Topsoil Amendment Research Articles

Adding Agricultural Topsoil and Growing Perennial Ryegrass (Lolium perenne L.) Enhanced the Rehabilitation of Metal/loids Enriched Iron Ore Mine Tailings

Revegetating iron-ore mine tailings is difficult due to their poor physicochemical and microbial properties. This experiment aimed to improve tailings properties for better plant growth and rhizosphere activities. First, a pot experiment was conducted to assess the influence of topsoil amendment on the remediation of tailings collected from two sites (coded A and B) in Western Australia to promote the growth of perennial ryegrass (Lolium perenne L. cv Ausvic). Each pot was filled with pre-defined ratios of topsoil to mine tailings (0, 10, 20, 30, 50 and 100% w/w). Perennial ryegrass was harvested 60 days after sowing and analysed for plant growth, root morphological characteristics and metal uptake by shoots. Second, a study on biological attributes and an incubation study over 84 days were carried out. The addition of topsoil significantly decreased pH, but EC and total organic carbon (TOC) increased with an increased proportion of topsoil. Total concentrations of As, Co, Cr, Cu, Ni, Pb, Zn, Fe and Mn decreased with an increased ratio of topsoil in growth medium. The highest root dry biomass was observed in the treatments with 30% and 50% topsoil addition to tailings, whereas shoot dry biomass only increased with 50% topsoil. Total root length increased significantly with 50% topsoil addition to site A tailings. A significant increase in microbial biomass carbon (MBC) was found with 50% addition of topsoil compared with the control. Microbial quotient (MBC/TOC) decreased significantly with the addition of topsoil to both types of tailings. Metal contents in perennial ryegrass shoots decreased with the increasing rate of topsoil, but perennial ryegrass was an effective phytoextractor of Cu, Zn and Mn. Further, the incubation study revealed that 50% topsoil application increased cumulative respiration emissions in both A and B tailings after 42 days. Iron ore mine tailings can be improved in terms of physicochemical and biological attributes by adding topsoil. However, further investigation should be carried out to determine the speciation of metal/loids in amended iron ore tailings.

Soil amendments impact root‐associated fungal communities of balsam poplar on a phosphogypsum reclamation site

During reclamation organisms like fungi directly interact at the soil–plant interface and can potentially impact plant growth, health, and overall revegetation success. Therefore, a study was conducted to determine how topsoil amendments (mycorrhizae, biochar, compost, manure) influence root‐associated fungal communities and growth of fast growing Populus balsamifera trees on a phosphogypsum (PG) reclamation site in Alberta, Canada. Tree height, diameter, biomass, and diversity of Ascomycota and Basidiomycota were assessed using Illumina MiSeq sequencing targeting the fungal internal transcribed spacer region 1 (ITS1) and ITS2. Topsoil amendments and root location (topsoil vs. PG within a treatment), greatly affected the root fungal community. Basidiomycota preferentially grew in PG, and had a high treatment specific root fungal community with highest diversity of ectomycorrhizal fungi and basidiomycete yeast in biochar PG and compost PG. Populus balsamifera roots were associated with a high diversity of Ascomycota, found equally in roots in topsoil and PG, with a trend towards higher diversity and abundance in PG. The core genus found across all samples was Fusarium, a potential plant pathogen. All topsoil amendments strongly reduced abundance of Fusarium and other Ascomycota in poplar roots. Biochar and compost reduced number and abundance of potential fungal pathogens and increased number of potential plant growth promoting Basidiomycota, indicating favorable growth conditions for P. balsamifera on a phosphygypsum reclamation site by application of these amendments. This study indicates compost and biochar can be effective soil amendments to support P. balsamifera establishment and growth on a PG reclamation site.

The soil microbiome unveils strong imprints of artificial erosion after 27 years

Soil erosion is a severe and widespread form of land degradation worldwide, and is being exacerbated by effects of climate change, such as increased storm frequency and intensity. It is important to study the impact of soil erosion on the soil microbiome because soil microbes are crucial drivers of many important soil biological processes in agriculture. In 2016 and 2017, we sampled a simulated soil erosion field trial established in 1990 to investigate the effects of different depths of topsoil removal and restorative soil amendments on soil pH, microbial biomass carbon (MBC) and the activities of enzymes that mediate C, nitrogen (N), phosphorus (P), and sulfur (S) cycling, plus the diversity and composition of soil prokaryotic (bacteria and archaea) and fungal communities. The one-time (1990) treatments consisted of a split-plot combination of three depths of topsoil removal (0, 10, and 20 cm) as main plots, and three restorative soil amendments (check, topsoil, and cattle manure) as subplots. Soil pH was higher in the eroded treatments than the noneroded treatment, but the opposite was observed for MBC and the activities of β-glucosidase (C cycling) and N-acetyl-β-glucosinidase (C and N cycling). The restorative amendments did not affect soil pH, MBC, or enzyme activities. The relative abundances of the archaea Thaumarchaeota was higher in noneroded treatments than in eroded treatments, but the reverse was observed for the bacteria Chloroflexi, Gemmatimonadetes, Planctomycetes, and Verrucomicrobia. For fungi, the relative abundance of Basidiomycota was lower in eroded treatments than in the noneroded treatment, but the opposite was true for Mortierellomycota. The β-diversity analyses also showed different prokaryotic and fungal community structures between eroded and noneroded treatments, but the restorative amendment effects were less distinct. Therefore, soil erosion and excavation can have lasting imprints on the soil microbiome, particularly negative imprints on total microbial biomass and its C and N cycling potential, while imprints of restorative measures such as manure or topsoil amendment were not as strong. A single desurfacing event has effects that last for decades, and our efforts to reverse them are largely ineffective when applied only once.

Effects of Nitrogen and Phosphorus Fertilizer and Topsoil Amendment on Native Plant Cover in Roadside Revegetation Projects.

Establishing vegetation on roadsides following construction can be challenging, especially for relatively slow growing native species. Topsoil is generally removed during construction, and the surface soil following construction ("cut-slope soils") is often compacted and low in nutrients, providing poor growing conditions for vegetation. Nebraska Department of Transportation (NDOT) protocols have historically called for nitrogen (N) and phosphorus (P) fertilization when planting roadside vegetation following construction, but these recommendations were developed for cool-season grass plantings and most current plantings use slower-establishing, native warm-season grasses that may benefit less than expected from current planting protocols. We evaluated the effects of nitrogen and phosphorus fertilization, and also topsoil amendment, on the foliar cover of seeded and non-seeded species planted into two post-construction roadside sites in eastern Nebraska. We also examined soil movement to determine how planting protocols and plant growth may affect erosion potential. Three years after planting, we found no consistent effects of N or P fertilization on foliar cover. Plots receiving topsoil amendment had 14% greater cover of warm-season grasses, 10% greater total foliar cover, and 4-13% lower bare ground (depending on site) than plots without topsoil. None of the treatments consistently affected soil movement. We recommend that NDOT change their protocols to remove N and P fertilization and focus on stockpiling and spreading topsoil following construction.

Early colonization of root associated fungal communities on reclamation substrates at a diamond mine in the Canadian Sub-Arctic

Mining sites are harsh environments and establishment of root associated symbiotic fungi may be crucial for plant establishment and long term community development. Diamond mining in the Northwest Territories produces large amounts of processed kimberlite, and in some cases lake bed sediment and reclamation is needed for re-establishment of ecosystem function. This study investigated early fungal colonization with arbuscular mycorrhizae and dark septate endophytes on common reclamation substrates of different ages, relative to native tundra. Natural colonization of vegetation free sites with mycorrhizal spores on a trajectory associated with substrate age and type was very low. Fungal spore quantity and diversity was significantly accelerated by establishment of vegetation. Dark septate endophytes dominated native site Cyperaceae whereas reclamation site grasses were dominated by arbuscular mycorrhizae. Topsoil amendment was most effective for fungal colonization on reclamation substrates suggesting that a single application of topsoil can have a long term effect on the soil fungal community.

Transport and fate of estrogens from swine manure in a biochar amended sandy soil in a freeze-thaw environment

Under growing concerns of their possible adverse effects on ecosystems, natural steroidal sex hormones, originating from liquid swine manure, have been detected at trace concentrations in a number of natural environments. Various studies have highlighted biochar’s potential in adsorbing such hormones, given its structural and physiochemical properties. The remaining hormone adsorption capacity of a 1% slow pyrolysis biochar topsoil amendment was tested after one year of its application to a sandy soil, housed in outdoor lysimeters irrigated with simulated rainfall. The fate and transport of estrogens, over a 46-day period following the incorporation of liquid swine manure (4 g N/L @ 16 L/m2) into the topsoil, was monitored in biochar-amended and non-amended lysimeters. While in the first year of biochar application, a significant spatial-temporal stratification of steroidal sex hormones had been observed in the biochar-amended soil (vs. non-amended soil), in the second year biochar absorbed hormones to a considerably lesser degree. Concurring with the findings of laboratory batch adsorption experiments on fresh and used biochar, the present study showed that 1% slow pyrolysis biochar`s capacity to absorb sex hormones (estrogens) released from liquid swine manure in sandy soil decreases during second year. This is presumably the freezing and thawing weather conditions of experimental site that resulted in biochar surface degradation leading to the release of soluble organic carbon, thereby facilitating a heightened mobility of hormones and their resultant leaching to lower depths in the soil profile.

Hardwood Seedling Growth on Different Mine Spoil Types with and without Topsoil Amendment

The goal of many owners of reclaimed mined land in the Appalachian region is to restore the diverse native hardwood forest for environmental, economic, and cultural reasons. However, native hardwoods often grow poorly on mined sites because they are planted in unsuitable spoils devoid of native topsoil. In a greenhouse experiment, we examined the suitability of four growth media available for use on many mined sites in the central Appalachians-forest topsoil (FT), weathered sandstone (WS), unweathered sandstone (US), and unweathered shale (UH)-as well as the effects of topsoil amendment (none vs. amended) on the growth of three native hardwood species: Fraxinus americana, Quercus rubra, and Liriodendron tulipifera. A 4 x 2 x 3 factorial greenhouse experiment was conducted with planted 1-yr-old seedlings. Tree growth, foliar nutrients, and soil properties were measured and characterized. The WS was the spoil most conducive to growth for F. americana and Q. rubra. Liriodendron tulipifera did not respond to any treatments. Tree growth was highly correlated with mineralizable soil nitrogen and extractable soil phosphorus. Topsoil amendment significantly increased growth on the UH but not on the US or WS. Topsoil amendment increased the number of native herbaceous plants growing in the pots and improved foliar nutrient content in F. americana and L. tulipifera. Many properties of the WS, such as pH, microbial activity, and water availability, more closely approximated the control soil than the US or UH. This study showed that trees are sensitive to spoil type and that certain spoil types that are conducive to good growth of native trees should be used during the reclamation process, particularly if forest topsoil is not applied. Forest topsoil amendment improved tree growth on some spoil materials, improved tree nutrition, and helped restore the native soil organisms and plants that were present before mining.

Role of continuous wheat and amendments in ameliorating an artificially eroded Dark Brown Chernozemic soil under dryland conditions

Complete loss of topsoil resulting from erosion or other causes generally results in reduced crop yield. To determine, under dryland conditions, the effect of loss of various amounts of soil and of various amendment practices suitable for use under a cereal production program on soil properties and crop yields, a field was artificially eroded during cut and fill of land-levelling in 1957. Continuous cropping to barley for 7 yr was followed by a wheat-fallow rotation for 22 yr. A continuous wheat experiment was conducted from 1987 to 1991 to determine the effects of five fertility amendments on restoring the productivity to soil from which 10–20 cm and 46+ cm of soil had been removed. In 1990, a below-average precipitation year, after 33 yr and 23 crops, yields from the unfertilized 46+ cm eroded field were only 44% of the yields from the uneroded field. However, with the increased precipitation in 1991 this value was 66%. A one-time topsoil amendment was beneficial in the earlier stages of the experiment, but lost its effect as cultivation mixed it into the "subsoil" over time. Plot treatments with annual applications of manure and high rates of fertilizer generally out-yielded the yields of the check plots of the uneroded treatment. Amendment with straw + fertilizer was not very effective. Soil, once lost, is non-renewable without amendments within the working lifetime of the producer. Key words: Soil erosion, manure, commercial fertilizer, topsoil soil, productivity

Comparison of Amendments and Management Practices for Long‐Term Reclamation of Abandoned Mine Lands

AbstractAbandoned mine lands containing pyritic spoil may become toxic due to production of sulfuric acid and subsequent high levels of heavy metals. A field study was initiated to compare the long‐term (10 yr) effectiveness of digested municipal sewage sludge (224 Mg ha−1), powerplant fly ash (448 Mg ha−1), papermill sludge composted with either coarse or line wood bark (67, 90, and 112 Mg ha−1), and limed topsoil (20‐cm depth) in maintaining a grass‐legume mixture on toxic abandoned mine spoil (initial pH 3.4). Management of reclaimed plots included an additional one‐time application of N, P, and K according to soil test 1 yr after reclamation and annual cutting of vegetation that was either removed from the plot or left on the surface. Soil was sampled at depths of 0 to 10 and 10 to 20 cm, with the lower sample representing soil (except for the topsoil treatment) to which the amendments had not been mixed. These soil samples were analyzed for pH and plant nutrients. Dry matter production declined sharply after 3 yr and then recovered the last 2 yr due to favorable weather, although to only two‐thirds of the initial levels. The topsoil and sewage sludge amendments maintained overall highest yields and highest percent vegetative cover (93 and 91%, respectively). Amended spoil experienced a gradual pH increase over the study period with the topsoil amendment exhibiting the highest pH (7.0) and fly ash the lowest pH (5.1) after 10 yr. The topsoil and sewage sludge amendments generally maintained the highest soil K, Ca, and Mg concentrations, while the sewage sludge and fly ash amendments had the highest P concentrations. pH values and P, K, Ca, and concentrations in the 0‐ to 10‐cm soil horizon were higher than in the 10‐ to 20‐cm horizon. Management did not result in differences in plant uptake of nutrients and metals, but a one‐time addition of lime and fertilizer did increase vegetative yields. We conclude that the papermill sludge and sewage sludge amendments were roughly equivalent to limed topsoil for the successful long‐term reclamation of toxic mine spoil. The fly ash amendment was least successful due to its inability to provide pH and nutrient levels sufficient for the maintenance of good vegetative growth.

Use Of Waste Gypsum In The Revegetation On Red Mud Deposits: A Greenhouse Study

The disposal of fine bauxite refining residue (red mud) has occupied huge areas of land which remain derelict and subject to wind and water erosion. The major constraints in rehabilitation are the high alkalinity, salinity and sodicity of red mud. This paper describes a greenhouse study to evaluate the use of waste gypsum as ameliorants for red mud. Red mud was amended with gypsum at 0, 2, 5 and 8% (w/w) and its effect on the growth of two grass species, Agropyron elongatum (Tall wheat grass) and Cynodon dactylon (Bermuda grass), was evaluated. Gypsum amendment significantly reduced the pH, electrical conductivity (EC), and Na and Al content of red mud and provided a continuous supply of Ca 2+, which resulted in a lower soil exchangeable sodium percentage (ESP). The improved soil conditions at ⩾5% gypsum amendment significantly increased seedling emergence and dry weight yields. The enhanced plant growth and seedling emergence show significant negative correlations with pH, Al and ESP of soil. Tissue analyses indicated that the availability of P, K, Mg and Ca also increased for ⩾5% gypsum amended red mud, while Na and Fe were less available. Results from the present study indicated that waste gypsum is an effective ameliorant for red mud revegetation and no topsoil amendment is required.

Use of Waste Gypsum in the Revegetation On Red Mud Deposits: a Greenhouse Study

The disposal of fine bauxite refining residue (red mud) has occupied huge areas of land which remain derelict and subject to wind and water erosion. The major constraints in rehabilitation are the high alkalinity, salinity and sodicity of red mud. This paper describes a greenhouse study to evaluate the use of waste gypsum as ameliorants for red mud. Red mud was amended with gypsum at 0, 2, 5 and 8% (w/w) and its effect on the growth of two grass species, Agropyron elongatum (Tall wheat grass) and Cynodon dactylon (Bermuda grass), was evaluated. Gypsum amendment significantly reduced the pH, electrical conductivity (EC), and Na and Al content of red mud and provided a continuous supply of Ca 2+, which resulted in a lower soil exchangeable sodium percentage (ESP). The improved soil conditions at ≥ 5% gypsum amendment significantly increased seedling emergence and dry weight yields. The enhanced plant growth and seedling emergence show significant negative correlations with pH, Al and ESP of soil. Tissue analyses indicated that the availability of P, K, Mg and Ca also increased for ≥ 5% gypsum amended red mud, while Na and Fe were less available. Results from the present study indicated that waste gypsum is an effective ameliorant for red mud revegetation and no topsoil amendment is required.

Enhancement of revegetation on construction fill by fertilizer and topsoil application: Effect on mycorrhizal infection

AbstractThe influence of topsoil and fertilizer application on denuded road construction sites was evaluated to assess its contribution to improvement of vegetation re‐establishment. the study sites were within a mixed hardwood and conifer forest on crushed, unweathered subsurface material with low fertility and low biological activity. Topsoils were removed from the site, stockpiled and reapplied to the site after construction. the effect of topsoil amendment on plant growth, soil fertility, mycorrhizal infection and an index of microbial biomass were measured in field and greenhouse experiments. Plant growth on the topsoil amended field plots were greatly increased relative to treatments with fertilizer but no topsoil. Three years after establishment, dry weight production on the plots without topsoil treatment was about 40 per cent of the plots treated with topsoil. Greenhouse experiments were designed to compare fresh, dried and stockpiled topsoil. These experiments indicated that storage of the harvested topsoil for five months in a stockpile had minor effects on plant growth, soil fertility, mycorrhizal infection and microbial biomass. Topsoil volumes had to exceed 20 per cent of the total soil volume to achieve statistically significant benefits and higher ratios showed greater benefit. the percentage of mycorrhizal infection was greatest in topsoil treatments without fertilizer. the addition of fertilizer increased growth but reduced the percentage of roots forming mycorrhizae. When the total weight of infected roots was calculated, however, infection was found to be greatest with a moderate level of fertilizer (equivalent to approximately 27 kg N ha−1 and 39 kg P ha−1), and was less in both higher fertilizer treatments and in unfertilized treatments. Topsoil amendment increased microbial biomass nitrogen but fertilizer treatment did not.