CN107892633A - Loess saline land greening tree planting soil conditioner - Google Patents

Abstract

The invention discloses a kind of loess saline land greening tree planting soil conditioner, the main points of its technical scheme are that dispensing compresses Nutrition Soil by loess, loess carbonizes the Concave-convex clay rod particle after native, acidifying, stalk, desulfurated plaster, humic acid, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly, Concave-convex clay rod, ferrous sulfate and water after acidifying form；Dispensing is stirred after being well mixed, is packaged as loess saline land greening tree planting soil conditioner.The sodium ion on calcium, magnesium ion replaceable salt affected soil colloid contained by soil conditioner, make the content of soil exchangeable sodium ion reduce, reduce the basicity of soil, the fertility of alkaline land soil can also be significantly improved simultaneously, increase the content of alkaline land soil organic matter, calcium, magnesium, silicon, sulphur, nitrogen, phosphorus and potassium, reach the purpose in improvement salt-soda soil, improve the survival rate of greening and afforestation, loess saline land greening tree planting soil conditioner is applied to improvement salt-soda soil and planted trees in saline land greening.

Description

Loess saline land greening tree planting soil conditioner

Technical field

The present invention relates to soil conditioner, and in particular to a kind of loess saline land greening tree planting soil conditioner.

Background technology

Salt-soda soil refers to that the salinity contained by inside soil has influence on the normal growth of crop, and serious salt affected soil area is planted Thing can hardly survive, and during carrying out greening and afforestation in varieties in saline-alkali areas, limited by alkaline land soil condition, contained in saline-alkali soil There is excessive solubility salt, make plant absorption moisture content and absorb the ability reduction of nutrient, soil organic matter content relative reduction, Nitrogen, phosphorus, potassium and trace element missing are serious, and soil granular structure destroys seriously, and gas permeability reduces, the microbial activity of aerobism Decline, soil-ripening is slow, so as to cause soil hardening.Because salinization of soil makes soil physico-chemical property be deteriorated, the life condition of plant Degenerate, the difficulty of the greening and afforestation work in alkaline land soil is big, and the survival rate of greening and afforestation is often than relatively low, greening and afforestation mistake Although Cheng Qian's phase Survival rate of nursery stock, the growth potential of nursery stock is very poor, does not reach the expected effect grown, greening and afforestation mistake The middle and later periods of journey, many nursery stocks will die in succession.

Carbonate mineral content is more in loess, mainly calcite, and clay mineral is mainly illite, montmorillonite, height Ridge stone, goethite, containing turgite etc.；Loess is a kind of very fertile soil layer, particularly important to agricultural production, but vegetation is dilute It is few, soil erosion, serious harm is all caused to agricultural production and engineering construction, it is necessary to which science is administered.

Desulfurated plaster is lime-lime stone to be ground slurries are made, and makes to contain SO after dedusting₂Flue gas, pass through slurry Liquid washer and remove SO₂, lime slurry and SO₂Reaction generation calcium sulfate and calcium sulfite, calcium sulfite is oxidized to change into sulphur Sour calcium, industry by-product gypsum, referred to as desulfurated plaster are obtained, being accumulated around thermal power plant has substantial amounts of desulfurated plaster, does not have Can utilization.

In the reclamation of salinep-alkali soil and processing scheme, frequently with desulfurated plaster as one of dispensing of adjustment saline-alkali soil pH value, The pH value index of desulfurated plaster is 5~9, detects, pH value >=8 of desulfurated plaster, directly applies desulfurated plaster by more sub-samplings Greening and afforestation is carried out in saline-alkali soil, the survival rate of nursery stock is also very low.

China Patent Publication No.：CN 106105962A, publication date：On November 16th, 2016, entitled " one kind is using length Imitate the method that solid phase Nutrition Soil carries out original soil greening to the salt-soda soil of containing sulfate ", disclose " a kind of to use long-acting solid phase nutrition The method that soil carries out original soil greening to the salt-soda soil of containing sulfate, including ditching earthing step, the ditching earthing step, including Nutrition Soil is covered, the Nutrition Soil includes following components：Pine soil, broad leaf tree fallen leaves soil, nitrogen-phosphorus-potassium compound fertilizer, attapulgite, reed It is luxuriant growth extract, gallic acid, red bean skin powder, beer groove, sesame seed meal, papaya muddy flesh, red worm powder, hodmadod powder, water-loss reducer, micro- Secondary element；The present invention also provides the preparation method of the Nutrition Soil.The original soil greening method of the present invention, eliminate and carry soil moved in improve the original Expense, cost is reduced, save labour cost 26%, had the function that to improve total nitrogen content of soil and improve soil moisture content, planted Mongolian oak, the speed of growth is fast, and the content of starch in fruit is up to 64.1-67.8% ".

The weak point of above-mentioned patent is：(1) the dispensing for salt resistance alkali and adjustment salt-soda soil pH is lacked in " Nutrition Soil ", (2) amination attapulgite can not increase the absorption of attapulgite and the effect of salt resistance alkali, and above-mentioned patent can be used for common " original soil greening ", be not suitable in " salt-soda soil carry out original soil greening ", during saline land greening tree planting, the survival rate of nursery stock Than relatively low.

China Patent Publication No.：CN 104591926A, publication date：On 05 06th, 2015, entitled " alkaline land soil Conditioner ", discloses that " a kind of composition of soil improvement, particularly relates to a kind of soil conditioner of saline-alkaline soil.The present invention's is saline and alkaline Ground soil conditioner is formed by following component mixed preparing by weight percentage：Cosan 20%~35%, humic acid 20%~ 30%th, bentonite 5%~10%, epsom salt 20%~25%, calcium superphosphate 8%~12%, white vitriol 1%~ 2%th, boric acid 2%~3%.It is horizontal that the soil conditioner of saline-alkaline soil of the present invention can adjust soil acid-base, effectively supplements in soil, be micro- Secondary element, improve crop nutritional deficiency symptom, chelate toxic heavy metal element in soil, reduce salinization and alkalization, promote Zinc fractions Crumb structure, improve crop root growth environment, enhancing crop salt resistance alkali, disease-resistant anti-adversity ability, reduce saline and alkaline to crop root Harm, while the available phosphorus that is cured by the soil of release increases soil fertility, water conservation section fertilizer, final thorough improved soil, recovers Soil fertility, increasing both production and income is realized, improve the utilization rate of crop quality and fertilizer ".

The weak point of above-mentioned patent is：(1) substantial amounts of Cosan has been selected in dispensing（20%~35%）, sulphur is easy Explosive material is fired, is mixed with air and is also easy to produce blast or burning, although for from toxicology, sulphur belongs to less toxic harmful influence, its The Sulfur Dioxide On Human occurred after steam and sulfur burning has severe toxicity, is not suitable in soil conditioner of saline-alkaline soil.(2) although " bentonite " is selected in dispensing, those skilled in the art knows altogether：The pH value of sodium bentonite is generally 8.5~10.2, Calcium-base bentonite is generally 6.9~8.5, and " bentonite " is a kind of alkaline soil, and therefore, " bentonite " is without the acidified modified place of progress Reason, is not suitable in soil conditioner of saline-alkaline soil yet.

The content of the invention

The purpose of the present invention is to overcome weak point in the prior art, there is provided a kind of loess saline land greening tree planting soil is adjusted Manage agent.

The dispensing of loess saline land greening tree planting soil conditioner compresses Nutrition Soil by loess, loess carbonizes soil, after acidifying Concave-convex clay rod particle, acidifying after stalk, desulfurated plaster, humic acid, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly, attapulgite Clay, ferrous sulfate and water composition.

The production method of loess saline land greening tree planting soil conditioner：By loess saline land greening tree planting soil conditioner Dispensing be stirred it is well mixed after, be packaged as loess saline land greening tree planting soil conditioner.

Loess pH value≤5.5 after acidifying.

Contains substantial amounts of nitrogen, phosphorus, potassium, organic matter and various trace elements in loess compression Nutrition Soil, be a kind of nutrition into The high-quality Nutrition Soil that part is complete, fertilizer efficiency is high, nontoxic, harmless, odorless and water retention property are good, can provide Salt And Alkali Tolerance seedling growth institute Necessary nutrient, be advantageous to the normal growth and development of Salt And Alkali Tolerance nursery stock, the loess compression Nutrition Soil sheet that the present invention selects The thickness control of thing is at 5~8 millimeters.

The discarded object warp after loess, active white clay waste slag, Concave-convex clay rod, bentonite and crushing in loess charing soil After crossing charing, it can not will can be converted into solvable by the phosphorus, potassium compound and various trace elements that Salt And Alkali Tolerance nursery stock directly absorbs Property phosphorus, potassium, trace element and organic carbon, loess carbonizes thickness≤6 millimeter of native sheet-like particle.

The production method of Concave-convex clay rod particle after acidifying using crush, sieve, be calcined for the first time, being acidified, draining, Drying and the technological process of second screening, make its needle bar shape group accumulated in a jumble become loose porous, increase void content and Specific surface area, substantially increase acidifying quality, adsorption efficiency and the acidification rate of Concave-convex clay rod, the attapulgite after acidifying After moisture content in clay particle absorption soil, disintegration will not be also produced, is advantageous to increase concave convex rod saline land greening tree planting soil The salt resistance alkali effect of conditioner, the Task-size Controlling of the Concave-convex clay rod particle after the acidifying selected of the present invention 0.125~ 0.42 millimeter.

Stalk after acidifying has the characteristics of preferable adsorptivity, thixotropy, heat endurance, plasticity and caking property, straw After the acidified calcination process of stalk, pH value≤5.5.

Desulfurated plaster is also known as flue gas desulfurization gypsum, and main component is calcium sulphate dihydrate as the natural gypsum, desulfurated plaster PH value be 5~9.

Humic acid is the remains of animals and plants remains, mainly plant, by the decomposition and conversion of microorganism, and it is geochemical A kind of organic substance that a series of processes learned are caused and accumulated, the pH value of humic acid is 3~5.

Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly is in acidity, can reduce the alkalescence of soil, and contained calcium ion replaceable is saline and alkaline Sodium ion on soil colloid, makes the content of soil exchangeable sodium ion reduce, so as to further reduce the sodium basicity of soil, Promote the formation of soil granular structure, reach the purpose in improvement salt-soda soil, the Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly that the present invention selects Grain fineness≤0.149 millimeter.

Concave-convex clay rod has unique layer chain structure feature, and crystal is in needle-like, threadiness or fiber collection shape, recessed Convex rod stone clay has good colloidal nature and the higher adsorption capacities such as unique scattered, high temperature resistant, salt resistance alkali, the present invention The Concave-convex clay rod grain fineness of selection is less than 0.074 millimeter.

Anhydrous slufuric acid ferrous iron is white powder, and the ferrous sulfate containing the crystallization water is pale green crystals, the sulfuric acid of 10% aqueous solution Ferrous is in acidity to reindeer moss, and pH value is about 3.7, can be used not only for adjusting loess saline land greening tree planting soil in the present invention The pH value of conditioner, is also used as the replenishers of plant ferro element, and physiological disturbance occurs because of iron deficiency, makes plant for preventing and treating plant Thing leaf color chlorosis.

The technical scheme is that：

1st, the dispensing of loess saline land greening tree planting soil conditioner is made up of following component by weight percentage：Loess compression battalion Support the Concave-convex clay rod particle 5~15% after soil 10~25%, loess charing soil 5~20%, acidifying, the stalk 5 after acidifying ~15%, desulfurated plaster 5~20%, humic acid 5~15%, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly 3~15%, Concave-convex clay rod 3~10%, ferrous sulfate 0~5% and water 5~20%.

2nd, the production method of loess saline land greening tree planting soil conditioner：By loess saline land greening tree planting soil conditioning The dispensing of agent be stirred it is well mixed after, be packaged as loess saline land greening tree planting soil conditioner.

3rd, the dispensing of loess compression Nutrition Soil is made up of following component by weight percentage：Loess 15 after acidifying~ 35%th, the gravel-shaped attapulgite flower after sludge 25~55%, high viscous Concave-convex clay rod 2~15%, biogas slurry immersion after being acidified The string 1~10% after peat 2~15%, biogas residue 2~15%, crushing after grass haydite 2~15%, crushing, expands leech Stone 0.5~5%, expanded perlite 0.5~5% and high hydroscopic resin 0.1~5%；Loess compresses the production method of Nutrition Soil：First Loess and sludge are subjected to acidification, then the dispensing of loess compression Nutrition Soil is stirred, compressed, after microwave low temperature sterilization Nutrition Soil is compressed for loess.

Loess compression Nutrition Soil uses was applied for by the present inventor " loess compression Nutrition Soil on 08 12nd, 2014 Production method ", Chinese patent Authorization Notice No. are：CN 104119188B, authorized announcement date：On December 09th, 2015.

4th, the dispensing of loess charing soil is made up of following component by weight percentage：Loess 15~35%, atlapulgite give up After slag 10~30%, mud coal 5~25%, Concave-convex clay rod 0~20%, bentonite 0~15%, zeolite 2~15%, crushing Discarded object 5~15%, vermiculite 0.5~5% and water 5~45%；The production method of loess charing soil：Loess is first carbonized into matching somebody with somebody for soil Material stirring is squeezed into sheet-like particle, is carbonized after charing process for loess native.

Loess charing soil is to use " the production of loess charing Nutrition Soil filed in the present inventor 2015 year 07 month 27 days Method ", China Patent Publication No. are：CN 105000990A, publication date：On October 28th, 2015.

5th, the production method of the Concave-convex clay rod particle after being acidified：1. first by by the adsorption stage concave convex rod of weathering Stone clay is carried out crushing after drying and sieved for the first time, and the Task-size Controlling of the adsorption stage Concave-convex clay rod particle after screening exists 0.149~0.42 millimeter；2. by the adsorption stage Concave-convex clay rod particle input revolution roasting in kilns after screening, sintering temperature control At 420~480 DEG C, roasting time controlled at 45~90 minutes system；It is 3. the adsorption stage Concave-convex clay rod particle after roasting is defeated Enter progress acidification, the preparation of dilute sulfuric acid in dilute sulfuric acid pond includes following component by weight percentage：The ﹪ of concentration 98 sulfuric acid 6 ~10%, water 90~94%, acidification time control was at 4~12 hours；It is 4. the adsorption stage after acidified processing is concavo-convex Rod stone clay particle takes out and drained away the water, input in rotary dryer drying for the Concave-convex clay rod particle half after acidifying into Product, drying temperature control is at 150~200 DEG C, and drying time was controlled at 45~60 minutes, the Concave-convex clay rod particle after acidifying Semi-finished product water content is less than 2.0%；5. it is acid that the Concave-convex clay rod pellet product after acidifying, which is carried out second after sieving, Concave-convex clay rod particle after change, the Task-size Controlling of the Concave-convex clay rod particle after acidifying is at 0.125~0.42 millimeter.

Concave-convex clay rod particle after acidifying on November 14th, 2015 using being applied for " having net by the present inventor Change the concave convex rod colour-wash powder of air function ", China Patent Publication No. is：CN 105272055A, publication date：2016 01 The moon 27.

6th, the production method of the stalk after being acidified：(1) stirred in the mixer first operated the input of stalk mixture, Dilute sulfuric acid is slowly added to again to carry out acidification in stalk mixture；(2) by the stalk mixture after acidification, by right The extruding of roller machine is stalk tablet, thickness≤3 millimeter of stalk tablet；(3) stalk tablet is transported to swinging drying oven Interior roasting, roasting time are 1~3 hour, and sintering temperature is controlled at 250~450 DEG C, the stalk tablet water content after roasting≤ 5%, the stalk tablet after roasting is the stalk semi-finished product after acidifying；The dispensing of stalk tablet is by weight percentage by following Component forms：Stalk mixture 75~95% and dilute sulfuric acid 5~25%；The dispensing of stalk mixture is by weight percentage by following Component forms：Stalk 68~92%, Concave-convex clay rod 7~30% and magnesia 0.1~3%；The dispensing of dilute sulfuric acid is by weight Percentage is made up of following component：Concentration is 98% concentrated sulfuric acid 1~25% and water 75~99%.

The production method of stalk after acidifying was applied " after acidifying using by the present inventor on 07 27th, 2014 Stalk ", Chinese patent Authorization Notice No. are：CN 104128354B, authorized announcement date：On 06 08th, 2016.

7th, the dispensing of Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly is made up of following component by weight percentage：The viscous attapulgite of height glues Concave-convex clay rod powder 5~15%, ardealite 10~30%, calcium superphosphate 5~28%, sulfuric acid after native powder 2~10%, acidifying Ammonium 5~25%, potassium sulfate 2~20%, high hydroscopic resin 0.05~5% and trace element mixture 0.01~1%；Powdery is saline and alkaline The production method of ground the fertilizer of retaining water and releasing nutrients slowly：(1) the dispensing of Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly is added to the Double-horizontal-shaft run to force In formula mixer, stir as the mixture of Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly；(2) by the mixing of Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly It is powder to be crushed in thing input pulverizer, grain fineness≤0.149 millimeter of powder, is Powdery saline-alkali soil water-holding slow-release Fertilizer.

Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly applied for " Powdery saline-alkali soil using by the present inventor on October 22nd, 2012 The fertilizer of retaining water and releasing nutrients slowly ", Chinese patent Authorization Notice No. are：CN 102898237B, authorized announcement date：On 02 26th, 2014.

Loess saline land greening tree planting soil conditioner is that a kind of powdery and graininess mixing are integrated, for improving soil The physics of earth and/or the organic-inorganic soil conditioner of biological property.

The loess compression Nutrition Soil of sheet, is applying into soil, is inhaling in loess saline land greening tree planting soil conditioner Loose Nutrition Soil is reduced to after water quickly, the weight of loose Nutrition Soil adds than the weight of former compression Nutrition Soil after water suction More than 5 times, contains substantial amounts of nitrogen, phosphorus, potassium, organic matter and various trace elements in loess compression Nutrition Soil, be a kind of nutrition into The high-quality Nutrition Soil that part is complete, fertilizer efficiency is high, nontoxic, harmless, odorless and water retention property are good,

It is useless after loess, active white clay waste slag, mud coal, Concave-convex clay rod, bentonite, zeolite, crushing in loess charing soil Gurry and vermiculite, can be by can not be by phosphorus, potassium compound and lot of trace that Salt And Alkali Tolerance nursery stock directly absorbs members after charing Element, it is converted into phosphorus, potassium, trace element and the organic carbon of solubility.

After the moisture content in Concave-convex clay rod granular absorption soil after acidifying, disintegration will not be produced, pH value≤5.5, greatly While amplitude improves the absorption property of Concave-convex clay rod, catalytic action, specific surface area, porosity, be advantageous to adjust saline and alkaline The crumb structure of ground soil, increase the salt resistance alkali effect of concave convex rod saline land greening tree planting soil conditioner.

After the acidified calcination process of stalk, pH value≤5.5.

Contain substantial amounts of calcium, magnesium, silicon, sulphur, nitrogen, phosphorus, potassium and a variety of micro- in loess saline land greening tree planting soil conditioner Secondary element, have and slowly discharge in it in nutrition and the function of retain water and nutrients, battalion necessary to Salt And Alkali Tolerance seedling growth can be provided Form point, keep the nutritional ingredient in loess saline land greening tree planting soil conditioner not to be lost in, be advantageous to Salt And Alkali Tolerance nursery stock Normal growth and development, be a kind of nutrition is complete, fertilizer efficiency is high, nontoxic, harmless, odorless and the water conservation time length salt-soda soil it is green Change tree planting soil conditioner.

Loess saline land greening tree planting soil conditioner is in acidity, pH value≤5.5, has loose porous, specific surface area is big, The characteristics of porosity height and strong adsorption capacity；Contained calcium, magnesium ion can generations in loess saline land greening tree planting soil conditioner The sodium ion changed on salt affected soil colloid, makes the content of soil exchangeable sodium ion reduce, and reduces the basicity of soil, can not only Pore structure in soil is adjusted, promotes the formation of soil granular structure, salt can also be significantly improved simultaneously in the basicity for reducing soil Alkali ground soil fertility, increase alkaline land soil organic matter, calcium, magnesium, silicon, sulphur, nitrogen, the content of phosphorus and potassium, reaches improvement salt-soda soil Purpose, improve the survival rate of greening and afforestation.

Because loess saline land greening tree planting soil conditioner is in acidity, after desulfurated plaster compatible use, can fully send out The useful effect of desulfurated plaster is waved, further reduces the basicity of soil, reduces the soil accumulation of salt in the surface soil, improves the effect in improvement salt-soda soil Fruit.

Loess saline land greening tree planting soil conditioner and the soil of locality are used in mixed way, and are advantageous to improve local soil Crumb structure, loosing soil is kept, strengthen soil fertility, reduce the leaching loss of nutrient in soil, more effectively water conservation and fertilizer conservation, and It can reduce because soil passes the generation of withered, the climing disease such as withered, viral.

The application method of loess saline land greening tree planting soil conditioner：(1) it is used to improve salt-soda soil, can be with salt-soda soil Original soil be used in mixed way.(2) it is used to cultivate flowers and plants in salt-soda soil, first can sows flowers and plants in loess saline land greening tree planting soil In conditioner, after flowers and plants emergence survives, then in conjunction with loess saline land greening tree planting soil conditioner, co-transplantation to salt-soda soil Afforested areas, humidity appropriate in loess saline land greening tree planting soil conditioner is kept, can ensure that flowers and plants are normal in salt-soda soil Grow.(3) it is used to plant trees in saline land greening, loess saline land greening tree planting soil conditioner first can be added into tree planting bag In after, greening seedling is transplanted in tree planting bag, after the greening seedling in tree planting bag survives, then by the loess salt in tree planting bag Alkali ground greening and afforestation soil conditioner and greening seedling, co-transplantation to saline land greening tree planting region are conventional by afforestation Management technique is conserved, and the survival rate after greening and afforestation is more than 95%.

Loess saline land greening tree planting soil conditioner is applied to improvement salt-soda soil and planted trees in saline land greening.

Embodiment

With reference to embodiment, the invention will be further described：

1st, the dispensing of loess saline land greening tree planting soil conditioner is made up of following component by weight percentage：Loess compression battalion Support the Concave-convex clay rod particle 8% after soil 20%, loess charing soil 10%, acidifying, the stalk 8% after acidifying, desulfurated plaster 12%th, humic acid 10%, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly 8%, Concave-convex clay rod 7%, ferrous sulfate 1% and water 16%.

2nd, the production method of loess saline land greening tree planting soil conditioner：By loess saline land greening tree planting soil conditioning The dispensing of agent be stirred it is well mixed after, be packaged as loess saline land greening tree planting soil conditioner.

Claims (3)

1. A kind of 1. loess saline land greening tree planting soil conditioner, it is characterised in that loess saline land greening tree planting soil conditioning The dispensing of agent is made up of following component by weight percentage：Loess compresses Nutrition Soil 10~25%, loess carbonizes soil 5~20%, Concave-convex clay rod particle 5~15% after acidifying, the stalk 5~15% after acidifying, desulfurated plaster 5~20%, humic acid 5~ 15%th, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly 3~15%, Concave-convex clay rod 3~10%, ferrous sulfate 0~5% and water 5~ 20%.
2. A kind of 2. loess saline land greening tree planting soil conditioner according to claim 1, it is characterised in that loess salt-soda soil The production method of greening and afforestation soil conditioner：The dispensing of loess saline land greening tree planting soil conditioner is stirred mixing After uniformly, loess saline land greening tree planting soil conditioner is packaged as.
3. A kind of 3. loess saline land greening tree planting soil conditioner according to claim 1, it is characterised in that loess compression battalion The thickness control of native tablet is supported at 5~8 millimeters, loess carbonizes thickness≤6 millimeter of native sheet-like particle, the concave convex rod after acidifying The Task-size Controlling of stone clay particle is at 0.125~0.42 millimeter, stalk thickness≤3 millimeter after acidifying, Concave-convex clay rod Grain fineness is less than 0.074 millimeter, Powdery saline-alkali soil the fertilizer of retaining water and releasing nutrients slowly grain fineness≤0.149 millimeter.