Effects of Soil Properties and Illumination Intensities on Matric Suction of Vegetated Soil

Matric suction induced by evapotranspiration is an important parameter for determining the hydraulic mechanisms of vegetation on slope stability. Despite evapotranspiration closely associated with atmospheric parameters and soil conditions, the influence of soil properties and illumination intensities on matric suction of vegetated soil has so far received the least research attention. In this paper, three kinds of soil, namely, fine sandy loam, sandy silt, and silty clay, were selected as experimental soils, and Indigofera amblyantha was chosen as the test plant. The test conditions were controlled, such as the use of homogeneous soil and uniform plant growth conditions. Each specimen was exposed to identical atmospheric conditions controlled in a laboratory for monitoring matric suction responses over 10 days. The results showed that illumination intensities play an important role in evapotranspiration, and the thermal energy from lighting had a direct impact on plant transpiration, whereas the lighting only affected plant photosynthesis. Plant roots in vegetated soil can effectively improve the air intake value of soil, and matric suction induced by plant transpiration in vegetated soil was 1.5–2.0 times that of un-evapotranspirated soil. There is a correlation between matric suction and the silt and clay contents, and the matric suction of silty clay was sensitive to changes in the soil moisture content. Compared to fine sandy loam, the water retention of sandy silt and silty clay was high, and a high level of matric suction was maintained in the corresponding time. The results for predicting soil water evapotranspiration based on matric suction have theoretical and practical significance for preventing soil erosion and shallow landslides. In addition, these results have great guiding significance for agricultural production, such as irrigation.

TEMPERATURE OF PLOUGHSHARE MATERIAL IN THE COURSE OF PLOUGHING

The change of temperature of subsurface layer material of ploughshare, occurring in the course of fine sandy loam (8% moisture and temperature 15.3°C) cultivation, done with bed making plough, was determined. Measuring system with 10 temperature sensors built in the ploughshare material was used in the research. Temperature value was registered with frequency of 1 Hz. The increase of temperature of subsurface layer of ploughshare blade material used in soil was fast – time of temperature stabilization was, depending on location the place of measuring from 17 to 43 s. In the course of ploughing the most heated was the initial area of the attack of landslide part of ploughshare blade and area adjacent to field edge – from 42.6 to 47.3°C. The temperature of material of trapezoid part of ploughshare blade was 26.6 to 29.7°C. In the conditions of the conducted measurements the rate of cooling of the subsurface layer of ploughshare blade material as the result of its cooling was 0.007 to 0.028°C·s-1 while plough was not working, however while making U-turns was from 3 to 7 times higher. In the places where the material of ploughshare blade was more heated the rate of cooling was of course higher. Faster cooling of ploughshare blade during U-turns was probably the result of intensified cooling induced by plough movement in the air.

Copper Mobility Assessment Using Speciation Schemes: Case Study–Mantrijeron District, Yogyakarta, Indonesia

factors such physical and chemical properties, especially mineralogical composition of such environment. This study focused on the mineralogical of two soils types (fine sandy loam and loamy fine sand) to retain/mobile Cu. Two non contaminated soils from Yogyakarta urban area, Indonesia, were artificially contaminated with Cu solution. Subsequently, soils artificially contaminated were extracted from various geochemical phases of soil by sequential extraction procedure. The results show that both of soils types can retain Cu well with maximum is 5.8 mg/g of loamy fine sand and 3.9mg/g of fine sandy loam. Additionally, the iron amorphous phase content in clay fraction is influence Cu retains in these soils. This is advantage in environment of Yogyakarta urban area, Indonesia, where this area underlain by loamy sand soil. Keywords: Copper, mobility, iron, sequential extraction.

Dissipation and Leaching of Pyroxasulfone andS-Metolachlor

Pyroxasulfone dissipation and mobility in the soil was evaluated and compared toS-metolachlor in 2009 and 2010 at two field sites in northern Colorado, on a Nunn fine clay loam, and Olney fine sandy loam soil. Pyroxasulfone dissipation half-life (DT50) values varied from 47 to 134 d, and those ofS-metolachlor ranged from 39 to 63 d. Between years, herbicide DT50values were similar under the Nunn fine clay loam soil. Under the Olney fine sandy loam soil, dissipation in 2009 was minimal under dry soil conditions. In 2010, under the Olney fine sandy loam soil,S-metolachlor and pyroxasulfone had half-lives of 39 and 47 d, respectively, but dissipation rates appeared to be influenced by movement of herbicides below 30 cm. Herbicide mobility was dependent on site-year conditions, in all site-years pyroxasulfone moved further downward in the soil profile compared toS-metolachlor.

The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review

Edwards, L. M. 2013. The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review. Can. J. Soil Sci. 93: 459–472. The importance of aggregate size and integrity in soil productivity and crop production is paramount, and aggregate size reduction or increase invariably becomes a primary concern in such soil management practices as tillage and organic matter manipulation. In this regard, therefore, the present review looks particularly at the consequence of freeze–thaw cycling (FTC) on agricultural lands in Prince Edward Island (PEI) where an annual average of 40 cycles induce measurable aggregate breakdown with mixed consequences. On the one extreme, the consequences are manifest in increased soil erosion. On the other extreme, reduced (or reversed) soil compaction and improved seedbed conditions are welcomed consequences where temperature alternation breaks up hard pans or soil clods, or where the predominance of smaller aggregates can be an asset in seedbed environments, favouring improved crop emergence and early-spring establishment. In the PEI soils studied, the greatest changes in aggregate size distribution with FTC occurred in the largest and smallest size fractions wherein fractions <0.5 mm showed a 33% average increase while, simultaneously, the 4.75–9.5 mm fractions showed a 28% average decrease. This breakdown is reflected most contrastingly where FTCs to maximum (asymptotic) breakdown averaged up to 3.5 times for a loam as it did for a sandy loam or a fine sandy loam soil. This review also examines FTC in a broader agricultural and environmental context where it can potentially impact agro-sustainability. Where FTC effects on a fine sandy loam were measured in terms of erosion, there was a sediment mass increase of about 90% in interrill flow and about 25% in rill flow. Further, this review emphasizes methodology that has proven to be workable under the circumstances of PEI's dominant agricultural soils and the FTC research objectives that they helped to shape. It was considered important in this review, also, to highlight the need for expanded research (commencing with regional cooperation), particularly on frost depth, to feed into moisture-availability modelling towards improved clarity for end-user benefit.