Rates Of Gypsum Research Articles

Calcium

A field study was conducted on a Hubbard loamy sand low in exchangeable Ca to determine the influence of gypsum on cauliflower (Brassica oleracea Botrytis cv. ‘Snow Crown') nutrition, yield, and quality. Four rates of gypsum (0, 560, 1120, and 2240 kg/ha) were incorporated before planting. Extractable soil Ca and S increased linearly with increasing gypsum rate. Despite increases in tissue Ca with gypsum application, tipburn of immature leaves was apparent in all treatments. Gypsum had no effect on final yield, curd size, or tipburn severity. Relative levels of Ca, K, P, and Mg were determined in frozen‐hydrated and freeze‐dried leaf tissue from tipburned and non‐tipburned leaves using a scanning electron microscope with x‐ray microanalysis. Distribution of these elements was also determined in digested leaf tissue using an ICP spectrometer. Results of x‐ray microanalysis indicated that Ca was relatively low and K and P relatively high near necrotic tip areas. No consistent differences in Ca, K, ...

IMPROVEMENT OF SOIL PROPERTIES AND PLANT GROWTH ON A BROWN SOLONETZIC SOIL USING IRRIGATION, CALCIUM AMENDMENTS AND NITROGEN

A 4-yr study was conducted on an irrigated Brown Solonetzic soil in southern Alberta to determine the effects of relatively low rates (4.2 Mg Ca ha−1) of surface-applied gypsum (CaSO4·2H2O) and lime (CaCO3) on soil chemical properties, water penetration and growth of bromegrass (Bromus inermis Leyss). Annual applications (155 kg N ha−1) of ammonium nitrate (NH4NO3) and ammonium bisulphite (NH4HSO3) were applied alone and in combination with the Ca amendments. Gypsum improved the chemical condition of the Bnt horizon by decreasing soluble Na and the electrical conductivity, and increasing levels of exchangeable Ca. The exchangeable Ca to Na ratio was increased from 5.5 to 16.9, while the sodium adsorption ratio was reduced from 18.1 to 7.6. Gypsum also decreased the EC of the Csk horizon from 12.7 to 5.2 dS m−1. In contrast, the lime amendment only increased the exchangeable Ca level of the Bnt horizon. Ammonium bisulphite decreased the soil pH of the soil profile, especially the Ap horizon (7.3–6.3), and increased the initial rate of water penetration into the Bnt horizon. Gypsum increased by threefold the rate of water infiltration into the Bnt horizon compared with the control soil. Plant yields were increased over the control by ammonium bisulphite (46%), ammonium nitrate (66%), gypsum (77%) and gypsum plus ammonium nitrate (111%). The study indicates that a combination of irrigation with gypsum was capable of moving Ca into a relatively high sodic Bnt horizon, causing an improvement in both the soil condition and plant productivity. Key words: Solonetzic soil, irrigation, gypsum, lime, sodic soil, ammonium nitrate

Sulfuric Acid Effects on Water Infiltration and Chemical Properties of Alkaline Soils and Water

ABSTRACT SULFURIC acid (H2SO4) is a potentially effective amendment for treating alkaline irrigation water and calcareous sodic soils. However, the chemical reactions involved and resulting effects on water infiltration are not fully understood. This subject is reviewed and analyzed when acid is applied to alkaline irrigation water, ammoniated water, and Na-affected calcareous soils. When injected into a closed water system such as sprinkler lines, acid converts HCOj(and C03= if present) to carbonic acid, and reduces the pH of the water below 7 at acid application rates less than equivalent concentrations of HCO^. Upon sprinkling, the accumulated carbonic acid decomposes to CO2, thus leading to Ca precipitation and limited effects on sodicity and water infiltration. When applied to open-ditch flow, acid removes HCO^and CO^^, prevents Ca precipitation at pH above neutral, and may solubilize Ca from soil carbonates. Resulting effects are to maintain or reduce sodicity and to increase electrolyte concentrations, all of which contribute to increasing infiltration of sodic irrigation waters. Water-run application of NH3, a common post-planting fertilization method in row crops, causes severe precipitation of Ca and induces sodium hazards. Acid applied to such water neutralizes alkalinity and minimizes or prevents Ca precipitation and associated infiltration reduction. Acid applied directly to calcarious sodic soils solubilizes CaC03, and at acidic pH releases P, Fe and Al, all of which help increase water infiltration. The amount of exchangeable Na removed by acid is approximately equal to that removed by the chemically equivalent rates of gypsum in moderately Na-affected soils. The closed system reaction under which one mole of H2SO4 potentially releases two moles of Ca would not occur in ordinary reclamation practices. Acid provides faster movement of leaching water than does the chemically equivalent rate of gypsum in severely Na-affected calcareous soils. When applied to moderately Na-affected soils, acid can provide faster leaching than CaCl2 applied at chemically equivalent rates. The effectiveness of acid as an amendment to improve water infiltration depends largely upon chemical properties of soils and water, and application methods.

Sulfate Retention by an Acid BE Horizon of an Ultisol

AbstractMany apparently conflicting reports on sulfate (SO2‐4) retention by soils suggest that a single, inclusive mechanism may not be adequate in explaining SO2‐4‐soil reactions and that additional experimentation is needed for different soils. An acid Benndale (Typic Paleudults) BE horizon, predominantly kaolinite and gibbsite in the clay fraction, was initially treated with either five lime rates or five gypsum rates. After 14‐d of incubation at field capacity, previously limed soils were amended with gypsum, and previously gypsum‐treated soils were limed. All samples were again incubated moist for 14 d, after which soil solutions were displaced and their chemical compositions determined. The sequence of Ca(OH)2 and CaSO4 additions did not affect SO2‐4 retention. Furthermore, SO2‐4 retention isotherms indicated that multiple mechanisms were involved because at low pH (<5.1) an adsorption‐precipitation type mechanism dominated, while at high pH (>5.6) electrolyte adsorption was dominant. This was further supported by the decrease in the ratio of OH‐ gain to SO2‐4 retention as soil pH increased. Sulfate retention was also accompanied by an increase in total exchangeable cations. Cation increases, however, varied with pH and SO2‐4 rates. The combined increases in OH‐ and exchangeable cations, particularly at low pH and high SO2‐4 rates, are inexplicable with current SO2‐4‐soil reaction models.

Effects of Saline‐Sodic Soil Chemistry on Soybean Mineral Composition and Stomatal Resistance

AbstractSoybean [Glycine max (L.) Merr.] productivity is severely limited by saline‐sodic soil conditions that occur in isolated spots in the river bottoms of western Kentucky. Productivity of soybeans grown on a gradient of soils of increasing saline‐sodic character were studied in greenhouse experiments. Soils with electrical conductivity (EC) exceeding 3.20 dS m−1 would not support soybean growth. Soybean plants accumulated significant quantities of Na when soil solution sodium adsorption ratio (SAR) exceeded 6.4 and relative tissue Na accumulation was highly correlated with SAR. Estimates of potential productivity were made by stomatal diffusive resistance measurements at three vegetative growth stages. Potential productivity was severely limited under conditions of high soil salinity. In soils of lower EC (< ≈ 2 dS m−1), soybean performance was affected to a greater extent by changes in SAR than by changes in EC. Dry matter production decreased with increasing SAR under low EC soil conditions.In a second experiment, saline‐sodic soil was amended with four rates of gypsum (CaSO4·2H2O), (0, 2.6, 6.0, and 12.9 g kg−1). Gypsum‐amended pots were leached until EC was < 3.0 dS m−1. Plant dry matter production was minimized with the 2.6 g kg−1 amendment, which also produced plants with significantly reduced and negligible Na contents. At early growth stages (V4 and V7), stomatal diffusive resistance of plants grown on the gypsum‐amended soils was not affected by increasing SAR. Diffusive resistance measurements of large vegetative plants (V10) increased significantly at low soil solution SAR. The addition of gypsum apparently reduced the detrimental effects of physical impedence to root development and function in the poorly structured soil as well as soil solution SAR. The improved physical structure of the gypsum‐amended soil could improve root development, function, and crop productivity.

Plant‐Available Sulfur as Measured by Soil‐Solution Sulfate and Phosphate‐Extractable Sulfate in a Ultisol1

AbstractBecause S deficiency in young small grain plants is not uncommon on limed, sandy Ultisols, a method predicting S requirement for the plants is needed. A greenhouse study was conducted to determine the effects of S at different pH levels on wheat (Triticum aestivumL.) growth, S concentration of plant tissue, soil‐solution sulfate (SO42−), and phosphate [Ca(H2PO4)2]‐extractable SO42−. A Benndale loamy sand surface soil (coarse‐loamy, siliceous, thermic Typic Paleudult) was treated with three lime rates (0,5.6, and 8.1 mmol kg−1) and four gypsum rates (0,10, 20, and 40 mg S kg−1for the first two lime levels and 0,8,16, and 32 mg S kg−1for the highest lime level). Plant tissue samples were taken 5,9,13, and 17 weeks after planting, and soil samples were taken at planting and 9 and 17 weeks later. There was a yield response to S at each harvest, regardless of soil pH. Yield and S uptake were both highly correlated with soil‐solution SO42−concentration and with Ca(H4PC4)2‐extractable SO42−. As a result of plant uptake, soil‐solution 42−decreased after each harvest, with the greatest redaction occurring at the highest lime rate. Sulfur mineralization from organic matter provided significant 42−to plants in low‐S treatments, and some added SO42−became nonextractable at high S rates. Minimum SO42−concentrations for maximum wheat growth was 0.25 mMin soil solution and 6.0 mg S kg−1in Ca(H2PO4)2extract. Minimum S concentration in plant tissue for maximum dry matter yield was 1.6 g kg−1.

Effects of By‐Product Sulfuric Acid on Phyto Availability of Nutrients in Irrigated Calcareous, Saline‐Sodic Soils

AbstractSulfuric acid (H2SO4) is produced during the SO2 scrubbing process at Cu smelters, and “spent” H2SO4 is a waste product from oil refineries. A 2‐year field study was conducted on two irrigated soils high in salts and Na in southcentral Montana to evaluate the effectiveness of H2SO4 for improving nutrient availability and growth of barley (Hordeum vulgare). Treatments included several rates of smelter acid, and comparisons with gypsum (CaSO4·2H2O), spent acid, and feedlot cattle manure in combination with smelter acid. Levels of P, Fe, Zn, Cu, and Mn were measured in the soil, and plant uptake of these elements plus N, K, Ca, Mg, and Na were determined for the second‐year harvest. Sodium adsorption ratio (SAR) was measured in soil extract from the 0‐ to 5‐cm layer at harvest.Sulfuric acid was an effective amendment for improving soil nutrient availability, barley dry‐matter yield, nutrient uptake, and for reducing SAR and plant uptake of Na. Both smelter acid and spent acid were similar in their effects. Equivalent rates of gypsum and H2SO4 compared in this research were similar for increasing soil Zn, Cu, and Mn availability and for increasing nutrient uptake and barley yield. Sulfuric acid, but not gypsum, increased available soil P and Fe levels.Sulfuric acid used in combination with manure provided a substantial additional increase in available soil P, Zn, and Mn over acid used alone. The manure‐plus‐acid treatment raised available P in the surface 20 cm of soil from an initial level of 5 mg/kg to a level adequate for good crop growth (ca. 24 mg/kg). Manure plus H2SO4 produced the highest barley yield and nutrient uptake.

A quantification of the effectiveness of an inhibitor on the growth process of a scalant

Suspension growth experiments were performed using the “constant composition method”, in order to quantify the influence of the growth inhibitor 1-hydroxy-ethylidene-1,1-bisphosphonic acid (HEDP) on the growth rate of gypsum at various selected growth conditions. During each set of experiments only one growth condition was varied, being either the HEDP concentration, the supersaturation or the pH of the solution, or the initial mass of added crystals. Additionally the adsorption of HEDP onto the crystal surface was measured by XPS to determine the surface coverage needed for inhibition.

Lime requirements of Boston ferns: II. Foliar and medium analysis

Abstract Growth response and nutrient levels in the foliage and growth medium were compared using Nephrolepsis exaltata (L.) Schott ‘Com‐pacta’ ferns grown in a peat‐perlite medium with 4 rates of dolo‐mitic limestone (0.0, 1.2, 2.4, and 6.0 kg/m3) and 2 rates of gypsum (0.0 and 1.2 kg/m3). Incorporation of dolomitic limestone and gypsum resulted in greater growth compared to treatments without dolomitic limestone and gypsum, but dolomitic limestone rates of 1.2, 2.4, or 6.0 kg/m3 resulted in no difference in fern dry weight. Addition of gypsum resulted in higher foliar S levels. Suppressed fern growth was associated with lower foliar Ca and S levels. When 6.0 kg/m3 of dolomitic limestone was added to the medium, foliar N was lower and nitrates in the medium were higher compared to ferns grown with no dolomitic limestone. Addition of gypsum and dolomitic limestone to the medium increased soluble salt levels.

Soil amelioration effects on peanut growth, yield and quality

In order to study the reasons for poor peanut (Arachis hypogaea L.) performance on an Avalon medium sandy loam, a three year field study was undertaken to investigate the effects of lime and gypsum applications on growth, yield and quality. Rates of up to 2,400 kg agricultural lime/ha/annum significantly increased soil pH (1N KCl) and exch. Ca and decreased levels of exch. Al and Al saturation in the soil (0–150 mm). The effect of the same rates of gypsum was much less marked, only exch. Ca increasing and Al saturation decreasing to any substantial extent. In the absence of lime (i.e. even where gypsum was applied). nodulation was poor and the plants developed a general chlorosisc. 90 days after planting. Liming markedly improved nodulation whereas annual applications of gypsum had the opposite effect. Liming significantly increased the hay, pod and kernel yields by up to 73, 105 and 117%, respectively. On average, gypsum applications had no significant effects. Liming increased shelling percentage, the percentage mature pods, 100-kernel mass and protein concentration in the kernel, and decreased the incidence of pops and kernels with black plumule. Applications of gypsum had little effect on quality except for a decreased incidence of black plumule. It appeared that the improved crop performance with liming resulted from a reduction in Al toxicity which improved nodulation. Calcium deficiency did not appear to be a major cause of poor peanut growth and quality in the unameliorated soil.

DYNAMICS OF PHOSPHORUS DURING RECLAMATION OF SODIC SOILS

This study describes the phosphorus status of sodic soils formed under the influence of sodium carbonate, aquic natrustalf, and its possible leaching during their reclamation. Uncultivated, barren sodic soils contained high amounts of Olsen's extractable phosphorus, which decreased with depth, and the amounts were highly correlated with the electrical conductivity of the soil. The incubation studies conducted at saturated moisture content with differential amounts of gypsum at 0, 25, 50, 100, and 200 percent of laboratory-determined gypsum requirement (GR) showed that Olsen's P decreased with increases in the rate of gypsum applied. The leaching studies conducted in the field showed that phosphorus in sodic soils moved down, along with other soluble salts, though the peak P concentration lagged behind the other salts. Leaching studies conducted in plexiglass columns in the laboratory brought out that substantial leaching of P, up to 60 ppm P, could occur when sodic soils are leached as such or after surface application of gypsum. It seems that under natural conditions, Na2CO3, which is the predominant salt in sodic soils, reacts with native calcium phosphate to form highly soluble sodium phosphates, which are leached during reclamation. Gypsum, mixed with soil at a rate of 100 percent GR and above, decreases the leaching of phosphorus. It seems due to (1) immobilization of soluble P by CaSO4 through the formation of less soluble Ca-P compounds; (2) common ion effect to decrease solubility of Ca-P compound; and (3) lowering of soil pH, which in turn decreases the soluble P in the pH range of 8.3 to 10.

Effects of Gypsum and Zinc on Rice Nutrition on Sodic Soil

SUMMARYA field experiment was conducted on a Zn-deficient highly-deteriorated sodic soil of the Ghabdan series to determine the effect of three rates of gypsum (G0, G25, G50% of the gypsum requirement of soil) and three rates of Zn (Zn0, Zn11, Zn22 kg Zn/ha) on rice variety PR 106. Gypsum application significantly increased yield and Zn uptake in rice because of a significant decrease in soil pH and increase in Ca and Zn supply. Zinc application alone significantly increased soil and plant Zn but yields were poorer than with gypsum application alone because of Ca deficiency/Na toxicity. The same rates of Zn applied together with gypsum markedly increased yield and Zn uptake, revealing a deficiency of both Ca and Zn. The best grain yield was recorded either at G50Zn11 or G25Zn22, indicating an economy in gypsum at higher rates of Zn or of Zn at higher rates of gypsum application.

On the existence of an anomalously high dissolution rate in films of non-Newtonian liquids with short contact times

It has been shown that the dissolution rate of gypsum in films of dilute sodium carboxymethylcellulose (SCMC) solutions is anomalously high compared with theoretical predictions. Two possible explanations of this phenomenon are discussed: either the coefficient of diffusivity in these solutions is much greater than it is in water, or the velocities close to the wall are increased due to a solvent layer formation. Preference is given to the second effect which explains the hydrodynamic behaviour of the solutions as well.

Effect of Gypsum on Yield, Grade and Incidence of Pod Rot in Five Peanut Cultivars1

Abstract Five cultivars of peanuts, (Arachis hypogaea L.), Florunner, Tifrun, Florigiant, Ga. 194 Va. and Early Bunch, were grown at Tifton, Ga. on a Stilson loamy sand, low in calcium (356 kg/ha), and at Plains, Ga. on a Greenville sandy loam, relatively higher in calcium (752 kg/ha), for three years (1977–79) to study the response of yield, grade and incidence of pod rot with applications of gypsum. Plots were topdressed with 0, 560, 1120, or 1680 kg/ha of gypsum. Pod rot did not occur at Plains and no significant difference occurred among gypsum rates for yield, percentages of sound mature kernels (SMK), extra large kernels (ELK), and value/ha for any cultivar. However, significant differences were detected for these variables among cultivars. At Tifton, severe pod rot occurred on plots receiving no gypsum, but the severity decreased for all cultivars as the rate of gypsum applied was increased. Differences in yield, percentages of SMK, ELK, pod rot, value/ha and kernel calcium occurred among cultivars, grown at different gypsum rates. Florunner was significantly higher in yield, percent SMK, and value/ha than the other cultivars at all gypsum rates, and significantly lower in pod rot at 0 and 560 kg/ha gypsum. The amount of calcium in kernels increased for most cultivars as rates of gypsum increased. These data support previous work which indicated a suppression of pod rot and an increase in yield and kernel calcium with applications of gypsum.

Assessing the Sulfur Status of Field‐Grown Wheat by Plant Analysis1

AbstractDiagnostic methods developed under laboratory or greenhouse conditions require field confirmation. This paper reports the relative field performance of four indexes for the diagnosis of S deficiency in wheat (Triticum aestivum L.) which were previously assessed in the greenhouse. Sulfate S (as percent total S), sulfate S concentration (as ppm dry matter), total S concentration (as ppm dry matter), and total N: total S ratio in the aboveground parts of a soft white wheat cultivar, ‘Olympic’, were compared as diagnostic indexes in a factorial experiment with five rates of gypsum (0 to 50 kg S/ha) and three rates of ammonium nitrate (0 to 100 kg N/ha). A strong relationship was found between final grain yield and each index at the following stages of growth; fourth leaf (61 days from sowing), fully‐tillered (92 days), and jointing (134 days). However, as the critical value for sulfate S (as percent total S) was least affected by the age of the plant or N supply, it is considered to be the most convenient index. The overall relationship between yield and sulfate S (as percent total S) was strong (r = 0.88) and the critical value at 90% of maximum yield was 13%. This compares with r values of 0.87, 0.96, and 0.91 and critical values of 14, 12, and 11% for the plant tissue at the individual growth stages examined. Where the adequacy of the S supply to a wheat crop is in question, the proportion of total S as sulfate S in the plants is indicated as a useful guide to the need for S fertilizer in securing optimal grain yield.

Study of a “solid + liquid → solid” reaction (hydration of calcium sulfate hemihydrate) by simultaneous isothermal calorimetry and electrical resistivity measurement

A simple experimental set was developed to measure isothermally and simultaneously the thermal flow and the variations of electrical resistivity during the hydration of an hydraulic binder slurry. The application in the case of the β calcium sulfate hemihydrate setting showed that dissolution rate of hemihydrate and crystalization rate of gypsum are never equal during the setting, which leads to new data to determine the exact kinetics and mechanism of hydration process.

Transient Changes in the Soil‐water System from Irrigation with Saline Water: I. Theory

AbstractTransient soil solution concentrations and salt precipitation rates in the root zone are shown to be influenced by the ion composition and concentration of the applied water and soil exchange complex as well as by the water uptake distribution and infiltration rate. Calculations are performed on three kinds of infiltration water to estimate the ionic composition of the soil solution, the rate of gypsum and CaCO3 precipitation, and the time to reach steady state for a given irrigation management. Solution concentrations adjusted for exchange interactions were shown to precipitate twice the quantity of salt in a given time, resulting in lowered solution concentration and altered composition of Ca2+, Mg2+, Na2+, and SO42‐ ion concentrations in the solution phase, with up to 1,600 days required to reach steady state through the top 150 cm for a leaching fraction of 0.05. The extent of precipitation is also found to depend strongly on the concentration of sulfate and degree of saturation with gypsum in the irrigation water. Diffusion and dispersion are also shown to influence the duration of the transient phase.

Zinc Nutrition of Rice as Influenced by Rates of Gypsum and Zn Fertilization of Alkali Soils1

AbstractThree field experiments were conducted on Zn deficient alkali soils, two on Natraquic calciorthids, and one on Aquic Camborthids, to determine the effect of gypsum and Zn fertilization alone and in combination on the Zn nutrition of rice IR 8 (Oryza sativa L.). Three rates of gypsum (0, 25, and 50% gypsum requirement of soil) and three rates of Zn (0, 11.2, and 22.4 kg Zn/ha, as ZnSO4‐7H2O) and their possible combinations were tried. At all the three locations, the growth of the rice crop was very poor and exhibited Zn deficiency symptoms in control plots. The yield and Zn uptake was higher in alkali soil high in CaCO3 and low in pH than in soils low in CaCO3 and high in pH. Gypsum application markedly decreased the soil pH, and significantly increased the yield and Zn uptake by rice. This resulted from a marked significant increase in soil and plant Zn concentration, though it remained within marginal levels. Zinc application decreased the pH, but not so appreciably as did gypsum; and markedly increased the available Zn from deficient to adequate levels. This in turn significantly increased Zn concentration and its uptake and resulted in a significant increase in rice grain and straw yield both over control and gypsum treatments. Optimum response of rice to Zn was observed at 11.2 kg Zn/ha except in one of the Natraquic calciorthids where it was 22.4 kg Zn/ha. Gypsum in conjunction with Zn application did not increase either the available Zn or the rice yield. The beneficial effect of Zn application to rice grown on the alkali soils under investigation was far more than that of gypsum.

Utilisation by white clover and ryegrass of sulphur from 35s‐Labelled Gypsum

Abstract This investigation reports the uptake of S from a surface application of 35S‐labelled gypsum by a ryegrass‐white clover mixture sward and by a pure ryegrass stand, each growing at three levels of N in the field. Nitrogen stimulated ryegrass growth, reducing the contribution of white clover to the total yield, whereas S did not influence the yield of either species. Gypsum, while not increasing the total S in the white clover, contributed 23 to 50% of the total S concentration. In contrast, gypsum increased the total S in the ryegrass. The level of N nutrition did not alter the fertiliser S in white clover, but depressed the total S in the ryegrass. Nitrogen enhanced the fertiliser S in ryegrass at the first harvest, however, at the second harvest N depressed the fertiliser S. Recovery of applied S was increased by N, reaching a maximum value of 19.8% by two harvest, and was decreased with increasing rate of gypsum. Without ‐N the white clover accounted for 50% and 27% of the S recovery by the mix...

建築材料としての無機複合材料に関する研究 : その 3・マトリックス相として見た石膏の性質・力学的性能

This paper is to follow the previous part 1 and 2, in which basic properties and responses to several conditions of the environment of Gypsum are studied. In this paper experimental results and some considerations on mechanical properties of cast Gypsum are explained and concluded as follows. The compressive strength of cast Gypsum which is made in the season when the monthly average temperature is lower than 18℃ or with the temperature arrangement, is possible to be attained constantly over 150kg/(cm)^2 under wet condition and over 300kg/cm^2 under dry condition. The young's modulus of cast Gypsum is around (10)^5kg/cm^2, almost half value of Cement Concrete, and decreases by absorbing water as in the case of the compressive strength. Cast Gypsum has very small bond strength between smooth surfaces like the round steel, but the bond strength over 10 percent of the compressive strength can be obtained by using deformed bars. The creep of cast Gypsum is prospected larger than Normal Portland Cement. By short time experiments the creep rate of cast Gypsum under dry condition becomes begger than 1 after 1 month loaded with 33 percent stress of the compressive strength. The tensile strength of cast Gypsum is from 3 to 10 percent of the compressive strength. It is sure that Gypsum is inferior to Cement Concrete in many mechanical properties mensioned above, but there are cirtain posibilities to use cast Gypsum as structural materials in buildings.