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Anionic p olyacrylamides – soil conditioners Jozef Kollár. 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 capacity increasing water use efficiency
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Anionic polyacrylamides – soil conditioners Jozef Kollár
Polymeric soil conditioners, were known since the 1950s. These polymers were developed to improve the physical properties of soil in view of: • increasing their waterholding capacity • increasing water use efficiency • enhancing soil permeability and infiltration rates • reducing irrigation frequency • stopping erosion and water runoff • reduce fertilizer and pesticides losses Wide commercial application failed even though the scientific basis for their use was quite wellestablished. • Reasons: • most of the studies with polymers were performed in the laboratory withoutconsideration for the economics at the production level in largescale agriculture • complexity of application and poor distribution in the soil
The most commonly used water-soluble synthetic soil-conditioning polymersincluded: poly(ethylene glycol) poly(vinyl alcohol) polyacrylates polyacrylamide poly(maleic anhydride-co-vinyl acetate) poly(isobutylene maleic anhydride)
Gelforming polymers Gelforming polymers or insoluble waterabsorbing polymers were first introduced for agricultural use in the early 1980’s. These polymers do not possess linear chain structures as described previously but the chains are rather crosslinked to form a threedimensional network. • Advantages • Greatwaterabsorbingproperties • Amountofcrosslinkerinfluenced a mechanicalpropertiesofhydrogels • Reducewaterstress of plants • Hydrogels are also claimed to reduce fertilizer leaching
Polyacrylamide (PAM) is one of the most widely employed soil conditioner • Advantages • Low toxicity • Safe • Inexpensive • Relatively stable PAM More recently,polyelectrolytes such as acrylamide/acrylate copolymers have attracted much attention as they havebeen shown to be most effective in improving the properties of soils. poly(acrylamide-co-acrylic acid)
PAM as soil conditioner • Reduce surface sealing • Increase seedling emergence • Reduce runoff and erosion • Reduce fertilizer and pesticides losses The adsorption ofPAM to soil particles depends on both the polymer and the soil properties. PAM differ with respect to molecular weight, charge density and charge type. Principle of adhering PAM molecule to soil particles
Polyacrylamide Types Granular Emulsion Solid
PAM can be used in furrow or sprinkler irrigation furrow irrigation sprinkler 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 irrigation Untreated furrow following irrigation
Synthesis of poly(acrylamide-co-tulipalin) hydrogels with crosslinker BIS α-methylene-γ-butyrolactone also known as Tulipalin A, is present in white tulipsand is identified as a substance with fungitoxic activity.
Swelling capacity in water dry hydrogel swollen hydogel
Rheology of hydrogels Rheology is study of deformation and flow of material prediction of viscoelastic properties of polymers.