Soil Chemical Variables Research Articles

IMPACT OF USED MOTOR OIL ON THE SOIL QUALITIES OF ORJI MECHANIC VILLAGE OWERRI, NIGERIA

The study investigated the effects of used motor oil on soil physical and chemical variables and their particle size distribution. Two (2) replicate soil samples were collected from three radial coordinates 50 31.114N 70 02.703E, 50 31.165 N 70 2.670E and 5023.35N 6059.176E respectively from the auto-mechanic village and agricultural land which serves as control; at depths of 0-15cm and 15-30cm. Standard methods were adopted both for field and laboratory analysis, utilizing such instruments as Atomic Absorption Spectrometer (model FS 240 Varian), Jewniary, digital pH meter, Refractometer (model E- Line R.ATC- ), lovibond instrument model Cm-21 and mercury-in-built thermometer. Twenty three (23) different soils parameters were analyzed comprising total organic carbon, heavy metals, soil texture and particle size (clay, sand and silt) organic carbon, exchangeable cations (Na, Ca and Mg), conductivity, salinity, nutrients (N, P, K), bulk density and organic matter. The result indicated a variation at the mechanic site and control point. The pH of the auto-mechanic soils were acidic with the range of 4.3- 5.0 in comparison with the control point which had a mean value of 5.6. Heavy metals had higher values in auto mechanic soils than in the control and their concentration decreased in this trend, Cu 0.940> Hg 0.211> Ni 0.093> Zn 0.051> Pb 0.021> Cd 0.015 > Ar 0.003; Hg 1.385> Cu 0.853> Ni 0.079> Zn 0.041> Cd 0.04> Pb 0.034> Ar 0.004. This showed that disposal of used motor oil on the soil affected the soil quality negatively. It is therefore; recommended that there should be a legislation to stop the indiscriminate dumping of spent oil and lubricants on the surface of the soil at Orji Mechanic village without treatment prior to disposal.

Cryptogams signify key transitions of bacteria and fungi in Arctic sand dune succession.

Primary succession models focus on aboveground vascular plants. However, the prevalence of mosses and lichens, that is cryptogams, suggests they play a role in soil successions. Here, we explore whether effects of cryptogams on belowground microbes can facilitate progressive shifts in sand dune succession. We linked aboveground vegetation, belowground bacterial and fungal communities, and soil chemical properties in six successional stages in Arctic inland sand dunes: bare sand, grass, moss, lichen, ericoid heath and mountain birch forest. Compared with the bare sand and grass stages, microbial biomass and the proportion of fungi increased in the moss stage, and later stage microbial groups appeared despite the absence of their host plants. Microbial communities of the lichen stage resembled the communities in the vascular plant stages. Bacterial communities correlated better with soil chemical variables than with vegetation and vice versa for fungal communities. The correlation of fungi with vegetation increased with vascular vegetation. Distinct bacterial and fungal patterns of biomass, richness and plant-microbe interactions showed that the aboveground vegetation change structured the bacterial and fungal community differently. The asynchrony of aboveground vs belowground changes suggests that cryptogams can drive succession towards vascular plant dominance through microbially mediated facilitation in eroded Arctic soil.

Converting Conventional Agriculture to Poplar Bioenergy Crops: Soil Chemistry

ABSTRACTWoody bioenergy is a viable source of alternative energy; however, questions remain on how purpose-grown bioenergy feedstock production management impact surface soil chemistry. In order to understand the soil processes under poplar (Populus spp.) trees and adjacent agricultural sites, surface (0–15 cm) soil samples were collected from four northwestern United States locations over a four-year period. Initial and final surface soil samples were analyzed for various soil chemical parameters, including organic matter, pH, cation exchange capacity and nutrient concentrations. Fields selected to compare poplar and agricultural management initially differed in some key soil chemical parameters. Many soil chemical parameters changed over time and the magnitude of change often depended on location; however, initial differences between management types within any one location did not change over time for most soil chemical variables. Consistent in-location differences between management types over time show poplar did not alter soil chemical parameters relative to agricultural management during the study period. Together all observations indicate that little of the overall soil chemistry was impacted by the introduction of poplar in the traditionally agricultural fields.

Does Dairy Liquid Manure Complementary to Mineral Fertilization Increase Grain Yield Due to Changes in Soil Fertility?

Abstract The main destination of manure is the application to croplands near livestock farms as nutrient source to enhance crop production. The aim of this study was to define the dairy liquid manure (DLM) dose, complementary to the mineral fertilizer, for higher crops yield, in rotation black oat-maize-wheat-soybean, and to identify the soil chemical variables improved by the manure that most affect the yield, in long-term. The experiment was conducted from 2006 to 2015, in no-tillage system, at Parana State, Brazil. The soil was a Latossolo Bruno Distrofico tipico, clayey texture. The treatments consisted by doses of DLM (0, 60, 120 and 180 m3 ha-1 year-1), complementary to the mineral fertilizer (applied in the same amount for all DLM doses). Crops yield and soil chemical variables were evaluated at six depths (0-10; 10-20; 20-30; 30-40; 40-50 and 50-60 cm). The DLM application increased the yield of all crops, but not in all harvests. The DLM even applied at soil surface improved the soil chemical variables in deep layers, resulting in high positive correlation between yield and exchange bases, P, Zn and Mn contents, and high negative correlation with Ca/Mg ratio and potential acidity at depth 0-10 cm. The DLM dose, complementary to the mineral fertilization, that provided higher soybean and wheat yield was about 130 m3 ha-1 year-1, while for maize this dose was equal to or greater than 180 m3 ha-1 year-1. This effect was not attributed to a single chemical variable but the improvement of all chemical variables evaluated.

PENGARUH DOSIS PUPUK KANDANG SAPI TERHADAP SIFAT FISIK DAN KIMIA TANAH PADA TANAMAN KACANG TANAH (Arachis Hypogaea L.)

The Effect of Dosage Organik Fertilizer on Physical Properties and Land Chemistry in Soan Beans (Arachis Hypogaea L.). This Research Aims To: Determine The Effect Of Cow Manure Does On Soil Physical Properties Of Peanut Plants. Knowing The Effect Of Cow Manure Does On Soil Chemical Properties In Peanut Plants. To Know Optimum Dose Of Cow Manure Can Affect Physical And Chemical Properties Of Soil Peanut Plant.
 The treatments used in this study were Pk0 (0 Ton Ha-1 or without Cow Manure), Pk1 (10 Ton Ha-1 Cow Manure), Pk2 (20 Ton Ha-1 Cow Manure), Pk3 (30 Ton Ha- 1 Cow Manure, Pk4 (40 Ton Ha-1 Cow Manure). The Observing Variables in This Study are Soil Physical Properties Variables, which include Bulk Density (G Cm-3) and Total Soil Pore Space (%), And Soil Chemical Properties Variables That Cover N-Total Soil, P-Soil Available, K-Available Soil, C-Organic Soil, And Ph Soil.
 Research Results Show That Giving Cow Cage Fertilizer in Peanut Plants In General Has an Effect of Improving Soil Physical Properties in the Form of Increasing Soil Volume Weight and Total Soil Pore Space, Giving Cow Cage Fertilizer in Peanut Plants Generally Affecting Improving Soil Chemical Properties in the Form of Increasing N-Total , P-Available, K-Available, C-Organic And Soil Ph As Well As The Optimum Dose Of Cow Manure That Can Improve The Physical And Chemical Properties Of Soil In The Best Peanut Plants Are 40 Tons / Ha.

Community study of dragon’s blood palm (Daemonorops spp.) in Harapan Rainforest, Sumatra

Abstract. Asra R, Witono JR, Fijridiyanto I, Elva, Scheu S. 2019. Community study of dragon’s blood palm (Daemonorops spp.) in Harapan Rainforest, Sumatra. Biodiversitas 20: 3632-3640. Dragon's blood palms are rattan species that produce red-colored exudate on its fruit skin, popularly called exudates 'dragon's blood'. It has a high economic value and plays an important role as an income source for indigenous tribes in Jambi, such as in Bukit Duabelas National Park who live Anak Dalam Tribe and Semerantihan Village live Talang Mamak Tribe. However, overexploitation and unsustainable harvesting method have caused its decline in its population in natural forest. This study aims to make an inventory and map distribution of Dragon's blood palms in Harapan Rainforest, at the boundary between Jambi and South Sumatra Provinces, Indonesia; to determine its sex ratio and identify environmental factors that influence sex of Dragon's blood palms. This research used purposive random sampling method at three areas in Harapan Rainforest, i.e.: Hamparan Bato, Hamparan Batang Kapas, and Hamparan between Block A and B. The results showed that three species of Daemonorops were found in Harapan Rainforest, namely Daemonorops didymophylla, D. draco, and D. longipes. D. longipes has the highest population (18 clumps). The highest number of clumps were found in Hamparan Bato (17 clumps)and Hamparan Batang Kapas (17 clumps) areas. The ratio of male and female plants of D. longipes is 1: 1.84, D. draco is 1: 2 and D. didymophylla is 2.2: 1. Most clumps of Daemonorops species in Harapan Rainforest grow on the river banks which have low organic matters. Soil chemical variables that most contribute to the growth of Daemonorops spp. in Harapan Forest are N, C and pH.

Soil Chemical Attributes, Soil Type, and Rainfall Effects on Normalized Difference Vegetation Index and Cotton Fiber Yield Variability

Understanding of how crop yield is influenced by interactions between the soil and environment is needed to minimize agricultural inputs and reduce the impacts of agriculture on the environment. The objective of this study was to determine the effect of soil chemical attributes, soil type, and rainfall on cotton (Gossypium hirsutum L.) yields and yield variability. In this study, the average cotton fiber yield was collected from 101 fields over nine crop seasons. In these fields, located in central Brazil, the average and standard deviation of normalized difference vegetation index (NDVI) were determined. Growing season rainfall and soil nutrients were measured. The variables analyzed were: average cotton fiber yield, NDVI from Landsat images calculated at the boll development phenological stage (enlargement and fiber filling phases), CV of the NDVI, precipitation during the cycle, and soil chemical attributes. The average field NDVI values collected at the boll development phenological stage were correlated to yield (r = 0.50; p < 0.05). Fields with a higher CV for the NDVI values generally had lower yields. The effect of precipitation depends on the cotton phenological stage and soil type. A high rainfall volume at the beginning of the cropping cycle increased plant height variability, which harmed the cotton fiber yield. The highest average values of aluminum content, aluminum saturation, and potential acidity promoted variability in cotton plant growth. Soil chemical attributes related to aluminum were negatively correlated with yield (r = −0.34; p > 0.05).Core Ideas Annual averages of NDVI and yield presented a significant correlation. The effect of precipitation depends on the cotton phenological stage and soil type. Soil chemical variables related to aluminium are negatively correlated with the yield.

Estrutura florestal e serapilheira acumulada predizem a velocidade da dinâmica demográfica em florestas secundárias da Mata Atlântica

O conhecimento dos fatores preditivos da dinâmica demográfica de florestas secundárias é útil para planejar estratégias de recuperação de áreas degradadas, estimar a produção de biomassa e para subsidiar o planejamento da utilização racional de recursos. O objetivo deste estudo foi investigar possíveis fatores bióticos e abióticos que predizem taxas de dinâmica demográfica da vegetação secundária da Mata Atlântica. Para isto, em seis florestas, que variaram em idade desde a última perturbação (25, 60, 75, 90 e mais de 100 anos), a ordenação por PCA das taxas demográficas (mortalidade, recrutamento, rotatividade em abundância, perda em área basal, ganho em área basal e rotatividade em área basal) foi utilizada como variável resposta em uma árvore de regressão. Como possíveis fatores preditivos foram utilizados: declividade, variáveis químicas do solo em diferentes profundidades, parâmetros da estrutura florestal, quantidade de serapilheira acumulada e padrões espaciais. A árvore de regressão revelou que variações locais nos padrões dinâmicos foram melhor preditas pela estrutura florestal e pela quantidade média de serapilheira acumulada. Locais com estrutura menos desenvolvida em relação ao diâmetro máximo, altura máxima e área basal ocorreram nas florestas mais jovens (25 anos) e em clareiras das florestas mais antigas (com 90 e 100 anos), onde foram observadas as maiores taxas de dinâmica demográfica. Áreas com estrutura mais desenvolvida foram frequentes em todas as florestas, independente da idade pós-perturbação. Nestas áreas, as mudanças foram mais lentas e a quantidade de serapilheira acumulada sobre o solo foi inversamente proporcional à rotatividade de árvores e de área basal.

Impact of nitrogen compounds on fungal and bacterial contributions to codenitrification in a pasture soil

Ruminant urine patches on grazed grassland are a significant source of agricultural nitrous oxide (N2O) emissions. Of the many biotic and abiotic N2O production mechanisms initiated following urine-urea deposition, codenitrification resulting in the formation of hybrid N2O, is one of the least understood. Codenitrification forms hybrid N2O via biotic N-nitrosation, co-metabolising organic and inorganic N compounds (N substrates) to produce N2O. The objective of this study was to assess the relative significance of different N substrates on codenitrification and to determine the contributions of fungi and bacteria to codenitrification. 15N-labelled ammonium, hydroxylamine (NH2OH) and two amino acids (phenylalanine or glycine) were applied, separately, to sieved soil mesocosms eight days after a simulated urine event, in the absence or presence of bacterial and fungal inhibitors. Soil chemical variables and N2O fluxes were monitored and the codenitrified N2O fluxes determined. Fungal inhibition decreased N2O fluxes by ca. 40% for both amino acid treatments, while bacterial inhibition only decreased the N2O flux of the glycine treatment, by 14%. Hydroxylamine (NH2OH) generated the highest N2O fluxes which declined with either fungal or bacterial inhibition alone, while combined inhibition resulted in a 60% decrease in the N2O flux. All the N substrates examined participated to some extent in codenitrification. Trends for codenitrification under the NH2OH substrate treatment followed those of total N2O fluxes (85.7% of total N2O flux). Codenitrification fluxes under non-NH2OH substrate treatments (0.7–1.2% of total N2O flux) were two orders of magnitude lower, and significant decreases in these treatments only occurred with fungal inhibition in the amino acid substrate treatments. These results demonstrate that in situ studies are required to better understand the dynamics of codenitrification substrates in grazed pasture soils and the associated role that fungi have with respect to codenitrification.

Metal distribution and biological diversity of crusts in paddy fields polluted with different levels of cadmium

The paddy-crusts (PCs) play an important pole in the transformation and transfer of heavy metal in paddy. Different PCs were collected from paddy fields whose soils contained cadmium (Cd) at four concentration levels (0.61, 0.71, 1.53, and 7.08 mg/kg) in Hunan Province, China P.R. at Sep 2017. This metal's distribution among and biological community structures of PCs were both measured. Our results indicated that PCs were able to accumulate Cd from irrigation water and soil. With greater Cd levels in paddy fields, the weak EPS-binding Cd fraction decreased whereas the non-EDTA-exchangeable Cd fraction increased. The sorbed Cd fraction was initially enhanced at low-to mid-level Cd concentrations, but then gradually declined. Biomineralization was shown to function as the dominant Cd accumulation mechanism in non-EDTA-exchangeable fractions. The biological diversity of soil microbes decreased with more Cd in soil, and the Proteobacteria, Bacteroidetes, and Cyanobacteria were the dominant phyla in all the sampled PCs. Canonical correspondence analysis (CCA) between the composition of microbial communities and soil chemical variables in the PCs clustered all samples based on the Cd-contaminated level, and demonstrated that Cd, Mn, and Fe all significantly influenced the microbial communities. In particular, the Alphaproteobacteria and Chloroplast classes of bacteria may play a significant role in Cd accumulation via the bio-mineralization process. Taken together, our results provide basic empirical information to better understand the heavy metal speciation transformation mechanisms of PCs upon Cd-contaminated paddy fields.

Tafonomía y preservación diferencial de restos óseos humanos del norte de la provincia del Neuquén (República Argentina)

Se presentan los resultados de los análisis tafonómicos realizados a dos conjuntos de restos óseos humanos de los sitios arqueológicos Aquihuecó y Hermanos Lazcano (departamento Chos Malal, provincia del Neuquén). Ambos se caracterizan por su similitud cronológica (comienzos del Holoceno tardío >3.500 años), posición geográfica y material asociado, pero el estado de preservación resulta desigual. Aquihuecó presenta un conjunto muy bien preservado con ejemplares óseos escasamente fragmentados. De forma contraria, Hermanos Lazcano se caracteriza por numerosos elementos óseos fragmentados. A los efectos de explicar esta preservación diferencial se realizó el análisis tafonómico y geoquímico en ambos sitios. Los resultados indicaron la presencia de una matriz sedimentaria favorable para la preservación de restos óseos para ambos sitios. A nivel tafonómico se registró un alto contenido de carbonato de calcio sobre los restos de Aquihuecó. Interpretamos que los depósitos de carbonato cálcico son responsables de su mejor estado de preservación, mientras que en Hermanos Lazcano la disolución ósea es el principal proceso de deterioro. Se destaca la necesidad de profundizar el rol del carbonato de calcio en la preservación ósea como también en los análisis geoquímicos y geoambientales a los efectos de aportar nuevas explicaciones a la historia tafonómica de los individuos.

Litter-, soil- and C:N-stoichiometry-associated shifts in fungal communities along a subtropical forest succession

Suites of fungal adaptation to nutrient acquisition and allocation of vegetations are observed along forest succession gradients. However, the mechanisms behind seral shifts in plant-associated fungi need to be uncovered. To bridge this knowledge gap, the current study investigated the litter and soil chemical variables as well as the fungal community using high-throughput Illumina MiSeq sequencing along a 30a-100a succession gradient of a subtropical forest ecosystem in Xishuangbanna, southwestern China. Litter nitrogen (N) content changed consistently with fungal alpha-diversity and the relative abundances of functional guilds, such as saprotrophs and arbuscular mycorrhizal (AM) fungi. However, this trend was opposite to that observed for ectomycorrhizal (EcM) fungi and litter carbon (C) content. The total and water-soluble C and N contents as well as the C/N ratios in soil decreased with stand age, while the relative abundances of Rozellomycota, Chytridiomycota and lichens as well as the microbial C and N use efficiencies exhibited increasing trends across succession stages. Multivariate analysis and multiple linear regression showed that the seral shifts in fungal diversity and composition were closely related to the C:N stoichiometry of soil and litter. Specifically, the litter C content either negatively explained the alpha-diversity and saprotroph abundance or positively explained the abundance of EcM fungi. In contrast, the litter N content presented opposite trends. Further, the variances in the abundances of Rozellomycota and AM fungi were negatively explained by water-soluble C content but positively explained by water-soluble N content in the soil. These findings confirm that the replenishment and reduction of available nutrients are determined by plant-fungus interactions via the C:N stoichiometry of litter and soil along the forest chronosequence.

Evaluation of reclamation success in an open-pit coal mine using integrated soil physical, chemical and biological quality indicators

The evaluation and success of ecological reclamation can be assessed by measuring soil physical, chemical and biological variables, either in isolation or combined into composite indicators. In this study we tested the suitability of biological, chemical and physical quality indicators–and their combination in a General Indicator of Soil Quality (GISQ)—to monitor soil quality in restored areas of an open cast coal mine. These composite indicators were computed with principal component analyses (PCA) and co-inertia multivariate analyses (CoIA). Our biological indicator showed a significant recovery of soil invertebrate communities along the chronosequence. Taxonomic richness increased from 7 taxa the 1st year to 13–17 taxa in 6–20-y sites, far less than in forests (19–20). Soil pH, bulk density and proportion of physical and macro aggregates were highest in the 1-y site, while soil organic matter (SOM), total N and proportion of biogenic aggregates were highest in older sites. In general, the three sub-indicators and the GISQ yielded the lowest values in the 1-y site (from 0.1 to 0.3 on a scale of 0.1 to 1.0), intermediate in the 16- and 20-y sites, (0.4–0.7) and reached highest values in the two forests (0.4–1.0). The GISQ methodology proved efficient in assessing progress in the reclamation process which should not be achieved only by monitoring vegetation cover changes.

Denitrification Potential and Carbon Mineralization in Restored and Unrestored Coastal Wetland Soils Across an Urban Landscape

The recovery of wetland function after tidal flow restoration may be influenced by water pollution and sea level rise. Our objective was to examine the effects of tidal flow restoration on denitrification potential and carbon (C) mineralization across an urban coastal landscape. Soil cores were collected from 32 tidal wetlands in Connecticut, U.S.A., spanning a wide range of salinity (0.3–29 ppt) and watershed development (<1–79%). In brackish wetlands, denitrification potential increased with time since restoration, while C mineralization showed no significant relationship. Soil chemistry was also a strong predictor of process rates; best fit multiple linear regression models for denitrification included both soil chemistry variables and time since restoration. Although principal components analysis revealed soil chemistry overlapped by wetland type (freshwater, saline, or brackish), process rates in freshwater versus brackish wetlands had different relationships with soil chemistry. In freshwater wetlands, denitrification potential and C mineralization increased with soil metal content. In brackish wetlands, denitrification potential decreased with increasing salinity and C mineralization increased with increasing organic matter, soil moisture, and ammonium. Our results highlight the potential for biogeochemical processes to recover after wetland restoration, along with complex interactions between these processes and chemicals in developed coastal landscapes.

Local soil characteristics determine the microbial communities under forest understorey plants along a latitudinal gradient

The soil microbial community is essential for maintaining ecosystem functioning and is intimately linked with the plant community. Yet, little is known on how soil microbial communities in the root zone vary at continental scales within plant species. Here we assess the effects of soil chemistry, large-scale environmental conditions (i.e. temperature, precipitation and nitrogen deposition) and forest land-use history on the soil microbial communities (measured by phospholipid fatty acids) in the root zone of four plant species (Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica) in forests along a 1700km latitudinal gradient in Europe.Soil microbial communities differed significantly among plant species, and soil chemistry was the main determinant of the microbial community composition within each plant species. Influential soil chemical variables for microbial communities were plant species-specific; soil acidity, however, was often an important factor. Large-scale environmental conditions, together with soil chemistry, only explained the microbial community composition in M. effusum and P. nemoralis. Forest land-use history did not affect the soil microbial community composition.Our results underpin the dominant role of soil chemistry in shaping microbial community composition variation within plant species at the continental scale, and provide insights into the composition and functionality of soil microbial communities in forest ecosystems.

Influence of selected soil physical and chemical variables on distribution of perennial plant species in different plant communities of Aawdhat Al Masodi, Saudi Arabia

Influence of selected soil physical and chemical variables on distribution of perennial plant species in different plant communities of Aawdhat Al Masodi, Saudi Arabia

The shift of bacterial community composition magnifies over time in response to different sources of soybean residues

The transformation of plant residues by soil microorganisms contributes significantly to soil carbon (C) sequestration. Although the contribution of different soybean residue sources (leaf, stalk and root) to soil organic C have been quantified in the highly productive Mollisols, the temporal dynamics of microbial community composition during the transformation has not. This study examined the effect of the soybean residues and incubation time on the bacterial community in a Mollisol during 150 days of incubation. Compared to the non-residue control, the presence of soybean residues increased abundances of Bacteroidetes, Actinobacteria and Firmicutes, but decreased those of Proteobacteria and Acidobacteria 15 days after residue amendment. The bacterial community composition differed between the residue sources after 60 days of incubation with the abundance of Niastella increasing in the leaf (from 4.5% to 19.1%) and stalk (from 6.5% to 25.7%) but not root treatments. The abundance of Bacillus significantly decreased in the stalk (from 12.2% to 2.2%) and root (from 4.0% to 1.6%) but not leaf-residue treatments. The abundance of bacterial genera was significantly associated with soil chemical variables including soil C, N, and pH. Overall, chemical variables drove the temporal response of the bacterial community succession, which provides insight into bacterial contribution to C turnover in soils.

Soil chemical attributes variability under tillage and no-tillage in a long-term experiment in southern Brazil

Soil chemical attributes variability under tillage and no-tillage in a long-term experiment in southern Brazil

A meta-analysis of exchangeable aluminium in New Zealand soils using the National Soils Database

Soil acidification and associated aluminium toxicity are critical issues in New Zealand, particularly in high and hill country areas. However, there have been few studies that have examined the key drivers of exchangeable Al concentrations in New Zealand soils. The National Soils Database was used to investigate the relationship between soil chemical, physical and environmental variables and KCl-extractable Al (AlKCl) for New Zealand soils. Soil AlKCl concentrations were strongly associated with base saturation, soil pH, cation exchange capacity, total N, total C and soil order. However, the relationships differed among the three depth zones (0–20cm, 20–50cm and 50–120cm). Soil acidity and high cation exchange capacity contributed to high concentrations of AlKCl in the soil, whereas high base saturation and total C had the opposite effect. Total N decreased with increasing AlKCl in the topsoil (0–20cm), which is likely a response to the effects of Al toxicity on biological N fixation by pasture legumes. Across a pHH2O range of 3.8–6.4, AlKCl was measured at concentrations that can be toxic to sensitive plants (&amp;gt;1.0 cmolc kg−1). Brown Soils and Podzols are likely more susceptible to Al toxicity, with the highest mean concentrations of AlKCl measured across all depth zones.

Improvement of mining soil properties through the use of a new bio-conditioner prototype: a greenhouse trial

The effect of a prototype of humic bio-conditioner (H-BC) was assessed on the development of edaphic properties and the growth of maize plants in an edaphic material used as topsoil in the rehabilitation of soils in a coal mine in Colombia. The trial was carried out in a greenhouse, using pots with edaphic material treated with the addition of doses equivalent to 0 (control), 1, 2, and 4 Mg.ha−1 of H-BC; maize seeds were sown and followed up on for 60 days. Plant growth and soil biological, chemical, and physical variables were registered. The 4-Mg.ha−1 treatment maintained a significantly higher enzymatic activity than the control on day 60. The respiration of the soil treated with H-BC increased significantly, with the 4-Mg.ha−1 treatment standing out. The 2-Mg.ha−1 treatment induced the most noticeable changes in soil metabolic activity profiles. Increases in root and leaf development were observed in the treatment with 4 Mg.ha−1; apparently, this dose improved the absorption of Ca, K, and S by plants; the physical and soil aggregation indices increased significantly with 4 Mg.ha−1. The results indicate that H-BC can be an alternative as an enhancer of the edaphic material used in soil rehabilitation processes.