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The rising cost of lime, traditionally used to address soil acidity and its detrimental effects on soil fertility, has prompted the exploration of organic by-products as more affordable alternatives for mitigating soil acidity, particularly for low-income farmers. Therefore, the objective of this study was to investigate effects of filter cake (FC) and bagasse ash (BA) application on soil acidity under greenhouse condition. The experiment was laid out in a completely randomised design with four replications. The FC and BA were investigated separately each with six levels (0, 20, 40, 60, 80, and 100) t/ha-1. The acidic soil was collected from Imdibir area at a depth of 0-20 cm, air dried, ground and passed through 4 mm sieve. Each pot was received 4 kg of soil with respective treatment material after they were well homogenised. The laboratory analysis revealed that the soil had an initial pH of 5.1, while filter cake and bagasse ash had pH values of 8.0 and 10.2, respectively. Application of FC increased soil pH from 5.1 to 7.3, along with improvements in organic matter, nitrogen, phosphorus, sulphur, potassium, calcium, magnesium, and cation exchange capacity. Similarly, BA application raised pH from 5.1 to 7.4 and enhanced organic matter, nitrogen, phosphorus, sulphur, potassium, calcium, magnesium, and cation exchange capacity. The maximum effects for both FC and BA occurred at the highest application rate (100 t/ha-1), while iron and manganese content increased with BA application but decreased as rates increased, and copper and zinc levels were positively affected by both FC and BA applications. Overall, both FC and BA applications significantly improved soil pH and nutrient content. The findings of this study can provide practical and cost-effective solutions for improving soil fertility and crop production

The rising cost of lime, traditionally used to address soil acidity and its detrimental effects on soil fertility, has prompted the exploration of organic by-products as more affordable alternatives for mitigating soil acidity, particularly for low-income farmers. Therefore, the objective of this study was to investigate effects of filter cake (FC) and bagasse ash (BA) application on soil acidity under greenhouse condition. The experiment was laid out in a completely randomised design with four replications. The FC and BA were investigated separately each with six levels (0, 20, 40, 60, 80, and 100) t/ha-1. The acidic soil was collected from Imdibir area at a depth of 0-20 cm, air dried, ground and passed through 4 mm sieve. Each pot was received 4 kg of soil with respective treatment material after they were well homogenised. The laboratory analysis revealed that the soil had an initial pH of 5.1, while filter cake and bagasse ash had pH values of 8.0 and 10.2, respectively. Application of FC increased soil pH from 5.1 to 7.3, along with improvements in organic matter, nitrogen, phosphorus, sulphur, potassium, calcium, magnesium, and cation exchange capacity. Similarly, BA application raised pH from 5.1 to 7.4 and enhanced organic matter, nitrogen, phosphorus, sulphur, potassium, calcium, magnesium, and cation exchange capacity. The maximum effects for both FC and BA occurred at the highest application rate (100 t/ha-1), while iron and manganese content increased with BA application but decreased as rates increased, and copper and zinc levels were positively affected by both FC and BA applications. Overall, both FC and BA applications significantly improved soil pH and nutrient content. The findings of this study can provide practical and cost-effective solutions for improving soil fertility and crop production [ABSTRACT FROM AUTHOR]

Abstract Background Organic carbon stored in forest soils (SOC) represents an important element of the global C cycle. It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity, but empirical evidence in support of this assumption from forests differing in tree species and productivity, while stocking on similar substrate, is scarce. Methods We determined the stocks of SOC and macro-nutrients (nitrogen, phosphorus, calcium, potassium and magnesium) in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient (560–820 mm∙yr− 1) in northern Germany and explored the influence of tree species, forest history, climate, and soil pH on SOC and nutrient pools. Results While the organic layer stored on average about 80% more C under pine than beech, the pools of SOC and total N in the total profile (organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm) were greater under pine by about 40% and 20%, respectively. This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands, indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils. The pools of available P and basic cations tended to be higher under beech. Neither precipitation nor temperature influenced the SOC pool, whereas tree species was a key driver. An extended data set (which included additional pine stands established more recently on former agricultural soil) revealed that, besides tree species identity, forest continuity is an important factor determining the SOC and nutrient pools of these stands. Conclusion We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients, which may be unrelated to productivity but closely linked to species-specific forest management histories, thus masking weaker climate and soil chemistry effects on pool sizes.

Peat soils are frequently analysed using the same standard methods and extractants as for mineral soils, despite the distinctive nature of organic soils. The extractants used are well-suited for peat soils of near-neutral pH but it is still unclear whether they are suitable for acidic tropical peat soils. The study reported here compared the effectiveness of three standard reagents in extracting potassium, calcium, and magnesium from tropical peat of different degrees of decomposition, collected from three field locations in peninsular Malaysia. Three basic cations (K+, Ca2+ and Mg2+) were extracted using Mehlich 1, NH4OAc (ammonium acetate) buffered at pH 7 and NH4OAc at pH 4. The results showed that raising the pH of the extractant reduced the amounts of K+, Ca2+ and Mg2+ extracted. The average amounts extracted by Mehlich 1 and NH4OAc at pH 4 were frequently significantly higher than the amounts extracted by NH4OAc at pH 7, in most of the peat types sampled regardless of location. Compared with the extraction using NH4OAc at pH 7, the extractions with Mehlich 1 and NH4OAc at pH 4 are likely to provide closer estimations of these basic cations, because the pH of the extractants reflects the true pH of tropical peat soils.

Background: Organic carbon stored in forest soils (SOC) represents an important element of the global C cycle. It is thought that the C storage capacity of the stable pool can be enhanced by increasing forest productivity, but empirical evidence in support of this assumption from forests differing in tree species and productivity, while stocking on similar substrate, is scarce. Methods: We determined the stocks of SOC and macro-nutrients (nitrogen, phosphorus, calcium, potassium and magnesium) in nine paired European beech/Scots pine stands on similar Pleistocene sandy substrates across a precipitation gradient (560–820 mm∙yr− 1) in northern Germany and explored the influence of tree species, forest history, climate, and soil pH on SOC and nutrient pools. Results: While the organic layer stored on average about 80% more C under pine than beech, the pools of SOC and total N in the total profile (organic layer plus mineral soil measured to 60 cm and extrapolated to 100 cm) were greater under pine by about 40% and 20%, respectively. This contrasts with a higher annual production of foliar litter and a much higher fine root biomass in beech stands, indicating that soil C sequestration is unrelated to the production of leaf litter and fine roots in these stands on Pleistocene sandy soils. The pools of available P and basic cations tended to be higher under beech. Neither precipitation nor temperature influenced the SOC pool, whereas tree species was a key driver. An extended data set (which included additional pine stands established more recently on former agricultural soil) revealed that, besides tree species identity, forest continuity is an important factor determining the SOC and nutrient pools of these stands. Conclusion: We conclude that tree species identity can exert a considerable influence on the stocks of SOC and macronutrients, which may be unrelated to productivity but closely linked to species-specific forest management histories, thus masking weaker climate and soil chemistry effects on pool sizes. [ABSTRACT FROM AUTHOR]

Peat soils are frequently analysed using the same standard methods and extractants as for mineral soils, despite the distinctive nature of organic soils. The extractants used are well-suited for peat soils of near-neutral pH but it is still unclear whether they are suitable for acidic tropical peat soils. The study reported here compared the effectiveness of three standard reagents in extracting potassium, calcium, and magnesium from tropical peat of different degrees of decomposition, collected from three field locations in peninsular Malaysia. Three basic cations (K+, Ca2+ and Mg2+) were extracted using Mehlich 1, NH4OAc (ammonium acetate) buffered at pH 7 and NH4OAc at pH 4. The results showed that raising the pH of the extractant reduced the amounts of K+, Ca2+ and Mg2+ extracted. The average amounts extracted by Mehlich 1 and NH4OAc at pH 4 were frequently significantly higher than the amounts extracted by NH4OAc at pH 7, in most of the peat types sampled regardless of location. Compared with the extraction using NH4OAc at pH 7, the extractions with Mehlich 1 and NH4OAc at pH 4 are likely to provide closer estimations of these basic cations, because the pH of the extractants reflects the true pH of tropical peat soils. [ABSTRACT FROM AUTHOR]

The fertiliser value of human urine has been examined on several crops, yet little is known about its effects on key soil properties of agronomic significance. This study investigated temporal soil salinization potential of human urine fertiliser (HUF). It further looked at combined effects of human urine and wood ash (WA) on soil pH, urine-NH_3 volatilisation, soil electrical conductivity (EC), and basic cation contents of two Acrisols (Adenta and Toje series) from the coastal savannah zone of Ghana. The experiment was a factorial design conducted in the laboratory for 12 weeks. The results indicated an increase in soil pH by 1.2 units for Adenta series and 1 unit for Toje series after one week of HUF application followed by a decline by about 2 pH units for both soil types after twelve weeks. This was attributed to nitrification of ammonium to nitrate leading to acidification. The EC otherwise increased with HUF application creating slightly saline conditions in Toje series and non-saline conditions in Adenta series. When WA was applied with HUF, both soil pH and EC increased. In contrast, the HUF alone slightly salinized Toje series, but both soils remained non-saline whenWA and HUF were applied together. The application ofWA resulted in two-fold increase in Ca, Mg, K, and Na content compared to HUF alone. Hence, WA is a promising amendment of acid soils and could reduce the effect of soluble salts in human urine fertilizer, which is likely to cause soil salinity.

Purpose: Research has shown that ants are tolerant of environmental pollution and improve the quality of polluted substrates at industrial sites. Here, we assessed the effects of ants on microbial biomass and activity and on the contents of organic matter, nutrients, and heavy metals in an ore-washery sedimentation basin. We also determined whether the effects of ant species were associated with differences in feeding preference and nest construction. Materials and methods: We examined the effects of Formica sanguinea, Lasius niger, and Tetramorium cf. caespitum on a substrate polluted by high heavy metal contents in an ore-washery sedimentation basin near Chvaletice in the Czech Republic. We collected soil samples from the center of nests and in the surroundings (>3 m from nests) in September 2014 and determined their texture, pH, microbial biomass and activity, and contents of organic matter, mineral nutrients, and heavy metals. Results and discussion: The properties of ant nests were generally similar to those of the surrounding soil except that microbial activity and the contents of total nitrogen, ammonia, and potassium were higher in F. sanguinea nests than in the surrounding soil. Heavy metal content, which was previously reported to be reduced in ant nests because of buffering by basic cations and because of increased porosity, was not lower in nests than in the surrounding soil. Conclusions: Nest properties were affected more by F. sanguinea than by L. niger or T. cf. caespitum, probably because F. sanguinea uses substantial quantities of organic matter in constructing its nests, stores debris in the nests, and prefers insects as a food source. The failure to detect additional significant effects of ants might be explained by the high heterogeneity of the substrate and the possibility that the nests were too young to have significantly affected many substrate properties. [ABSTRACT FROM AUTHOR]

The study tested a data mining engine (PARACUDA®) to predict various soil attributes (BC, CEC, BS, pH, Corg, Pb, Hg, As, Zn and Cu) using reflectance data acquired for both optical and thermal infrared regions. The engine was designed to utilize large data in parallel and automatic processing to build and process hundreds of diverse models in a unified manner while avoiding bias and deviations caused by the operator(s). The system is able to systematically assess the effect of diverse preprocessing techniques; additionally, it analyses other parameters, such as different spectral resolutions and spectral coverages that affect soil properties. Accordingly, the system was used to extract models across both optical and thermal infrared spectral regions, which holds significant chromophores. In total, 2880 models were evaluated where each model was generated with a different preprocessing scheme of the input spectral data. The models were assessed using statistical parameters such as coefficient of determination (R2), square error of prediction (SEP), relative percentage difference (RPD) and by physical explanation (spectral assignments). It was found that the smoothing procedure is the most beneficial preprocessing stage, especially when combined with spectral derivation (1st or 2nd derivatives). Automatically and without the need of an operator, the data mining engine enabled the best prediction models to be found from all the combinations tested. Furthermore, the data mining approach used in this study and its processing scheme proved to be efficient tools for getting a better understanding of the geochemical properties of the samples studied (e.g., mineral associations). [ABSTRACT FROM AUTHOR]

The study was conducted on 18 locations and 11 dominant soil types in the Republic of Croatia including their evolution-genetic horizons. In total, 51 soil samples were examined. Analysis of soil was done by saturating patterns using barium chloride solution in three replications. Descriptive statistics of the analyzed data was conducted. Basic statistical parameters were calculated, and functional dependence between the base saturation (V%) of analyzed soil samples and their pH was observed. The correlation coefficient (r) between base saturation (V%) and pH for all examined soils was r=0.79 (n=51; very strong correlation). For acid soils it was r=0.82 (n=17; very strong correlation), for neutral soils r=0.75 (n=8; very strong correlation), and finally for alkaline soils r=0.15 (n=26; very weak correlation). Cation exchange capacity values ranged from 2.39 cmol+*kg-1 to 33.8 cmol+*kg-1 depending on soil type, pH, organic content and other soil parameters. The content of exchangeable cations in the sum of basic cations ranged from: Ca2+ (16% - 94%), Mg2+ (2% - 41%), K+ (1% - 68%) and Na+ (

Compostos orgânicos hidrossolúveis de resíduos vegetais depositados na superfície do solo podem melhorar a fertilidade do subsolo, pela neutralização da acidez e transporte de Ca e Mg. Com o objetivo de avaliar o efeito dos compostos orgânicos hidrossolúveis de materiais vegetais nos atributos químicos de um Latossolo Vermelho distroférrico, foi desenvolvido um experimento no Instituto Agronômico do Paraná (IAPAR), Londrina, com amostras de solo acondicionadas em colunas nas quais se aplicaram os tratamentos: água destilada, calcário incorporado na camada 0-5 cm de profundidade, calcário e percolação com extratos de nabo forrageiro, aveia preta, palha de trigo, milho e soja. No extrato percolado, foram determinados os teores de ligantes orgânicos hidrossolúveis (LOH) por potenciometria com eletrodo seletivo de Cu2+; ácidos orgânicos tituláveis (AOT) por titulação ácido-base e ânions orgânicos (AO) pela soma de bases. As concentrações de AO e AOT variaram de 7,0 a 32,0 mmol L-1 e de LOH de 0,60 a 2,23 mmol L-1. Todos os extratos vegetais aumentaram o pH, os teores de Ca, Mg e K trocável e diminuíram a acidez potencial e o Al trocável até 15 cm de profundidade, enquanto o efeito da calagem sem extrato foi observado somente até 10 cm de profundidade. A concentração de compostos orgânicos solúveis oriundos dos materiais vegetais correlacionou-se com o pH, Al trocável, H+Al e V % do solo na camada de 0-20 cm, confirmando a participação destes na melhoria dos atributos químicos do solo e ação da calagem superficial quando o material vegetal está presente.The water-soluble organic compounds of plant residues released on the soil surface can improve the subsoil fertility, due to the neutralization of acidity and Ca and Mg transport. An experiment was conducted at the Instituto Agronomico do Parana (IAPAR), Londrina, to evaluate the effect of water-soluble organic compounds of plant extracts on the chemical characteristics of a dark Red Latosol (Typic Haplortox), on soil samples in columns. The treatments consisted of: distilled water, lime incorporated in the 0-5 cm soil layer, lime and percolation of the following plant extracts: oilseed radish, black oat and wheat, maize and soybean straw. The following properties were determined in the plant extracts: the water-soluble organic ligand (WSOL) by potentiometry with selective Cu2+ electrode; titration of organic anions (TOA) and organic anions (OA) by base addition. The OA and TOA concentrations varied from 7.0 to 32.0 mmol L-1 and WSOL from 0.60 to 2.23 mmol L-1. All plant extracts increased pH and exchangeable Ca, Mg and K and decreased the potential acidity and exchangeable Al down to a soil depth of 15 cm, while the effect of lime without plant extract was only observed down to 10 cm. The soluble organic compound concentrations of the plant residues were correlated with pH, Al3+, H+Al and soil base saturation in the 0-20 cm layer, confirming the role of these organic compounds to improve the chemical characteristics of an acid soil as well as the action of the surface-applied lime.

Soil acidification in managed ecosystems such as agricultural lands principally results from the increased releasing of protons (H+) from the transformation reactions of carbon (C), nitrogen (N) and sulphur (S) containing compounds. The incorporation of liming materials can neutralize the protons released, hence reducing soil acidity and its adverse impacts to the soil environment, food security, and human health. Biochar derived from organic residues is becoming a source of carbon input to soil and provides multifunctional values. Biochar can be alkaline in nature, with the level of alkalinity dependent upon the feedstock and processing conditions. This review covers the fundamental aspects of soil acidification and of the use of biochar to address constraints related to acidic soil. Biochar is increasingly considered as an effective soil amendment for reducing soil acidity owing to its liming potential, thereby enhancing soil fertility and productivity in acid soils. The ameliorant effect on acid soils is mainly because of the dissolution of carbonates, (hydro)-oxides of the ash fraction of biochar and potential use by microorganisms. [Display omitted] • In managed ecosystem, soil acidification results mainly from the carbon and nutrient cycling. • Acidification is a major soil constraint impacting soil health and heavy metal toxicity. • The level of alkalinity in biochar depends on the feedstock and processing conditions. • Biochar liming value is derived from carbonates, and hydro-oxides of the ash fraction. • Biochar ameliorates acid soils by suppling base cations and reducing aluminium toxicity. [ABSTRACT FROM AUTHOR]

The increasing demand for fertilizers and the fact that the world reserves of phosphorus (P) and potassium (K) are depletable make appropriate soil management a critical factor in agriculture. Techniques for the fertilizer use and soil acidity corrective are becoming increasingly necessary to minimize the cost of yield and increase the nutrient efficiency. In view of the aforementioned, the present study aimed to assess the effects of gypsum application on the leaching of cations in the soil profile. A completely randomized design in a 5 × 4 factorial arrangement, with five replicates, was used. The treatments corresponded to five gypsum rates (0, 1, 2, 4, and 8 magnesium (Mg) ha−1) applied on broadcast of soil and at four depth sampled (0–5, 6–10, 11–15, and 16–20 cm). Gypsum application increased the fertility in depth, with the leaching of cations. There was an increase in soil pH, exchangeable K+and calcium (Ca2+), sulfur (S–SO42−), P, boron (B), and manganese (Mn) concentration, cation exchange capacity (CEC), K+and Ca2+saturation, Ca2+/Mg2+, Ca2+/K+, and K+/(Ca2+ + Mg2+) ratios, and electrical conductivity in soil depth. On the other hand, there was a decrease in exchangeable Mg2+and potential acidity hydrogen and aluminum (H+ + Al3+), available silicon (Si), Mg2+saturation, and Ca2+/K+and Mg2+/K+ratio. These results demonstrate that the gypsum application in an Oxisol with 690 g kg−1of clay improves the root system with a significant increase in the soil fertility in the profile. [ABSTRACT FROM AUTHOR]

The study tested a data mining engine (PARACUDA®) to predict various soil attributes (BC, CEC, BS, pH, Corg, Pb, Hg, As, Zn and Cu) using reflectance data acquired for both optical and thermal infrared regions. The engine was designed to utilize large data in parallel and automatic processing to build and process hundreds of diverse models in a unified manner while avoiding bias and deviations caused by the operator(s). The system is able to systematically assess the effect of diverse preprocessing techniques; additionally, it analyses other parameters, such as different spectral resolutions and spectral coverages that affect soil properties. Accordingly, the system was used to extract models across both optical and thermal infrared spectral regions, which holds significant chromophores. In total, 2880 models were evaluated where each model was generated with a different preprocessing scheme of the input spectral data. The models were assessed using statistical parameters such as coefficient of determination (R2), square error of prediction (SEP), relative percentage difference (RPD) and by physical explanation (spectral assignments). It was found that the smoothing procedure is the most beneficial preprocessing stage, especially when combined with spectral derivation (1st or 2nd derivatives). Automatically and without the need of an operator, the data mining engine enabled the best prediction models to be found from all the combinations tested. Furthermore, the data mining approach used in this study and its processing scheme proved to be efficient tools for getting a better understanding of the geochemical properties of the samples studied (e.g., mineral associations).

The study was conducted on 18 locations and 11 dominant soil types in the Republic of Croatia including their evolution-genetic horizons. In total, 51 soil samples were examined. Analysis of soil was done by saturating patterns using barium chloride solution in three replications. Descriptive statistics of the analyzed data was conducted. Basic statistical parameters were calculated, and functional dependence between the base saturation (V%) of analyzed soil samples and their pH was observed. The correlation coefficient (r) between base saturation (V%) and pH for all examined soils was r=0.79 (n=51; very strong correlation). For acid soils it was r=0.82 (n=17; very strong correlation), for neutral soils r=0.75 (n=8; very strong correlation), and finally for alkaline soils r=0.15 (n=26; very weak correlation). Cation exchange capacity values ranged from 2.39 cmol+*kg-1 to 33.8 cmol+*kg-1 depending on soil type, pH, organic content and other soil parameters. The content of exchangeable cations in the sum of basic cations ranged from: Ca2+ (16% - 94%), Mg2+ (2% - 41%), K+ (1% - 68%) and Na+ (<0.01%) also depending on soil type, depth, location and other physical and chemical soil parameters. [ABSTRACT FROM AUTHOR]

Abstract: We conducted a study to determine why the pH of wood ant nest materials is typically higher than that of the surrounding forest soil. An experiment with litter bags demonstrated that the pH of litter increased significantly (after only 7 months) in ant nests. Because the food that foraging ants bring into the nest contains easily decomposed carbohydrates and basic cations (largely in the form of honeydew and prey) that can cause increases in pH, we then estimated the amount of this influ of basic cations and easily decomposed carbohydrates. Based on these estimates, we conducted a second experiment to determine whether addition of field-determined quantities of an easily decomposed carbohydrate (glucose) or a basic cation (Ca2+) would increase the pH of the litter in artificial ant nests in the forest. Both glucose and Ca2+ additions significantly increased the pH of the litter but the increase was greater with Ca2+. The rate of pH increase in the artificial nests was similar to the rate of increase in natural nests. According to our study, ants collect substantial amounts of mineral-enriched materials in this ecosystem, which collectively increase the pH of nest material. [Copyright &y& Elsevier]

Commercial forestry plantations as a postmining land use in the Upper Hunter Valley of New South Wales, Australia are restricted by both the poor nutrient availability of mining substrates and low regional rainfall. An experiment was conducted to investigate whether municipal waste products and saline groundwater from coal mining operations could improve early tree growth without impacting on the environment through salt accumulation and/or nutrient enrichment and changes in groundwater quality. Potential impacts were investigated by quantifying the nutrient cycling dynamics within the plantation using an input–output mass balance approach for exchangeable calcium (Ca2+), exchangeable magnesium (Mg2+), exchangeable potassium (K+), exchangeable sodium (Na+), nitrogen (N), and phosphorus (P). Measured inputs to and outputs from the available nutrient pool in the 0–30 cm of the overburden subsystem were used to estimate the net effect of unmeasured inputs and outputs (termed “residuals”). Residual values in the mass balance of the irrigated treatments demonstrated large leaching losses of exchangeable Ca, Mg, K, and Na. Between 96% and 103% of Na applied in saline mine-water irrigation was leached below the 0–30-cm soil profile zone. The fate of these salts beyond 30 cm is unknown, but results suggest that irrigation with saline mine water had minimal impact on the substrate to 30 cm over the first 2 years since plantation establishment. Accumulations of N and P were detected for the substrate amendments, suggesting that organic amendments (particularly compost) retained the applied nutrients with very little associated losses, particularly through leaching. [ABSTRACT FROM AUTHOR]