Self-watering SMAG soil: Moisture can be obtained from the air

In general, you don’t see a variety of crops growing in arid areas — especially if irrigation is not practical and/or affordable,media reported. However, this could change with the development of so-called “autonomous watering soil” technology.

Self-watering SMAG soil: Moisture can be obtained from the air

The material, which was invented by engineers from the University of Texas at Austin, is made up of a 1:3 weight ratio hydrogel and natural sand. It is called SMAG soil, smAG full name super moisture absorbent gels (super absorbent gel).

The engineers began by grinding the gel together with the sand and slowly adding water during the grinding process. The dry mixture is then placed in a vacuum furnace at a temperature of 90 degrees C for 12 hours to form a solid reactor. Then crush the pile and eventually get a soft block of soil.

When the soil is placed in an outdoor field, the gel absorbs moisture from the relatively humid and cool night air. It is reported that a 1 g of soil can absorb about 3 to 4 grams of water. At higher temperatures during the day, the gel releases stored water to other parts of the soil mixture, which can be absorbed by the plant’s roots.

Self-watering SMAG soil: Moisture can be obtained from the air

For some crops, 0.1 to 1 kg of SMAG soil is said to provide sufficient moisture to irrigate about 1 square metre of farmland. Another benefit of this soil is that the moisture evaporated from the soil during the day makes the atmosphere around the crop more humid, so more water can be absorbed from the air at night.

Tests conducted in outdoor planting tanks found that four weeks later, SMAG soil retained about 40% of the water that had been initially retained. By contrast, the control box for ordinary sand retains only 20% of the water after a week.

In addition, a batch of radish grown in SMAG soil survived for 14 days after starting irrigation once. On the other side, radishes grown in plain sand die within two days of the end of the first four days of irrigation.

In the future, the same basic technologies could be used in applications such as cooling solar panels and access to drinking water.

The study was published in ACS Materials Letters.