Effect Of Topsoil Research Articles

陕西黄土台塬近三十年耕地动态变化的表层土壤有机碳效应

陕西黄土台塬近三十年耕地动态变化的表层土壤有机碳效应

Phosphorus fertilization by active dust deposition in a super‐humid, temperate environment—Soil phosphorus fractionation and accession processes

The inventory of soil phosphorus (P) is subject to significant changes over time. The main primary form, bedrock‐derived apatite P, becomes progressively lost through leaching, or transformed into more immobile and less plant‐accessible, secondary organic and mineral forms. Here we studied the rejuvenating effect of dust deposition on soil P along an active dust flux gradient downwind of a braided river. Along the gradient, we measured soil P fractions to 50 cm depth of six Spodosols and one Inceptisol, supplemented by tree foliage P concentrations. While an increasing dust flux correlates with a twofold increase of foliar P and soil organic P along the gradient, apatite P declines from ~50 to 3 g m−2 and total P shows no response. Compared to dust‐unaffected Spodosols, depth distribution of total P becomes increasingly uniform and organic P propagates deeper into the soil under dust flux. Further, the effect of topsoil P eluviation attenuates due to higher organic P content and the zone of high apatite P concentrations associated with un‐weathered subsoil becomes progressively removed from the upper 50 cm. We interpret these patterns as being consistent with upbuilding pedogenesi and conclude that dust‐derived mineral P is assimilated in the organic surface horizon and does not reach the mineral soil. Dust‐derived mineral P is temporarily stored in the living biomass and returns to the soil with plant and microbial detritus as organic P, which is subsequently buried by further dust increments. We further conclude that (1) the efficiency of P fertilization of the ecosystem by dust accession is higher than through P advection in dust‐unaffected Spodosols and (2) organic P may serve as an important source of labile P in a high‐leaching environment.

Forest structure and soil fertility determine internal stem morphology of Pedunculate oak: a modelling approach using boosted regression trees

This study aims at the explanation of internal stem morphology of vital (co)dominant Pedunculate oak (Quercus robur L.) trees in homogeneous even-aged high-forests by the factors tree age, forest structure and site quality, using boosted regression trees as a powerful modelling technique. The study area covers the region of Flanders (Northern Belgium), which is characterised by the absence of strong topographic and climatic gradients. For 76 adult sample trees covering the entire productivity range of Pedunculate oak, morphological characteristics were derived from measurements of ring width or heartwood area on wood cores. Forest structure, soil physicochemical properties, humus quality, vegetation indices and litter nutrient contents were quantified at each sample location. Model predictive performance and generality are good. Tree age effects correspond to expected trends in age-related radial growth and heartwood portion. Even if management of oak trees in even-aged high-forests is rather similar over Flanders, forest structure is the most important factor determining ring width, followed by soil fertility. Heartwood portion is determined by soil fertility and crown structure. Effects of topsoil and humus physicochemical characteristics, litter nutrient contents and water supply mainly confirm autecological knowledge on oak. However, variables related to soil water availability are only occasionally relevant, and always of lower importance than soil fertility. The low importance of water availability in the models contradicts results from other studies, and the potential effect of confounding is discussed. The observed growth reduction at low litter N/P ratios might be indirectly linked to early litterfall.

Natural revegetation on forest topsoil and subsoil along roadsides in boreal forest

AbstractQuestions: Does natural revegetation from indigenous soil improve the restoration success of roadside areas? What are the effects of topsoil, subsoil and fertilization on natural revegetation?Location: Akershus county, SE Norway (10°25′ E, 59° 44′ N).Methods: We used a recently constructed road through a boreal coniferous forest for a three year (2000–2002), fully replicated revegetation experiment (six replications). Treatments were soil type (two levels; one topsoil and one subsoil type) and fertilization (two levels; NPK and unfertilized control). Ordination methods, constrained ordination methods as well as univariate statistical methods, such as Wilcoxon's signed‐rank test and correlation analysis, were used to assess the relative importance and significance of treatments on the plant species composition.Results: There was no fertilization effect on species composition. The species composition on both soil types was stabilised by the second year. The species dominating the topsoil were more in accordance with the indigenous vegetation than was the case on the subsoil. The significant difference in species composition among blocks, persisting for the entire study period, indicated that local factors are important determinants of the outcome of revegetation.Conclusions: Unfertilized topsoil provides a revegetation result in better accordance with the indigenous vegetation than does subsoil.

Effect of Topsoil Treated with J2581 on Reproduction in the Oriental Fruit Fly (Diptera: Tephritidae)

Prepupae of the oriental fruit fly, Dacus dorsalis , Hendel, were exposed to topsoil treated with a benzyl-l,3-benzodioxole derivative (BBD), J2581 (5-ethoxy-6-[4-methoxyphenyl] methyl-l,3-benzodioxole). At a concentration range of 0.83-13.20 mg J2581 per g of soil, pupation, adult emergence, and egg production were not affected, but egg hatch was significantly reduced. J2581 activity in soil was retained for ≥30 d at concentrations >4 mg/g soil. When soil was subjected to temperatures of 25, 35, and 45°C for 1 h, activity was reduced. The activity was still significantly higher than in soil treated with acetone alone. Crossing experiments between treated and control males and females revealed that males were primarily affected by J2581. Spermatozoa in the testes of treated males lacked motility. Spermatozoa were also absent in a significant number of spermathecae from females mated to treated males. Rec-assays for potential mutagenicity of 10 BBDs were all negative.

Performance of three warm‐season grasses used in mine spoil revegetation

Abstract One objective of a multifaceted study was to investigate the performance of warm‐season grasses in revegetating coal mine spoils in southeastern Montana. The effects of fertilizer and mulch were assessed for Bouteloua gracilis (blue grama), Bouteloua curtipendula (sideoats grama), and Schizachyrium scoparius (little bluestem). Treatments were applied on raw spoils, topsoiled spoils, and irrigated raw spoils. Highest densities were obtained for warm‐season grasses on areas without fertilizer or irrigation. Effects of topsoil and mulch varied with species. Ranked from most to least abundant the species were Bouteloua curtipendula, Schizachyrium scoparius, and Bouteloua gracilis.

Effects of Topsoil and Subsoil Improvements in Low-Yielding Satsuma Mandarin Orchard : Influences to Yield and Fruit Quality

Effects of Topsoil and Subsoil Improvements in Low-Yielding Satsuma Mandarin Orchard : Influences to Yield and Fruit Quality

Effects of Topsoil and Subsoil Thickness on Soil Water Content and Crop Production on a Disturbed Soil1

Data by which we can quantify effects of soil depth upon productivity from controlled experiments are essentially lacking for semiarid regions. In connection with mined land-reclamation research in North Dakota, an experiment was established in which soil was reconstructed by building a wedge with productive subsoil (B and upper C horizon) on top of leveled sodic mine spoils derived from shale. Thickness of the subsoil wedge ranged from 0 to 210 cm. Topsoil (A horizon) was then spread over the subsoil wedge to provide a topsoil either 0, 20, or 60 cm thick. A fourth treatment consisted of mixing subsoil and topsoil within the wedge in a 3:1 ratio (no topsoil on the surface). Four crops—alfalfa (Medicago sativa L.), crested wheatgrass (Agropyron desertorum), native warm-season grasses (Bouteloua gracilis and Bouteloua curtipendula), and spring wheat (Triticum aestivum L.)—were grown each year on these plots from 1975 through 1979. Yields of all crops increased as total soil thickness (topsoil plus subsoil) increased to the 90- to 150-cm range. Highest yields equaled or exceeded yields that would be expected in these years on similar undisturbed soil types under good management in the same county. In most instances, over 90% of the maximum yields observed was obtained when 70 cm of subsoil plus 20 cm of topsoil covered the sodic spoils (SAR = 25, clay = 38%). Yields from 60 cm of topsoil were similar to those from 20 cm of topsoil. With no topsoil, only native grama grasses produced over 75% of maximum, but all crops except wheat produced at least 90% of maximum with at least 90 cm of the mixed subsoil-topsoil spread over spoils (wheat yields were only about 80% of maximum). Water was extracted from the upper 30 to 90 cm of spoils when the soil-spoil interface was within 90 cm of the soil surface. Thickness of topsoil had no influence on depth of water extraction. Alfalfa extracted water to about 135 cm if sodic spoils were within 90 cm of the surface and to about 175 cm where spoils were covered with at least 150 cm of soil materials. Depth of water extraction by crested wheatgrass under these two situations was about 120 and 150 cm; by native grasses about 80 and 120 cm; and by spring wheat about 75 and 90 cm, respectively. There was no evidence of any accumulation of soil water just above the soil-spoil interface under any situation.