Chapter 5.29

5.29 -Super Absorbent Polymer Seed Coating to Reduce Impacts of Climate Change Inflicted Drought

Emily Buliung , University of Guelph, Canada

Suggested citation for this chapter.

Buliung,E. (2022) Super Absorbent Polymer Seed Coating to Reduce Impacts of Climate Change Inflicted Drought, In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

Introduction

In arid and tropical regions around the world climate change is impacting the agricultural industry. The increasing heat stress inflicted from rising atmospheric temperatures is causing increased water evaporation in soils (Gornall, 2010). Therefore, adaptive technologies and agriculture practices need to aim to combat drought in these regions (Gornall, 2010).

Seed Treatments to Combat Drought

Treating the seed before it is planted is a beneficial way to protect the crop from potential failure (Su, 2017). In most cases for subsistence farmers, it is not economically possible for them to replant if the first sowing fails. Thus, in cases of climate-inflicted drought, applying a Super Absorbent Polymer (SAP) seed coat can alleviate drought induced oxidative stress and membrane damage to seeds as well as improve overall yields (Schultz, 2013). SAPs have been shown to increase germination of seeds and water absorption in the soil (Tao, 2018).

Super Absorbent Polymers increase germination and water absorption in the soil by charged surfaces that bind and hold onto water like a diaper hydrogel (Barros, 2017). Farmers who plant on the onset of rainfall could make good use of a SAP as there will be enough water for the chemical to absorb and then store for the germination period. This also ensures that there will be enough water for the seed to germinate since rainfall is unpredictable in drought conditions (Schultz, 2013).

Some companies that sell SAPs are: Dongying Naxing Trading Co., Ltd, Qingdao ST-ARN Imp and Exp Co., Ltd., SOCO chem and many more which can be found using the global trade website Alibaba.com (Alibaba, 2019) (see online links below).

The composition of SAPs can be altered to best suit a target crop or need, making SAP a universal seed treatment and especially useful for subsistence farms in geographical regions like Africa and Asia which are most impacted by drought (Muller, 2011). A study conducted with SAP on maize in China, where the average water requirement for crops is 810 mm, has shown that that an application of 30 Kg of SAP per hectare was sufficient to increase yields and greatly improve soil water retention (Islam et al, 2011).

How to Use Super Absorbent Polymer Seed Coatings

SAPs can be applied to the seed before planting it or on the field once planted just like many other seed treatments (Campion, 2001). On a subsistence farm it would be more economical to treat the seed prior to planting as this would reduce the amount of product needed in relation to the surface area to be covered.

Often, large seed coating machines are used on large scale farms which can cost thousands of dollars (Changing times, n.d). This poses a major barrier to a subsistence farmer who does not have the means to purchase machinery or who does not have access to the machinery. A subsistence farmer could easily mimic the function of these machines with less expensive equipment (Rapsomanikis, 2015) as described below.

There are two methods of seed coating processes; the first being applying the treatment in a powder form where the polymer is dusted onto the seeds in a uniform fashion (Changing times, n.d). This method could be adapted on a subsistence farm with the use of a fine sieve which could be purchased at very low cost, to dust the treatment onto a pan of seeds that are uniformly laid out.

Some polymers need to be mixed with water before application; machines that do this spray the solution onto the seeds uniformly, mixing the seed well and then drying them before planting (Campion, 2001). A simple alternative to this machinery could be using a hand spray bottle such as the Kisan Kraft manual sprayer (see link below) or a low cost spray bottle, followed by mixing the seed well and then laying the seeds out in the sun on a pan to dry, making sure that they are spaced out so that they do not stick together.

By using smaller hand held tools with minimal steps, this could easily be accomplished by a female cooperative on the farm. This video demonstrates how to use a sieve; a farmer cooperative would swap out the flour for the SAP and dust the correct amount over the seeds. https://www.youtube.com/watch?v=IluT_hedurc

This video shows one method of applying a liquid to seedlings. Instead of applying to seedlings, the farmer cooperative would be applying the SAP to seeds. One must place the correct amount of solution into the bottle and then administer it to the seed the way it is shown in the video. https://www.youtube.com/watch?v=iZntggXHq0c

Safety Hazards and Critical Analysis

SAPs come in a powder form and it is important to follow the instructions given on the package, including the WHMIS and SDS labels. In addition to this, some acrylamides are potent neurotoxins in high doses (Erkekoglu, 2014). Therefore, it is important to wear personal protective equipment (PPE) when handling the product. Ingesting a small amount of the powder or liquid will not have detrimental health effects but still pose health risks (Erkekoglu, 2014). It is necessary to wear a face mask and gloves while applying the treatment. SAPs are relatively stable chemicals and transform to a neutral pH upon absorption of water making them safe to use on crops (Applications of Super Absorbent Polymers in Agriculture, n.d.).

Additionally, SAPs can absorb and hold fertilizers or pesticides that are mixed with the water in the soil (Applications of Super Absorbent Polymers in Agriculture, n.d.), thus potentially reducing input costs.

Unfortunately, because of the high absorption rates, SAPs easily absorb moisture from humidity (Guan et al, 2017). This is a potential problem, because in arid and semi-arid regions of the world, there can occasionally be high humidity which could pose a threat to any stored SAP. This makes it important to use the SAP quickly after it is delivered or to store the SAP under low humidity conditions.

A natural alternative at the village level that could be used instead of an SAP is silt – as a soil additive. Due to the large surface area to volume ratio of silt particles, it has high water and nutrient holding capacity.

How to Handle Treated Seed and What Precautions to Take

Visit this link to learn more about how to treat seed and what safety precautions to take: https://www.seed-treatment-guide.com/wp-content/uploads/2013/03/Guide-to-Seed-Treatment-Stewardship.pdf

How to Purchase SAPs

In addition to the manufacturers noted above, the online retailer Alibaba.com is one example of a global supplier that has representatives in Africa and Asia. The link below shows a sample of SAP that is for sale by the Tiffany Anderson Group, in South Africa (Alibaba, 2019). Their minimum order requirement is 100 Kg at $2.00 USD per Kg which would convert to 1000 applications of 100 ml solution/ 100 kg of seed.

1 Kg = 1000 g =1000 mL 100 ml/100 kg is the recommended dosage (Zambia Agriculture Research Initiative, 2013) https://www.alibaba.com/product-detail/Polymer-super-absorbent-polymer-PP-Polymer_50035697244.html?spm=a2700.7724838.normalList.2.66725245AAvdFN

In rural Africa or Asia, a subsistence farmer may not require 100 Kg of product and may choose to sell or trade the product to others at a market as a small business much like the trade of fertilizers.

Cost Analysis

In Nicaragua and Nepal, the FAO estimates that half of a subsistence farmers annual budget goes towards food. That leaves half the budget for clean water, household needs, medical needs and planting materials (Rapsomanikis, 2015).

Food sales positively correlate with annual income, but when most of the crop is used to feed the family there is less to sell in the market (Rapsomanikis, 2015). An average subsistence farmer in Kenya makes $2527.00 USD yearly which includes a farm sales revenue of $404 USD, but many African and Asian smallholder farmers have a much lower income. Thus, the flexibility of the budget will vary between farms and years (Rapsomanikis, 2015).

However, investing in farming aids like SAPs has been shown to increase crop yields which would increase annual income and mitigate the input costs required to purchase this product.

Figure 1. Cost-benefit analysis of estimated values for a Kenyan subsistence farmer purchasing SAP at a rate of 30 Kg SAP per hectare on a 2 hectare farm.

Even a small increase of 10% has the ability to generate extra income for a family. This could be the difference between paying for medicines or a doctor or school tuition for children, and moreover protects the family from crop failure since smallholder farmers typically do not have a crop insurance policy.

Environmental Sustainability

SAPs are produced in factories that produce emissions, all of which collectively contribute to increasing atmospheric temperatures. This may be contradicting to the initial goal of combatting climate change, however, large seed companies like BASF have sustainability initiatives. Additionally, most of the polymers used for SAPs are biodegradable and leave no residue in the soil (Tao, 2018).

Critical analysis

Overall, super absorbent polymers have the ability to greatly improve the yields of a subsistence farm in arid or tropical regions that are impacted by drought (Su, 2017). If instructions are followed and the correct application method is used, then the growth of seedlings can improve up to 10% (Li-qiang, 2017). However, if safety precautions are not accounted for, then there is a potential for accidental poisoning to humans or livestock (The Guide to Seed Treatment, n.d). Lastly, the basis of a super absorbent polymer still relies on water. If there is not enough available water or rainfall during the growing season, the SAP will not be able to store enough water to act as reservoir during drought conditions and will have little effect on the overall yield (Tsujimoto, 1999).

Helpful links to get started

- BASF: https://agriculture.basf.com/en/Crop-Protection/Products.html

- Bayer (location in East Africa): https://www.cropscience.bayer.ca/Products/Seed-Treatments

- Bayer (location in East Africa): https://www.bayer.com/en/east-africa.aspx

- Alibaba (Global Trade): https://www.alibaba.com/showroom/hydrogel-seed-coating.html

- SOCO chem: https://www.socochem.com/

- Bayer Coatings https://www.seedgrowth.bayer.com/coatings

- For more information about the product http://vikaspedia.in/agriculture/crop-production/super-absorbent-polymer-for-agriculture-farming-and- horticulture#section-2

YouTube Videos

• This video demonstrates the water absorbing properties of super absorbent polymer and how it can be applied to the soil in the field around a seedling. https://www.youtube.com/watch?v=e7rOjlhYN3E

• This video shows a wet application of polymer to seeds and an application in the soil. It also discusses the uses of super absorbent polymer and how it is especially beneficial in drought conditions https://www.youtube.com/watch?v=74ruDld3v7Q

References

1. Alibaba: Global Trade Starts Here (n.d). Polymer Seed Coating. Retrieved from https://www.alibaba.com/countrysearch/CN/polymer-seed-coating.html?searchweb=Y&

2. Barros, A., Pimentel, L., Araujo, E., Macedo, L., Martinez, H., Batista, V., and Paixao, M. (2017) Super absorbent polymer supplication in seeds and planting furrow: it will be a new opportunity for rainfed agriculture. Semina: Ciências Agrárias, Londrina. 38 (4), 1705-1706. Retrieved from http://www.uel.br/revistas/uel/index.php/semagrarias/article/view/26173/21350

3. Campion, D. R. (2001). Oregon Pesticide Applicator Training Manual Seed Treatment. Urbana, Illinois: University of Illinois Board of Trustees. Retrieved from https://www.oregon.gov/ODA/shared/Documents/Publications/PesticidesPARC/PesticideApplicatorSeedTreatmentTrainingManual.pdf

4. Changing Times (n.d). Dry Applicator Instructions and Adjustments. Retrieved from https://ctapplicators.com/wp-content/uploads/2018/01/6-gallon-12v-instr-only-low.pdf

5. Erkekoglu, P., and Baydar, T. Acrylamide Neuotoxicity (2014). Nutritional Neuroscience An International Journal on Nutrition, Diet and Nervous System. 17, 1-3. Retrieved from https://www.tandfonline.com/doi/abs/10.1179/1476830513Y.0000000065

6. Gornall, J., Betts, R., Burke, E., Clark, R., Camp, J., Willett, K., and Wiltshire, A (2010). Implications of climate change for agricultural productivity in the early twenty-first century. The Royal Society. 365, 2973-2989. Retrieved from https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2010.0158

7. Li-qiang, S., Jia-guo, L., Hua, X., and Xiao-feng, W (2017). Super absorbent polymer seed coatings promote seed germination and seedling growth of Caragana korshinskii in drought. Journal of Zhejiang University science. 18 (8), 696-706. Retrieved from https://link.springer.com/article/10.1631/jzus.B1600350

8. Muller, C., Cramer, W., Hare, W., and Campen, H (2011). Climate change risks for African agriculture. Proceedings of the National Academy of Sciences. 108 (11)¸4313-4315. Retrieved from https://www.pnas.org/content/pnas/108/11/4313.full.pdf

9. Rapsomanikis, G. (2015). The economic lives of smallholder farmers. Rome: Food and Agriculture Organization of the United Nations. Retrieved from http://www.fao.org/3/a-i5251e.pdf

10. Schultz, T., Finnel, A., Pill, W., and Kmiec, E (2015). HydroCoat- Hydrotropic seed coating and soil water retention. Horizon Partners Ventures LLC. 3-4.

11. Su, L., Li, J., Xue, H., and Wang, X (2017). Super absorbent polymer seed coatings promote seed germination and seedling growth of Caragana korshinskii in drought. Journal of Zhejiang University. 18 (8), 700-701. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565517/

12. Tao, J., Zhang, W., Liang, L., and Lei, Z (2018). Effects of eco-friendly carbohydrate-based superabsorbent polymers on seed germination and seedling growth of maize. The Royal Society Open Science. 5, 1-3. Retrieved from https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.171184

13. The Guide to Seed Treatment Stewardship (N.d). Asta and Crop life America. Retrieved from: https://www.seed-treatment-guide.com/wp-content/uploads/2013/03/Guide-to-Seed-Treatment-Stewardship.pdf

14. Tsujimoto, T., Sato, H., and Matsushita, S. Hydration of seeds with partially hydrated super absorbent polymer particles. United States Patent 5930949. 1-7 (1999). Retrieved from http://www.freepatentsonline.com/5930949.pdf

o. Zambia Agriculture Research Initiative (2013). How to inoculate soybean. Retrieved from: http://africasoilhealth.cabi.org/wpcms/wp-content/uploads/2015/04/79-ZARI-How-to-inoculate-poster.pdf

15. Islam, M., et al (2011). A lysimeter study of nitrate leaching, optimum fertilization rate and growth responses of corn (Zea mays L.) following soil amendment with water-saving super-absorbent polymer. Society of Chemical Industry. Retrieved from https://www.researchgate.net/profile/Xuzhang_Xue/publication/273660515_A_Lysimeter_Study_for_Leaching_Losses_Sustainable_Fertilization_and_Growth_Responses_of_Corn_Zea_mays_L_Following_Soil_Amendment_with_a_Water-Saving_Superabsorbent_Polymer/links/58b63cd7aca27261e5166477/A-Lysimeter-Study-for-Leaching-Losses-Sustainable-Fertilization-and-Growth-Responses-of-Corn-Zea-mays-L-Following-Soil-Amendment-with-a-Water-Saving-Superabsorbent-Poly

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17. Guan, Li, Junbo, Zhang, Biyu, Yu, & Xunmin. (2017). Synthesis, Properties, and Humidity Resistance Enhancement of Biodegradable Cellulose-Containing Superabsorbent Polymer. 2017: 3134681. Retrieved from https://www.hindawi.com/journals/jpol/2017/3134681/.