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Soil
Published in Stanley E. Manahan, Environmental Chemistry, 2022
The most important soil horizon for plant growth is topsoil. Plant roots permeate the topsoil and take water and plant nutrients from it. Topsoil is the layer of maximum biological activity. The rhizosphere is the part of topsoil in which plant roots are especially active and in which the elevated levels of biomass are composed of plant roots and microorganisms associated with them. There are strong synergistic relationships between plant root systems and microorganisms in the rhizosphere. The surfaces of root hairs are commonly colonized by microorganisms, which thrive upon carbohydrates, amino acids, and root-growth-lubricant mucigel secreted from the roots. The microorganisms in turn aid in the uptake of nutrients by plant root hairs, and in the case of legume plants, bacteria growing in nodules on the roots convert N2 gas to chemically bound nitrogen that the plants can utilize as a nutrient.
Combating Strategies
Published in Ajai, Rimjhim Bhatnagar, Desertification and Land Degradation, 2022
There are several advantages to this method, such as:It keeps the fertile topsoil intact even on slopes. This prevents the loss of organically rich fertile topsoil. In fact, contouring can reduce soil erosion by as much as 50% in moderate slope areas. However, for steep slopes, this alone is not sufficient. Additional measures to prevent erosion are neededIt slows down the speed of surface run-off water. As a result, the water gets more time to penetrate and replenish the water tableSince the water table gets replenished, this conserved water can be efficiently utilized for irrigation in the absence of rainThe conserved water in storage basins are better in quality with a reduced quantity of suspended matter and are less turbidThe protected soil reduces the need for manuring. In fact, it gives 10–15% additional yield
Revegetation of Mine Sites
Published in Bruno Bussière, Marie Guittonny, Hard Rock Mine Reclamation, 2020
On mine sites, at the beginning of a mine project, the natural soils present at the location of the future pits, buildings, working pads, roads, and waste or water storage areas are worth saving for revegetation, if they are not contaminated. Topsoil, which is the superficial soil colonized by organisms (roots and soil fauna) and containing OM (darker color), is a strategic material for revegetation. It brings OM, soil organisms, native plant seeds as well as nutrient stock in balance with the surrounding natural environment to the revegetated area (Marcus 1997; Cooke and Johnson 2002). Thus, topsoil use will help the establishment of plant and soil organism species from the native ecosystem (Martinez-Ruiz and Fernandez-Santos 2005). To optimize topsoil as a source of seeds and spores, only the superficial layers should be collected because seed density rapidly decreases with soil depth (Rokich et al. 2001; Singh et al. 2002). Moreover, long duration of topsoil storage can decrease seed viability, and direct placement after excavation should be considered (Rokich et al. 2001). However, topsoil is generally in limited quantity, which restricts its use on large surfaces (Whitbread-Abrutat 1997). Under the topsoil, the mineral soil (also called overburden when covering the ore) can also be of interest for the site revegetation. It contains no or low OM. Digging a trench to observe the soil profile can help separate topsoil and mineral soil to manage them separately.
Mn concentration and mycorrhizal colonization in understory native species grown at areas of manganese mine tailings disposal
Published in International Journal of Phytoremediation, 2019
Elzane Freitas Leite Silva, Fatima Maria de Souza Moreira, Jose Oswaldo Siqueira
Compared to the location revegetated by Planting of Seedlings (PS) and to Native Forest (NF), the location revegetated through the use of Topsoil (T) exhibited greater diversity of plant species after 12 years. This result shows the importance of topsoil (surface soil layer) management for revegetation of mined areas, since removal of the surface layer is necessary for ore extraction (Moreno-de las Heras et al. 2008; Ribeiro et al. 2011; Leal Filho et al. 2013), but it can be reused to advantage in revegetation. Topsoil is not only a seed bank but also adds organic matter to the system, improving many soil properties, and it restores macro- and microbiota, which have a fundamental role in soil formation and promotion of plant growth (Souza et al. 2006; Moreno-de las Heras et al. 2008). In a study developed in a coal mine, Moreno-de las Heras et al. (2008) used two recovery techniques on hillsides with different ages of vegetation, showing that after 15 years, the plant communities in areas revegetated with topsoil had greater diversity and plant cover than the diversity and cover observed in areas revegetated through planting of seedlings.
The effects of Pinus tabuliformis on soil detachment under different influencing factors in the Loess Plateau of China
Published in Chemistry and Ecology, 2018
Dandan Wang, Xinxiao Yu, Guodong Jia, Jianjun Zhang, Ziqiang Liu
Soil erosion has been regarded as a principal environmental threat since the 1930s. Soil erosion leads to the loss of topsoil and nutrients, damage to the soil structure and a decrease in soil quality. These effects have resulted in land degradation and desertification, limited the productivity of forests and agricultural land, and contributed to natural disasters that threaten human safety [1,2]. The Loess Plateau, accounting for about 40% of the total land area in northwestern China, suffers from a serious soil erosion problem. The erosion rate in most areas has reached 5000–10,000 mg km−2 year−1, and even more than 59,700 mg km−2 year−1 in some regions [3]. Previous investigations have shown that 90% of sediments from the Loess Plateau are discharged into the Yellow River, nearly 25% of which settled on the river bed, leading to an annual increase in bed depth of 8–10 cm [3,4]. To address these problems, numerous engineering and vegetation restoration measures have been implemented in the past few decades in the Loess Plateau. To increase vegetation coverage, extensive tree planting has been undertaken since the early 1970s, which has resulted in 43% of cultivated slope farmlands being converted to forests (38%) and grasslands (5%) [5]. However, soil loss has remained a serious issue until the late 1990s. Farmlands are considered to represent the land use most strongly threatened by soil erosion because of the soil disturbance during farming activity. Zhang et al. [3] reported that soil detachment capacity of farmland was 2–13 times greater than that of woodland, shrub land, grassland or wasteland. In 1999, the Chinese government initiated the ‘Grain for Green’ policy with the aim of reducing soil loss on sloping farmland [6,7]. As a result, large-scale soil and water conservation measures have improved the ecological environment in the Loess Plateau.
The Effect of Soil Particle Sizes on Bioremediation Efficiency of Petroleum Contaminated Soils
Published in Soil and Sediment Contamination: An International Journal, 2023
Emmanuel Emeka Arinze, Benjamin Nnamdi Ekwueme, Anthony Chibuzo Ekeleme
Haghollahi, Fazaelipoor, and Scaffie (2016), reported that high amounts of organic matter decreased the effectiveness of bioremediation. Topsoil is rich in organic matter, mostly obtained from dead plants and animals. While laterite has little to moderate amount of organic matter.