Question:
Has anyone ever used a water/nutrient storing polymer? The one I am considering is not a starch-based, but a cross-linked polyacrylamide. Any info, opinions, or applications that have positive or negative effects. Cost effective?….farming, ornamental, trees, home gardening? Thanks Mark Hart
Hi, Mark. I’ve used hydrophilic gel (acrylamide copolymer) in large and small pots, hanging ‘baskets’, hanging slat baskets, seed flats, and in one ground bed. I’ve read some posts here that say the gel will draw water from the soil and even from the plants, but my experience has been entirely opposite. Plants grown in medium amended with hydrophilic gel go much longer before showing any signs of water shortage, and the medium in the pots and bed stays moist much longer. It seems to me that the plants and soil are drawing water from the gel, instead of the gel robbing them of water. Someone in the group noted that they found it useful in seed flats, but less so in pots. I suspect the reason may be the particle size. The stuff I use (Terra-Sorb) is available (from A.M. Leonard) in different sizes, from less that 1mm to 3mm. The smallest size is intended for small containers (like seed flats) and the largest for soil beds and large containers. I buy the largest size, since I learned that it can easily be made whatever size I want by chopping (like gelled aspic) with a knife once the particles are soaked in water. The only problems I have had were with using the large size in seed flats. The 3mm particles soak up enough water during our summer downpours that they can expand to something like inch in diameter. When that happened they would force their way out of the cells of the flats, along with whatever was atop them. The solution was simply to use much smaller particles. In large pots or soil beds there seems to be no need to first hydrate the gel, although doing so certainly wouldn’t hurt. I can’t give you any idea of how cost effective it might be, but I can tell you that I intend to continue using it. It has reduced the frequency of required watering greatly in all applications where I’ve tried it, which is extremely valuable to me. For example, standard tomatoes grown in very large pots of ProMix or similar composts needed to be watered two or three times a day in the summer, but those with the gel were able to go two or three days without watering. The grower for one of our better local garden centers confided that they started using a gel in all of their hanging baskets (really plastic pots) because of the same problem, and with the same results. What is possibly the sunniest bed in my mostly shaded back yard is usually kept bone dry by its composition (sand, a trace of clay, and lots of compost) and tree roots that rob water almost as soon as it is applied. The gel has made it possible to grow plants there and has reduced the need to water to every other day at the peak of summer. The smallest advantage I’ve noticed with using the gel is in wood slat baskets filled with osmundine and planted with epiphytic orchids, but even there it has been useful. As osmundine ages it loosens considerably and eventually becomes too open to hold enough water long enough. Filling the spaces with gel particles kept the medium moister, and allowed me to put off repotting for many months until it was more convenient. I don’t intend to use it on my orchids regularly though, since I’m aware of how much air epiphytic orchids’ roots need and I believe that the gel does nothing to increase aeration. As always, if anything I’ve said is unclear or prompts any questions, please let me know. Harold Covington, LA, USA USDA Zone 8B
Response:
I have used the gels in the garden when planting hydrangeas. They are supposed to last for about 3 years before they start to break down. This is just enough time to get these water loving plants started. Remember not to use too much or they will expand to above ground and/or pop you plants out of the ground.
Response:
- Hide quoted text — Show quoted text -Kitty litter is just gound up clay. If you already have some clay content in your soil, it may not ba a good idea to add more. Ideal soil is about 1/3 clay, 1/3 grit, 1/3 organic material. Obviously then for people with sandy soil it could be a good idea, if too expensive in a large area. DM Yes kitty litter is clay, but it is not in loose form but is a pellet. This gives a concentrated area of moisture that the roots can choose to be near but not in. I line the bottom of my peat pots with kitty litter when I start my seedlings. This slows down the penetration of the roots through the bottom of the pot. When a seedling dies I put the pot in my dispose area and no longer water it. After a while the peat pot turns lighter in colour as it dries out except near the bottom where the clay layer is. This gives me an idea of the water holding ability of the kitty liter. Try it yourself. As pseudo water crystals I mix the pellets in the potting soil, but I do not break them up. I used to also mix in some alfalfa kitty litter pellets, but I can no longer locate a supplier.
Your use as described I won’t argue. For short term use in a pot – ok. But as a general soil amendment where the soil already has a significant clay content - not so good. The pellets will completely soften over time, and if the % is high you will get airless goo. I see this where my wife has dumped old litter in a pit off in the woods. It’s become one gooey lump. If your seedling pots were in use for a long while the drain hole would become blocked.
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In place of expensive polymer gel I use unscented non clumping kitty litter. How does this work? I am curious, because I have seen twenty-pound bags of the stuff for as little as US$1.99.
Kitty litter is just gound up clay. If you already have some clay content in your soil, it may not ba a good idea to add more. Ideal soil is about 1/3 clay, 1/3 grit, 1/3 organic material. Obviously then for people with sandy soil it could be a good idea, if too expensive in a large area. DM
Response:
- Hide quoted text — Show quoted text – In place of expensive polymer gel I use unscented non clumping kitty litter. How does this work? I am curious, because I have seen twenty-pound bags of the stuff for as little as US$1.99. Kitty litter is just gound up clay. If you already have some clay content in your soil, it may not ba a good idea to add more. Ideal soil is about 1/3 clay, 1/3 grit, 1/3 organic material. Obviously then for people with sandy soil it could be a good idea, if too expensive in a large area. DM
Yes kitty litter is clay, but it is not in loose form but is a pellet. This gives a concentrated area of moisture that the roots can choose to be near but not in. I line the bottom of my peat pots with kitty litter when I start my seedlings. This slows down the penetration of the roots through the bottom of the pot. When a seedling dies I put the pot in my dispose area and no longer water it. After a while the peat pot turns lighter in colour as it dries out except near the bottom where the clay layer is. This gives me an idea of the water holding ability of the kitty liter. Try it yourself. As pseudo water crystals I mix the pellets in the potting soil, but I do not break them up. I used to also mix in some alfalfa kitty litter pellets, but I can no longer locate a supplier.
Response:
- Hide quoted text — Show quoted text – In place of expensive polymer gel I use unscented non clumping kitty litter. How does this work? I am curious, because I have seen twenty-pound bags of the stuff for as little as US$1.99. Kitty litter is just gound up clay. If you already have some clay content in your soil, it may not ba a good idea to add more. Ideal soil is about 1/3 clay, 1/3 grit, 1/3 organic material. Obviously then for people with sandy soil it could be a good idea, if too expensive in a large area. DM Yes kitty litter is clay, but it is not in loose form but is a pellet. This gives a concentrated area of moisture that the roots can choose to be near but not in. I line the bottom of my peat pots with kitty litter when I start my seedlings. This slows down the penetration of the roots through the bottom of the pot. When a seedling dies I put the pot in my dispose area and no longer water it. After a while the peat pot turns lighter in colour as it dries out except near the bottom where the clay layer is. This gives me an idea of the water holding ability of the kitty liter. Try it yourself. As pseudo water crystals I mix the pellets in the potting soil, but I do not break them up. I used to also mix in some alfalfa kitty litter pellets, but I can no longer locate a supplier.
Dear Henry, The kitty litter does hold on to the water…….but does it *let go* of it, when the plants need the scarce water? We only raise this question because we read someplace that the ability to release the water is just as important as the ability to hold it. Bill & Harvey zuffalig/SKID Zone 6 CT USA
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writes: Has anyone ever used a water/nutrient storing polymer? The one I am considering is not a starch-based, but a cross-linked polyacrylamide. Any info, opinions, or applications that have positive or negative effects. Cost effective?….farming, ornamental, trees, home gardening?
I wouldn’t grow plants in containers outside without it. During hot summer days, it’s the only thing that gets containers through a full day without drought-stressing the plants. Now that I use water-storing gel and Osmocote (slow-release fertilizer) in summer containers, the plants stay alive and in flower through the whole summer.
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- Hide quoted text — Show quoted text – writes: Has anyone ever used a water/nutrient storing polymer? The one I am considering is not a starch-based, but a cross-linked polyacrylamide. Any info, opinions, or applications that have positive or negative effects. Cost effective?….farming, ornamental, trees, home gardening? Thanks Mark Hart I have used the polymer, but dont actually know which one. I found it to draw water out of the soil and into itself. I use clay pots for my houseplants which dry out quickly anyway. I didnt notice much difference with the polymers. For houseplants I found soil conditioners like worm castings to be a better way to hold water and nutrients. I have a feeling the polymers work better in plastic pots. I never used them in the soil outside. If anyone has and it is a good thing, please post. Victoria*
I knew a proffesor who worked with them. He was looking at soil applications for golf courses. They breakdown to fast to be feasible. However in pots they did OK. They do tend to pull moisture from the soil and can actually pull it from the plant if in close proximity to roots (and the soil is dry). The tricky part is (without explaining water potentials), the capsules can actually start pulling water BEFORE there is water stress on the plant do to their high affinity for water. Keith — 1