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First year effects of rock type and surface treatments on mine soil properties and plant growth
... In 1982, the sawdust and 224 Mg ha· 1 SS treatment plots contained the highest percentages of organic matter. The native soil treatment was a mixture of the A, E, B, C, and Cr horizons, therefore, SOM content was substantially lower than other treatments and actually no higher than the control treatment (Daniels et al., 1983). Soil organic matter in the sawdust-treated plots declined by almost one-half, while the plots treated with 112 Mg ha· 1 SS treatments declined only slightly over the past 16 years. ...
Soil organic matter (SOM) is an important indicator of soil quality and site productivity. Organic amendments may be a means for ameliorating mine soils and other soils that have been depleted of organic matter. In 1982, a mined site was amended with seven different surface treatments: a control, 30 cm of native soil, 112 Mg/ha sawdust, and municipal sewage sludge (SS) at rates of 22, 56, 112, and 224 Mg/ha. Four replicates of each treatment were installed as a randomized complete block design. Each replicate was subsequently split according to vegetation type: pitch x loblolly pine hybrid (Pinus rigda x taeda) trees and Kentucky-31 tall fescue (Festuca arundinacea Schreb.). Soil analyses of composite samples indicated that organic amendments initially improved C and N status of the mine soils, but after 16 years their levels converged to that of the control treatment. Tree volume and biomass were used as indices of the effects of organic matter content 16 years after initial amendment. Individual tree volumes of the sawdust and 22, 56, 112 Mg/ha. SS treatments retained 18 to 26% more volume than the control. Overall, forage production was the same among treatments. Organic amendments improved initial soil fertility for crop establishment,more » but it appears that they will have little or no long-lasting effect on plant productivity.« less
... Whole soil bulk densities ranged from 1.27 to 1.51 Mg m -3 with the organicallyamended soils exhibiting lower bulk densities than the control and native-soil treated plots. Daniels et al., (1983) reported the existence of traffic pans on the amendment study at the 20 and 60cm depths which might account for the variation and slightly higher bulk densities. Overall, mine soils amended with at least 22 Mg ha -1 sludge or more organic material exhibited significantly lower bulk densities than either the control or the nativesoil treatments. ...
Natural soils on steeply sloping landscapes in the Appalachian coal fields of Virginia. West Virginia. Kentucky, and Tennessee are often thin, rocky, acidic and infertile, making the topsoiling of surface mined sites impractical in many cases. Topsoil substitutes composed of blasted rock fragments are commonly used in this region. The proper selection and placement of designated topsoil substitutes is therefore critical to long term reclamation success. These mine soil surfaces are not in equilibrium and with the surface environment, and it is quite difficult to diferentiate among dissolution, adsorption, desorption and precipitation reactions as these surfaces weather with time. Severe compaction limits the productivity of many otherwise suitable topsoil substitutes. A minimum non-compacted thickness of 1 m is desirable to insure long run mine soil productivity for a variety of post-mining land uses. Significant changes in the physical, chemical, and mineralogical properties of mine soils occur within one year after placement. Mine soils high in silt content often form hard vesicular surface crusts, particularly when left unvegetated. The long term survival of plant communities on these mine soils is dependent upon mine soil organic matter accumulation and N and P cycling. Little is currently known about N and P dynamics in these mine soils, but P-fixation is a profound problem in high Fe(3-) spoils. Revegetation practices that were designed to meet 2-year bond release requirements may not he sufficient to meet new 5-year release standards. Hard rock derived mine soils can often equal or exceed native topsoil in productivity and post mining land use potential.
A thin-film optical waveguide with free-space-wave add-drop multiplexers consisting of focusing grating couplers and distributed Bragg reflectors was designed for intra-board chip-to-chip optical interconnects. Two-wavelengths device was fabricated, and 0.5Gbit/s optical signal transmission was demonstrated.
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