in the dump. The maximum fissure depth was 47 cm, and the minimum was 16 cm. The ground fissure widths ranged from 0 cm to 14.98 cm, and the fissure width and fissure width-to-depth ratios decreased with increasing soil depth. The stained area was greater than 90% in the 0–5 cm soil layers of the three fissures, and water movement was dominated by matrix flow. The stained width decreased from 90 cm to 20 cm with increasing soil depth. The preferential flow was mainly concentrated on both sides of the fissure, which was distributed as a “T” shape. The preferential flow stained area ratios were 27.23%, 31.97%, and 30.73%, respectively, and these values decreased with increasing soil depth. The maximum stained depths of the preferential flow among the three fissures were different, and the maximum stained depth of GF II was significantly larger than that of GF I and GF III (P < 0.05). The stained path numbers of the three fissures ranged from 0 to 49. With increasing soil depth, the stained path number first increased and then decreased. The stained path widths of the three fissures ranged from 0 cm to 90 cm. With the increase in soil depth, the stained path width decreased. The stained area ratio was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter, and sand content and was significantly negatively correlated with soil water content and clay content. The stained path number was significantly positively correlated with ground fissure width, the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity and soil organic matter. The stained path width was significantly positively correlated with the ground fissure width-to-depth ratio, soil saturated hydraulic conductivity, soil organic matter and sand content and was significantly negatively correlated with clay content. Plant roots could significantly increase the stained area ratio, stained path number, and width and promote the formation and development of preferential flow.

Progress in soil organic matter research

2007 ◽  
Vol 31 (2) ◽  
pp. 131-154 ◽  
Author(s):  
Vineet Yadav ◽  
George Malanson
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Decomposition ◽  
Soil Aggregates ◽  
Plant Litter ◽  
Monitoring Methods ◽  
Plant Litter Decomposition ◽  
Research Themes ◽  
Climatic Scenarios ◽  
Decomposition Models

Retention and sequestration of soil organic matter is extremely important for the maintenance of soil structure, agricultural productivity and carbon sequestration. Research in soil organic matter has advanced on many fronts in the last half century. During this time understanding of the factors governing plant litter decomposition has increased considerably resulting in the formulation of process and organism-based models. Remote sensing has been shown to be useful for quickly monitoring stocks of soil organic carbon in the topsoil although much remains to be done to establish its efficacy. Fluxes of soil organic matter in the changing climatic scenarios have been studied though outcomes remain debatable. In this paper an attempt is made to present these various aspects of soil organic matter cohesively. The focus is mainly on litter decomposition, models and monitoring methods, role of soil aggregates and erosion, impact of climate change on long-term dynamics of soil organic matter and impending research themes needing further attention.

The Relation between Stability of Aggregates on Surface and SOM of Red Bare Soil in the Karst Area of East Yunnan, China

2014 ◽  
Vol 1030-1032 ◽  
pp. 920-925
Author(s):  
Lei Zhang ◽  
Jia Xue Wang ◽  
Meng Jing Xiao ◽  
Bao Qiang Liu
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Aggregates ◽  
Geometric Mean ◽  
Physical Property ◽  
Significant Negative Correlation ◽  
Bare Soil ◽  
Karst Area ◽  
Structure Stability ◽  
Water Stable Aggregate

Red bare soil is a kind of soil remained on plateau from ancient ages. Researchs toward better understanding of the relationship between stability of surface aggregate and SOM (Soil Organic Matter) based on 14 typical samples indicate that red bare soil clay (<0.002mm) contents between 12.18% and 64.02% which belongs to poor cultivation performance soil. The number of macro-soil aggregates after dry sieving were far more than the number after wet sieving. Water-stable aggregate content (WSAC) informed the feature of red bare soil. The WSAC were between 28.77% ~ 52.87% at the size >0.25mm and the aggregates destruction rate (PAD0.25) were 34.28% to 68.10%, mean weight diameter (MWD) were at the size of 0.53 to 1mm, geometric mean diameter (GMD) were between 0.37 and 0.58mm, fractal dimension (FD) were between 2.79 and 2.92. The 5 index above indicated the structural stability, anti erodibility and physical property were both poor when compared with other typical soil samples in southwest karst area of China. The research also indicated that soil organic matter (SOM) and WSAC has more effect than mechanical aggregate. SOM has significant positive correlation with MWD and GMD, and significant negative correlation with PAD0.25 and FD. Lack of SOM and exposed led to soil structure stability deterioration. These can be the reason why soil erosion seriously and can’t grow vegetation in red bare soil area.

Localization of soil organic matter in soil aggregates using synchrotron-based X-ray microtomography

2014 ◽  
Vol 78 ◽  
pp. 189-194 ◽  
Author(s):  
Stephan Peth ◽  
Claire Chenu ◽  
Nelly Leblond ◽  
Anneka Mordhorst ◽  
Patricia Garnier ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Aggregates ◽  
X Ray
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