What is a farming device invented during the song dynasty

The Dragon Backbone pump is the correct answer.

Explanation:

The dragon backbone pump was a farming device that was used for irrigation. It was invented during the Song dynasty and was used for about 300 years. It was utilised for collecting water from fresh water areas and wells. It was mostly used to fill the canals that brought water to the paddy field. Other pumps were also in use but Dragon backbone pump was most efficient and required only one man to operate it. It worked faster if more then one man operated it. Its portability made irrigation easier.

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