May be coconut pith could help you to some extent, even though it is not a polymer

Maybe this might also be interesting for your project:

In the inner Mongolia and Gobi desert the effectiveness of cyanobacterial crusts in terms of soil restoration is tested. Application of cyanobacteria on the soil leads to a biological crust formation which retains the soil and enables development of topsoil. After a view years of succession ->moss-> gras scrubs and trees appear.

Below some Information:

The scientists involved in this projects will surely provide more detailed Information.

"Engineering Application of Integrative Artificial Algal Crust Technology in Shifting Sand Stabilization"

A Project of the Institute of Hydrobiology (CAS), der Inner

Mongolia Academy of Forestry Science, der Wuhan High-tech Agriculture Group und der Gaolin Biotech Development Co., Ltd. of Inner Mongolia Autonomous Region.

Standort: Shapotou Scientific Station of the Chinese Academy of Sciences

Links:

http://english.ihb.cas.cn/rh/rps/200909/t20090923_40041.html

http://www.jipb.net/pubsoft/content/2/3503/45-8-6.pdf

http://www.springerlink.com/content/uqt2800m50775198/

http://en.cnki.com.cn/Article_en/CJFDTOTAL-SSWX200001001.htm

http://www.sciencedirect.com/science/article/pii/S0140196302002926

http://www.sciencedirect.com/science/article/pii/S0140196306000814

Thank you, Devadas Thampi, for the coconut pith suggestion. However, the nearest outdoor coconuts are some sullen ones 1,300km away from the Algarve in the Canaries. Moreover, even coir fibre is likely to decompose quicker than the synthetics which can last years.

The cyanobacterial angle sounds much more promising and I shall certainly pursue it. Many thanks, Peter Richter.

Wish you luck with your important and interesting Project! Maybe you can contact Prof. Yongding LIU from the IHB ([email protected]). He can provide valuable advices and ideas about soil restoration.

Best regards

Peter

There are some Hygroscopic polymers available in market. One of the such product in India is Jalshakti. However I understand that this Jalshakti is out of production. Similar product must be available elsewhere. If I happen to get my literature I will let you know because I obtained such product from Banglore (India) about 8-9 yrs back. The product can be placed in holes as desired by you

Thanks, Ashok, for your just-discovered comments. From what I can tell, Jalshakti is a manufacturer of water tanks, not (or no longer) polymers. So information on other sources will be welcome, In the meantime, I await samples and a CD from Agripol in the UK,

You say nothing about the Bangalore material, Was it used to reduce sorghum irrigation? Were you unconvinced?

Sir, I obtained crystal long back i.e.during 2002. My mails indicate that polymer was named Water Works Crystal and pl try to contact Mr P N Sadanand whose mail address was/is ? [email protected]. Hoperfully you will be successful

My thanks again, Ashok, for the follow-up. But, again, no word about your views of the product.

I had used for other purpose not as yours but I am sure it can help you. It absorbs watrer perhaps 100 times of its weigh & slowly release as per demand.

Do you know if the polimers really will retain the water and keep it available to the trees? Will not be better to put it around the seedlings or small trees and see if they really retain the water under different environmental conditions?

Yes, may use around seedlings also. I am sure it works.

Investigate also the possibility of mycorrhizae inoculation of your tree seedlings. This will improve drought resistance as well as nutrition and thus survival.

I believe Terracottem inoculates its polymers.

Thank you, Ashok, Virginia and Yves, for your input. A few comments:

- Hygroscopic polymers will indeed retain rain or irrigation water many times their weight and do so for about five years.

- In the process they become gelatinous. Significantly, they also expand and thus help aerate the soil they are mixed with.

- Polymers come in various granule sizes. Smaller ones, of course, capture less moisture; but they do so more rapidly. For seedlings a dip is made from a polymer powder. Standard applications are 1gm per litre of planting mix.

- I shall recommend the polymers, also, to compost makers such as MSW landfillers in Portugal. Less water will be needed in the composting and the resulting medium will possess the same water-retentive qualities.

- In light of these benefits it is a mystery why hygroscopic products are not widely known and used.

- Mycorrhizæ inoculation is definitely a good idea and not just in equatorial environments. Another benefit can be plant-benefiting fungi that combat harmful ones. So collecting some soil and humus together with seeds or seedlings is a good strategy.

Sir, I think much of your quiries can be answered by usding polymer. I am confident, it works. Popularity of product depend upon cost and perhaps unawareness. You may use it on small scale in the begining, judge and then proceed.

you can get in touch with Dr. Jagdeesh Sunkad in India ([email protected]) He deals with PUSA Hydrogel.

Thank you, Sundaram, I have written to Dr Sunkad,

Thank you, Hachemi Merouani, for your endorsement. (I am grateful, also, for your work on cork acorn conservation which I found valuable.)

To anyone who is still following the subject, I should make one important correction and clarification thanks to Agripol, a UK polymer manufacturer. From the start I have attempted to understand why a product which according to (a few) internet reports could benefit a world of dwindling water resources is so little known, still less used. Repeated appeals to FAO and the Stockholm International Water Institute have proved fruitless.

A single negative report from a US researcher states "As the gels begin to dry out, they soak up surrounding water more vigorously [and] they will start taking water directly from plant roots." This, however, applies strictly to Super Absorbent Polymers (SAPs) such as the hygroscopic components used in nappies/diapers. The polymers considered for reforestation, on the other hand, are not hygroscopic (scavenging water from the atmosphere and environment) but HYDROPHILIC and will absorb excess liquid water from the soil adhesion and capillary water layers when these are supersaturated.

Lambe, I do not see much difference between the two you describe. For our convenience we call Super Abosrbent Polymers or Hydrophilic. SAPs are not natural living things to feed voraciously / compete on / with plant roots and Hydrophilic are not docile cows to wait and watch till water come nearer to them. Both are one and the same.

Sundaram Seshadri wrote:

"I do not see much difference between the two you describe. For our convenience we call Super Abosrbent Polymers or Hydrophilic...Both are one and the same."

I am not a materials scientist, only an architect and environmentalist. That said, the posted statement may furnish more convenience than accuracy. In my, again limited, understanding the physics and chemistry of polymers can be tailored to meet a wide range of characteristics and needs. Whether the outcome is hygroscopic or hydrophilic, and I concede that there is an ambiguous grey spectrum between the extremes, polymers vary considerably. Their chemical formulation and, I imagine, their manufacturing determines structural and chemico-physical properties resulting in quite different finished products. So some polymers, like the SAPs mentioned, bind water molecules aggressively. But others, such as those used in the food industry, are made to absorb large amounts of water but have a poor gel strength and release water readily. Agripol tell me their products are made to bind water at plant-accessible pressures, allowing roots to extract over 95% of the water stored, and also to resist soil chemistries for years of repeated use.

These polymers are expensive here in Mexico, however we are doing field tests with good results. The clue is to find the minimal amount of the substance that gives good results from the point of view of soil-plant-water-relationships, as well as make a profitable práctice. We are using the polymer in maize ferti-irrigated (drip irrigation) with runoff wáter.

Polymers are available from China, India, Japan

My thanks, Carlos, for the recent points. You are correct about the cost although water, if available, can be expensive too; and is likely to become more so. On the other hand recommended polymer amounts are modest: 1gm/litre of planting mix. And they will perform for years: ~5 years for Potassium-based gel and twice that for (more expensive) Sodium products, I understand. Perhaps Lithium compounds could last even longer.

And there are other considerations: just as the gels hold water, which would otherwise sink beyond reach, near plant roots they will also hold dissolved fertiliser there where one wants it reducing what seeps into the water table where one doesn't.

Compliments to A Lambe for bringing this important discussion. As stated 1gm/lit should bring down cost but benefits are more. Thank

Pl. be aware that it cannot be mixed with water. But can be applied directly into soil. It is not used as 1gm/lit. It is used like 3-5 grams per tree. The effect can last for a max. of 6 months only.

Thank you, Ashok and Sundaram, for your latest. It is true that polymer granules should be dry before mixing in soil. But doing so is not, I believe, essential. However, saturated gels are much heavier and bulkier and the mixing task will be more onerous. In this case, also, the lumps will get broken up into smaller bits which one may or may not want.

An important additional benefit of the polymers' bulking process, previously unmentioned, should be noted. Particle expansion and contraction creates air spaces which may matter little in friable or sandy soils but can be essential for plant health in heavy, clayey ground.

As for quantities, the prescriptive "3-5 grams per tree" is convenient but must, surely, be qualified by a host of factors, in particular: tree size and xerophylly, soil type and climate.

I cannot comment on polymer durability although this may vary from manufacturer to manufacturer. I would qualify the preciseness of any claim, however. I assume polymer water storage characteristics decline gradually with age, temperature, soil chemistry, full/empty cycles, etc. Further thoughts about this and also about dry storage in damp climates will be welcome.

That's why I said the life time is max. 6 months for these gels. Its better to mix soil with dry gels and water them sufficiently. Its also good to add gels below the upper soil layer so that whenever there is water, it will be retained in the subsurface area. Moreover, as observed by you, the gels are prone to various factors viz. temperature, soil chemistry, water logging etc.