Water-absorbing polymers are products capable of holding more than 100 g of water per gram of dry polymer. They are used in many fields such as hygiene products, waterproofing additives in construction, making dried flowers, and water-resistant padding.
In agriculture, these polymers are used to retain soil moisture, improve soil structure, transport plants over long distances, and as carriers for fertilizers or for potted crops. Because they can absorb and release large amounts of water repeatedly, their use is highly valuable for expanding agricultural production, protecting plants from drought, and maintaining soil ecological stability.
Incorporating water-absorbing polymers into soil also improves fertilizer efficiency. Nutrient ions from fertilizers can diffuse into the polymer’s porous network or bond with the –COO groups of acrylic acid (through coordination bonds and electrostatic forces). These nutrients are then slowly released to plants, reducing nutrient leaching and helping prevent water pollution.
Field trials on coffee and tea in Lâm Đồng Province
In 2005, the Nuclear Research Institute tested the product on coffee in Di Linh District, applying 200–300 g of polymer per coffee tree. Results showed excellent moisture retention—over 11 months in the soil—and much greater drought resistance compared with control plots that required three irrigations during the dry season. Yields increased by about 20 %, beans were larger and shinier, and the proportion of double-seeded cherries was higher. Normally three irrigations in the dry season cost about 15,000 VND per tree; using the polymer from the Da Lat Nuclear Research Institute cut watering costs by roughly 50 %.
The institute also tested the polymer on tea plants in Bảo Lộc, applying 3 kg of polymer per tea row (about 64 m²). The tea grew well with no wilting, yields rose 20–25 % over the control, and the value of tea harvested in the dry season increased 140–150 % (because fresh tea shoots fetch higher prices in the dry season). After the dry season the tea plants recovered quickly and produced new shoots about a month earlier than untreated plants.
These trials show that water-absorbing polymer products should be widely promoted, especially in areas lacking irrigation systems. The polymer helps maintain soil moisture and nutrients, reduces drought stress and related damage, and saves farmers both time and money by reducing the amount and frequency of watering and fertilizing. It can be used for perennial, annual, and ornamental crops.
Recommended technique for applying the polymer to coffee in Lâm Đồng during the dry season
Apply 200–300 g of polymer per coffee tree. Before application, mix the polymer with humus or fine soil at a ratio of 1.5–2 g polymer per kilogram of soil. In a dry period, pre-hydrate the polymer by soaking it in water for about 4–6 hours and then mix with the soil. Spread this mixture evenly around the coffee tree under the canopy at about 20 cm depth, then cover it with a 10 cm layer of soil. The best time to apply is at the end of the rainy season—around September to October—so the last rains can fully charge the polymer with water for maximum effectiveness.