Plant fibres

    According to cottoninc.com there has been a great improvement in the way that cotton is grown with respect to use of pesticides, insecticides specifically, and growers are able to produce 50% more cotton on the same tract of land. Despite this optimism, most other sources still emphasize that even if there is a reduction in the pesticides used in cotton production they are still extremely dangerous to humans and animals. 

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    Cotton covers 2.5% of the world's cultivated land, but uses 16% of the world's insecticides. Furthermore, the second most common insecticide used for cotton is Aldicarb, which has been reported to be mildly to highly hazardous and is present in the groundwater of 16 states in the U.S. ( EJF. (2007). The deadly chemicals in cotton. Environmental Justice Foundation in collaboration with Pesticide Action Network UK: London, UK. ISBN No. 1-904523-10-2.). Also, cotton is considered a very "thirsty" plant, requiring a HUGE amount of water especially in drought times. In fact, recycling cotton saves 20,000 liters of water per kilogram of cotton! That's a lot of water. There is a huge movement toward organic cotton, with growing demand for it from the garment and textile industries. Organic cotton helps lessen the use of pesticides, but it still needs a huge amount of water so recycling cotton is definitely the best way to go.

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Some other plant fibers are bamboo and hemp, which are supposed to be super sustainable. Bamboo is thought to be sustainable because it is a quick growing, highly invasive plant that requires little or no chemicals to thrive. Since bamboo grows so quickly it is a common practice to simply take the soft young pulp from the plant and then to replant the bamboo each year. One problem with this idea is that bamboo still requires a lot of water to grow, and it is not just grown in fields, but a lot of native forests are cut down to obtain the resource. Some valued qualities of bamboo are: the fabric retains the plant's antibacterial nature which is good for controlling body odor, the fabric breathes well, and it is naturally very smooth without the use of chemicals and so rarely produces an allergic reaction. (http://www.wisegeek.com/what-is-bamboo-fabric.htm)

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Hemp is claimed to be extremely sustainable as well, but a majority of websites that sell hemp say that it is from Europe or China so it's energy footprint is quite large due to the distance it must travel to reach its market. Similar to bamboo, no chemicals are required for hemp to thrive as it is a natural weed suppressor, however it does require a significant amount of water still.

I still say bamboo and hemp can't beat recycling fabrics in sustainability if recycling is done in a responsible manner. These crops require too much water while water is a resource that we need to protect.