In the latest in our series on unusual and exotic harvesting equipment, Nick Wigdahl looks at how cotton is harvested and baled in one operation. Cotton requires plenty of rainfall or irrigation (60-120cm/year) and heavy soils, but it is moderately drought and salt resistant and is well suited to semi-arid lands. White is the most common colour of the cotton bolls, but green, red and brown variants are also available. Genetically modified cotton is widely grown to resist the larvae of various species of moths. China is the world’s biggest cotton producer with 7m tonnes harvested a year, followed by India with 6.6m tonnes, the US with 2.8m tonnes, Pakistan with 2m tonnes and Brazil 1.6m tonnes. Average yield in the US is about 0.9t/ha.  Cotton is measured in bales, each weighing 220kg and containing enough fibre to make about 1,200 T-shirts. However, prices to farmers fluctuate wildly. They reached an all-time high of 211c/lb in March 2011 but have fallen steadily since then to today’s price of 65c/lb. That’s the equivalent of about £1/kg or £1,000/t Before mechanisation came along, cotton picking required huge amounts of hand labour. This was the key driver behind the slave tra...