Soil conditioner

Soil management is aimed at effectively maintaining or increasing agriculture production for the benefit of society and preserving or improving the environment. 

There are various natural and synthetic materials used for soil reclamation. They are added to the soil surface or around the seedling roots at the time of planting, thereby improving the soil s physical properties [21]. 

There are three major classes of synthetic polymeric materials used as soil conditioners to improve agricultural production  

The formation of weak secondary valence gels occurs in poor solvents, which will not prevent all secondary valence bonds between the polymer coils by solvation. The solvation equilibrium is temperature dependent, i.e., it increases at higher temperatures. (ii) The chemical gel is a network structure (crosslinked) formed by covalent hnks between polymer chains. Chemically crosslinked materials are formed by copolymerization, chemical modification, or radiation of linear polymers. The crosslinked network will swell but not dissolve, because the covalent CTossUnks cannot be broken by any solvent and the swelhng depends on the degree of crosslinking. 

The application of polymeric soil conditioners as additives to soils to improve their aggregate conditions can be extended into other areas to reduce soil erosion and to prevent crust formation and general stabilization. 

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Krilium The trade name of a soil conditioner. The solid form of Krilium has as active in-gredienl a copolymer of about equal molar proportions of vinyl ethanoate and the partial methyl ester of maleic acid. It may be formulated with lime, bentonite, etc. In aqueous form, Krilium contains a copolymer of about equal molar proportions of isobutene and ammonium maleamate. Other polymers are also used. 

Flocculants are also used for soHd—Hquid separations in other industries such as the sugar industry (1). Recent experiments have shown flocculants to be effective soil conditioners for agricultural land, which effectively reduce mn-off and erosion (2). However, they have not been used on a large scale for this appHcation. 

Most carbide acetylene processes are wet processes from which hydrated lime, Ca(OH)2, is a by-product. The hydrated lime slurry is allowed to settle in a pond or tank after which the supernatant lime-water can be decanted and reused in the generator. Federal, state, and local legislation restrict the methods of storage and disposal of carbide lime hydrate and it has become increasingly important to find consumers for the by-product. The thickened hydrated lime is marketed for industrial wastewater treatment, neutrali2ation of spent pickling acids, as a soil conditioner in road constmction, and in the production of sand-lime bricks. 

Soil conditioners are materials that measurably improve the physical characteristics of the soil as a plant growth medium. Typical uses include erosion control, prevention of surface sealing, and improvement of water infiltration and drainage. Many natural materials such as peat and gypsum are used alone or in combination with synthetics for soil conditioning. This article is concerned with synthetic soil conditioners, many of which are introduced as polymeric systems similar to the gels and foams formed in situ by chemical grouts. 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

M. F. De Boodt, Soil Colloids and Their dissociation indiggregates NATO ASI Sei. B 215, 1990, pp. 517—556, applications of polymeric substances as physical soil conditioners. 

A. Wallace and G. A. Wallace, ia Soil Conditioner and Amendment Technologies, Vol. 1, Wallace Laboratories, El Segundo, Calif., 1995. 

S. N. Floerger, "Polymer Soil Conditioners," undated product Hterature, Saint Etienne, Erance describes functions and uses of cross-linked anionic polyacrylamides in agriculture. 

By-Products. The biomass from the fungal fermentation process is called mycellium and can be used as a supplement for animal feed since it contains digestable nutrients (25,26). The lime-sulfuric purification and recovery process results in large quantities of calcium sulfate cake, which is usually disposed of into a landfill but can find limited use in making plaster, cement, waUboard, or as an agricultural soil conditioner. The Hquid extraction purification and recovery process has the advantage of Htde soHd by-products. 

An expanded mica (hydrated magnesium-aluminium-iron silicate). Used in lightweight aggregates, insulation, fertilizer and soil conditioners, as a filler in rubber and paints, and as a catalyst carrier. 

The largest user of phenol in the form of thermosetting resins is the plastics industry. Phenol is also used as a solvent and in the manufacture of intermediates for pesticides, pharmaceuticals, and dyestuffs. Styrene is used in the manufacture of synthetic rubber and polystyrene resins. Phthalic anhydride is used in the manufacture of DMT, alkyd resins, and plasticizers such as phthalates. Maleic anhydride is used in the manufacture of polyesters and, to some extent, for alkyd resins. Minor uses include the manufacture of malathion and soil conditioners. Nitrobenzene is used in the manufacture of aniline, benzidine, and dyestuffs and as a solvent in polishes. Aniline is used in the manufacture of dyes, including azo dyes, and rubber chemicals such as vulcanization accelerators and antioxidants. 

Sludge cake from vacuum filters, because of its pasty nature, cannot be readily spread on land as a fertilizer or soil conditioner. It must be further air-dried. At some plants the sludge cake is stockpiled on the plant site over winter. Freezing, thawing and air drying result in a material which breaks up readily. 

In contrast, composting processes utilize a mixture of solids and yard waste under controlled environmental conditions to produce a disinfected, humus-like product. Three common composting systems are a horizontal agitated reactor, a horizontal nonagitated reactor, and an aerated static pile system (nonproprietary). Compost can be marketed as a soil conditioner in competition with such products as peat, soil, and mulch. Although a large potential market exists, significant effort is required to penetrate this market. Yard waste revenue of 6.50/m (S5/yd ) and product revenue of 2.00/m ( 1.50/yd ) appear to be reasonable market values based on various studies reported on the Web. 

Interest in the chemistry of water-soluble polymers (polyelectrolytes) has been continually increasing during the past 45 years. The tremendous scope of utility for water-soluble polymers has led to a vigorous search for new materials and the rapid development of polyelectrolytes into a dynamic field of industrial research. Growth in this field has been especially rapid since 1960 and today, many companies are engaged in synthesis and applications research on polyelectrolytes that are primarily used in four main marketing areas water treatment, paper, textiles, and oil recovery [1]. Polyacrylamide gel was also used as soil conditioner [2-4]. 

Handbook of Soil Conditioners Substances That Enhance the Physical Properties of Soil, edited by Arthur Wallace and Richard E. Terry Environmental Chemistry of Selenium, edited by William T. Frankenberger, Jr., and Richard A. Engberg... 

Agricultural waste. To prevent overregulation of farms and promote waste recycling, solid wastes generated by crop or animal farming are excluded from the definition of hazardous waste provided that the wastes are returned to the ground as fertilizers or soil conditioners. Examples of such wastes are crop residues and manures. 

Acryl amide is an important bulk chemical used in coagulators, soil conditioners and stock additives. The chemical synthesis has several drawbacks because the rate of acryl amide formation is lower than the formation of the by-product acrylic acid [54]. Further, the double bonds of the reactants and products cause by-product formations as well as formation of polymerization products. As a result of optimization with methods of molecular engineering, a very high activity of the biocatalyst nitrile hydratase at low temperature is yielded, enabling a successful biotransformation that is superior to the chemical route. Here, the synthesis is carried out at a low temperature of about 5°C, showing a conversion of 100%. 

To make sewage sludge compatible with plant life in an environmentally friendly way and also to make it usable as a safe soil conditioner, it is desirable to convert it into living humus by aerobic composting. Irradiation of sludge cake and subsequent composting have revealed the following (see Kawakami et al., 1981) ... 

Applications as soil conditioners (2) and in the dewatering of phosphate slimes (3) were among the first successful uses of synthetic polymeric flocculants. For this reason, several test methods based on permeability have been developed, including the re-filtration rate method of La Mer (3). 

Sewage sludge contains significant concentrations of nutrients, particularly N and phosphorus and is recognised as having considerable potential as a fertiliser material and soil conditioner. Concentrations of nutrients vary considerably between sludges. Sommers [4], reported ranges of <0.1-17-6% for total N, <0.1-14.3% for total P, and 0.02-2.64% for total potassium. 

When leaves drop from trees in the fall, they decay on the ground to form a rich, dark material called leaf mold, which is an excellent soil conditioner. Making leaf mold in your yard is easy to do. All you need is a supply of fallen leaves, and a simple container to stop them from blowing away. Throwing leaves out with the trash, or burning them, is a waste of a valuable resource. 

Mordenite and cHnoptiloHte are used in small volume in adsorbent applications including air separation and in drying and purification [24]. Natural zeolites have also found use in bulk applications as fillers in paper, in pozzolanic cements and concrete, in fertihzer and soil conditioners and as dietary supplements in animal husbandry. 

Calcium hydroxide [Ca (OH) ] is known as slaked or hydrated lime and is formed by exposing calcium oxide to water. Slaked lime is less caustic than quick lime. Therefore, it is used to line football fields. (Unslaked lime, CaO, is very caustic when wet, and if it is used on playing fields, players may receive caustic burns.) Calcium hydroxide has many uses, including as an ingredient for stonemasons mortar, cements, whitewash, and soil conditioner (high pH), as a food additive, and as a human depilatory. 

The recovery of alcohol by distillation, concentration of organics, and use of waste activated sludge as a soil conditioner and fertilizer has also been reported [35]. 

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