Anionic polyacrylamides soil conditioners

Jozef Kollr

Polymeric soil conditioners, were known since the 1950s. These polymers were developed to improve the physical properties of soil in view of:increasing their water holding capacityincreasing water use efficiencyenhancing soil permeability and infiltration rates reducing irrigation frequencystopping erosion and water runoffreduce fertilizer and pesticides lossesReasons: most of the studies with polymers were performed in the laboratory without consideration for the economics at the production level in large scale agriculturecomplexity of application and poor distribution in the soilWide commercial application failed even though the scientific basis for their use was quite well established.

The most commonly used water-soluble synthetic soil-conditioning polymers included: poly(ethylene glycol) poly(vinyl alcohol) polyacrylates polyacrylamidepoly(isobutylene maleic anhydride)poly(maleic anhydride-co-vinyl acetate)

Gel forming polymers or insoluble water absorbing polymers were first introduced for agricultural use in the early 1980s. These polymers do not possess linear chain structures as described previously but the chains are rather crosslinked to form a three dimensional network. Gel forming polymersAdvantagesGreat water absorbing propertiesAmount of crosslinker influenced a mechanical properties of hydrogelsReduce water stress of plants Hydrogels are also claimed to reduce fertilizer leaching

Polyacrylamide (PAM) is one of the most widely employed soil conditionerAdvantages Low toxicity Safe Inexpensive Relatively stablePAMMore recently, polyelectrolytes such as acrylamide/acrylate copolymers have attracted much attention as they have been shown to be most effective in improving the properties of soils. poly(acrylamide-co-acrylic acid)

Reduce surface sealing

Increase seedling emergence

Reduce runoff and erosion

Reduce fertilizer and pesticides losses

PAM as soil conditionerPrinciple of adhering PAM molecule to soil particlesThe adsorption of PAM to soil particles depends on both the polymer and the soil properties. PAM differ with respect to molecular weight, charge density and charge type.

Polyacrylamide TypesEmulsionGranularSolid

PAM can be used in furrow or sprinkler irrigationfurrow irrigationsprinkler irrigation

PAM in furrow and sprinkler irrigation

Reduces soil loss

Prevent the loss of nutrients

Increase infiltration

Improvement of aggregate stability

Increase quality of soil as well as water

PAM treated furrow following irrigationUntreated furrow following irrigation

Synthesis of poly(acrylamide-co-tulipalin) hydrogels with crosslinker BIS

-methylene--butyrolactone also known as Tulipalin A, is present in white tulips and is identified as a substance with fungitoxic activity.

Swelling capacity in waterdry hydrogelswollen hydogel

Swelling capacity in water

Rheology of hydrogelsRheology is study of deformation and flow of material prediction of viscoelastic properties of polymers.

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