Gypsum Treatments Research Articles

Enhancement of bauxite residue as a low-cost adsorbent for phosphorus in aqueous solution, using seawater and gypsum treatments

Bauxite residue (red mud), the by-product produced in the alumina industry, is being produced at an estimated global rate of approximately 150 Mt per annum. Due to its highly alkaline nature, many refineries use neutralisation techniques such as mud farming (atmospheric carbonation), direct carbonation using carbon dioxide or reactions with seawater, to treat the bauxite residue and reduce its alkalinity prior to disposal in the BRDA (bauxite residue disposal area). Applying a treatment can render the bauxite residue non-hazardous and may also prepare the bauxite residue for reuse, particularly as an adsorbent. In this study, gypsum and seawater treatments were applied to the various bauxite residue samples obtained and the effects on its mineral, elemental and physiochemical properties were examined, as well as the effect on its phosphorus (P) adsorption capacity. It was found that in addition to reducing the alkalinity of all bauxite residue samples used, the P adsorption capacity was also enhanced following amendment with seawater or gypsum, particularly with gypsum. A positive correlation was detected between P adsorption and both Ca and CaO. A negative correlation was detected between the P adsorption and pH of the media. Fitting the data obtained from a batch adsorption experiment to the Langmuir adsorption isotherm, the maximum adsorption capacity was estimated to range from 0.345 to 2.73 mg P per g bauxite residue, highlighting the re-use potential for bauxite residue as an adsorbent for P.

Desodification from calcareous saline sodic soil through phytoremediation with Phragmites australis (Cav.) Trin. ex Steud. and gypsum

ABSTRACTThe reclamation of saline sodic soils requires sodium removal and the phytoremediation is one of the proven low-cost, low-risk technologies for reclaiming such soils. However, the role of Phragmites australis in reclaiming saline sodic soils has not been evaluated extensively. The comparative reclaiming role of P. australis and gypsum was evaluated in a column experiment on a sandy clay saline sodic soil with ECe 74.7 dS m−1, sodium adsorption ratio (SAR) 63.2, Na+ 361 g kg−1, and pH 8.46. The gypsum at 100% soil requirement, planting common reed (P. australis) alone, P. australis + gypsum at 50% soil gypsum requirements, and leaching (control without plant and gypsum) were four treatments applied. After 11 weeks of incubation, the results showed that all treatments including the control significantly reduced pH, EC, exchangeable Na+, and SAR from the initial values, the control being with least results. The gypsum and P. australis + gypsum were highly effective in salinity (ECe) reduction, while sodicity (SAR) and Na+ reductions were significantly higher in P. australis + gypsum treatment. The reclamation efficiency in terms of Na+ (83.4%) and SAR (86.8%) reduction was the highest in P. australis + gypsum. It is concluded that phytoremediation is an effective tool to reclaim saline sodic soil.

Soil management and application of agricultural gypsum in a Planosol for soybean cultivation

ABSTRACT: This study investigated the effects of soil management systems, tillage, and application of gypsum agricultural to soil, on soybean development in lowland areas. The experiment was carried out on an Alfisol in a randomized complete block design in a factorial arrangement. The two soil tillage practices were without deep tillage and with deep tillage. Gypsum treatments were no gypsum application, 500kg of gypsum ha-1, 1000kg of gypsum ha-1, and 1500kg of gypsum ha-1. Deep tillage resulted in less soil resistance to root penetration during ryegrass cultivation during the soybean offseason, 11 months after applying the management treatments, resulting in higher dry mass of ryegrass in the offseason and higher soybean yield in the following year.

Response of Jatropha integerrima Plants Irrigated with Different Levels of Saline Water to Nano Silicon and Gypsum

An open field experiment was carried out during 2015 and 2016 seasons at the experimental nursery of the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Egypt. The purpose of present research was to investigate the effect of foliar application of nano silicon with different concentrations and gypsum soil application on growth, flowering and chemical constituents of Jatropha integerrima plants irrigated with different levels of saline water. The concentrations of saline water were (1000, 2000 and 4000 ppm), in addition to tap water (270 ppm) as a control, simultaneously plants were received monthly foliar application of nano silicon 1 and 2 mM or soil application of gypsum at 20 g/plant, either applied individually or in combination.The results showed that, elevating salt concentration in irrigation water decreased vegetative growth characteristics, flowering traits, leaves anatomy and chemical constituents. In contrast, increasing salinity of irrigation water boosted contents of proline, Ca%, Na%, Cl%, total phenolic and flavonoids. On the other hand, foliar application of nano silicon and soil addition of gypsum treatments either individually or in combination had favorable effects on enhancing vegetative parameters and chemical constitutes, meanwhile decreasing accumulation of Na%, Cl%, total phenolic and flavonoids in leaves. It can be concluded that, foliar spray of nano silicon combined with soil addition of gypsum was the best effective and economic treatment recommended for mitigating the harmful effect of salinity stress on Jatropha plants irrigated with saline water at concentration up to 4000 ppm.

A DOC coagulant, gypsum treatment can simultaneously reduce As, Cd and Pb uptake by medicinal plants grown in contaminated soil

The efficiency of gypsum, as a dissolved organic carbon (DOC) coagulator, for the simultaneous immobilization of two heavy metals (Cd and Pb) and one metalloid (As) in agricultural soils near an abandoned mining site was examined. The agricultural soil was defined as long-term contaminated as As (1540mgkg−1), Cd (55mgkg−1) and Pb (1283mgkg−1) concentrations exceeded the Korean guideline values for As (25mgkg−1), Cd (4mgkg−1), and Pb (200mgkg−1). Gypsum was incorporated into the contaminated soil at 3% (w/w). In comparison two commonly using immobilizing agents (lime and compost), together with a mixture (lime+gypsum) were also included in the pot trial for the cultivation of two medical plants (A. gigas and A. macrocephala) and to evaluate the effectiveness of gypsum on As, Cd and Pb immobilization. The results showed that even though pH change-induced immobilizing agents such as lime were more effective than gypsum at immobilizing Cd and Pb, addition of gypsum also effectively reduced heavy metal phytoavailability as indicated by decreases in the concentration of Cd and Pb in medicinal plants. Furthermore, gypsum and gypsum+ lime were also most effective in reducing As concentrations in both plants studied. This was mainly attributed to significant decreases in soil DOC (48–64%) when gypsum and gypsum+lime were applied to the soil. Consequently, it was concluded that enhanced DOC coagulation with gypsum, could be considered as a promising technique for the immobilization of both metals (Cd and Pb) and metalloids (As) in agricultural soils.

Relevance of Reactive Fe:S Ratios for Sulfur Impacts on Arsenic Uptake by Rice

Human arsenic exposure from rice consumption is a global concern. Due to the vast areas of naturally contaminated soils in rice-producing regions, the only possibility for reducing hazardous exposure is to prevent As uptake and translocation to rice grain. Sulfur inhibits As mobility both in soil and plant, indicating that soil S content may be a primary factor controlling As uptake; indeed, gypsum (CaSO4·H2O) has been proposed as a potential amendment. Here, we investigated S controls on rice As uptake within two naturally contaminated soils (15.4 and 11.0 mg As per kg soil, respectively) from Cambodia, by adding gypsum at two levels (20 and 60 mg per kg soil). We found that although gypsum initially decreased As release to soil solution, the concentrations then increased compared to the control treatment. Further, As concentrations in rice biomass were generally insignificantly affected by the gypsum treatments and trended in opposite directions between the two soils. Single and multivariate statistical tests indicated that Fe exerted stronger control on As uptake in rice than S and that the initial ratio of reactive Fe to sulfate-S had an overriding impact on As uptake in rice. However, in the soil with higher inherent sulfate content (91 mg SO42−-S per kg soil) the additional S provided by gypsum appeared to increase the ability of the rice plant to prevent As translocation to grain. We conclude that S may contribute to regulating grain As concentrations, but that the effect is highly dependent on S:Fe(As) ratios. Thus, at modest amendment rates, gypsum has limited potential for minimizing As concentration in rice when applied to naturally contaminated soil, particularly if the reactive Fe(III) content is high.

Alfalfa Responses to Gypsum Application Measured Using Undisturbed Soil Columns.

Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG)] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. The objective of this study was to evaluate the effects of (1) untreated, (2) short-term (4-year annual applications of gypsum totaling 6720 kg ha−1), and (3) long-term (12-year annual applications of gypsum totaling 20,200 kg ha−1) on alfalfa (Medicago sativa L.) growth and nutrient uptake, and gypsum movement through soil. The study was conducted in a greenhouse using undisturbed soil columns of two non-sodic soils (Celina silt loam and Brookston loam). Aboveground growth of alfalfa was not affected by gypsum treatments when compared with untreated (p > 0.05). Total root biomass (0–75 cm) for both soils series was significantly increased by gypsum application (p = 0.04), however, increased root growth was restricted to 0–10 cm depth. Soil and plant analyses indicated no unfavorable environmental impact from of the 4-year and 12-year annual application of FGDG. We concluded that under sufficient water supply, by-product gypsum is a viable source of Ca and S for land application that might benefit alfalfa root growth, but has less effect on aboveground alfalfa biomass production. Undisturbed soil columns were a useful adaptation of the lysimeter method that allowed detailed measurements of alfalfa nutrient uptake, root biomass, and yield and nutrient movement in soil.

Recovery of a dystrophic Red Latosol (Oxisol) and pasture as a function of gypsum in the Cerrado biome

ABSTRACT This study was conducted to evaluate the chemical effects of gypsum on the soil and on the recovery of a pasture established with palisade grass (Urochloa brizantha) in a Cerrado biome region. A randomized block experimental design with six treatments and four replications was adopted. Treatments consisted of five levels of gypsum (0, 450, 900, 1800, and 3600 kg ha−1) plus an unmanaged control treatment (without gypsum or additional chemical fertilizers). The gypsum treatments received addition of fertilizer (200 and 40 kg ha−1 of N and P respectively). The soil treatment started in October 2012. The application of gypsum provided an increase in plant height, number of tillers, and dry matter of the shoots of palisade grass. Gypsum combined with chemical fertilizers provided an increase in productivity compared with chemical fertilizers alone. The use of gypsum improved the chemical characteristics of the soil, increasing calcium and sulfur in the deeper layers, consequently, providing greater development of the palisade grass root system. High gypsum levels impaired the development of the root system, especially in the 0.20–0.40 m layer. Gypsum provides recovery of soil and degraded pastures.

Flue gas desulfurization gypsum: Its effectiveness as an alternative bedding material for broiler production

Flue gas desulfurization (FGD) gypsum may be a viable low-cost alternative bedding material for broiler production. In order to evaluate FGD gypsum’s viability, a study was conducted to determine its influence on live performance (body weight, feed consumption, feed efficiency, and footpad dermatitis), litter characteristics (caking, moisture percentage, and surface temperature) and ammonia volatilization in 3 successive flocks. FGD gypsum was compared with pine shaving (PS), pine bark (PB), PS + FGD gypsum (second material was top dressed over first), PB + FGD gypsum, PS + PB, FGD gypsum + PS, and FGD gypsum + PB. Bedding had no significant influence on feed consumption (FC), feed efficiency (FE), and mortality (M). Body weight and adjusted feed efficiency (AFE) were significantly lower with FGD gypsum compared to that of PS for flock 1, with no differences being observed among the other bedding materials. No differences were noted in live performance for flocks 2 or 3. Incidences of footpad lesions were lower with FGD gypsum than the other bedding materials, but only for flock 1. Bedding treatment had no influence on litter surface temperature. Gravimetric moisture content of gypsum treatments was lower than that of non-gypsum treatments; however, visually, the FGD gypsum was more compacted and had a surface crust. Reductions in ammonia volatilization also were observed during the initial flock with FGD gypsum; however, its effectiveness had diminished by flock 2 and 3.

Sulfur accumulation in gypsum-forming thiophores has its roots firmly in calcium

Recent studies suggest sulfur-accumulators (thiophores and gypsophiles) produce foliar gypsum (CaSO4·2H2O) as a novel biomineralogical tolerance mechanism against sulfate salinity and excess soluble calcium (e.g. gypsic soil). However, little is known of the geochemical and ecophysiological aspects of foliar gypsum. The compositional, developmental (biomass, root development) and functional responses (photosystem performance and water relations), to soils with contrasting relative SO42− and Ca2+ pore-water concentrations (incl. a gypsum treatment), were examined in two gypsum-forming desert thiophores (Acacia bivenosa L. and A. ligulata A.Cunn. ex Benth.) and a sympatric non-thiophore comparator (A. ancistrocarpa Maiden & Blakely). Sulfur and calcium were accreted broadly as a function of the relative abundance of Ca2+ and SO42− ions in soil solution, and interspecific responses revealed thiophores are preferentially Ca accumulators, tending to maximise Ca uptake for the given conditions and scaling sulfate accumulation in relation to Ca, a co-regulation behaviour absent in the comparator. The thiophores were also sensitive to sulfur limitation, and these observations are consistent with cytosolic Ca2+ and SO42− regulation through gypsum precipitation. However, the gypsum-forming species were not comparatively tolerant to the gypsum treatment, most likely due to a lack of tolerance to limited P bioavailability resulting from the formation of sparingly-soluble calcium-phosphate soil minerals. The outcomes indicate that the capacity for gypsum biomineralisation does not, by itself, confer tolerance to the full suite of geochemical stress factors presented by gypsic soils (e.g. constrained P bioavailability). The findings steer future research towards testing alternative hypothesis pertaining to the ecophysiological basis of gypsum formation (e.g. osmoregulation) as well as examining whether obligate gypsophiles, which are also challenged by constrained P bioavailability, benefit by forming gypsum biominerals.

Addressing biophysical constraints for Australian farmers applying low rates of composted dairy waste to soil

AbstractThis study examined the response of forage crops to composted dairy waste (compost) applied at low rates and investigated effects on soil health. The evenness of spreading compost by commercial machinery was also assessed. An experiment was established on a commercial dairy farm with target rates of compost up to 5 t ha−1applied to a field containing millet [Echinochloa esculenta(A. Braun) H. Scholz] and Pasja leafy turnip (Brassicahybrid). A pot experiment was also conducted to monitor the response of a legume forage crop (vetch;Vicia sativaL.) on three soils with equivalent rates of compost up to 20 t ha−1with and without ‘additive blends’ comprising gypsum, lime or other soil treatments. Few significant increases in forage biomass were observed with the application of low rates of compost in either the field or pot experiment. In the field experiment, compost had little impact on crop herbage mineral composition, soil chemical attributes or soil fungal and bacterial biomass. However, small but significant increases were observed in gravimetric water content resulting in up to 22.4 mm of additional plant available water calculated in the surface 0.45 m of soil, 2 years after compost was applied in the field at 6 t ha−1dried (7.2 t ha−1undried), compared with the nil control. In the pot experiment, where the soil was homogenized and compost incorporated into the soil prior to sowing, there were significant differences in mineral composition in herbage and in soil. A response in biomass yield to compost was only observed on the sandier and lower fertility soil type, and yields only exceeded that of the conventional fertilizer treatment where rates equivalent to 20 t ha−1were applied. With few yield responses observed, the justification for applying low rates of compost to forage crops and pastures seems uncertain. Our collective experience from the field and the glasshouse suggests that farmers might increase the response to compost by: (i) increasing compost application rates; (ii) applying it prior to sowing a crop; (iii) incorporating the compost into the soil; (iv) applying only to responsive soil types; (v) growing only responsive crops; and (vi) reducing weed burdens in crops following application. Commercial machinery incorporating a centrifugal twin disc mechanism was shown to deliver double the quantity of compost in the area immediately behind the spreader compared with the edges of the spreading swathe. Spatial variability in the delivery of compost could be reduced but not eliminated by increased overlapping, but this might represent a potential 20% increase in spreading costs.

Phytoremediation of calcareous saline-sodic soils with mesquite (Prosopis glandulosa)

ABSTRACTWe evaluated phytoremediation potential of a calcareous saline-sodic soil with Prosopis glandulosa relying on either N2 fixation (NFIX) or inorganic N (IN) and gypsum. Straw and root dry matter of NFIX were 60% and 67% higher than that of IN, respectively. While both plants relying on IN or NFIX retained nearly similar Ca2+, Na+ level in IN lysimeters was 1.8 folds that of NFIX, whereas levels of Na+ and K+ in roots of NFIX were 13% and 24% higher than that of IN plants. P. glandulosa relying on NFIX and IN released 39% and 50% Na+ of that released by the gypsum. P. glandulosa produced more than the gypsum treatment and induced 24% of Ca2+ solubilization found in the gypsum treatment. Translocation factor of Na+ and the K+/Na+ ratio in NFIX and IN were 0.58, 0.99 and 13.2, 7.0, respectively. The practical implication of this study conclude that P. glandulosa grown with NFIX or IN is an alternative practice for amelioration of calcareous salt-affected soils.

Field trial and modelling of different strategies for remediation of soil salinity and sodicity in the Lower Murray irrigation areas

Rising saline groundwatertables and drought in the Lower Murray Reclaimed Irrigation Area (LMRIA) has created soil salinity and sodicity conditions, which has resulted in a decline in agricultural production. A 2 month field experiment was conducted at Mobilong irrigation area using a randomised block design with trial plots (4m2) in each of the three blocks containing the following six treatments: (1) control (not irrigated), (2) irrigation (River Murray water) only, (3) gypsum application (1.5 kg/m2) and irrigation, (4) limestone application (1.5 kg/m2) and irrigation, (5) seawater (source of dissolved Ca2+) application (100mm depth) and irrigation and (6) acid (pH 3) drainage (to dissolve CaCO3 in soil to release Ca2+) application (100mm irrigation water depth) and irrigation. Soil electrical conductivity (EC), pH, exchangeable cations (Ca2+, Mg2+, Na+, K+), exchangeable sodium percentage (ESP) and saturated hydraulic conductivity were measured. The decrease in EC was greatest in the irrigation only treatment followed by the gypsum and limestone treatments. At the end of the trial, the EC in the irrigation only treatment was about one-quarter of the control, in which the EC increased. The seawater and acid drainage treatments reduced the soil EC relative to the control but the EC was 2–3dS/m higher than the irrigation, gypsum and limestone treatments at the end of the trial. The gypsum, irrigation only and limestone treatments approximately doubled the exchangeable Ca relative to the control and exchangeable Na was reduced. Unsaturated water and solute transport model (HYDRUS-UNSATCHEM) simulations were able to represent the general trends in the field results. The results suggest that only River Murray water irrigation and drainage could be effective for the management of soil salinity and sodicity in the LMRIA but further research is required to establish the threshold electrolyte concentration to prevent soil dispersion.

Yield and yield components of Arachis hypogaea L. as influenced by NPK chemical fertilizers, farm yard manure and gypsum

Field trials were conducted to evaluate the effect of chemical fertilizers, farmyard manure (FYM) and gypsum on yield and yield components of groundnut (Arachis hypogea L.). There were nine treatments included unfertilized treatment and full doses of recommended NPK fertilizers (65:100:75 kg/ha) or reduced doses of recommended NPK fertilizers (30:50:37.5 kg/ha) and FYM@10 t/ha in combination with different levels (0, 150, 300 and 450 kg/ha) of gypsum. The results exhibited that full dose of NPK fertilizers with 300 kg/ha gypsum treatment gave significantly (P<0.05) higher seed yield (2777.28 kg/ha) than the full dose of NPK fertilizers alone (typical control) which had 2276.05 kg/ha. On the other hand, application of reduced dose of NPK fertilizers + 10 t/ha FYM with 450 kg/ha gypsum resulted 2609.88 kg/ha seed yield followed by 300 kg/ha gypsum application which had 2521.98 kg/ha and both values were statistically similar. Thus, use of 300 kg/ha gypsum could give high seed yield of groundnut with full dose of NPK fertilizers alone or reduced dose of NPK fertilizers and 10 t/ha FYM. However, combined application of organic and inorganic fertilizers is better practice especially on sandy regosol when considering human and soil health.Bangladesh J. Sci. Ind. Res. 51(4), 285-290, 2016

Reclamation of a coastal reclaimed tidal land soil by gypsum and rice straw

ABSTRACTThis study was to evaluate the application effect of gypsum and rice straw on the saline–sodic soils of coastal reclaimed tidal lands during newly reclamation process by leaching method. Soil used in the lysimeter experiment is classified as Greyic Hydragric Anthrosols (Sodic Arenic). The experiment was carried out over a period of 1 year from May 2014 to July 2015 inside a plastic film house. Saturated electrical conductivity (ECe) and exchangeable sodium percentage (ESP) values of soils in gypsum treatment and gypsum with rice straw treatment then reached the desalinization criteria (ECe = 4.0 dS m−1, ESP = 15%) after the five or six pore volumes leaching cycles. However, in spite the 10 pore volumes leaching cycles in control and rice straw alone treatment, the values did not reach the desalinization criteria. The results showed that effectiveness of improvement of sodicity and salinity in coastal reclaimed tidal land soils was in the order of gypsum = gypsum + rice straw > rice straw = control. Our study has shown that gypsum alone treatment or gypsum with rice straw treatment in a coastal reclaimed tidal land soils improves their physicochemical characteristics.

Effect of tillage and application of gypsum In a No-Till field under supplementary irrigation with sodium bicarbonate waters

Supplementary irrigation is widespread in the Humid Pampa of Argentine, where the main source of water for irrigation has elevated content of sodium bicarbonate. The combination of irrigation and rain increases the sodium absorption ratio of soil (SARs), consequently raising the clay dispersion and reducing infiltration. The water quality standards for irrigation indicate that SARs values ​​should remain below 3.5. An alternative to mitigate these disadvantages is the application of a gypsum amendment. This study targeted the following objectives: measure the impact of tillage and the addition of gypsum on: infiltration, bulk density, sodium content and crop yield in a soil (Argiudoll and petrocalcic Paleudoll association) under no-till with supplementary irrigation. One treatment consisted of applying a gypsum liming of particle size less than 3mm. After application, the plots were tilled to a depth of 15cm. Sunflower (Helianthus annuus L.) was seeded 30days after the completion of the amendment. Applying gypsum improved water infiltration into the soil. Tillage treatment without adding gypsum reduced SARs and increased infiltration the same way as tillage and gypsum treatment. This can be attributed the dissolution of native or precipitated carbonate by irrigation water. Tilled treatments, with or without amendment, had higher yield compared to no-till treatment.

Increasing rice production in sodic soil through ferti-irrigation with distillery spentwash

Field experiment was conducted in sodic soil (pH 8. 9 ESP- 31.5 %) to study the extent of reclamation achieved due to basal application of raw spentwash (RSW) and to study the effect of primary spentwash (SW) used for ferti-irrigation on extent of reclamation incidentally achieved due to spentwash application in comparison with gypsum and also on growth and yield of paddy. Highest grain, straw yield and nutrient uptake was recorded in RSW @ 100 % GR+100 % RDN through SW (3 splits) and lowest was recorded in T1 which received gypsum @50 % GR + recommended NPK. Per cent increase in grain yield 47.34 per cent (T9) was noticed in spentwash amended plot compared to gypsum treatment (T1). Reduction in soil pH was highest in T9 (RSW @ 100% GR+100% RDN through SW (3splits)) and lowest in T1 (Gypsum@50% GR+ Rec.NPK). Application of RSW @ 100% GR+100% RDN through SW (4 splits) recorded significantly lower exchangeable sodium content and ESP compared to other treatments. The cost economics of cultivation revealed that highest benefit cost ratio (2.69) was obtained with raw spentwash @ 100 % GR+ 100 % RDN through treated spentwash in 3 splits while the lowest 0.53 was with gypsum @ 100 % GR+ rec.NPK

Use of a Bioaugmented Organic Soil Amendment in Combination with Gypsum for Withania somnifera Growth on Sodic Soil

Limited availability of organic matter is a problem to sustain crop growth on sodic soil. Organic soil amendments are a cost-effective source of nutrients to enhance crop growth. A field study was conducted to evaluate the effect of an organic soil amendment bioaugmented with plant growth-promoting fungi (SFOA) in combination with gypsum on soil properties and growth and yield attributes of Withania somnifera, one of the most valuable crops of the traditional medicinal system in the world, on a sodic soil at the Aurawan Research Farm of CSIR-National Botanical Research Institute, Lucknow, India. The SFOA used was prepared by pre-enriching farm waste vermicompost with plant growth-promoting fungi before mixing with pressmud and Azadirachta indica seed cake. The application of SFOA at 10 Mg ha−1 after gypsum (25.0 Mg ha−1) treatment significantly (P < 0.05) increased root length (by 96%) and biomass (by 125%) of Withania plants compared to the control without SFOA and gypsum. Similarly, the highest withanolide contents were observed in leaves and roots of Withania plants under 10 Mg ha−1 SFOA and gypsum. Combined application of SFOA and gypsum also improved physical, chemical and enzymatic properties of the soil, with the soil bulk density decreasing by 25%, water-holding capacity increasing by 121%, total organic C increasing by 90%, pH decreasing by 17% and alkaline phosphatase, β-glucosidase, dehydrogenase and cellulase activities increasing by 54%, 128%, 81% and 96%, respectively, compared to those of the control. These showed that application of the SFOA tested in this study might reclaim sodic soil and further support Withania cultivation and results were better when the SFOA was applied after gypsum treatment.

Enhancement of the rootability of a structurally fragile tropical soil using gypsum and leguminous residues to increase the yield of maize

AbstractIn humid tropical areas, a combination of factors related to soil conditions for root development contribute to decreased nutrient use efficiency. Our aim was to evaluate the combined effects of the application of gypsum and mulch from leguminous trees on rootability of root zone soil, root growth, phosphorus recovery efficiency and maize yield in a sandy loam soil prone to hardsetting. The experiment involved a randomized block design with four replications and six treatments: no residue or gypsum (control, C); leguminous residues (L); leguminous residues and 6 t/ha of gypsum (LG6); urea and 6 t/ha of gypsum (UG6); leguminous residues, urea and 6 t/ha of gypsum (LUG6); and leguminous residues, urea and 12 t/ha of gypsum (LUG12). Application of gypsum plus leguminous residues enhanced soil rootability, when applied to a tropical Arenic Hapludult, through the combined effects of increased porosity and decreased penetration resistance. These improvements facilitated root growth in deeper soil layers and greater nutrient uptake. Application of leguminous residues increased the input and retention of calcium in deeper layers. The use of large amounts of gypsum with leguminous residue, despite a significant increase in phosphorus uptake, did not result in a proportional increase in maize yield. Given the small differences in calcium content between the 6 and 12 t/ha gypsum treatments, applying a low dose of gypsum combined with leguminous residue, rather than administering a single large gypsum dose, is recommended for tropical sandy loam soils with low cation retention capacities.

Influence of lime and gypsum application on soil properties and yield of cassava (Manihot esculenta Crantz.) in a degraded Ultisol in Agbani, Enugu Southeastern Nigeria

The experiment was carried out to examine the influence of lime and gypsum on soil physicochemical properties in a degraded Typic paleusult during 2013 and 2014 rainy season in Agbani, Enugu Southeastern Nigeria (6°29′N and 7°54′E). A Randomized Complete Block Design (RCBD) using lime and gypsum as treatments at the rate of 5000kgha−1 lime, 2500kgha−1 gypsum, 5000kgha−1 lime+2500kgha−1 gypsum and a control without lime and gypsum treatments, replicated five (5) times using cassava (TMS 0304) as test crop was used for the experiment. Soil pH in plots amended with 5000kgha−1 lime (5.7 and 5.4) increased relative to the control by between 16 and 17% for both planting seasons. Soils amended with 2500kgha−1 of gypsum had lower pH relative to plots amended with 5000kgha−1 lime. However, Soil application of a combination of 5000kgha−1 of lime and 2500kgha−1 of gypsum increased soil pH by 19–20% when compared to the control for both seasons. Soil application of a combination of 5000kgha−1 of lime and 2500kgha−1 of gypsum increased soil exchangeable Ca2+ by 57% when compared to the control for both seasons. Soil percent base saturation was significantly improved from 72.8% to 93.0% relative to control when 5000kgha−1 lime+2500kgha−1 gypsum was applied to the soil. Results showed that at 90 DAP in both seasons, soil dry bulk density in plots amended with 5000kgha−1 lime (1.58 and 1.62Mgm−3) decreased relative to the control by between 5 and 7% for both planting seasons. Soil application of a combination of 5000kgha−1 of lime and 2500kgha−1 of gypsum reduced soil dry bulk density by about 17% when compared to the control for both seasons. The highest soil total porosity (46.4%) was found in plots with a combination of lime and gypsum at 5000kgha−1 and 2500kgha−1 respectively. The result also showed that soil water transmissivity improved from about 31.85cm3h−1 in the control plots to 37.60cm3h−1 in plots treated with 2500kgha−1 gypsum and up to 35.7cm3h−1 in treated with 5000kgha−1 lime then to 41.40cm3h−1 in plots treated with 5000kgha−1 lime+2500kgha−1 gypsum. At 90 DAP the highest mean plant height of cassava (86–92cm) was found in plots treated with 5000kgha−1 lime+2500kgha−1 gypsum. This was followed by plots treated 2500Kgha −1 gypsum (59–62cm) and those treated with 5000kgha−1 lime (61–66cm) whereas the untreated (control plots) had a plant height of 61–64cm. Plots treated with 5000kgha−1 lime+2500kgha−1 gypsum had the highest mean fresh tuber yield of 9.5Mgha−1. This was followed by plots treated with 2500kgha−1 gypsum which gave a mean fresh tuber yield of 7.2Mgha−1, plots treated with 5000kgha−1 lime followed with 6.8Mgha−1 while the lowest tuber yield was found in untreated plots which had 6.1Mgha−1. The significant treatment differences on soil physical and chemical properties of the study soil due to effect of the treatments could be attributed to the ability of Ca2+ applied via lime and gypsum to flocculate soil particles thereby creating an enabling soil physical condition for better nutrient uptake, proper infiltration and aeration, increased P availability and optimum pH for proper growth of cassava.