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Hydrogels are hydrophilic cross-linked polymer chains.

They are formed through physical, ionic or covalent interactions.

Due to hydrophilicity, they have the ability to absorb water and swell growing in weight and size.

Depending on the hydrogel type they can absorb and hold up to even 1500 of their weight. Similarly, they can release this water.

The speed of water absorption depends on the type of the hydrogel. Some of the synthetic polymers can take up to 6 hours to swell to complete hydration while natural ones may require only 2 h.  

The volume transitions – absorbing and releasing water may depend on the external stimuli which can be physical (temperature, electric or magnetic field, light, pressure, and sound) or chemical (pH, solvent composition, ionic strength, and molecular species).

Hydrogels have various applications: in agriculture, drug delivery, coal dewatering, food additives, tissue engineering…

Hydrogels are extremely useful in agriculture since they can save water and prevent land erosion.

They prevent the soil from being washed away and hydrate it, helping it retain moisture and increase the water-holding capacity. This makes plants survive for longer periods in drought or require less frequent irrigation.

Frequent and intense irrigation can damage the soil making it erode, form crust or harden. The hydrogel gives soil stability, increases permeability and enables better plant growth.

Adding hydrogels to the surface of the soil increases the soil water-holding capacity and the rainfall percolates the soil quite easily. 

Not only this, but they reduce the need of fertilization, since the nutrient loss is prevented by reducing runoff.

Alternatively, some hydrogels are made as fertilizers and even have controlled water release so that the dose of the fertilizer is adjustable in time. The nutrient is available for the plant over a longer period of time rather than a rapid availability that ammonium nitrate, ammonium phosphate or potassium chloride provide.

The controlled or slow release of fertilizers from hydrogels do not have official differences. They are achieved by coating or encapsulating the conventional soluble fertilizers. The coatings can be water insoluble, semi permeable or impermeable with pores.

The same principles apply to pesticides and herbicides.

The use of hydrogels is extremely beneficial in cases where post plantation irrigation is limited.

Water release is controlled so that the fertilizer is released according to plants’ needs.

Hydrogels can be made of:

• synthetic polymers
• natural polymers
• combination of natural and synthetic polymers.

The synthetic polymers are mechanically stronger and durable and can absorb more water. They can, therefore be more efficient in agriculture as they hold more water and lost longer.

On the other hand, hydrogels made from natural polymers are biodegradable and often do not leave any bi-products so they are more environmentally friendly.

Drying out before the next hydration makes the hydrogels less efficient so good irrigation is a necessity for the maximum effect.

It is noticed that in saline soil the hydrogels have lower efficiency. 

Hydrogels can be applied by being mixed with the soil or by spraying. 

Read more of my content - here.

Please watch my recent TEDxSingapore Women talk on the importance of food plant diversity in the context of feeding 9 billion people by 2050. 

Thanks for watching! 

https://www.youtube.com/watch?v=Zk-oC_yKrk4 

A pipeline carrying crude oil for refining developed cracks and spilt oil in about 100 acres of farmland in a village in Nagapattinam district, officials said.

They said people of Manjavadi village detected the leak after they found their farmlands flooded with oil. The oil was being transported through pipeline from the Oil and Natural Gas Commission owned oil well at Adiyakkamangalam to Narimanam for refining, they said. Officials said it was not clear whether the pipe had broken due to recent heavy rains or the soil becoming loose.

ONGC officials said the pipes might have got corroded due to the saline condition in the area.

In August 2011, a similar rupture along the pipeline near river Devanadhi ruined Samba paddy fields. However, the damage was contained by the river, which washed away the oil slicks into the sea.

But now, the crude oil spill has begun flowing along the Kohur irrigation channel, which irrigates over 300 acres, across the villages of Manjavaadi, Anaimangalam, Kohur, Thenkarai and Vadakarai.

It is telling on the already weak prospects of the samba crop. Several acres of paddy fields irrigated by the oil slick-laden water from the channel have been ruined.

Article Source: Hindustan Times and The Hindu

Climate change has made the agrarian communities living in coastal, tropical and sub-tropical regions of Odisha its worst victims. The change in the time and amount of rain during the cropping seasons has badly hit the agriculture making it an unviable livelihood option. As a result, the communities’ vulnerability to livelihood loss and food insecurity has increased and Youth of the communities are now forced to migrate as labourers.