Hydrogel: The Potentialities to Produce More Crops per Drop in Agriculture. Varanasi , Uttar Pradesh, India

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1 Kheti Volume -2, Issue-4 (October-December), 2014 Available online at popularkheti.info ISSN: Hydrogel: The Potentialities to Produce More Crops per Drop in Agriculture S. K. Choudhary 1, A. L. Jat 1 *, P. K. Upadhyay 1 and R. K. Singh 2 1 Department of Agronomy, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi , Uttar Pradesh, India 2 Indian Agricultural Research Institute, New Delhi , India * of corresponding author: aanandiagro508@gmail.com Most of the area of India is located in Arid and Semiarid Regions, more efficient use of water is essential in the field of agriculture. Implementing proper management practices in agriculture to maintain soil moisture and increase water holding capacity is considered as one of the ways to save water. Super absorbent polymers (SAPs) hydrogel can swell to absorb huge volume of water or aqueous solution. This property has lead to many practical applications of these new materials in particular in agriculture for improving water retention of soils and the water supply of plants. They have been successfully used as superabsorbent materials, cell encapsulation and tissue repair due to their high water content. Considering the fact that water retention in the hydrogels. The objective of this manuscript is to give a brief review on existing in the field of hydrogel swelling and effects of using super absorbent polymer on performance of the plant and some properties of soil and the results of investigations showed that the use of super absorbent polymer resulted in increased performance level, water use efficiency and some growth indices of some crop. Introduction Hydrogel is a generic term referring to hydrophilic polymers used in oil recovers, medical grafting supplements, clarification of potable and waste waters, dewatering sludge, mining separations, food processing, personal care products, laboratory supplies etc. Hydrophilic gels called hydrogels are cross-linked materials absorbing large quantities of water without dissolving that absorb substantial amounts of aqueous solutions. Softness, smartness and the capacity to store water make hydrogels unique materials (Shibayama and Tanaka, 1993). Hydrogel-forming natural polymers include proteins such as collagen and gelatin, and polysaccharides such as alginate and agarose. Synthetic polymers that form hydrogels are traditionally prepared using chemical polymerization methods. Approaches using genetic engineering and biosynthetic methods to create unique hydrogel materials have been recently reported. Another aspect of hydrogels is that the gel is a single polymer molecule, that is, the network chains in the gel are connected to each other to form one big molecule on macroscopic scale. The terms gels and hydrogels are used interchangeably. The gel is a state that is neither completely liquid nor completely solid. These half liquid-like and half solid-like properties cause many interesting relaxation behaviours that are not found in either a pure solid or a pure liquid. Hydrogels may exhibit drastic volume changes in response to specific external stimuli, such as the temperature, solvent quality, ph, electric field etc. (Tanaka, 1978). Depending on the design of the hydrogel matrices, this volume change may occur continuously over a range of stimulus level, or, Kheti ISSN:

2 discontinuously at a critical stimulus level. Inspite of their excellent fluid absorption and retention release characteristics utility of super absorbent polymers (SAPs) has not been systematically evaluated in agriculture unlike other application domains leading to inconclusive statements on their usage under practical field situation. Agricultural hydrogels are synthetic polymers generally made from petroleum products. They absorb many times their weight in water, and can be distributed into dry regions in order to improve the soil ability to absorb water. Learn how they're made and how they can be used. Agricultural hydrogels can change the physical properties of soils by 1. Increasing their capacity to hold water 2. Reducing erosion and runoff 3. Reduce frequency of irrigation 4. Increase the efficiency of the water being used 5. Increase soil permeability and infiltration 6. Reduce the tendency of the soil to get compacted 7. Help plant performance. The high cost of these hydrogels has been an inhibiting factor that has drastically affected their universal use. Unless costs are brought down, its use will get limited to government and other well funded organizations, leaving out the private farmers and agriculturists who can benefit from its use. Application of Super Absorbents in agriculture In agriculture Super absorbent polymers (SAPs) are used as a soil additive, as reservoir of nutrients, and as water super absorbent in the soil. Properties of this material are dependent on many factors, such as their chemical and compositional characteristics, soil texture, plant species and also environmental factors. Super absorbent polymers made from Polyacrylamide are of these materials and are used as water adsorbents for increased capacity of the soil to absorb and retain water and this property is very important to encounter the impacts of dehydration and reduce impacts of drought stress in crops. Biodegradation rate of super absorbent polymers in soil depends on the dimensions of soil particle and amount of organic matter. Also, with decreasing Oxygen in soil and in turn reducing activities of bacteria, biodegradation rate of super absorbent polymers will be reduced. Super absorbent polymers have influence on water infiltration rate in soil, bulk density, soil structure and the rate of evaporation from the soil surface. Also, the super absorbent polymers while raising water-holding capacity of light soils can address soil permeability problems of heavy soils and difficulties in washing fertilizers (Asgari et al. 1994). Since that super absorbents absorb water hundreds times of its own weight and being converted to long lasting gels, have a special place in agriculture, landscaping, erosion control and desert reduction. Quickly absorbing water and keeping it by super absorbents, raises absorption efficiency of water obtained from scattered rainfall. In the case of irrigated soil, they increase irrigation intervals (Allahdady, 2002). The amount of this increase depends on the physical conditions of the soil, climate of the region and the utilization amount of super absorbents in soil. According to their ph Close to neutral, super absorbents have no adverse effect on the soil, and are not considered as toxic in soil. Also, after 4-7 years, depending on the type and composition of soil, they are destroyed by microorganisms and do not cause environmental pollution. In addition to retaining water, super absorbents due to continuous volume change (expansion during inflation and contraction during losing water) will increase Kheti ISSN:

3 amount of air in the soil (Kabiri, 2005). These compounds will cause better performance of some types of fertilizers and also better activities of soil microorganisms. Desirable Characteristics of Hydrogel for Applications in Agriculture 1. high absorption capacity in saline and hard water conditions 2. optimized absorbency under load (AUL) 3. lowest soluble content and residual monomer 4. low price 5. high durability and stability in the swelling environment and during storage 6. gradual biodegradability without formation of toxic species 7. ph neutrality after swelling in water 8. photo stability 9. Re wetting capability. Salient Features 1. Exhibits maximum temperatures ( C) characteristic of semi-arid and arid soils 2. Absorbs water 400 times its dry weight and gradually releases the same 3. Stable in soil for a minimum period of one year 4. Less affected by salts 5. Low rates of soil application 1-2 kg / ha for nursery horticultural crops; kg/ ha for field crops 6. Reduces leaching of herbicides and fertilizers 7. Improves physical properties of soils and soil less media 8. Improves seed germination and seedling emergence rate 9. improves root growth and density 10. Helps plants withstand prolonged moisture stress 11. Reduces nursery establishment period 12. Reduces irrigation and fertigation requirements of crops 13. Promotes early and dense flowering and fruiting/ tillering. 14. Delays onset of permanent wilting point 15. Reduction in nursery establishment period of chrysanthemum (18 days as compared to 28 days in control) 16. Extensive root growth resulting in increased water and nutrient use efficiency 17. Decrease in no. of fertigation booms required to raise nursery and the crop of tomato in field (37 as compared to 52 in control) 18. Significant enhancement in the efficiency of seed germination and seedling growth as compared to control. Environmental Safety Aspects Related to Hydrogel 1. Major issue: Inherent toxicity of the unreacted monomer acrylamide, acrylic acid, acrylate etc. present in the finished products. 2. Reality: Super absorbent polymers (SAPs) materials cannot return to their starting monomers, i.e. they are scientifically irreversible to toxic initiating materials. 3. Moderately bio degraded in the soil by the ionic and microbial media to convert finally to ammonia and carbon dioxide. 4. Worldwide research has shown little or no consistent adverse effect on soil microbial populations. 5. A very simple and efficient HPLC method to estimate residual monomer content in the hydrogels has been developed in our laboratory 6. It has been confirmed that Pusa Hydrogel does not contain any traceable residual unreacted monomer and is thus environmentally safe. Kheti ISSN:

7. Hydrogels of this type degrade completely into carbon dioxide, water and ammonia within one year. 8. Recommended application rate of Pusa hydrogel is very low i.e. 2.

4 7. Hydrogels of this type degrade completely into carbon dioxide, water and ammonia within one year. 8. Recommended application rate of Pusa hydrogel is very low i.e. 2.5 kg ha -1 for most of the crops which is equivalent to 2.5 ppm per unit weight of the soil. 9. Whereas commercial materials are purely synthetic in nature, Pusa Hydrogel is semi synthetic in nature resulting in reduced load of monomer component in the finished product. Significance of Hydrogel 1. It significant improvement in the quality of agricultural produce in terms of fruit size and colour enhancement in yield (10-50%) and increased plant biomass. 2. Application of super absorbent polymer increases dry yield of flaxseed oil plant, kidney beans, tomatoes and maize. 3. It has also resulted in 30-50% reduction in the frequency of irrigation (thus reducing drudgery in terms of labour involved in frequent irrigation, particularly in vegetable) 4. It 22-30% reduction in the dosage of fertilizers, improvement in hydro- physical environment of soil and high benefit cost ratio. 5. The polymer is releasing fertilizer agent in soil matrix, and decreases ammonium leaching rate. 6. While increasing in water retention in light soils, polymers can address permeability problems in heavy soil and problems in leaching fertilizer. 7. Super absorbent polymer biodegradation in soil, increases bulk density (or apparent specific weight) soil. 8. As an effective material, super absorbent polymer were identified as effective in reducing the effects of drought stress and thereby increasing plant resistance to stresses and increasing plant performance. 9. Super absorbent polymers cause to increase aggregate stability and prevent crust formation, prevent on farm runoff formation and reduce soil erosion. 10. And the most important benefit of hydrogel usage is preventing deep penetration of water of root environment and leaching salts and its effect on the accumulation of proline and soluble sugars. Fig: The comparative performance of Pusa hydrogel with untreated in vegetables, flowers, ornamental plants and field crops. Kheti ISSN:

5 Conclusion Hydrogel application in almost all the test crops (cereals, vegetables, oilseeds, flowers, spices etc) has resulted in significant improvement in the quality of agricultural produce in terms of fruit size and colour, enhancement in yield and increased plant biomass. It has also resulted in reduction in the frequency of irrigation, reduction in the dosage of fertilizers and improvement in hydrophysical environment of soil and high benefit cost ratio. References Allahdady Examining application effects of super absorbent hydrogels on reducing drought stress in plants. Second specialized course, learning agricultural and industrial applications of super absorbent hydrogels, Iran polymer research institute of petrochemical. Pakistan journal of biological sciences 10(23): Asgari FN, Omidian H and Hashemi V Syntetic Reorganization and Modification the Properties of Superabsorbent Polymers. Journal of applied Polymer Sciences 2(54): Kabiri Introduction and Application of Super Absorbent Hydrogels, the Third Training Course and Seminar on Agricultural Applications of Superabsorbent Hydrogels. Iran Polymer and Petrochemical Institute. Iranian Polymer Journal 17(6): Shibayama M and Tanaka T Phase transition and related phenomena of polymer gels. Advances in Polymer Science 109: Tanaka T Collapse of gels and the critical end point. Physical Review Letters 40: Kheti ISSN:

The soil is a very. The soil can. The manure. Soil Characteristics. effective manure treatment system if manures are applied at the proper rate.

The soil is a very. The soil can. The manure. Soil Characteristics. effective manure treatment system if manures are applied at the proper rate. The soil is a very effective manure treatment system if manures are applied at the proper rate. The soil can filter pollutants and prevent them from reaching groundwater. The manure application rate should