Ameliorate Soil Acidity Research Articles

Differential response by seedlings of three sub-boreal conifer species to high- and low-carbon wood ash amendment

In Canada, there is a need to implement value-added uses for wood ash (hereafter ash) generated from bioenergy facilities as most ash is landfilled. Ash application to forests can provide benefit via nutrient supply, amelioration of soil acidity and, sometimes, increased tree growth. However, information is limited on the response of conifer species to different wood ash types applied to fine-textured soil typical of north-central B.C. We conducted a 16-month seedling pot trial that examined the response of Douglas-fir ( Pseudotsuga menziesii), lodgepole pine ( Pinus contorta var. latifolia), and hybrid white spruce ( Picea glauca × engelmannii) to high- (HCA) and low-carbon ashes (LCA) applied (up to 10 Mg mineral matter ha−1 equiv.), with and without fertilizer N (200 kg N ha−1 equiv.), to fine-textured forest soil. Pine and spruce exhibited a 1.6- and 1.4-fold increase in shoot biomass at the high rate of HCA with fertilizer N. At study end, the high rate of LCA had the greatest soil pH, EC and total K in the upper forest floor, but the HCA had greater total B, P and Zn. LCA elicited increased foliar B in pine, but HCA increased foliar Ca in spruce when co-applied with fertilizer N. In general, Douglas-fir growth did not respond to ash treatments, and seedling mortality was observed in some LCA treatments. Ash treatments helped offset some nutrient deficiencies induced by N fertilization. Ash type influenced soil chemical as well as seedling growth and nutrition responses.

Simultaneous removal of ammonium, phosphate, and phenol via self-assembled biochar composites CBCZrOFe3O4 and its utilization as soil acidity amelioration

ABSTRACT High concentrations of ammonium, phosphate, and phenol are recognized as water pollutants that contribute to the degradation of soil acidity. In contrast, small quantities of these nutrients are essential for soil nutrient cycling and plant growth. Here, we reported composite materials comprising biochar, chitosan, ZrO, and Fe3O4, which were employed to mitigate ammonium, phosphate, and phenol contamination in water and to lessen soil acidity. Batch adsorption experiments were conducted to assess the efficacy of the adsorbents. Initially, comparative studies on the simultaneous removal of NH4, PO4, and phenol using CB (biochar), CBC (biochar + chitosan), CBCZrO (biochar + chitosan + ZrO), and CBCZrOFe3O4 (biochar + chitosan + ZrO + Fe3O4) were conducted. The results discovered that CBCZrOFe3O4 exhibited the highest removal percentage among the adsorbents (P < 0.05). Adsorption data for CBCZrOFe3O4 were well fitted to the second-order kinetic and Freundlich isotherm models, with maximum adsorption capacities of 112.65 mg/g for NH4, 94.68 mg/g for PO4 and 112.63 mg/g for phenol. Subsequently, the effect of CBCZrOFe3O4-loaded NH4, PO4, and phenol (CBCZrOFe3O4-APP) on soil acidity was studied over a 60-day incubation period. The findings showed no significant changes (P < 0.05) in soil exchangeable acidity, H+, Mg, K, and Na. However, there was a substantial increase in the soil pH, EC, available P, CEC, N-NH4, and N-NO3. A significant reduction was also observed in the available soil exchangeable Al and Fe (P < 0.05). This technique demonstrated multi-functionality in remediating water pollutants and enhancing soil acidity.

Wood ash application for crop production, amelioration of soil acidity and contaminated environments

Agriculture is vital to human life and economic development even though it may have a detrimental influence on soil quality. Agricultural activities can deteriorate the soil quality, endangers the ecosystem health and functioning, food safety, and human health. To resolve the problem of soil degradation, alternative soil conditioners such as wood ash are being explored for their potential to improve soil-plant systems. This study provides an overview of the production, properties, and effects of wood ash on soil properties, crop productivity, and environmental remediation. A comprehensive search of relevant databases was conducted in order to locate and assess original research publications on the use of wood ash in agricultural and environmental management. According to the findings, wood ash, a byproduct of burning wood, may improve the structure, water-holding capacity, nutrient availability, and buffering capacity of soil as well as other physico-chemical, and biological attributes of soil. Wood ash has also been shown to increase agricultural crop yields and help with the remediation of polluted regions. Wood ash treatment, however, has been linked to several adverse effects, such as increased trace element concentrations and altered microbial activity. The examination found that wood ash could be a promising material to be used as soil conditioner and an alternative supply of nutrients for agricultural soils, while, wood ash contributes to soil improvement and environmental remediation, highlighting its potential as a sustainable solution for addressing soil degradation and promoting environmental sustainability in agricultural systems.

Evaluation of Different Agricultural Limes for Bread Wheat and Fababean Production in Acid Soil of West Shewa Zone, Ethiopia

The application of lime is believed to enhance soil health status through improving soil pH, base saturation and reduces Al and Mn toxicities. Liming effects depend on the source, composition, purity and fineness of the lime. The performance of three liming materials and one control treatment was evaluated in a field trial, further evaluation and validation was done at three districts on different farmers’ sites during 2023 main cropping season. The liming materials included calcitic lime, hydrated lime, and quick lime. The treatments laid out in randomized complete block design. The results of the study showed that all tested lime materials (calcitic lime, hydrated lime, and quick lime) improved yield and agronomic performance of wheat, barley and fababean in comparably. This implies that hydrated limes can serve as an alternative agricultural lime to ameliorate soil acidity. Hence, these liming materials can be used as agricultural lime material and the result is confirmed through validation across locations on different testing crops (wheat, barley and Faba bean). So, it is recommended that liming materials which can be easily accessed for the farmers is recommended because of there is no significant difference among liming material tested.

Combining lime and organic amendments based on titratable alkalinity for efficient amelioration of acidic soils

Abstract. Ameliorating soil acidity using a combination of lime and organic amendments (OAs) can be an alternative to lime alone, but determining the appropriate OA rates can be difficult. We developed a new method for calculating the combined application rate of lime and OAs (wheat straw, faba bean straw, blended poultry litter, biochar, and compost) that is based on the titratable alkalinity of OAs and the equilibrium lime buffer capacity (LBCeq) of acidic soils. The effect of calculated soil amendment rates on soil pH was validated at soil water contents of 60 %, 100 %, and 150 % of field capacity (FC). The soil used to develop and validate the method was a sandy loam with a soil pH in deionised water (pHW) of 4.84 and a soil pH in 0.01 M CaCl2 solution (pHCa) of 4.21. The LBCeq of the soil was 1657 mg CaCO3 kg−1 pH−1 (where “CaCO3 kg−1 pH−1” denotes the amount of lime required to raise the pH of 1 kg of soil by one unit). The titratable alkalinity of the OAs ranged from 11.7 cmol Heq+ kg−1 for wheat straw to 357 cmol Heq+ kg−1 for compost. At 60 % FC, faba bean and wheat straw amendment increased the soil pHW to 6.48 and 6.42, respectively, but lower pH values were reached in soil amended with less biodegradable or resistant OAs (ROAs) (i.e. blended poultry litter, biochar, and compost). At 150 % FC, the two straws increased the soil pHW to only 5.93 and 5.75, respectively, possibly due to slower decomposition under submerged conditions, resulting in limited alkalinity production, whereas amendment with ROAs produced pHW values close to 6.5. With an increasing lime-equivalent value (LEV) of the OA, from 5.8 g CaCO3 kg−1 (wheat straw) to 179 g CaCO3 kg−1 (compost), the lime requirement to reach pHW 6.5 in lime–OA combinations decreased from 2.72 to 0.09 g CaCO3 kg−1. The developed method was shown to be effective in determining the appropriate rates of OAs (with or without additional lime) for the management of acidic sandy loam soils in this study and highlights the importance of the soil water content with respect to its acid-neutralising effect.

Soil and Crop Effects of a Subsurface Fluid Lime Applicator

Highlights Continuous no-tillage with fertilizer deep-banded below the seed can result in stratified soil acidity that cannot be rapidly addressed with surface-applied lime. We modified a tractor-driven sweep implement to inject fluid lime that targets sub-surface soil acidity with minimal disturbance that maintains surface crop residues, and tested it prior to seeding winter peas at 4 liming rates. Soil chemistry, microbiology, and crop growth were monitored over the season. Abstract. Deep-banding ammonia and urea-based nitrogen fertilizers under continuous no-tillage can result in stratified acidification at the fertilizer-injection depth. Currently, producers address this acidification through primary tillage operations that mix the soil and dilute the acidification, but increase the hazard of soil erosion. Typically, lime is required to ameliorate soil acidity; however, surface-applied lime does not immediately address subsurface acidity, and often tillage is used to incorporate lime and correct acidified layers created through deep-banded fertilizer placement under no-tillage. Here, we designed, developed, and tested a subsurface applicator for fluid lime that can target specific soil depths and rates. The liming system was tested in Eastern Washington on a field that had been under continuous no-tillage for 25 years, had stratified soil acidity, and was to be planted to winter pea, a crop known to be sensitive to acid soil conditions. Soil pH and carbon distribution, microbial changes, biomass, and leaf area index (LAI). Results indicated that the lime targeted the seed zone and raised pH significantly; effects on biomass were marginally significant; and effects on LAI and vegetation cover were insignificant. Topography had a significant effect on all variables due to changes in applicator effectiveness with changes in soil mechanics, meaning as-applied rates varied from desired rates. Keywords: Liming, No-tillage, Precision agriculture, Soil acidity, Soil microbiology.

Response of faba bean (Viciafaba L.) varieties to lime application in wolaita zone, Southern Ethiopia

Soil acidity and scarcity of faba bean varieties adapted to lower pH soils are major factors that limit faba bean production in Ethiopia. Therefore, an experiment was conducted to find the lime rate and faba bean can improve the yield of the crop. Four rates of lime (0, 2, 4, and 6 t ha–1) and five-faba bean varieties (local, Dosha, Gebelecho, Tumsa, and Bobicho) were used as treatments, which laid out as CRD with six replications. The main and interaction effects of lime rates and varieties significantly (P &lt; 0.05) influenced all growth, yield components, and yield parameters. Nevertheless, root morphological parameters were significantly (P &lt; 0.05) affected by the main effects of the lime rate. Accordingly, the most significant high aboveground biomass of 47.92 g pot–1, and seed yields of (19.16 g pot–1) were obtained in response to the interaction of the Tumsa variety with 3 g pot–1lime rate (2 t ha–1). The lowest aboveground biomass of (32.08 g pot–1) and seed yield of (12.84 g pot–1) were obtained in response to the local variety planted with no lime application. Overall, in terms of seed yield, the Gebelcho and Tumsa varieties performed best by attaining their maximum seed yields in response to the application of 3 g lime pot–1 (2 t ha–1). Thus, 3 g pot–1 (2.0 t ha–1) liming rate with the Gebelcho and Tumsa varieties was found to be the best-combined treatment to improve the yield of the crop in the study area. The results of the study indicated the need to ameliorate soil acidity and select acid-tolerant faba bean varieties for enhancing the yield of the crop.

Can biochar conserve soil moisture and improve soil properties for sustainable intensification of acid soils in the Eastern Indian Himalayas?

AbstractThe marginal Himalayan ecosystems have great potential for biochar application for conserving soil moisture, ameliorating soil acidity, improving soil fertility, and thus, contributing to sustainable intensification. Thus, the efficacy of biochar was tested along with nutrient management practices (NMP) on the performance of maize (Zea mays L.)‐French bean (Phaseolus vulgaris L.) as the emerging cropping system in an acid soil under rainfed hill ecosystem. The rainy season maize was grown with three levels of biochar (0, 2.5, and 5 Mg ha−1, applied only once in the first year), and four NMP (100% recommended dose of fertilizer [RDF] [80:60:40 N:P2O5:K2O kg ha−1], 75% RDF, 75% RDF + 4 Mg ha−1 farm yard manure [FYM], and 50% RDF) under minimum tillage. After harvesting of maize, French bean was grown under no‐till with four NMP (100% RDF [50:60:40 N:P2O5:K2O kg ha1], 75% RDF, 75% RDF + 4 Mg ha−1 FYM, and 50% RDF). The soil properties after 3 years viz., soil moisture, soil organic carbon (SOC), pH, and available N, P, and K status were significantly improved under 5 Mg ha−1 biochar than no biochar. Among the NMP, 75% RDF + FYM and 100% RDF had higher soil moisture, water infiltration, pH, SOC concentrations, and available N, P, and K status than others. The interaction effect of 5 Mg ha−1 biochar and 75% RDF + 4 Mg ha−1 FYM registered the highest SOC content (15.7 g kg−1). Available N was the highest in soil under 75% RDF + 4 Mg ha−1 FYM whereas, available P in soil under 100% RDF. Application of 5 Mg ha−1 biochar produced significantly the highest mean grain yield of maize and succeeding French bean. The combined application of 100% RDF and biochar 5 Mg ha−1 produced the highest maize equivalent yield. Thus, 5 Mg ha−1 biochar and application of recommended fertilizers are suggested for sustaining soil fertility and sustainable intensification of rainfed hill agriculture under acidic soil.

Combined resource utilization of ash from biomass power generation and wheat straw biochar for soil remediation

The lack of power resources leads to the rapid development of biomass power generation. Biomass power generation technology can not only rationally utilize biomass resources, but also alleviate energy crisis. But if this biomass ash is not handled properly, indiscriminate dumping can cause serious environmental problems such as dust, air and water pollution. The purpose of this study was to use the basic physical and chemical properties of biomass waste ash and biochar to evaluate the effects of mixed uses on soil pH、heavy metal remediation and plant growth. Plant growth was undertaken using ryegrass to examine the potential value of an ash-biochar mixture to ameliorate soil acidity and heavy metal pollution. The special fertilizer for rice was prepared by adding ammonium dihydrogen phosphate, potassium chloride, and urea to the ash and biochar. The results showed that the mixed use of ash and biochar could ameliorate soil acidification, reduce the absorption of cadmium and lead by the plants (43 % and 35 %, respectively), and promote plant growth. Determining of its total nutrients, soluble phosphorus, nitrate nitrogen, and particle size supported that it fell within the high concentration fertilizer range of the national standard for compound fertilizers. The special fertilizer can be used as high quality fertilizer to promote crop growth. In-depth research on the treatment and recycling of biomass power generation waste ash has an essential effect on reducing secondary environmental pollution and waste recycling .It can reduce random dumping, thereby reducing dust, air and water pollution. This was conducted to provide a reference for the preparation of soil amendments and to develop a better amendment and high-quality special fertilizer for rice with biomass waste ash and biochar.

Long-Term Application of Pig Manure to Ameliorate Soil Acidity in Red Upland

While the application of manure to improve soil quality has attracted attention, the effect of pig manure application rates on soil acidity remains poorly understood. In this study, we analyzed the changes and correlations between soil acidity, pH buffer capacity (pHBC), soil chemical properties, and crop yields after 8 years of pig manure application at different rates (i.e., 0, 7.5, 15, 30, and 45 Mg ha−1) in a red upland soil (Ultisol). With an increase in the application rates, the crop yields were 0.77–8.85 times higher; the pH was enhanced by 0.4–0.8 units; and the soil organic matter (SOM), pHBC, iron activation (Feo), exchangeable calcium (ExCa), and exchangeable magnesium (ExMg) contents increased by up to 74.1%, 92.7%, 36.7%, 62.2%, and 48.7%, respectively, whereas that of total exchangeable acid (ExAcid) decreased by 17.2–52.9%. The crop yields were positively related to the soil pH but negatively correlated with ExAcid. Redundancy analysis revealed ExAcid and pHBC were more sensitive than pH was to the other chemical indicators. ExAcid was negatively correlated with SOM and ExCa; pHBC was positively correlated with ExMg, TN, SOM, and Feo. In conclusion, the crop yield could be improved by adjusting the soil acidity characteristics, and the application of pig manure reduced the soil acidity, with an optimal application rate of 15 Mg·ha−1.

Amelioration of Soil Acidity in Ferralsols of Central Uganda

Soil acidity is one of the major constraints limiting crop productivity in Central Uganda. Thus, the ideal soil pH for crop production ranges from 5.5 to 6.8, but in Central Uganda, crops are believed to be cultivated in soils with pH below these ranges. Given the adverse effects of soil acidity to agricultural production, appropriate measures such as the use of lime could be an option to improve the productive capacity. Henceforward, soils were sampled from farmers’ fields in Mpigi, Mubende and Wakiso Districts representing Central Uganda to evaluate rates of CaCO3 and corncob biochar in a greenhouse incubation study. Afterwards, 2 kg of soil was weighed, placed in a plastic container and thoroughly mixed with 0, 1, 3 and 5 g equivalent to 0, 1, 3 and 5 tons/ha CaCO3 and corncob biochar. Soils were arranged in a Complete Randomized Design (CRD) and moistened with 500 ml of water to bring it to about field capacity and pH determination done for a period of three (3) months until equilibration. The analysis of variance (ANOVA) showed significant effect (P&lt;0.001) on soil pH when CaCO3 and corncob biochar were applied with the three districts recording a near neutral pH of 6.7.&#x0D; After pH equilibration in the greenhouse, rates of CaCO3 and corncob biochar that raised the soil pH in each medium were used to calculate the lime rates i.e., 0, 120, 360 and 600 g applied in the fields. In a Complete Randomized Design (CRD) consisting of four replications, soybean varieties were applied as the main plots while rates of CaCO3 and corncob biochar were applied as the sub plots. The analysis of variance (ANOVA) showed that CaCO3 had significant effect (p&lt;0.001) on soil pH with Mpigi recording the highest soil pH (6.7) followed by Mubende (pH 6.6). Rates of CaCO3 and corncob biochar also showed significant effect (p&lt;0.001) on soybean grain yield compared to 0 g CaCO3 and corncob biochar. Application of 600 g of corncob biochar showed significant effect (p&lt;0.001) on soil pH in the different study locations. Besides, increased in CaCO3 rate to 600 g recorded the highest (7137.5 kg ha-1) soybean grain yield in Wakiso District while 600 g of corncob biochar recorded the highest (5637.5 kg ha-1) soybean grain yield in Mpigi District thus signifying the potential effect of CaCO3 and corncob biochar in Acid Ferralsols.

Combined influence of ash and poultry manure on soil reaction and performance of maize (&lt;i&gt;Zea mays&lt;/i&gt;) in a coarse-textured acid soil of South-East, Nigeria

Crop production can be limited by soil acidity. A two-factor factorial experiment involving three levels each of ash and poultry manure (PM) was conducted to determine the effects of ash and PM on soil reaction and performance of maize in an acid soil. The ash comprised of mixture of ash from wood, cocoa husk and palm bunch. The levels of ash (0.00, 3.00, 6.00 t ha–1 ) and PM (0.00, 4.00, 8.00 t ha–1 ) were combined to obtain nine treatment combinations (control, 3.00 ash and 0.00 PM, 3.00 ash and 4.00 PM, 3.00 ash and 8.00 PM, 0.00 ash and 4.00 PM, 3.00 ash and 0.00 PM) which were replicated thrice. The experiment was laid out in a randomized complete block design. Soil samples were collected at 3, 6, 9 and 12 weeks after planting (WAP), plant height measured at 3, 5, 7, and 9 WAP while cob oven-dry weight was measured after oven-drying harvested cobs at maturity. Analysis of variance was conducted on the data collected using GenStat version 14. The highest plant height of 132.50 cm at 12 WAP and the highest oven-dry cob weight of 7.15 t ha–1 were obtained from plots treated with 6.00 and 8.00 t ha-1 of ash and PM, respectively, and these were significantly (p ≤ 0.05) different from the other treatments. The lowest exchangeable acidity of 1.33 cmol kg–1 which varied significantly (p ≤ 0.05) from the other values observed at the other plots was obtained at the plot treated with the combination of 6.00 and 4.00 t ha–1 of ash and PM, respectively at 12 WAP. The combination of ash and PM at 3.00 and 8.00 t ha–1 gave the highest pH of 6.80, and this was significantly (p ≤ 0.05) different from the other treatments. Therefore, ash and PM at varying levels of combination can simultaneously ameliorate soil acidity and improve maize performance; however, the best combination of ash and PM application which showed the potential to produce optimum effect in simultaneously ameliorating soil acidity and increasing maize performance was the combination of 6.00 tonnes of ash and 8.00 tonnes of PM.

Biochar-Acid Soil Interactions—A Review

Soil acidity is a major problem of agriculture in many parts of the world. Soil acidity causes multiple problems such as nutrient deficiency, elemental toxicity and adverse effects on biological characteristics of soil, resulting in decreased crop yields and productivity. Although a number of conventional strategies including liming and use of organic and inorganic fertilizers are suggested for managing soil acidity but cost-effective and sustainable amendments are not available to address this problem. Currently, there is increasing interest in using biochar, a form of biomass derived pyrogenic carbon, for managing acidity while improving soil health and fertility. However, biochar varies in properties due to the use of wide diversity of biomass, variable production conditions and, therefore, its application to different soils can result in positive, neutral and or negative effects requiring an in-depth understanding of biochar-acid soil interactions to achieve the best possible outcomes. Here, we present a comprehensive synthesis of the current literature on soil acidity management using biochar. Synthesis of literature showed that biochars, enriched with minerals (i.e., usually produced at higher temperatures), are the most effective at increasing soil pH, basic cation retention and promoting plant growth and yield. Moreover, the mechanism of soil acidity amelioration with biochar amendments varies biochar types, i.e., high temperature biochars with liming effects and low temperature biochars with proton consumption on their functional groups. We also provide the mechanistic interactions between biochar, plant and soils. Altogether, this comprehensive review will provide guidelines to agricultural practitioners on the selection of suitable biochar for the reclamation of soil acidity.

Ameliorating soil acidity with calcium carbonate and calcium hydroxide: effects on carbon, nitrogen, and phosphorus dynamics

Ameliorating soil acidity with calcium carbonate and calcium hydroxide: effects on carbon, nitrogen, and phosphorus dynamics

Disentangling the effects of rice husk ash on increased plant growth and nitrogen recovery

Rice production generates large quantities of residues, whose disposal can pose environmental and health risks when not managed properly. The residue after rice husk combustion for energy production, rice husk ash (RHA), is currently underutilized despite its great potential as a soil conditioner. We aim to test the impact of RHA application on wheat growth, functional characteristics of the soil nitrifiers community and on N recovery using a 15N tracing greenhouse experiment. To distinguish between the effects caused by its liming capacity and P content, liming and P application treatments were included in the experiment. The amelioration of soil acidity (by both lime and RHA) lead to reduced losses of applied N fertilizer, but only RHA improved plant growth and plant N uptake. On the other hand, unlike RHA, lime application had strong effect on nitrification, increasing the potential maximal nitrification capacity (NEA) and reducing the affinity for N-NH4+ of soil nitrifiers (NHScom). The application of P reduced losses of applied 15N fertilizer particularly in the control pots, where additional P supply was likely critical to enhance N utilization by soil microorganisms. We therefore conclude that RHA effects on studied parameters are not only caused by soil pH amelioration nor by the P supply, but are likely driven by other inherent RHA properties (such as for instance its high content of macro- and micronutrients). The lack of observed effects on nitrification parameters and enhanced plant growth after RHA application can lead to considerably lower N losses and higher C sequestration in comparison to liming, while helping to solve the problems linked with RHA disposal.

Effect of Soil Acidity Amelioration on Soil Properties and Yield of French Bean (Phaseolus vulgaris L.) under Rainfed Condition in Arunachal Pradesh

Under rainfed conditions yield potential of French bean reduced in the acid soil of Arunachal Pradesh due to low fertility and metal toxicity. Therefore, the current experiment was conducted in ICAR, Basar, Research Farm during rabi season (October–January) of 2018, 2019 and 2020 to study the effect of soil amelioration using organic amendments combined with inorganic fertilizer on the yield of French bean and important soil properties. The soil amendment treatments i.e., control, vermicompost (Vc), vermicompost+lime (Vc+lime), 50% RDF (Recommended dose of fertilizer), 50% RDF+lime, 50% RDF+Vc, 75% RDF, 75% RDF+lime, 75% RDF+Vc, 100% RDF were laid in randomized block design with three replications. The doses of vermicompost, lime and RDF were 2.5 t ha-1, 400 kg ha-1 and 50-50-50 NPK kg ha-1. Results showed soil pH recorded maximum and exchangeable aluminum, exchangeable acidity and total acidity recorded minimum in 75%RDF+lime. The soil organic carbon, soil cation exchangeable capacity, soil moisture content and soil available nutrients (N, P, K, S, Fe, Mn, Zn, Cu) recorded maximum and soil bulk density recorded minimum in 75%RDF+Vc. Vermicompost along with 75%RDF was most effective in increasing the yield (4.85 t ha-1). The study indicates soil acidity amelioration using vermicompost and/or lime along with inorganic nutrients reduced soil acidity and improved the soil fertility making the soil environment favorable to achieve an optimum yield of French bean in acid soils of Arunachal Pradesh.

Calcium-based polymers for suppression of soil acidification by improving acid-buffering capacity and inhibiting nitrification

Soil acidification is a major threat to agricultural sustainability in tropical and subtropical regions. Biodegradable and environmentally friendly materials, such as calcium lignosulfonate (CaLS), calcium poly(aspartic acid) (PASP-Ca), and calcium poly γ-glutamic acid (γ-PGA-Ca), are known to effectively ameliorate soil acidity. However, their effectiveness in inhibiting soil acidification has not been studied. This study aimed to evaluate the effect of CaLS, PASP-Ca, and γ-PGA-Ca on the resistance of soil toward acidification as directly and indirectly (i.e., via nitrification) caused by the application of HNO3 and urea, respectively. For comparison, Ca(OH)2 and lignin were used as the inorganic and organic controls, respectively. Among the materials, γ-PGA-Ca drove the substantial improvements in the pH buffering capacity (pHBC) of the soil and exhibited the greatest potential in inhibiting HNO3-induced soil acidification via protonation of carboxyl, complexing with Al3+, and cation exchange processes. Under acidification induced by urea, CaLS was the optimal one in inhibiting acidification and increasing exchangeable acidity during incubation. Furthermore, the sharp reduction in the population sizes of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) confirmed the inhibition of nitrification via CaLS application. Therefore, compared to improving soil pHBC, CaLS may play a more important role in suppressing indirect acidification. Overall, γ-PGA-Ca was superior to PASP-Ca and CaLS in enhancing the soil pHBC and the its resistance to acidification induced by HNO3 addition, whereas CaLS was the best at suppressing urea-driven soil acidification by inhibiting nitrification. In conclusion, these results provide a reference for inhibiting soil re-acidification in intensive agricultural systems.

Short-Term Effects of Bamboo Biochar and Oyster Shell Powder on Soil Organic Carbon Fraction, Microbial Respiration, and Enzymatic Stoichiometry in a Lei Bamboo Plantation

Both biochar and oyster shell powder have been known as promising amendments to ameliorate soil acidity and enhance soil fertility. However, it is still unclear how their application alone and in combination affect the soil organic carbon (C) fraction and microbial activity in subtropical bamboo plantations. Therefore, to investigate the effects of biochar and oyster shell powder on soil microbial respiration, organic C fractions, microbial biomass, and enzyme activities related to C, N and P cycling, topsoil samples were collected from plots in a bamboo (Phyllostachys praecox) plantation that has been amended with oyster shell powder at 4 t ha−1 (T), bamboo biochar at 10 t ha−1 (B), and their combination (TB, with 4 t ha−1 T and 10 t ha−1 B) for 8 months. Our results showed that T alone significantly increased soil microbial respiration by 21.5%, whereas B alone and TB significantly decreased soil microbial respiration and metabolic quotient compared with T. T alone also increased soil pH, the size of labile C pool and the activities of β−glucosidase and cellobiosidase, whereas TB rather than B increased soil pH, the recalcitrant C pool size and declined these enzyme activities relative to T. T alone significantly enhanced microbial C limitation by 28.6% and decreased P limitation by 13.0%, while TB decreased microbial C limitation and increased microbial C use efficiency (CUE). Structural equation modeling indicated that T enhanced soil microbial respiration through increasing soil pH and enzyme activity, while biochar co-addition weakened the stimulation of T on microbial respiration by increasing soil recalcitrant C pool size and microbial metabolic quotient. Our study suggests that adding bamboo biochar together with oyster shell powder could be a better strategy to decrease soil C loss and ameliorate soil acidity in bamboo plantations compared with the application of oyster shell powder alone.

Effect of different nutrient management practices on nutrient availability and uptake in Vaikom kari soils of Kuttanad, Kerala

A field experiment was laid out in RBD with 16 treatments in three replications with rice variety Uma. The treatments were dolomite, lime + MgSO4 or Rice Husk Ash (RHA) + MgSO4 along with 100% package of practice recommendations of Kerala Agricultural University (POP) alone or with 100% POP + foliar spray of 13:0:45 (1%) or borax (0.5%) or 13:0:45 + borax at PI stage. Lime + MgSO4 + 75% POP + 13:0:45 + borax as well as lime without MgSO4 + 100% POP combined with 13:0:45 or borax or both were also included as treatments. The treatment dolomite + POP + 13:0:45 produced the highest grain yield of 5.42 and 5.57 t ha-1 during 2015 and 2016 respectively. This treatment was followed by dolomite + POP + 13:0:45 + borax and lime + POP + MgSO4 + 13:0:45 during both the years. Lower yields were produced by the treatments involving RHA and 75% POP. The pooled analysis of two years' data also proved the significance of the treatments involving dolomite + POP or lime + POP + MgSO4 on grain yield. The highest yield of 5.49 t ha-1 was recorded by dolomite + POP + 13:0:45 followed by dolomite + POP + 13:0:45 + borax and lime + MgSO4 + POP + 13:0:45. The treatments involving RHA and 75% POP registered significantly lower grain yield in the pooled data. The treatments involving dolomite registered lower status of soil available Fe and higher status of available Mn and B. Higher status of available Zn was registered by the treatments involving dolomite or lime + MgSO4. The treatments involving dolomite, lime + MgSO4 or RHA + MgSO4 along with POP registered higher available Cu in the soil. Dolomite treatments recorded lower status of Na and exchangeable Al in the soil. Dolomite or lime + MgSO4 along with POP + 13:0:45 with or without borax registered higher uptake of Fe, Mn and Zn while dolomite + POP + 13:0:45 with or without borax recorded higher uptake of Cu and B. The treatments involving RHA and 75% POP recorded lower uptake of micronutrients during both the years. Uptake of Na was the highest with RHA + POP + MgSO4 + 13:0:45 during first year and with dolomite + POP during second year. Higher Al uptake was observed with lime + POP + 13:0:45 with or without MgSO4. The grain yield was significantly and positively correlated with the uptake of Mn, Zn, Cu and B and significantly and negatively correlated with Fe during the first year. During the second year, the yield was significantly and positively correlated with uptake of nutrients except Na and Al. The results indicated that amelioration of soil acidity is a crucial management practice for improving the availability and uptake of nutrients resulting in higher yield.

Impact of silicate and lime application on soil fertility and temporal changes in soil properties and carbon stocks in a temperate ecosystem

Most agricultural soils are unproductive due to soil acidity which limits crop growth and yield. To ameliorate soil acidity constraints and enhance the ecosystem services the soil renders to achieve optimum crop yields, lime, and silicate are mostly used. However, there are few studies reporting the impacts of the combined application of silicate and lime on soil properties, soil fertility and carbon stocks and stratification in long-term experiments. This study evaluated the impacts of the combined application of silicate and lime on soil fertility indicators (pH, soil organic matter (SOM), available phosphorus, exchangeable potassium, magnesium, and calcium, and available SiO2), carbon stratification and stocks in comparison to sole lime and sole silicate applied to a Fluvaquentic Eutrudepts over a 67-year period. Each treatment’s rate of application was calculated to raise the soil pH to 6.5. Incorporation of the treatments increased the soil pH by 1.30, 1.22, and 1.35 folds in the sole silicate, sole lime, and combined silicate and lime-treated soils, respectively, relative to the baseline soil pH (5.5). The combined application of silicate and lime resulted in significant decreases in C stratification and C stocks. The significant reduction in the C stocks in the silicate and lime-treated soils implies that its long-term application could potentially reduce carbon sequestration and increase the carbon footprint of rice cultivation. This information is crucial to develop sustainable soil management interventions to curtail the environmental footprint in rice paddy ecosystems. Comparatively, the combined silicate and lime treatment caused an increase in the relative change of soil fertility by 65.7% and the average annual growth rate in the soil fertility improvement by 0.0115, as compared to the untreated soil. Among the soil variables, soil pH, exchangeable calcium, and available silicate contributed most to the variation the soil fertility. The obtained results could serve as a guide in revising the lime and silicate fertilization programs instituted by the Korean Government and reviewing national soil fertility management systems in temperate paddy ecosystems.